CA1053337A - Method for defrosting frozen food and an apparatus therefor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A method of defrosting frozen food having a high water content in a convection-heating chamber, which comprises enclosing the frozen food, which reaches a temperature region in which ice crystals and liquid water coexist in the food, within a smaller chamber for dielectric heating and provided in the convection-heating chamber, and heating the frozen food in the smaller chamber by conductive heating and dielectric heating simultaneously while regulating the power of the two heating means to be at least approximately equal until the frozen food to be defrosted passes through the said temperature region.

Description

~53337 This lnvention relates to a method of defrosting various kinds of frozen food, especially precooked frozen food and to an apparatus for realizing said method.
In the present specification and claims, the word "defrostiny" is intended to include returning said frozen ~ood from the frozen state to the original state and then reconstituting or reheating the same to the proper temperature suitable for consumption.
The procedure being adopted to an increasing degree today i5 for fully precooked complete menus to be frozen and thus preserved, so that after a certain de~rosting and reheat-~n~ period, the previously cooked menus are ready for the ta~le without any ~itional work.
However, the defrosting art, up to now, has been less advanced than the freezing art. The latter has been improved in various respects and thus by adop-ting proper freezing methods high quality preservation has become possible.
As in the freezing procedure, there are two important problems in the defrosting procedure, namely, achieving a faster rate - of defrosting through the temperature zone of maximum ice-crystal gro~th of t~e ~ood ~usually in the range o -5 to -1C) and achieving a greater uniformity in temperature distribution or defrosting rate at all points in the food.
It should be noted that the requirements of higher de~rosting rate and uniformity thereof are essentially incom-patible with each other.
Further, these difficulties are increâsed as the water content in the food or menu increasesO
29 With prior known methods of defrosting, the cb/ ~ 1 '. ~ ' ' ' '': ' ''. . '~

~ [)53337 , problems,mentioned above are not completely solved, because they do not provide conditions for the effective transfer of heating energy to the frozen food in said temperature zone, p wherein f~sion and refreezing of the water contained in the food mainly takes place~
In the case of adopting a conventional defrosting apparatus of the o~en type, heat conduction through the frozen ~o~d in said temperature zone is not sufficient for supplying t~e large latent ~eat ~f the water, so that this apparatus is ` 10not so eff~ct~-ye in ac~ieving a fast rate of defrosting through sa~d te~perature ~one. Further, heat conduction through the ~id tempera~ure zone,~n wh~ch both ice and water are present, ~s particularly hindered by the fact that the heat conductivity o~ water ~n the liquid state is considerably lower than that ~n t~ sol~`d state.
In the case of conventional dielectric heating by m~crowave irradiation, wherein the frequency employed is usually the order o~ a few thousand MHZ, pure ice-crystals are hardly ', he~ted at all, only liquid water being appreciably affected in t~s heattn~ process, so that a large non-unifo~nity of tempera-~u~e through the defrosted ~ood inevitably results.
If the rate of defrosting through the temperature zone of maximum ice crystal grow~h is low, recrystalliæa~ion or large crystal growth of the water contained in the ~ood is greatly accelerated during defrosting thereof through said temperature zone and thus degradation of organization,texture and colloidal properties of the frozen food become inevitable.
Now, these de~ects are overcome by the inv~ntion 29by t~e ~act that ~or de~rostlng and warming deep-frozen food cb ~ - - 2 -, . . .. , ~3337 and especially fully precoo]ced menus, by applying di-electric . ~microwave~ heat~ng and conductive heating cooperatively to said food or menus in said temperature zone, higher and more unifor~ rates of def~osting through the temperature zone of maxi~um ice-crystal growt~ of said food or menus can be .~ achie~ed.
The term "conductive heating" as used in this specification is intended to mean heating, such as by means o~ oyens, steamers and IR heaters, whereby the transfer of . lQ ~eat ener~y thxough the food is malnly by heat conduction.
- Accord~ng to the invention thexe is provided a ~ethod of defrosting frozen foods in a convection-heating cham~er, w.hich comprises enclosing the frozen food, which reaches a temperature region in which ice crystals and l~uid ~ter coexist in the food, within a smaller chamber for dielectr~c heating and provided in the convection-heating c~a~ber, and heatin~ the frozen food in the smaller chamber by; conductive heat~ng a~d dtelectric heating simultaneously ~hile ~egulating the power of the two heating means to be ~t le~$.t approx;.mately e~ual until the frozen food to be de~ro~ted passes through t~e sa~d temperature region.
Further according to the invention there is provided a defrosting apparatus for froz~n food, comprising a casing de~ining a chamber and provided with an inlet for putting trays into said casing and an outlet sv dimensioned as to en~ble said trays to ~e taken one by one out of said casing, xay.c~rculatin~...s~stem adapted to circulate said..trays_ _ ~n said cas~'ng w~th e~ch tray always in a horizontal position, 29 a coYer ~onsist~ng o~ a pair o mem~ers pro~ided in the upper c~ ~ _ 3 _ .

;, . .
. ,: . ~ , . .- :

~ 3337 portion of said casing and adapted to be opened during the ; tray-circulating operat~on so as not to prevent the circulation o~ trays and to be closed when the tray circulation stops so as to de~ine an enclosed chamber for enclosing a predetermined one of said trays, a means for irradiating said tray within s~id coyer wit~l micro-waves, a means for forming an atmosphere of heated dry atr, heated humid air or steam within said casing and a control means for tr~nsporting the predetermined one of the circulating trays to just below said cover, closing said . 10 coyer and irradiating said tray enclosed by said cover with micro-~a~es for a requ~red time.
Yet further according to the inventi~n there is provided a defrosting apparatus for frozen food comprising a casing defining a chamber and provided with an inlet for putti~g trays into said casing and an outlet so dimensioned as to enable said trays to be taken one by one out of said casing, a number of trays for mounting various kinds and a large amount of frozen food thereon, said trays being partly or entirely coloured in predetermined colours to t~dicate the defrostin~ conditions which said frozen Pood :
Qn ~d trays requires, a tray c;rculating system adapted to ci~cul~te saId trays In said casing with each tray always in a horizontal position, a cover consisting of a pair of members pro~,~*ed ~n the upper portion of said casing and adapted to be opened during the tray circulating operation so as not to pre-vent t~e circulat~on and to be closed when the circulation stops so as to define an enclosed chamber for enclosing a predeter-mined one of said trays, a means for irradiating said tray 29 ~1thin said cover with micro-waves, a means for forming an ~ .
cb~ 4 _ ; . . . : : . . . .

: ~ ~5;3337 ; atmosphere of heated dry air, heaked humid air or steam within said casing and an operating device provided with operating buttons coloured similarly to said trays so as to indicate suitable defrosting conditions for said food.
Further, a defrosting apparatus according to the present in~ention may be provided with a means for irradiating ~nfrared radiation onto a tray enclosed by said cover and a me~ns for spraying water onto said tray enclosed by said cover.
In a defrosting apparatus according to the present invention, the inlet provided on the casing is not only for ~:, putting trays into the casing but for af~ording an operator to anter the casing for the purpose of mending or inspection of the tray circulating system provided in the casing or clean-ing a cha~ber in the casing, so that said inlet is at least o d~mensioned as to afford a man to pass through.
Further, one of the features of a defrosting appar-atus according to the present invention is an outlet provided only ~or putting trays out of the casing. This outlet`is for putting out trays wh~ch have been subject to the predetermined de~r~st~n~ treatment one by one, and therefore it is dimensioned a~ 11 as poss~ble in correspondence with the size of a tray as to ~nLmize the emIssion o~ heat out of the casing.
On the contrary~ an outlet provided in a casing of the con-yentional defrosting apparatus is adapted to be used as an ~nlet ~or trays and therefore it is dimensioned rather large ~n comparison with the capacity o~ the casing. Therefore in the appar~tus so constructed, most of heat within the casing emits therefrom through the opening at the time of taking trays out, and the predetermined temperature within the casing begins g cb~- 5 : . , .. ' , :
- ` ' `
'' ' 5~3337 to drop suddenly. Thus, after taking trays out it takes a fairly long time to obtain -the predetermined temperature in ;~ the casing again. The conventional defrosting apparatus is economically very disadvantageous since a large amount of heat ener~y is emitted every time treated food is removed and ~urther the apparatus must then stop its operation, thus lower-ing the operation efficiency.
In a defrosting apparatus according to the present invention, the heat energy to be lost at the time of taking out of ~ood is much less than that in the conventional appar-atu~, t~e operation efficiency o~ the apparatus is very high ~th an Improved economy.
Further, doors for the inlet and the outlet of an apparatus according to the present invention comprise means ~or obsexving the contents in the casing. An apparatus according to the present invention has the following treat-ing functions.
T. A dielectric heating treatment This comprises a microwave irradiating process (A).
II. ~ conductive heating Heated dry air treatment ~B) This heated dry air results from the air in the c~sin~ heated by a ~eating means.
Heated humid alr treatment ~C~
This results from a water-spray heated by a heating means.
Steaming treatment ~D) Thls is steam produced by vaporization of the water 29 supplied ~n the casing, or introduced from outside.

cb ~ - 6 -;, . ,: . '" ' ~, '. .' ' Immersing ln the hot water'in the casing (E) Infrared irradiating process (F) By properly combining abovementioned treatments (A), ~B), CC), (D) and ~E), unequality in defrosted extent and uneven formation of defrosted food can be completely overcome.
According to the present invention, the following co~binatlons of defrosting methods can be achieved.
1. (A~ +
', 2. ~ C~
1~ 3. ~ +
4. ~ + ¢C~ ~ ~E~
5 . ~A) ~ (B) + (F) 6 . ~ C~ + ~F) 7 . (A ~ (F 1 8. (.A.I + (,C) + ~E). + tF) In a defrosting apparatus according to the present inventlon, the treating functions (B), ~C), (D) and ~E) are used or the primary defrosting o frozen food while (A) is ~ for the secondary or finish defrosting. In other words, 2Q frozen food ls primarily defrosted in the first step through external heating ef~ect. In this case, frozen ~ood can be uni~ormly and e~ecti~ely defrosted even if a temperature d~ erence is present in the casing, since said fro~en food ci~rcula~ed by t~e tray circulating system~ Then, only rozen food on an optionally selected tray is put into the enclosed chamber of the cover, where said selected frozen ~ood is completely de~rosted by the secondary defrosting treatment with m~crowave energy.
29 Further in an apparatus according to the present .~,j.~ .

: . - ,~. , :: . - . .
., ~6~53337 invention, th2 infrared treatment (F) is applied to frozen food requiring to be baked on the surface thereof when eating.
; And frozen food in the enclosed chamber may be further applied with microwave and water spray during infrared irradiating.
In an apparatus according to the present invention, ; the ~arious de~rost~ng combinations 1-8 can be optionally and selectively set by the conventional means. When an optionally re~uired combination is set, frozen food on trays is circulated for a predetermined time during which said food i9 subject to the pri~ary defrosti:ng treatment, and the said primarily de~rosted frozen food is finally and completely defrosted with-out unevenness ~y means of a microwave irradiator for a pre-determined tlme in the enclosed chamber of the cover. By opening the door of the outlet, the defrosted food on the tray ls taken out through the outlet. This outlet is provided separ~tel~ from the inlet for thè trays and is so dimensioned only to afford the taking out of a tray, thus the temperature in the casing can be effectively kept and the heat emission therefro~ can be minimized, making the apparatus economical.
A~ above~mentioned, an apparatus according to the present invention is provided with the primary defrosting ~unctions (BL - ~E) and the secondary defrosting function ~A), b~ both o~ which ~rozen food can be uni~ormly defrosted. In usin~ the apparatus, only one of the primary and the secondary de~rosting treatments can be independently applied. For example, frozen food such as Sashimi (raw fish), pudding or hors-d ' oeuvres which need not be completely defrosted but need to be ohly half de~rosted and left to be defrosted in 29 the t~me bE~ore eating is sufficiently subject only to the cb~ - 8 -~ .
r defrosting treatment ~) of microwave irradiation. Further, in the primary de~rosting treatment, treatments ~B), (C), ~D) and (E) are selectively applied according to the kind of frozen ~ood to be;de~rosted.
Each tray may be partly or entirely predeterminedly colored in accordance with the defrosting treatment condition to be applied to fro~en food. On the other hand, a control means may be provided which has control buttons colored in t~e same color with the corresponding trays so as to set t~ de~rosting condltion relating to each of the colors.
And further, doors of the outlet and the inlet of the casing ma~ co~prise a memher affording to see the inside of the casing t~rough said doors. ~ith the abovementioned construction, it is unnecessary to confirm the content of frozen food at every time of operating the defrosting apparatus with the considera-tIon of a suitable de,rosting condition. The color of the tray indicates the necessary de~rosting condition, so that ~y operatin~ a ~utton colored similarly to the tray, the necessary defrost~ng treatment is applied. In other words, 2Q be~ore us~,ng t~e defrosting apparatus, various kinds and a l~rge'a~ount of fro~en food is divided into a ~umber of groups ~n ~ccordance wit~ the defrosting conditi~ns such as a suit-able temperature o~ defrosted food when eating, and the said ~rozen ood i.n each group is mounted on a tray or trays pre-deter~inedly colored in common in accordance with the defrost-ing condition o~ the group, and stored in a proper freezing chamber. Colors to be applied to the tray~ may be decided in the order o~ spectra of the light.
29 According to one embodiment of an apparatus of the cb~ g ' ' ' ' :
1a~53337 present invention, . (a) slue color is applied to frozen food which : need not be completely defrosted but need only to be half defrosted and then subject to natural defrosting in the time before eatin~. :
; (b) Green color is applied to frozen food which requires heating to room temperature.
~ c~ Yellow color is applied to frozen food which re~u~res heatin~ above room temperature.
~d~ Red color is applied to frozen food which ~equLred heating above tc~.
The colors representing the abovementioned defrost-ing condltions Ca~ - ~d~ are decided ordinally with relation to t~e treating temperature for frozen food.
Trays colored ~n blue, green, yellow or red as above- .
~entioned are di~ided on the ~asis of color representing the eatin~ temperature, and contained within the casing in the order ~rom t~e lower to the higher eating temperature. Further, each tray is pro~ided a spec~f~ed number or designation thereon.
On the other ~and, t~e buttons of t.he control device are pro-.~ded with numbers representing the order of arrangement o the trays in corxespondence therewith. Further, on the button ~s) ~emovably pro~ided is a seeing.-through color plate which is colored s~mtlarly to the colors applied to the trays ~Blue~
green, yellow or red)O The numbers on the buttons a~e visible through each of said color plate. Therefore, by operating buttons with seeing the colors representing eating temperature and the numbers, a required froæen food can be rapidly and 29 surely defrosted under the necessary de~rosting conditions.

.. . . .

- ~53337 .
The new constructions and conditions of the method or apparatus for realizing said method are more fully explained by the following examples given with reference to the drawings.
Other and further objects of this invention will become obvious upon an understanding of the illustrative .: embod~ents about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employ-ment OX t~e invention in practice.
Figure 1 is a sectional side view of an embodiment o~ a defrosting apparatus of the present invention;
Figure 2 is a vertical longitudinal sectional Yiew of an apparatus o~ Figure l;
Figure 3 is an elevational view in section of a tray circu~ating system in a defrosting apparatus of the present tnYent~On;
Figure 4 is an enlarged side view in section of a system of Figure 3;
: Figure 5 is a perspective view of buckets and trays to be set ~n the buckets;
~ gure 6 is a fragmentary enlar~ed detailed sectional yiew of a system taken alon~ the line VI-VI in Figure 3;
Figure ~ is an enlarged detailed side ~iew in ~ection o~ the lower poxtion o~ a system of Figure 3;
F~gure ~a is an enlarged sectional view taken ~lon~ the line VII~VII in F~gure ~; and is located on the ~ame page o~ drawings as Figure S;
Figure 8 is a fragmentary enlarged detailed view 29 ~n ~ect~on oX ~he upper portion of a defrosting apparatus . .
., , ,:

1~353337 of the present invention;
Figure 9 is another embodiment of a d0frosting apparatus of the present invention; .
Flgure 10 is an enlarged deta.iled view in section o~ the upper portion o~ a defrosting apparatus of Figure 9, illustrating an in~rared Irradiator within a cover;
Figure 11 is a block schematic diagram of a water-supply and draInage controlling system;
Figuresl2, 13 are a temperature or a moisture con-trolling system respectively;
Figure 14 is a block schematic diagram of a drive controllin~ system for a tray clrculating system;
Figure 15 is a schematic diagram illustrating the operating process o~ a motor for driving a tray circulating system, a pulse motor for dr~v~ng a co~er opening and closing ..
~ean~s, a micro~ave ir.radiator and a water spraying means;
Figure 16 is a perspective view of a defrosting appar~tus of the present ;nvention illustrating the outline thereof, especi~lly a control panel for automatic control;
: Figure 17 is an explanatory view of another embodi-~ent of the present invention;
~igure 18 ~ is a graph representing the relation ~etween the temperatures of the sur~ace and the central por-t~on o~ hamburgers and the standard deviation, and treating ti~e ~n case of de~rosting frozen hamburgers by only micro-~av~ ~rradiat~on by means of a defrosting apparatus according t~ the present ~nvention;
Figure 18 ~ is a graph representiny the relation 29 between the tempexatures of the surface and the central portion cb/ ~ - 12 -~053337 of hamburgers and the standard deviation, and treating time in case of defrosting frozen hamburgers by both of micro-wave irradiation and an o~en;
Figure 18 ~C) is a graph representing the relation between the temperatures o~ the surfac~ and the central por-~ tion of hamburgers and the treatin~ time in case of defrosting - ~rozen hamburgers only by an oven;
Flgure 19 is a graph representing the relation bet-ween the lapse o~ time and the heating temperature in case of applying a ~eatin~ treatment only with an oven to frozen food ~c~awan-mushi, beef stew and curried rice);
~igure 20 Is a graph representing the relation bet-ween the lapse of time and the heating temperakure in case o~ ~pplyin~ a hea~in~ treatment only with magnetron micro-wave ~rradi~tion;
Figure 21 is a graph representing the relation bet-~een the lapse of time and the heating temperature in case of applying a heating treatment both with an oven and magnetron micro-wave irradiation;
Figure 22 is a graph representing the relation bet-~en the lapse of time and the heatin~ temperature in the ca~e o~ applytn~ jo~ntly steaming and micro-wave irradiation;
Figures 23 and 24 are ~raphs representing the temperature distribution in rice dishes having high water content and a variety of materials, in the ~ase of apply-ing steaming only, or ~ointly with micro wave irradiation.
A defrosting apparatus according to the presènt invention is presented in Figure 1 and Figure 2 wherein 29 re~erence numeral 10 indicates a casing inside which is B
c!~ - 1 3 , . .

. . . , , :, ., ::

:. .. :~: - . ::

1~53337 `- formed a chamber. On the front wall of said casing are pro-vided an inlet 12A for trays at the upper portion and a~ out-let 12B therefor at the lower portion, said outlet 12B being J
so dimensioned that only one tray 24 mentioned below can be taken out at a ~ime, so as to minimize emission of heat from the casin~ 10, Said inlet 12A and outlet 12B have respective doors 12a, 12b, which are adapted to be opened and closed freely.
The ~ajor part of said doors 12a and 12b is formed of a trans-parent material.
Disposed within the c~amber of the body 10, is a tray ; circulatin~ system 13 which is constructed so as to make a number of trays successlvely or intermittently circulate upwardly and downwardly with each tray always maintained in horizontal position by means`o~ below mentioned suspending buckets. Dis-posed on said trays are many ~roups of food eacll requiring dl~erent defrostlng cond~tions. There are shown detailed structures of the abovementioned tray circulating system in Figure 3 to Figure 6. With particular reference to Figures

2 and 3, the tray circulating system 13 is arranged within the ~a~n casing lQ sho~n in dash-dotted line. Disposed within the casin~ 10, located at opposite sides thereof, are a pair o~ yertical supporting ~rames l~A, 14A horizontally spaced rom each other, on which are mounted a pair of horizontal ~upporting frames 14B~ 14B vertically spaced from each other.
Also disposed above the upper supporting frame 14B and below the lower supporting frame 14B, in parallel with said support-ing ~rames, are two horizontal shafts 15, 1~ respectively.
A~ shown in Figure 3, each o~ two end portions of the shaft 29 15 is rotatably journalled in a bearlng 17A, and also each cb( - 14 -.~ .

, 1 ~ . ' . ,: . ' ' ' , .. , . :

~0~3337 of two end portions of the shaft 16 is rotatably journalled in a bearing 18. ~urther, on each of two ends of the shaft 15 is mounted a sprocket 19. Also mounted on each of two ends of the shaft 16, is a sprocket 20.
Sa~d one sprocket 19 mounted on one end of the sha~t 15 and one sprocket 20 mounted on one end of the shaft 16 are of the same slze, and these two sprockets 19, 20 form one of two pairs. One of each pair o~ sproc~ets 19, 20 is connected through a ~ain endless chain 21 to the other.
~s ~een ~n Figure 6, the main endless chain 21 com-prises a large number o~ llnks 21a lnterconnected through suitable pins, and on which a number of main supporting arms 22 are mounted through pivot pins 2~ uniformly spaced from each other along the length of the chain 21. Each pivot pin 23 is held by a bearing member 21b secured to a suitably selected link 21a. Pivoted on the pivot pin 23 are two main supporting arms 22, one end portion of each of the two support-in~ arms 22 overlapping each other.
Numeral 24 illdicates a tray which comprises a bottom plate 24~, lateral s~de plates 24b, 24b and longitudinal ~de plates 24c, 24c as shown in a larger scale in Figure 5.
Said tray 24 is adapted to be removably set in a suspending bucket 25 of the tray circulating system, said bucket 25 com-prising a substantiall~ triangular holding plates 25a, 25a and ~ suppoxting plate 25b. On the bottom plate 24a of each txay 24 and the supporting plate 25b of the bucket 25 are proyided a number of air holes 2~d, 25c respectively~
The outer end of one of a pair of supporting 29 a~ms 22 and the outer end of one of another adjacent pair cb~

' ' ~ . , -~53337 of supporting arms 23 are pivoted on the holding plates 25a, 25a of the suspending bucket 25 by means of a shaft 26, said two ends overlapping each other. These two supporting arms 22 pi~oted on the pin 23 and a part of the main endless chain 21 form ~ triangle.
As shown in Figures 2, 3, disposed below the shaft 15 is a horizontal shaft 27, each end of which is journalled in a bearing 17B. Mounted on opposite end portions of the sh~ft 27 are two sprockets 28 of the same size as of the sprockets 19, and former two sprockets 28 are vertically spaced ~rom the latter~
The shaft 27 is connected to a driving shaft 27a adapted to be driven by means of an undermentioned dri~ing unit. The shaft 27 is operatively connected through a gear assembly 15a to the shaft 15, so that said two shafts 27, 15 can rotate in the same direction and at the same speed.
~ s seen in Figure 2, provided on an axle 29a on the lower ~nside port~on of each of bearings 18 is a rotat-able sprocket 29 o~ the same size as the sprocket 20 and vertically spaced from the latter.
The distance between the axes of sprockets 19, 28 is the same as that between the axes of sprockets 20, 29.
The upper sprocket 28 is connected through an auxiliary end-less chain 30 to the lower sprocket 29. The length of the auxil~ary chain 30 is the same as that of the main chain 21 extending between the sprockets 19, 20.
As seen in ~igure 7, on the auxiliary endless chain 30 comprising a large number of links 30a interconnected 29 through suitable pins, a number of auxiliary supporting arms cb~ - 16 -B

'.' . ' `' ' ' , . ' : " '.~ ' ' ' ' ' " ~ ' ' ' ' ~ 53337 31 are pivoted by means of pivot pins 32 spaced from each other at a cerkain pitch along the length of the chain 30.
Each auxiliary supporting arm 31 is rotatably held by a respective bearing member 30b which is integrally secured to a suitably selected link 30a. The distance between two adjacent p~,vot pins 32 of the auxiliary chain 30 is the sa~e as between two adjacent pivot pins 23 of the main chain 21. One end of each supporting arm 31 is pivoted on the plvot pin 32, while the other end is pivoted on a shaft 34. The sha~t 34 is ~ixedly connected through a connecting member 33 to the shaft 26, that is, the upper end of the connecting me~ber is mounted on the shaft ~6, while the lower end is ~ounted on the shaft 34. Said connecting member 33 is a,lways ~aintained vertical.
The upper end of the connecting member 33 is inte-grally secured through.the shaft 26 to the top portion of the holding plate 25. The lower portion of the member 33 is spaced from the plate 25 as shown in Figure 3. Mounted rotatably through the shaft 34 on the lower end portion of the member 33~ qre the respective outer ends o~ two adjacent ~URporti~g ar~s 31. T~ese two adjacent arms 31 and a part o~ t~e aiuxiliary chain 30 form a triangle. As mentioned aboYel t~o adjacent supporting arms 2~ mounted on the main cha,~n 21 and a part o~ saId chain 21 form a trian~le. Thus two trian~les are assoc~ted with each tray 24. The length o~ the supporting ~irm 22 is the same as of the arm 31 t and the d~stance bekween the pivot pins 23, 32 is the same as bet~een t~e sh~ksi26, 34. Therefore, the lower one of t~o arms 22 belonging to a triangle is always parallel with ~ 17 ~

, ., ~. .. . - . ,. . . . - .

ii333~
the upper one ~f two arms 31 belonging to another triangle, and the conn~cting member 33 is also parallel with the main and auxiliary chain 21, 30.
Reference numeral 37A, 37B indicate an inner guide rail and an outer guide rail respectively. The inner guide rail 37A is ad~pted to guide a plurality of rollers 35, each roller 35 being rotatably mounted on a respective shaft 26.
The outer guide rail 37B is adapted to guide a plurality of rollers 36, each roller 36 being rotatably mounted on a respective shaft 34. These guide rails 37A, 37B extend vertically parallel with the chains 21, 30. The rails termin~te at or near the boundary between a linear section L ~nd ~ curve of section C, as shown in Figure 4, of the path ~ollowed by the buckets. Therefore, in the circulation o~ ~he buckets 25, the rollers 35, 36 thereof run off the g~ide ~ils 37A, 37B, being free in the curve of section C.
The inner and the outer guide rails 37A, 37B
are shown in an enlarged detailed sectional view in Figure 7~, 2Q As shown in Figure 2, the casing 10 is provided at ~ts outside w~th a drivin~ motor 38 which is operatively çonnected through a reduction ge~r 39 and a transmission ~eans 40 to the dr~v~ng sha~t.
In said tray circulating system 13, each shaft 26 i5 mounted on each o~ two respective holding plates 25a pro-vided with a respective bucket 25, and the connecting member 33 is mounted at the upper end thereof on said shaft 26 so that the bucket 25 ~s ~ntegr~l with the connecting member 29 33~ whereb~ said buckat is always in the horizontal position . ,g, j ,, .: . . , . -. i. . . -, . ,, ~ , ~5;3337 when said,member 33 is in the vertical position. The two main supporting arms 22 and the two auxiliary supporting arms 31 are pivotall~ mounted on the upper and the lower portion o~ th~ connectin~ membex 33 respectively, so that each tray 24 connected to said member 33 is always held in the horizontal ,' position. The length of the main c~ain 21 is the same as th~t o~ the auxiliary chain 30, said main chain 21 being tted with a pair of upper and lower sprockets 19, 20 while s~id auxiliary cha1n 30 is fitted with a pair of upper and 10 l~wer sprockets 28, 29, each of said sprockets 19, 20, 28 ~nd 2~ be~ng of the same size. A number of the main and the auxiliar~ supporting arms 22, 31 are pivotally mounted at uni~orm intervals on the main or the auxiliary chains 21, 30 ~, xespectivel~, eac~ said supporting member 22 being pivotally ~ounted throu~h the shaft 26 on the upper end portion of each connecting me~ber 33, each supporting arm 31 being pivotally mounted throu~h the shaft 34 on the lower end portion of i,d connecting member 33, the distance between the two adja-cent sh~fts26,-34 being the same as that between the two adj~cent sha~ts 15~ 17 ~arallel with each other, whereby ',' e~ch connect~ng member 33 is always in the vertical position ~hen each bucket 25 is situated in an~ section ~whether the li,near section L or the curved section C~, so that each bucket 25 is al~ays kept in the hor~zontal position.
Each bucket 25 would be kept in the horizontal position when the chains 21, 30 are vertical even if guiding rails 37A, 3~B for the rollers 35, 36 were not present~
2~ EIowever 7 if no support means is provided in ~b~ B - 19 .. ... . . .. . . . . ... .. .. . . . . . .. ~... .

- 10533~7 the lineax sections L of the chalns 21, 30, it is necessary ~or the guide rails 37A, 37B to guide the rollers 35, 36 so that the chains 21, 30 are not crooked under the influence : o~ the loads o~ trays,arms ~nd the like, and that each bucket 25 ~s ke~t in the hori~ontal position.
o~ course, such guide rails 37A, 37B may be omitted i~ suita~le support means are provided in the linear sections o$ the c~ains 21, 30.
' As shown in Figure 1 ~nd Figure 2 t defined within the casin~ 10 at the lower portion thereof, is a reservoir ~ection 41 which communicates through a conduit 42 with a heat exchan~er 43. Near the point where the conduit 42 ns the reser~oir is connected a feed water pipe 47, to ~ic~ is connected a suitable water source (not shown), said piPe 4~ being provided with a magnetic valve 48. Dis-~osed within the heat exchanger 43, are a sheathed heater 44 . and t~o ~ater~level detectors 45, 46 vertically spaced from ; e~ch othe~. The magnetLC val~e 48 is adapted to be actuated ~n Fes~onse to sa~d water~level detectors 45 and 46 so that a predeterm~ned ~uantity of water may be supplied into the conduit 42 qnd the reservoir 41. The conduit 42 is provided ~t it$ other end portion ~ith an exhaust valve 49 for exhaust-~ng the wa,ter ~n the casing 10.
The heat exchanger 43 has a conduit 50 which lS
positi~ned between the water-level detectors 45, 46 and communicates with the reservoir section 41. Said conduit 50 is provided at the outer end thereo with a non-return valve 51 which prevents the counter-flow from the reservoir to the 29 he~t exch~nger 43 cb~ 20 ~ ' ,,,, ' ' ,: , ' , ,. ' ~ :
- . - ~ ,: . ~ , : . . . .- . , .. . .. . . . .. . . . .

~5~3~7 --On the top portion of the heat exchanger 43 are a ~an 53 driven by a motor 54 and a duct 55 communicating with t~e interior o~ the casing 1~. Mounted on the inside wall of the xeserYoir sectlon 41 is a thermostat ~not shown).
As shown in Fl~ure 1, provided at the upper portion o~ the casing 10, is a microwave irradiator 57 which comprises ~a~netron 58 and a wave guide for guiding the microwave~, ~aid ~aYe guide extending from the magnetron 58 through an op~ning 59 ~ormed in the upper wall 10A. Provided on the top ~all 10A of the casing 10 ts ~ cover 61 comprising two half members 61a, 61b which are adapted to open and close freely by ~eans o~ a below-mentioned link mechanism. The cover 61 ~ opened in order not to prevent the movement of the trays 24 when they are circul~ting under the operation of the tray c~rculating system 13.
When one of the trays 24 comes to a required posi-tion by stopping of the circulation of the trays 24, the two h~l~ members 61a, 61b are closed through the link mechanism, ~nd enclose said one tray 24. The food on the enclosed tray is then ~rradiated with microwaves by the microwave irradiator.
In Figure 8, an embodiment of the link mechanism is illustrated in detail. One end of a irst lever 63 is pivotally mounted through a pin 63a on one half m~mber 61a, while the other end is ~ixedly mounted on a driving shaft 64 which is supported by a bearing 65 p~ovided in a recess 10B
formed in the top wall 10A of the casing 10O The driving shaft 64 is operatively connected to a suitable pulsemotor ~not ~hown). Also mounted pi~otally on said half member 61a 29 through a pin 66a, is one end of a first link me~ber 66 of cb/ g _ 21 -. :~ . ' ` ', , ' , ' , ' ; ' . ' . ' , , ', ' , , ' ' ' ~

5333~
the same len~th as of the first lever 63. The other end of the ~irst link member 66 is pivotally mounted through a pin 66b on the top wall lOA. In this arrangement, the first lever 63 is ~l~ays pa~allel with the first link member 66.
Mounted pivotally on the lo~er end portion of the ; ~irst l~nk member 66 throu~h a pln 67~, is one end of a second l~nk member,the other end of which is pivotally connected through a pin 67b to one end of a third link member 68. The ot~er end o~ the member 68 is fixedly mounted on a shaft 69 W~ich is rotatabl~ supported by a suitable bearing ~not shown) proYided in ~ recess lOC formed in the top wall lOA. Mounted ~ixedly on the shaft 69, is a first gear 70 meshing with a second ~ear 71. The second gear 71 is fixedly mounted a shaft 72 which is supported by a suitable bearing (not shown).
Mounted fixedly on the shaft 72, is one end of a fourth link member 73, the other end of which is pivotally mounted through a pin 73a on the half member 61b. Also mounted pivotally through a pin 74a on the half member 61b, is one end of a second leyer 74, the other end of which is p~yot~lly mounted through a pin 74b on the top wall lOA.
The seco~d lever 74 ~s the same length as of the ~ourth link ~embex 73 and is alw~ys parallel with said member 73.
In operation of the abovementioned cover 61, when the pulsemotor actuates to turn the shaft 64 clockwise through a predetermined angle, the first lever 63 and the ~irst link member 66 turn together about the respective pivat axes 64, 66b, whereby the half member 61 is moved to the left pos~t~on as shown in the chain-dotted line. The 29 turn~n~ of the first link member 66 causes, through the . .
cb/ ~ - 22 -.....

, .- ' . , : ' , ., , ., . . ' '' ' ', ~ ! ' , .:
~ ' ' ' ~ . ` ' '' ' ' :

~ L~53337 second link me~ber 67, the third link member 68 to turn clock-wise through the~ same turnlng angle as the member 66. Such a clockwise turniny of the third link member 68 causes, through the ~irst and second ~ears 70, 72, the fourth link member 73 to turn anti-clockwise, whereby the half membex 61b is moved to the right position as shown ln the chain-dotted line.
Thus, as the first lever 63 is turned by means of t~e pulsemotor, the two half members 61a, 61b are moved away from each other to be opened.
Contrariwise, when the pulsemotor is actuated to cause the f~rst lever 63 to turn anticlockwise, the two hal~ members 61a, ~lb are closed to define a chamber therein and isolate one o~ the trays from the other trays.
The opening and closing operation of the two half members 61a, 61b, may be carried out by any other ~echanism operated by suitable mechanical and/or electrical driving means. For example, said two half members may be opened or cl~sed by two hydraulic~lly and synchronously operated ~yl~nders eac~ o~ which is mounted on one of the half members.
As shown in Figure 8j provided at respective `
engagin~ portions of the two half members 61a, 61b are a pair of apertures 75, 75 so that the inwardly extending portion 26a of the s~a~t 26 carrying each holding plate 25 does not obstxuct the closing operation o~ the half members, a sub-~t~ntially enclosed chamber being thereby defined.
N~meral 76 designates a hole perforated through the waveguide duct 60 in order to insert a water spray n~zzle 81 for preventing excessive dryin~ of the frozen 29 ~ood ~ur~ace durin~ the microwave irradiation~
cb/ - 23 ' : ~S333~

, Numeral 77 indicates a spray nozzle positioned above the heater 44 for obtain~ng heated vapor, said nozzle being adapted to atomize the water introduced through an electro~a~netic pu~p 78 and an electromagnetic valve 79.
This ~tomized water is heated by the heater 44 to become the above~entioned "heated vapor" and ls blown by the fan 53 into the c~sing.
Numeral ~OA designates a humidistat provided on ,; the inside wall of the casing 10, said humidis~at 80A being connected throu~h a humidity controller 80B to the valve 79.
Also proyided at the upper portion of the casing 10, is a ? wataX spray no~zle 81 ~dapted to be operated by apening and closin~ o~ an electromagnetic valve 82 to spray water into the enclosed coyer 61 for a predetermined time which may be ~djusted by using an ad~ustment timer 83.
In the abovementioned arrangements, the lower ~te~level detector 46 is actuated when the level of water in the reservolr section 41 drops to the level of said detector 46. The heater is then energized and the fan 53 F~tated~ whereby heated humid air is generated within the ca~ing 10. The he~ted humid a~r fills the casing 10 whereby ~rozen food disposed on each tray 24 o~ the tray circu}ating s~stem 13 is heated. In this case, the wet hot blast is ~tirred up to fill uni~ormly the casing 10.
Thus, the frozen food is defrosted by said wet hot-blast (a p~imary derosting).
Thereafter, when the trays 24 circulate in the c~sing 10 and then one of the trays comes to the required 29 pQS~t~on belo~ the micxowave irradiator 57, the two half cb/ - 24 -B
... ~ . . , .................... . . . ~ , . ;

.

~1)53337 -members 61a, 61b of the cover 61 which are hitherto open, close to surround said tr~y 240 The ~rozen ~ood on the tray 24 within the cover 61 is t~en irradiated wlth microwave radiation generated by the magnetron 58. ~uring the microwave irradiation, water $pray is applied to the food on the tray 24. In this case, as said food has already been subjected to the primary r'',l defrostin~, a relatively short microwave irradiating time does not lessen the de~rosting effect. Consequently, ~rozen meat which can be only insufficiently defrosted when he~ted w~th wet hot blast only is fully defrosted.
' As stated a~ove, the fro~en food contained in;~' t~e casing 10 of the apparatus is subjected to two kinds ' o$ heat treat~ent. one i5 radiant and/or conductive heating ~for example, with wet hot blast~, and the other is di-electric internal heating with microwaves.
Applying a convection oven heating with a dry hot blast jointly with microwave irradiation using a maynetron re$ults in a multiple effect, so that frozen food can be com-pletel~, unlfor~ly and properly defrosted without unevenness~in ~eatin~ and uneven formation thereof.
There~ore the taste of the derosted food is not spoiled, and the expensive magnetron has a longer life because the m~crowaYe ~rr~diating time can be shortened.
~urther by applying ~ wet hot blast to frozen food within t~e cover simultaneously with microwave irradiation, excessive dry~n~ of the defrosted food isurace is prevented.
When the exhaust valve 49 is opened to discharge 2a completely the water in the reservoir 41, the conduit 42 c~ - 25 - , .

: and the heat exchanger 43, the heater 44 is switched on.
., .
: The fan 53 is rotated and the air heated by the heater 44 is circulated as a dry hot blast from the conduit 55 through the casinc~ lO to the conduit 42 and back to the.heat exchan~er 43. This dr~ hot blast heats the food in the casing lO.
. The temperature o~ the hot blast is controlled by the thermo-. sta~ 56.
`~ When water is sprayed through the nozzle 77 dis-posed in the heat exchanger 44, the sprayed water is heated to beco~e he~ted vapox, which is circulated in the same manner ~s the dry hot blast, whereby the casing 10 is filled with the : he~ted ~por. The food is defrosted under the presence of the , he~ted v~por, and here subjected to microwaves in the same m~nner as said wet or dry hot blast to obtain a multiple e~fect.
Further, when the water level detector 45 is actuated to keep a predetermined quantity of water in the reservoir section 41 and the heater 44 is supplied with electric current to heat the water, the water in the reser-20 ~oir section 41 is heated up to a predetermined te~perature under the control of the thermostat 56. Thus, the food on the lowest tray 24 o~ the tray circulating system 13 is . d~p~ed in hot or boiling water and, is thereby, s~bjected to a de~rosting treatment. :Cn this case, too, microwave ~adiation b~ the magnetron can be applied jointly with ~id dipping treat~ent, In the apparatus according to the present invention, a~ shown in Flgure 9, a multiplicity of sheathed heaters 84 29 ~a~ be p~ovided on the bottom o the reservoir section 41.

cb/ . ~ 26 -~g .

. ~ ,.. ; .. . .

;~ The heat exchanger 43 can be th~n eliminated but a fan may be provided at an appropriate position in the casing 10 for '- circulating air, heated humid air, heated dry air or steam.
, .
,, Sald fan is provided particularly for circulating ', air, wet or dry hot blastt or heated vapor. However, such ;,. a fan is not absolutely essential since the air, the wet `` hot blast or the heated vapor in the casing 10 is circulated ,`,'~ b~ the cIrcul~ti:n~ syst~m.
, ~, ~",, By providing an infrared irradiatior in addition '' 10 to the microwave irradiator 57 as shown in Figures 1 and 2, ,, this defrost,ing apparatus can be used as a roaster. In , pi~uxe 10, a defrosting apparatus is shownj wherein two ,"~' infrared irradiators or ~nfrared heaters 85 are provided withln the cover 61 of the microwave irradiator 57. Refer- ~
, ence numerals of other parts of the defrosting apparatus in , ,. . ~ . .
'; F~ures 6~ 7 are the same as o the corresponding parts in ' ~igures 1, 2. With reference to Figure 10, each of the infra-' ,r,ed irradiators'85 is fixed to each of the half members 61a, ~;, .,',, 61b orming the cover 61 in such a position as to irradiate ~ 20 ~ozen food to be defrosted.
. .
~"~ After one of the trays 24 is stopped between the ,, two half members 61a, 61b with these in an open state, said ;
,, two half members are closed and perfectly enclose said tray ,',', 24. Said infrared irradiators 85 are respectively adapted ;';, to irr~diate ~rozen food on said tray 24 when it is enclosed . "~. .
f,.i~' w~th~n the cover as ~bovementioned. And the micro~wave ...
'~ i;xrad,~ator 57 is adapted to irradiate said frozen food simul--'~ taneously ~ith ~bovementioned infrared irradiation. In ', 29 thi5 casel the in~rared irxadiator 85 and the microwave . , .
.
~q ~ ~ b/ ' - 27 ~

~``; l(~S3337 -.,. .,:.
~ ...`: .
~ irradiator may be adapted to operate on detecting the position ~,`,`,! .
:~ where the cover 61 ls closed.
In th~s case the position of the cover 61 being ~:l closed may be detected by a limit switc~ ~not shown).
. .:, .
^i Infrared irradiation of frozen food by the infra-!, .:
; red irradiator 85 may be applied either simultaneously with ~`j` ~icro-waVe irradi~tion by the micro-wave irradiator 57 or :' -!
Vft separately therefrom. For example, when a tray 24 is stopped ,;......................................................................... .
~; in the required position and said cover 61 is closed, infra-Fed irradiation may be applied to the frozen food sealed ~ithin the coyer for a predetermined time, and the micro-.`; wave irradlator may then begin to operate.
i, ~, .
- An exhaust duct 86 and a suction blower 87 are provided for exhausting smoke generated from said food ~n infrared irradiation by infrared irradiators 85 out of the sealed chamber inside the cover 61 ~Figure 9~
~;: The defrosting apparatus including infrared irrad-~ iators sho~n in Figure 10 has the same structure as the defrost-; iSng app~ratus shown in Figures l-S, except for the above-ment~oned infrared irradiator and the accessories thereof, so that details of said structure are not referred to.
As above-mentioned, in the preceding embodiment o~ the present invention, there are also provided defrosting ;` mean~ or preheating means ~or heating frozen food with wet or dr~ hot blast, or heated steam prior to said infrared ~, ~xradiation~ There~ore fro~en food can be ~eheated by the :':'1 . .:, in~rared ~radiator ~fter being de~rosted e~fectively enough to ~eep the qu~lity thereo, so that extremely effective re-29 heat~ng ~s achieved ~ithout spoiling the taste of the food.
, .

l i, ',"';. ~ : '. : ' ~L~533~7 , ~ ., .
'~,, In an apparatus o~ the present invention, as tra~s . ,.:
;, ~re adapted to be,circulated in the c~sing, wet or dr~ hot .i~ bl~st, or heated steam wh~ch is a primary defrosti~g or pre-' heating medium is uniformly s~read within the casing of the ' -': a~p~r~tuS, so th~t frozen food is accurately and effectively `'' defrosted and preheated at any position in the casing.
. The following operation of appaxatus according to the ,~. FXeSent inYention, with particular reference to the above- ' :',. ,~entioned second embodiment thereof will now be described with .~', ,',,~ 10 ,re~erence to Figures 10-15.
' The defrosting fu~ctions carried out by apparatus accord-.-, ~n~ to the present invention are stated again as follows:
i . .
`',~", I. Dielectric heating treatment :, ',~,;, a micro-wave irradiating process ~ ~A) ,~,. II. Conductive heating treatments:
,~
,: ~B) - ~) ''~ a heated dry air process - (B) L:, ~ a heated humid air process - ~C) steam process - ~D) ..~
'~ 20 a dipp~ng process - (E) ,,,.,.!, an ~nfrared ir~adiating process - (E') ~ As mentioned in the preceding description, these pxocesses are combined in accordance with the kind of frozen , ~ood to be defrosted, forming a ~eries of treatment processes.
~ s~id series o~ t~eatment processes, each process except .
,. t~e ~n~rared irradiat~ng process ~J does not occur simul- .
~, t,a,neousl~ with the other process but after one process is '' ,,~ c~mpleted ~nother one ~ollows. Therefore the items,of each .
'~ 29 ~xoce~s ~wh~ch requi~e ~e~ng checked and set are checked .
~ .

.. . .
, and set, if required be~ore the beginning of each process, : and then that process is begun by turning on a main switch.
In thig case, a suitable timer means may be provided for ,` turning on a main switch after a predetermined time and at ~",,;. . .
~, ~he sa~e t~me operating an audible indicating means. Each process is similarly carried out in succession, until the ~` $eries of processes is completed.
s;... .
; For example, for a defrosting process comprising i" a heated dry air process CB)I a steam process (D) and a .;, .. . . .
: 10 ~lcro~w~ve irradiating process combined in this order, the ollowing operations are carried out:
Firstly, checking and setting the items of the process ~) which requixe checking and setting are carried out.
, Secondly, the main switch is turned on.
~;~ Thirdlyl t~e main switch is turned off after the required time.
Fourthly, checking and setting of the items of t~ steam process ~D~ which require checking and setting are c~rried out.
.-~ 20 Fifthly, the main switch is turned onO
,,.~, Sixthly, the main switch is turned off after the xequired time, ,, .
SeYenthl~ checking and setting of the items of the ~; m~crowaye irradiating process which require checking and ";~ ~ett~ng ~re carried out.
.;.:,: i Eighthly the m~in switch is turned onO
~nd ninethl~ the main switch is turned off after .
t~e requ~red time.
s 29 In this operation, the required times are to be .. ; . .

~ cb~ _ 30 _ . : . ,~ .

. , ... .
, ~ ....

`~ predetermined and the timer set accordingly/ but ~t is more convenient that these times be further manually adjustable with reference to observation of the food to be treated.
:, ., The items checked and set are described as follows.
The items checked aind set comprise operative elements and ` ~djust~ble parameters of the following seven kinds of control s~stemis, namely:
(I~ A water supply and draining control system ~Il A temperature and moisture control system ~ A tra~ circulating system control system . .,~ i ~- (IV~ A treatment time control system ~V) A specified tray calling control system VI~ A water atomization control system ;i ~yI~L ~n ~nfrared irradiation control system .~, '~ ,!
~', These w~ll now be described in detail as follows:
i ~L Water supply ana drain control s~stem ~see Figure 11) As above-mentioned, on the lower inside wall of the casing 10 of the defrosting apparatus are provided a ~, ~igh water leveI detector 45 in the upper portion and a low ~ 2Q w~ter le~eI detector 46 in the lower portion, said two water .j,: j ,.
`/' leveI detectors being both connected to a magnetic valve 48 ~or water supply and a magnetic valve 49 for draining. On .!l the control panel ~Figure 16) a first change-over switch 101 can be connected to the high water level detector, to the ' low ~ter level detector, or may be put in a draining position tn ~ccord~nce w~th the k~nd o~ the process selected. If tlle first change-over switch 101 is connected to the hiqh water le~el detector terminal 108, the high water level detector 45 29 ~s ~ctuated during de~rosting, whereby ~or example~ through ; . :
~/ ~ 31 ~ ~

; ,.
a driving circu~t 103, relays 104, 105 and a switch 106, ;.,..:
m~netic valves 48, 49 are operated to keep the water level constantly at the position o~ said detector 45. And if the j~:
` ~irst change-over switch 101 is connected to the low water :
~eyel position 109, similarly the water level is kept con- -stantly at the position of the low water level detector 45.
,:
` Further, i~ water is not required, for example, ~n the case of the heated dry air process (B) said first ~- ch~nge~oyer switch is connected to the draining terminal Cth~s is the position s~own in Figure 11), whereby said ,,~ ,.. . .
magnetic valve 48 or water supply is closed and said ~ magnetic v~lye 49 ~or draining i5 opened, while said two ;~ detectQrs 45, 46 are d2sconnected. Said change-over swltch ~ ~ay be adapted to be manually connected to the draining .. i termin~lO If the electric current flows into the sheathed heater 44~ said heater 44 is damaged, so that it is necess-.,.:', ary to open the door and wait till the heater is dried. In this case, the first water supply and draining must precede ,..1 turnlng on the main s~itch 111, and therefore it is necessary 2~ to cause the electric current to flow into said heater by means of a switch 101 in a circuit other than that of the main ~Witch 111.
~,$' ' ~II A temperature and moisture control system ~see Fiaures 12, 13 ... i ~ On the side wall o~ the casing 10 of the derost-.; " .
ing apparatus, there are provided a thermostat 56A in a posi-tion suitable or sensing a temperature which is substantially the me~ temperature inside t~e interior of the casing body, 29 ~nd ~nother thermostat 56B in a position suitable for sensing ., ~ b/ - 32 -.: .,. . : , , . ~ , .,. .: . . . : - :. ~ ,. , ~,. .

:
~ 53337 -the water temperature when sa~d water level is high, said two ther~ostats 56A, 56B be~ng connected to said sheathed : ~eater 44, Said thermostats 56A, 56B may be adapted to ., .
define a s.uitable range o~ temperature, in accordance with ~h~ch the electric current is supplied to or shut off from . the sheathed heater 44. Further the thermostats 56~, 56B
:
`. are connected to the sheathed heater 44 through a second : c~ange~over switch 112 which enables either thermostat to be ,l connected ln accordance with the defrosting process selected.
` 10 Said thermostats 56A, 56B may be replaced by a more precise .~ thermocouple and a te~per~ture controller connec~ed thereto ....
~. ~Qr contxolling the sheathed heater 44. Further on the .i .
dewall o~ ~he body 10, a moisture lndicator 80A is provided ; ~nd a mo~sture controller 80B is provided on the control nel ~or controlling a magnetic valve 79 to keep the mois--' : ture lnside the casing at a predetermined value.
' Said valve 79 is connected to a pump 78, and ~d pump 78 is connected to the main switch 111. Further ... .
. a m~gnetic val~e 82 of the water spray nozzle 81 mentioned ; i~, ~1 20 below is also connected to the pump 78. The connection o~ .
.. , ~ .
t~e magnetlc valves 79, 82 to the pump 18 are changeable by .~ operating a third change-over switch 113 in accordance with the de~rosting process.
: Further an ~uxiliary switch 114 is provided bet-w~en the pump 78 and the main switch 111, and thereby, it ~s posslble ~f re~u~red ~n the de~rosting process to prevent t~e electr~c curren~ from f~owing into the pump when the 28 ~n ~w~tch~lll is on.
,~ ' , .
cb~
:
.,, ~ .

.. . . . .

~ ~333~ ~
.
~III) A control system ~or a tray circulating system '` (see ~ure_14)_ :- ~
; Trays in the tray circulating system have to be ~ circulated by a motor either continuously or intermittently ;, in accord~nce w~th the de~rosting process selected. For ,-; example, in a de~rosting method comprising a heated dry air process CB)~ ~ heated humld air process ~C~ and a steam ` process ~; said circulation may be uniformly continuous, .
thus assisting st~rring of the atmosphere inside the casing.
" 10 But in ~ dlpping process or a microwave irradiating process, ;- the trays must ~e kept still in hot or boiling water or in ~ the position for micro-wave irradiation for a predetermined ,.~ ti~ne~
,,.. ; ~
A change-over can be effected between continuous ~;i,; circulat~on and intermittent circulation by a fourth change-,; oyer switch 115, Said intermittent circulation with required ~, cycles can be realized by pro~iding a cycling timer 116.
~' However, i~ the number of kinds of intermittent cycles :' required for the frozen food to be defrosted is assumed preyiousl~ known, a plurality of such timers 116 may be pro~
y~ded ~n parallel. Said fourth change-over switc~ 115 i5 ) then changed over to the appropriate timer 116 in accordance With the k~nd o~ fxozen ood to be derosted, Referring to F~gure 15, it w~ll be seen thak the interrupting time P
! ~n ~n intermittent c~cle would appear to be determined by t~e time Q = Q1 ~ Q2 ~or openlng and closing the cover 61 t~ough operat~on of said pulse motor ~not shown~ and the ~cro~wave irrad~ating time~ Ro Practically, however, said 29 ~nteX~upting t~me P is determined to be a little longer than .
cb~ ~ 34 _ ". ~$
.

.~ ....... ... . .. . , ~ . ~

t ,: ' .' ~ ~ ~ ' ' ;`
D5~3337 ~.
~ ~Q ~ R) by using a delay timer 127 at R. The operating time ! ~ . .
S in the intermittent cycle is the time required for a tray ' on the tray circulating s~stem to move through one interval.
. .
, ~ s~eci~ied tr~y can be stopped at a predetermined position b' by providing at a suitable position a limit switch connected ., .
,;,, to said motor 38.
: ,..
..... :
,s Furt~er, another limit switch is provided on said ~' cover 61 which is adapted to be switched on by opening of . ~
~ sa~d cover 61 and said micro-wave irradlation may be initiated ~ ,".~ ' ' .
''`' 10 by the switcl~ing on of saId limit switch. Said pulse motor ,` ~,s ~dapted to rot~te in reverse direction on termination of `s~'; , '~;` ,m,icro-wa~e ~rradiat~on.
~ n Figure 15, a,indicates operation of the motor ~ ~A
;~;, 38; b, stopp.ing of t~e motor 38; c, forward movement of the ~ pulse motor; d, stopping of the pulse motor; e, reverse ,.,:
"',' ~oy~ent of t~e pulse motor; f, micro-wave irradiation; g, ` :!
;' ~topping of micro-wa~e irradiation; and h and i indicate , ~eratlon and stopping of water spray respectively.
~IVl Tr;eatment time control system .,,. ~ .
', 20 The treatment time required for each defrosting :~.. ..
,'~';, process depends upon the kind of frozen food to be defrosted, ..;. . ~ .
,',,,, and therefore it is convenient to connect a timer to the main ~ itc}~ 111 and set the tlmer at the required time ~or treat-:' ~ent be~ore carrying out a process. In this case, by using '' ~n automatic reset timer the required treatment times may be eset before the beginn~ng of each process, or a number of ,i',' ti~er~ 122~1~7 may be provided in parallel, these timers being ''i" tuxned on by ~ fifth ch~nge~over switch 117 according to the ', ,; 29 ~r~ces$ selected. ~ water atomizing process and an infraxed ,::., !'j, i~ ' ~ ( , 35 _ , :. . . .. , . - . . .,. . i,. -, . . .

. . . . . . : . .
. ~ , . , .. : ~ . : , - .:

- ~ ~53337 , ixradiating process are carrled out simultaneously with a micro-wave irradiating process as expla~ned with reference : .-to Figure I50 ~Vl A tray calllng control s~stem This control system ls for the case when not allthe t~ays of a tray CIrCUlating system are used, or when the ~rozen foods to ~e defrosted on the trays are not all o~ the : s~me k~nd. Howe~er, in a heated dry air process ~B), a heat-ed ~et a~r process (C~ and a steam process (D~, all the trays ;~; 10 ~re cont~nuously circulated in the casing, and therefore the ,, .
`3,'.~ tra~ calling control s~stem is not applied. That is, this control system is for calling a tray carrying frozen food to b~ defro$ted thereon to the predetermined position in the beginning of a dipping process ~E) or a micro-wave irradiating ~` process CA1. Th~s control is realized by providing a detecting .. ~ .
~ means such as a limit switch, or a proximity switch on all the .. ~ .
trays or a speclfied tray and at the same time providing means or receiving and then transmitting signals made by said detect-~ng means. When each of the trays 24 of the tray circulating ~system 13 is provided ~ith a said detecting means, by pushing .:
`~ a ~pecific numbered button of a group of buttons on the control ~anel, the detect~ng means of the corresponding tray is actuated, c~us~ng sa~d motor 38 to move, whereby all the trays are con~
tinuously circulated. If the fourth change-over switch 115 h~s been turned to the intermittent position, said trays in c~ntinuous circulation stop on the arrival of a said specified tra~ at t~e predetermined position, and said detecting means ~re t~en ~wLtched o~f~ In this case, the mo~or 38 may be a two-29 sReed motor, and said motor 38 may ~e adapted to turn at the higher speed during tray callin~ When said detecting means ; is provided only on a specified tray, the motor 38 may be ,.;
actuated by pushing one of a group of buttons corresponding ~ to said tray number, which gives a detecting signal including : the distance between the tra~ corresponding to said pushed '.:'.
` button and said specified tray.
~YIl A water atomizin~ control system (see Figure 15) ~; Water atomizing is applied for preventing excessive ; dr~ing o~ the frozen food surface to be defrosted. ~his pur~ose can be re~lized b~ synchronizing said water atomizing , ~ .
~ith, for example, the beginning or the termination of ~icro-wa~e irradi~tion~
The water atomizing time can be fixed as required - by using a delay timer as a water atomizing timer. By providing ; . ~
: an auxili~ry switch 130 on the control panel, said water atom-`;, i~zing process can be carried out independently of the other , t~e~ting processes.
` ~VII~ ` An infrared irradiating control system An Infrared irradiating process is a finishing pro-cess ~or suitably scorching the surface of food to be defrosted.
,;.~
; T~erefore s~id infrared irradiation is carried out at the .,.; ~
latsst after said water atomizing process, if the latter is ~plied, Said infrared irradiating process is adapted to syn-i .
,` ahronize with the mlcro~wave irradiating process by pus~ing a ~'~ button 119 ~r infrared irradiation. If said button 119 is .....
pu~he~, the ~nfrared irradiating process does not start till the w~ter atomiz~ng timer ~s turned off O Further i the infra-, ~ .
red irr~diating process has not finished when the micro-wave ~, j 2~ ~rrad~atin~ process Is completed, said timer 125 gives an ~'' , ~I cb/
i`,;f`~

.' . , ~ . .`, ~ . ;., :

~ ~Lo53337 ..
alerting signal to said pulse motor, and the pulse motor is actuated on cessation of the infrared irradiation in order to open said cover 61.
~, Numeral 153 indicates an operating devlce provided with operating buttons on the operaiting plate o f the defrost-; ing ap~aratus A. On these buttons are a series of numerals ~ .
or design~tions indicating the arrangement order of the trays ; i~n t~e c~rculating system~ They are colored with colors sim-;;
~lar to the colors of the corresponding trays classified on ,~, l t~e basis of the temperature at which the food is to be eaten.
When the operating device is adapted to set each ~ one of the defrosting conditions by a single operating button s only~ ~or example, w~en these defrosting conditions comprise ~icro-wa~e irradi~tion as the dielectric internal heating treatment and t~ese conditions are dif~erent only in the length o~ the ti~e of ~icro~wave irradiation, the buttons for sett-~ng e~c~ defrost~ng condition are preferably colored the same , co~or as the corresponding trays respectively. In other words, ; ~hen frozen food is d~v~ded 'nto three groups comprising ~a) cool food whic~ re~uires heating only to a comparatively low ~, temperajture~below room temperature, (b~ room kemperature food ,:ii ~hic~ requires heating to room temperature and ~c) hot food ~hich requires heating to ~ comparatively hot temperature aboye ~oom tem~erature, t~e trays containing these food are colored in three dif~erent colors and the buttons in the , ,', .
operating device are colorad in such a manner as that referred ~, to ~n Fi~ure l71 for e~ample, the button 153~ is colored blue . ( ; to ~ndicate cool ~ood, the button 153b ls colored green for 29 Xoo~ tem~erature ~ood ~nd the button 153c is colored yellow b~ - 38 -i,.,. ~ , .

~;
~ ~53337 ... ..
,~ for hot food. The de~rosting conditions are controlled corres-', pondingly by these operating buttonsO If the oper~ting device : .;
',',, is not mono-functional, and an operator has to control elements ~;7', such as bu~tons to ~et a given defrost~ng condition, only ,, some speci~ied control elements in each defrosting operation, ,',, ~or example, the buttons 153a, 153b and 153c, and the steam : yalve are colored in the same color as the tray.
- Numeral 154 indicates a dial display means for con-. ~rmin~ which tray is now enclosed in the cover. ' i,' .,: 10 ~n order to defrost frozen food on trays 24 colored , . . .
~' in correspondence with the defrosting condition which the food "`, requires, frvzen food is mounted on trays colored in corres-.. ; ~ .
', pondence with the required defrosting condition and stored .' . .; . .'~, in groups for each day in a storage box 150 (Figure 17).
',~ Then the trays are taken out on respective days by opening ;,,` respective doors 151 of the storage box 150, and transported "', ma,nuall~ or b~ means of ~ belt con~eyor 152 to tlle defrosting ,,~, aRparatus A. In this case, the trays are closely piled up ,',,',l ~rom the lower portion to the upper portion, but the operator ~j 20 c,a,n take out the necessary trays from the upper or in~ermediate hel~ w~th the knowledge, from the color of the side of the .,.;.
',.'l tra,y ~acing the outside of the storage box, what kind of frozen ood i~ conta.ined in t~e tray he is taking out and what defrost-n~ cQnd~tion is needed ~or said fxozen food. Thereore, he c~n rapidly take out the necessary tray without confirming the c~ntent of the tra~, thus preventing cool air from leaking , j wa~ ~rom the storage box. When another tray of frozen food ",', ~ needed~ sa~d ~rozen ~ood ls obtained by tak.ing out a tray 29 o~ the corresponding color.

..:;,~.
:,..
~,'" ~ b( - 39 -,:., ; .. ,,. . .. . ~. : ~.. .. . .. . . . . . . .. . . . .

'' ! . , . , , , , . ~ ' . , . ' . ~ ' - ~ .

: `:

5333~7 ..
, .~
.If the trays transpoxted to the defrosting apparatus A are of the same kind or in the same color, they are put ~:, through the inlet into the apparatus A and set in a suspended . bucket of 'the tray circulating system, so that the defrosting ., operation can be started by one by pushing the operating button colored sImilarly to the trays.
"'"`,~ If the trays transported to the defrosting apparatus ... , ~ ~re o~ a pluralIty of ki:nds, for example, two kinds, each 5~ k,~nd r~ trays is set in the tray circulat~n~ system in each ",~'., 10 group respecti~ely. And lf one group of frozen food requires ':~ treatment with humid air and micro-wave irradiatlon and the .. ,,- othex re~u;~,res only a treatment with humid atr~ humid air . treat~ent ~,s appl~ed to the two groups of frozen food at the e ti~e'by pu~hing an appropriate button. Thereafter, the ~: .
,'.~, f~od ite~s constitut~ng the predeterm~nedly defrosted latter ';: group of frozen ~ood on the trays are taken out one by one through ~, the outlet 12B, and then by operating a button micro-waves ....
re'irradiated onto sa~d trays one after another. In the micro-';,i.'~ ~ye'i~rr~di~t~on~ the numeral of the tray enclosed in the cover t 2~ ~ s~n on the display means 154 each time, The trays contain-~ng de~rosted food are similarly taken out one after another . through't~e outlet 12B.
~.,' Thus, by partly or wholly coloring each ~ray in a ""~. predetermined color in correspondence with the d~frosting ~, conditions ~or frozen food and by providing an operating dey~ce c~mprising a button colored the same color as the corres-pond~n~ trays ~nd ada~ted to set the defrosting condition ., xe~resented by ~a~d color, the operation of the defrosting "';,.. 29 ~paratus becomes ver~ easy and high efficiency can be :, ~ .
.;;
~ b/ . - 4~ -::.
. , .. , .. . ...... ,. :..... , :, I , . .. . .. .

obtained. Further, the foregoing ~eatures can pre~ent production o pa~tly de~rosted food due'to lncorrect opexation of the appar-'; a~us.
In the embod~ment as shown in Figure 17, frozen foodto be stored in the freezing chamber is precooked at a food center, :, cont~ined and arranged directly or through packaging in the trays, which ~re predeterminedly colored on the basis of the kind of , ~ozen food and then frozen. A number of trays containing such ~' frozen food may ~e put into groups, for example, according to ''- 10 a menu from Sunday to Saturday, transported to schools,'hospitals, ~' or reStaurants and there systematically arranged in a previously ~, ',' installed freezing chamber. Thus, this defrosting apparatus .. .
u can be used as ~n automatic apparatus ~or systematically defrost-. , .
;',' ~n,g of large numbers of items o~ frozen food en masse, these :
,,", ite,m,s being standardized cool or hot foods. This enables for ~ exa,mple a ~elf-service restaurant to be supplied.
;,, ~' As above-mentioned, by systematically combining a .. .
defrosting ~pparatus according to the present invention with cook-~ng, ~ood and freezIng and storage stations, a new type of a ~, 2Q conyenient restaurant can be established. This apparatus can ~,~ cont~ibute much to aùtomation and reduction of labor in the ,` re~t~u~ant ~nd catering trades.
., j The following are the results of defrosting experi-', ments using de~rosting apparatuses ~or realiæing the method ccording to the present invention, especially apparatuses as described in the p~eceding examples embodying the present invention 2~ ~,ho~n ~n Figures 1~4J.

,, ~ . , Y,.j .
~" cb~ ~ 41 ~ ~
,.' '~ .
;......................... .

. , . . . . . . ~ . .. : .:
.:

. ~ ~5333 . ~ , Example 1 Firstl~ the conyent~onal defrost~ng method comprising dielectric internal heating ~y micro-wa~e trradiation was appl~ed ~de~rosting experiment ~1], and secondly a defrosting ~ethod in accordance w~th the present invention, comprising the cOmbin~t~on of heating by a high temperat~re convection ro,yen and a dielectric internal he~ting was applled ~defrosting experiment (B~], and then said two methods were compared with . .~, .
each other. In these experiments, a hamburger is used as a , . ~ .
~ lO ~ample of frozen food to ~e defrosted.
,.:;.
The sizes of the defrosting apparatus used in these ' exper~ments are as follows:
~ i~ Outside measurements of the casing - 2.12 m ; ~width~ x 2.0 m ~height) x 1.0 m (depth) j ii) Inside measurements of the casing and capacity -,,.j,l 1.15 m Cwidth~ x 1.~ m ~height) x 0.8 m ~depth) =
~ 1.4~ m~
.... .
Number of trays - 24 Meaurement o a tray - 26 cm (width) x ,.. . .
J 2Q 80 cm ~length) , `~ ~x~er~ment ~A) ..... microwave irradiation 24 hamburgers ~measurements of each hamburger, 8 cm i, ~length1 x 5 cm Iwidth) x 1.6 cm ~thickness), 80 g (weight)~
re d~sposed in foux lines on one of the trays set in the tra~ circulating system in the defrosting apparatus, and ., .
., .
. J' cb~ ~ 42 ,~.. ~ , .
`.', ~ ~ .

. ~ iC)53337 .
t said tray,is enclosed by ai cover of a micro~wave irr~diator.
~ . . .
; Then the tra~ was subjected to micro~wave irr~di~tion and the ~, te~pe~ature o~ the sux~ce and ~he central portion of the ham-burgers wa~ measured with a thermistor thermometer every three ~, ~inutes. The measured values are shown in Table 1. In this ::;
,'~,, ca~e, the te~perature of the inside of the defrosting apparatus , . . .
~ s nearl~ 403C.
,:;, The meanings of the symbols used in Tables 1, 2 are ~, a~ follo~s;
~ 10 n .. , number of the samples, i.e. hamburgers .;;~ ts~C~ ,~, surface temperature of a hamburger ~;' tc~C~ ...... temperature of the central portion ' , ~,~ - C0.9 cm deep from the sur~ace~ of ~,, ' said hamburger . ~;.
~ X1 CC1 = ts - tc ~ts ~ tc) or ; i ,,,i,~ tc ~ ts ~c ~ tsl i,,,3~ ~S, ~C, ~ .. ....means of ts, tc, Xi respectively ,....... .
.O~ standard deyiation xi - xi ) 2/n ~ .
This standard deyiation indicates the extent of t~e'~c~tter, ,a,nd ~here~y the extent of unevenness in defrost-~n~ ~y be estimated.
Ex~eriment (B) ,~, micro-wave irradiation + oven ,~.~,... .
The'de~rosting apparatus including the tra~ circulat-~i~n~ ~stem was prev~ously operated, and the inside of the casing ... .
the a~p~rat~s heated up to about 180C. Then a door of the ~j c~ n~ o~ the appaxatus was opened, and 24 ~rozen hamburgers 28 ~ the s~me s~ze ~s tho~e used ~n Experiment ~A) were introduced ` cb~ - 4 3 ,1 ~ .

,'' '' '," ' '. ' ` . ' . ' ''' . '' ' . '. ' ~'': ' '' j ' .: . ' . ' . ~ ',, ' . ' .
. .

~C~53337 in 4 lines on one o~ the trays of the tray circul~tin~ system as ~entioned ~bove with reference to Experiment ~. The door "
was closed. In this case, the chamber inside the casing of the apparatuS w~s ~illed wIth a dry hot blast, and the temperature ` thereo~ kept cons~ant at about 180C.
,:
After sa~d hamburgers were put into the chamber, said tr~ on which the hamburge~s were disposed, was substantially ., .
;~ enclosed within the coyer, and at the same time microwave irradia-t~on was applied to said tray fox about 3 minutes. After said i:; 10 first micro-waYe ~rradiation was completed, temperatures of the surface and the central portion of the hamburgers were measured with the thermistor thermometer. (The first temperature measure-.... .
mentL. Then the said cover was opened, and the microwave irradiat- -~'!',' ed ~amburgers on the tray were c~rculated below a high temperature ; convection oven providing heat by dry hot blast in the casing ~,;
o~ t~e apparatus. After said heating by dry hot blast is completed, the second temperature measuxement was made ~8 minutes after , ............ .
' putt m g the hamburgers in the chamber). Then these hamburgers :r. ~ere ~gain encLosed within the cover and the second microwave ~- 20 i~radiation was applied to the hamburgers for 3 minutes. After S'! ~a~d second mlcro~ave trradiation was completed, the third ,' temperature measurement was made ~11 minutes after putting said ~mburgers into the chamber). The temperature data obtained in the.f~rst, second and thlrd measurements are shown in Table ~I! which IS similar to Table I.
".

, . .
, ~ , .
., . :.
cb/ - ~ 44 - ~

`` ` ~L~5~337 Table 1~1 Micro-wave irxadlation .. : . sampleafter 3 minutes . _~___.
~, . number .... . ts .C . tc C Xi C
.. _ . . . .
.:.; 1 2 . -4 6 , . . 2 1 -S 6 ~`il 3 10 17 7 . 4 . -2 _5 7 . 6 4 _3 1 ` ~ ~ 8 -3 11 ~; 10 1 1 5 .~ 11 2 -5 7 12 :l9 2 13 . 6 -2 _3 3 ~,~ 19 2 ~ -2 4 21 _i -5 4 ,~ . 22 19 10 9 23 5 . . -3 ~
; I ~4 16 ~1 5 vç~, . ... .... . . . ..................... ..
~, _ _ _ ~ , . , ~......... .valur ~s=5.04 t--c--1.25 X~i=6 63 f '"

: ', ' ' ' ' ' :
',' j' .
, ~, .: .
:'"i, .
~ ........ . .
,';,~ : , 45~

O ~ . ~ . ... . :

~C~5~3~
-;. Table 1 2 : -...................... .
! ~. : . . . . .
~ sample a~.ter. .6. m~nutes , : . . number ...... ts.. c........ tc.. G xi :. _ _ ;.:;; 2 31 . 16 15 .. 3 56 5~3 2 ~, 4 39 34 5 .-. 5 23 28 5 .. . 6 37 36 1 .. ~. . 7 38 40 ~!
.` . 8 40 36 4 .. 11 25 lt3 . 7 . 1~ 56 67 11 r: 13 71 75 . 4 .. 15 58 56 2 ;,~, 17 33 32 1 ~;~; . 18 31 33 2 'ii' 19 2B 28 0 ,~: 20 . 30 31 1 ' 1 : 21 2g 21 3 `'''`' . 22 54 . 56 2 23 ~L0 42 2 .l 24. .... 5~..... ..... 64 .. 1.0 ,.~" . ~ ...... _ _ ~.... _ _ . . ..
.~ mean ~s=39 . 91 tc=39 . 71 Xi=3 . 87 , . val.ue .............. _ . _ . . ~ -4.. Ø7. . . :
,~,. . . ..
'~'I ': . ' :
,, ~ . , ' . .:

.,' , , ' ' ' .
;, , ' .
.~, , .

6.
~ j ! , ~ , , .` ~able 1-3 ~ .. .. ~, , ~:. 5ample . after 9 mlnute~ _ number .... tS .C... ... tC C Xi C
.:: . ..

. . 2 . 66 61 5 ': 3 84 76 8 . . ~1 7û 62 8 . . 6 68 64 4 ~i ~ 57 53 4 .~ . . 10 81. 63 18 .~ 11 54 58 4 ~: 1~ 87 8~ . 5 .
: 13 84 83 1 . .

.. ~ 15 74 77 3 "~. 17 ~1 59 2 ~; 18 62 64 ~ .
.~.. ~ 19 57 53 4 .

:~` 23 . 7648 66 1 ts=68.67 I t-(=65.S4 ~ Xci 4 34 i~.................... .
,~ , , .
...................... . .
~""
...
.
, , .
..
,.. . . .
4 ;!
.,, , . ~
' ! . ........... ,.. _.. _ _ . ._ . _. ,.. _, _ .

;' ~'~ . ' ' . ' .
r ' ~ ' . .

~i;.` ` ~ ` ~ o5333~
. -. Table 1-4 `'' . .... ,.,.,,., ,. ......... ,, ., ' .:

.~. . sample . ... ... af.ter 12 minutes . ntunber t .C t C X C . .
:. ...... ..... s.. ..... ..... c,.
.. , . . .... ... .. __ : 1 88 84 4 . 2- 80 78 2 ; 3 89 85 . 4 ::: 4 . 81 . ~3 2 :;. . S . 80 76 4 : . . 6 86 79 7 . 7 7~ 7~ 3 . 83 66 17 ;, . 9 72 . 67 5 . . 10 74 . 7g 5 ~'. .11 ~9 68 1 ~ . 12 82 82 4 ., 14 76 75 1 ,,;` 15 76 83 7 .. 16 69 71 2 17 73` 76 3 ~, 18 81 79 2 19 74 67 . 3 .' " !'1 20 73 75 2 .. . 21 68 66 2 : . 22 77 ~0 3 ~4. . 82 ........ . 82 0 ~. . ~_ ~ . _ . . ~ _~ .
.`., mean t-s=77.71 tc-76.50 Xi=3 54 .
. . .
"l ... . .
.. . .
':. , . .:

.~ , : :, ,, ~ .
... . .
::,:l $ 48- ~
. ~ . .

'f " .

105333~7 , ;.
., ~, .
Table 2~1 High temperature convection -~ oven and micro-wave irrQdiation ;;
~ ., .. ~ .
'':!j'',sample. . after 3 minutes .
6~ number . . ts .C . . tc c xi C
. ........... .
1 45 34 11 .
. 2 28 25 ` 3

3 .43 . 29 14 ~. . 4 ~2 39 3 :~ .5 45 3~ 6 ., 6 32 27 5 .,. 7 . 41 54 13 . ~j 8 46 51 5 ;~ . 9 45 40 5 .

14 44 _ _ i~ 15 47 48 1 ..... i.i 16 38 _ _ ,~i.`, 187 37 51 4 .
~ 19 33 37 ~

~, . 22 72 _ _ .. ~ 23 54 52 2 .
,:, . .. 2.4... ......66..... .... . - . .. -. .
,....... . ._ .... _ , .el.ue . ts=45 . 79 tF-43 . 83 Xi-5 17 ,~;: . i . .

... . . .
'. ,:, .
;., ..,,.
,~.. . .

~ j ! ~4 9 .. :, . . ~

53337- :
~; ~ . Table 2-2 .:,.~:
i . _ ..._ v . ... . _ ~. sample after 8 minute' . _ .s. number ts C tc C Xi C
., ! ; . .
~ 2 ~ 52 ~ 3 ~ ~ 7 .14 53 57 4 17 1 '54 1 3 }.~ 18 53 52 23 58 Gû ~ _ .

: .:value es=61 DO tc=61. 91 X~i 2 66 :' "1 ' :. . .
.~ , . . . . .

...... .
.....
~' .

,i, , .

)5333~
,`;., :
.~ Table 2~3 ... . .
;.. ~, .
~,~. .. . . . .. . .
.,~; ,. _ ~ . .. . , . .... _ . ~
. sample . .. after 11 minutes .. ~ . number . . . ts. ..C . . . . . tc C Xi . 1 86 B6 0 .: 2 ~6 71 15 . 4 82 887 - . 78 86 B
~` 6 80 82 2 .. 8 90 88 2 .,. 9 84 83 1 `.~. 10 78 85 7 11 78 81 . 3 .~j~; 12 82 89 7 .; 13 83 8.7 4 .',7.' 15 85 84 1 ,~ 16 78 77 1 i' . 18 80 77 3 ~;i.. ! 19 77 78 1 . 20 83 66 17 .~,i 22 80 80 0 23 7g 80 1 ... ~ .24 . . .... 82. . 86 .. 4 ' - ~ . . . ;
~ value. . t~=81. 75 tc=81. 83 a -~a ,t;'' . .
.
.... ..
....

.

;:~., ,, ,: .

. .. . .; .. . c ~. ~ . . .. . ..
.

.. . .

. Figure 18~A). and ~B) are graphs plotting the ~aximum, ean and minimum yalues a,nd th.e standard de~iation of the :., measured values of the temperatures (of the surface and the central portion o~ ha~burgers) shown in Table 1~ 4 and Ta,bles 2-1 - 2~3, which show the results of defrosting treat-~ents, tn Tables 1-4, with only micro~wave irradiation, and in Tables 2wl to 2-3, wrth both of micro-wave irradiation .
; and ~eated dr~ alr provided by a high temperature convection ~ !. ' ~` Qyen F~gure 18~ s a graph representing for reference the :~

xelation between treating ti~e and heating temperature in , t~"'' defros*ing frozen hamburgers with heated dry air only, supplied ~ a hlgh temperature convection oven.
.:i ,, Firstly, the graphs 18(A~ and 18(B) may be compared .~ With eachother. Taking the mean values, in the defrosting :;. t~eatment with micro-wave irradiation only, the difference :;
~' ~etween the temperatures of the surface and the central portion ~f the hamburgers is about 6C after 3 minutes from the beginning of the treatment, and there is substantially no difference ., a~ter 6 minutes, ~ut the.re are differences of 3'JC and 2C
,.,.;;j .
~ri 2a a~.ter ~ and 12 minutep respectively. In contrast, in the .l defrost~ng treatment with both micro-wave irradiation and : ,;
:~ an oyen~ the temperature differences after 3, B ana ll minutes ~re about 2~C, 1C and 0.}C respectively, which indicates j t~a,t.t~e difference is ~ery small from the beginning o the eatment and disappears with lapse of time. Next taking the $tandard devi~tion, in t~e defrosting treatment with micro-wave r~ad~tion on}y, the deviat~on is at first rather small at 2.3 a~ter 3 m~nutes but becomes as large as 4.1 - 3~8 after 6-8 :~i ~ 2~ ~inute~. ~n contr~t, in the treatment both with microwwave . . .
` ~ b/ - 52 - -.

5~337 ..
^'~', irradiation and an oven, the st~ndard deyia~ion is at first .,. ~ .
;,~' rather large at about 3.8 a~te~ -3 minutes, but ag small as s~:, 2,0 after 8 ~inutes. From this, it is found that in the ,.. ,,:
,',' defrost~n~ treatment ~oth with micro-wa~e irradiation and , . ..
:'~ an oYen a very~ prefexable result is obtained after about 8 . ;, .
nutes and unevenness in the extent of defrosting ~unevenness `~`'` i,n temperature) ~s overco~e.
. ................ .
On the other hand, referring to Figure 18(C), the f,e~ence between the temperatures of the surface and the ; 10 ~e~tral portion of the h~mburgers does not become small with lapse of time and indeed is as large as 8-16~C throughout , the whole defrosting period, and unevenness in the extent ,`;;~ ~f de,~rosting is substantIally~- not overcome.
As apparent from the description above given with ' referen~e to Figures 18 ~) ~B) ~C), unevenness in the extent ;'.,;', ~, o~ defrostln~ is not overcome by a defrosting treatment on]y ~ ith micro-waye irradiation or an oven, but it is substantially i~ oyerco~e ~y applying of both micro-wave lrradiation and an oven.
.j~, ~ speci,al~y, by the defrosting treatment with both of micro wave ,`,i' 20 ~ir,r~diation and an oven, ~rozen food is defrosted and heated in ~sh~rter time than ~n the treatment only with one of them, ~" a,nd ~urthermorer the m~cro~wave irradiating time is much shorter, ~;',i, ~,hi,ch i~ econo~ic~lly advantageous~
',',' By thus combi,n~n,~ a micro-wave irradiating means ~nd an oyen ~which i~ an example of a radiant and conducti~e ~atin~ means other ~eans such as means for applying heated id ai,r or steamIng can be also used), the remarkable advantage obt~ined that uneVennesS in the extent of defrosting can be 29 oyerc~me. This results ~n t~at defrosted cooked ~ood ca~ taste .. . ~

. . . . .
, . . . . . , :
: ~

`~
, ~ ~ 5 ~ 3 ~

as good as said food before freezing.
`, In the ~bove~mention~d defrosting experiments, h~m,bur~ers with rather un~form formation were used as samples becaus,e of'being ayailable and easy for measurement. Even , ,in case o~ such hamburgers it was shown that the combination Q,~ a m,icro-wave irradlating means and a radiant and conductive means can ~ring better de~rosting results than a defrosting ,m,eans consistlng o~ onl~ one of these means. Therefore, if ~,~ a~ ~a~terial with uneven $ormation such as curried rice is used ,~ 10 to ~rovide experimental sam~les, the above-mentioned effects ~ill appear ~ore markedly.
,'~ Exam~le 2 ~,' Using a defrosting apparatus similar to the one ,'', used in Example 1, defrosting tests using a high temperature ,,'1 conyection oven only ~AI~, using magnetron micro-wave irradiation onl~ and using bot~ t~e oven and the micro-wave irradiation toget~er ~'~ respectively were performed Gn three kinds of samples~ chawan-mush~" CJapanese food), beef stew and curry r~ux, ~ 20 Chawan-mushi:
'x:i ' '''`'''~ ' ' .
'-, Stirred egg w~s added to soup seasoned with soy sauce or ~alt. Said soup with some ingredients such as sliced chicken, atsudake'l mushroom and "kamabokol' ~boiled fish paste~ was .i ~ut i,nto cups. Said cups wer2 further ~acuum~packed in a bag o~ polypropylene material and then frozen. Four tra~s each with ,~ ~ouX cu~s o~ $ai,d ~aicked ~nd frozen chawan-mushi thereon were p~e~ared ~The total number o~ the cups ~as there~ore sixteen).
The net weighit of a cup of chawan-mushi ~excluding the weight 29 io~ t~ cup~ ~as 3~0 ~ ~ ~ 54 ~
: ' :

.. :, . . . .. . .. - . . . . .
, . : , . .. . . . , . . ., . . .:, ... . . . .. . .

. ~ ~

`'~'; Beef stew,:
,:' S~all pieces of beef, potato, onlon ~nd other foods ~, .
~ th some water were cooked, ~acuum-packed in polypropylene :, ~a,~s and ~rozen. Four trays each with four packs of beef .. . .
. stew thereon.were prepared ~the total number of the packs was sixteen~, The we~ght of each pack was 300g.
Curxy roux:
s~ Small p~eces of beef, carrot and potato, green-peas .', and other foods were boiled with some water. Curry powder ,', 10 ~nd flour wexe added thereto during boiling. Said curry rou~
,:.~. .
'.':,. ~as.~cuum--packed in polypropylene bags and frozen~ Four `,,;..:~
'" ~x~ys each with four packs of curry roux thereon were prepared ."~
,'"'., ~the'total number o~ the packs was 16~. Tlle weiyht of each pack , ~:
,.,',. ~a,s 30.0g, :;:
Defrosting tes't ~A~ ... oven only ~',',~, An atmosphere of heated dry air at a temperature ~. :!
of 100C - 120C was kept in the casing, and the tray cir-.cula1ting system was operated so that the above-mentioned ~acks of chawan-mush~, beef stew and curry roux were circulated.
T~e ~elation between the lapse o tTme and the temperature of ",~ the centr~l portion o~ eac~ sample is shown in the graph of ure 19.
Defrosting Te t ~A~ .. ~-icro-wave irradiation only ., . _ ,.;. .
.,. The inside of the casing was kept at xoom tem-peratuxe'~nd the tray circulating system was operated so that ',.; t~ay~ with'the sa~ples thereon were intermittently put into .~ t~e coyer and sub~ected to m~c~o-wave irradiation for three .,' ~i~utes at one t~me,' The relation ~etween the lapse of time 29. ~nd the temperature of th~ central portiQn o~ each sample is ., .
. ~ ~ 55 _ . .

.. . . .
'.,,. ~ . . ' : ' :' . - ~ . . . .
: . . . .

.. . ... . . .

~.~S333~
:.:
shown in Figure 20.
Defro ~ test (s~'~ ... oven and m~cro-wave irradiation together An ~tmosphexe o~ heated dry air ~t a temperature about 100C ~ 120C was m~intained in the casing. The tray circulatin~ s~ste~ w~s ~perated so that the trays with sa~d samples thereon were intermittently put into the cover ~., .
~nd subjected to micro-wave irradiation for three minutes at one time. The relation between the lapse of time and the ; tem~erature of the central port~on of each sample is shown in F~gure 21~
.... .
`~ Referr~ng to Figures 19-21, the results of the tests ~ill now be analyzed.
i Chawa~~mushi was heated to 1C after 20 minutes' ,: .
heatIng with the o~en only as shown in Figure 19 and to 30C
~lso a~ter 20 minutes' heating with micro-wave irradiation only ;. .
as shown in Figure 20, wh~le as shown in Figure 21 it was ~eated to ~8C also after 20 minutes' heating with both of ~i~ the oyen ~nd m~c~o~wave irradiation together. In other words, ~ co~b~ning the oven and mtcro-wave irradiation, a temperature 2Q ~8QCI far above th~ ~u~ o~ t~e temperatures obtained by ~ep~ately appl~ing e~ch of t~e two (1C ~ 30C = 31C) was .: .
~bta~ned; this may be termed multiple ef~ect.
After 20 ~nutes' heating, beef stew was heated to lloC wit~ the oven only ~nd to 30C with micro-wave irradiation :: , ~nL~ but ~as heated to 60C using both the oven and micro-wave ; ~radiation together. SImilarly, after 20 mi~utes, curry roux ~aS heated to 15C w~th t~e oven only and t~ 38C with micro-~ye irrad~at~on only while it was heated to 71C with both 29 ~ them to~ether.
cb~ ~ 56 -B
` ;~, , ., . . ,....... . . . . ~ . . . ;

'. ' ' ' : ` ' . ' ' ' ~5333~
In the same manner, the other e~perimental results ~f ap~l~ing ~icro-~a~e lrxadiat~on and steaming jointly ,............................................... .
t~ the precooked ~rozen foods ~re glvPn in Figure 22~
Figures 23 and 24 give experimental results obtained ; by ~ppl~ing stea~ing only or cooperatively with micro-wave irradi~tion to rIce d.ishes packed in a lunch-box.
,. . .
~s seen fro~ F~ure 23 and 24, excellent uniformity ~ n te~perature distribut~on through the foods can be obtained .~ by applying conductive and dielectric heating cooperatively.
Toda~, throughout the world, rice dishes which are ~n Or~ental food are served not only in hotels but in ordinary rest~urants. For example, a rice dish such as curried rice comprises rice and various kinds o~ materials such as minced eef, carrot, potàto, green ~eas, and curry powder. These ~ater~als have different heat transfer rates respectively due to the differences in thickness, size and water content.
Further, other rice dishes such as chicken rice, hashed meat .. . .
~ice, frizzlea ricef ~nd sushi which are Japanese foods also r",~ ~ye une~en heat transfer r~tes, and therefore if they are ~ 20 ~de Lnto frozen ~oods~ they are not uniformly defrosted ~.,i ~ ~ the conventional methods. In other words, it is subst~ntially ,, .
~mpo~sible to make these rice dishes into frozen food, and ~;; t~ere~ore they ha~e usual~y been put up in ~ans for preservation.
However, such canned rice ~oods have lo~t ~heir original taste ~nd thus there ~s l~ktle dem~nd therefor.
Now, these defects in the prior art have been o~er-co~e b~ the present defrosting method as clearl~ seen from t~e above examples.
Z 29 ~ apparent ~rom Examples 1 and 2 above, a dielectric '~ a~ - 57 -;;i, ~1 ` ~ , ' ' ' ' " ' ' ' ': , '` ' ~ :, ' ' ~0~3337 ~ heating treatment and ~ conductive heating treatment such as :. with an oyen ~re applied in combinatxon b~ means of a defrost-: ~ng ap~aratus according to the present invention. Precooked rozen food can thus be effectively de~rosted without uneven-~: ness in the extent of defrosting and in a short time defrost-. ~ng carried out in this way shows what has been referred to .. , abo~e as a he~ting temperature multiple effect, whereby pre-.- 8 Coo~ed frozen food can keep its pre-freezing taste.
, . :.

.,,. ~ .
, . .
.~:
~ :
, . .
... .

.

., .
... . .

.... .
:, ., .
.,, , . .
, ., :
.',', ' .
.... .

... .
'. .

~ cb ~ - 58 -.' .

~, . . , . ; . . ~

,, ~, . .. ~
. ~ , . .

Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of defrosting frozen food having a high water content in a convection-heating chamber, which comprises enclosing the frozen food, which reaches a temperature region in which ice crystals and liquid water coexist in the food, within a smaller chamber for dielectric heating and provided in the convention-heating chamber, and heating the frozen food in the smaller chamber by conductive heating and dielectric heating simultaneously while regulating the power of the two heating means to be at least approximately equal until the frozen food to be defrosted passes through the said temperature region.

2. A method as claimed in claim 1 wherein said conductive heating is carried out by at least one of the following methods:
heated dry air, heated humid air, steaming, immersing in hot water in a casing, and infrared irradiation.

3. A method as claimed in claim 1 further characterized by regulating the heating energies supplied from said two heating means to said food so as to achieve uniform heating through said temperature zone.

4. A defrosting apparatus for frozen food comprising a casing defining a chamber, a plurality of trays for carrying various kinds of frozen food thereon, means for circulating said trays along a fixed path in said casing while each of said trays is always retained in a horizontal position r the trays being removably mounted on the circulating means, the casing being provided with an inlet opening for the trays and an outlet opening for the trays, the outlet opening being sized to be as small as possible but to permit one tray at a time to be removed there-through, a cover consisting of a pair of half members movably mounted in the upper portion of said casing, means for closing said half members when actuated by the below-mentioned control means, means for irradiating micro wave energy onto said tray within said cover, means for selectively forming an atmosphere of heated dry air, heated humid air or steam within said casing, and a control means for successively actuating:
a) said means for circulating trays to position one of said trays between said half members, b) said means for closing said half members to define said enclosed chamber for enclosing a tray, and c) said irradiating means for a predetermined period of time.

5. The defrosting apparatus of claim 4 including means for spraying water onto said predetermined trays in said cover.

6. The defrosting apparatus of claim 4 including means for irradiating infrared rays onto said predetermined trays in said cover.

7. The defrosting apparatus of claim 4 including a control panel on the surface of said casing, the control panel having operating buttons for operating said control means and being colored in accordance with the defrosting conditions provided by the apparatus, each of said trays having a color selected from the colors of said buttons and in accordance with the defrosting condition to be applied to frozen food contained on the tray so that the selective operation for defrosting said frozen food is achieved by pushing the operating button having the same color as the tray.

8. The defrosting apparatus of claim 7 including means for spraying water onto said predetermined trays in said cover.

9. The defrosting apparatus of claim 7 including means for irradiating infrared rays onto said predetermined trays in said cover.