CA1065632A - Method of and apparatus for cooking foodstuffs - Google Patents

Abstract

ABSTRACT

A method of and apparatus for cooking food-stuffs by boiling and/or steaming including the steps of placing the foodstuff in a disposable liquid-tight film or foil insert which is open at the top, posit-ioning the insert in a cooking vessel so that it is spaced from the bottom and walls thereof and heating the foodstuff by means of steam and water in the vessel.
The insert may be of plastics material or metal. It may be shaped or in the form of a bag, and it is preferably held in a supporting holder within the vessel.

Description

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The present invention relates to a method of and apparatus for cooking foodstuffs, in particular by boiling and/or steaming.
When boiling food in cooking vessels it is usu-ally impossible to avoid deposits on the bottom and walls of the coo]cing vessel. In certain cases these deposits are extremely difficult to remove by cleaning. For this reason it is in many cases impossible to clean the cook-ing vessel in a satisfactory manner in, for instance, a dishwasher, and it is only with difficulty that it can - be cleaned manually. The deposits may also contain flav-ouring matter which tends to linger in the vessel, for instance as with potatoes, certain other vegetables and fish. In the preparation of food containing fat such as sauces, purees and milk, a fat deposit is obtained on the inner surface ofthe cooking vessel, which also makes clean -.r ::
ing difficult.
Attempts have been made to place inserts of a --disposable character in the cooking vessel, the insert consisting of aluminium foil for example being designed to be in contact with the inner wall and the bottom of the cooking vessel. -However, it has been found that for various reasons such an arrangement is not satisfactory. In the first place water or other liquid may be trapped between -the bottom of the vessel and the insert. Dur-ing heating this will rapidly vaporise and expand and -may resul-t in such violent expulsion of steam that the ~ contents of the vessel may be partially expelled.

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Secondly it is difficult to provide a suitable heat-resistant material with good heat transfer properties. Good heat-resistance is necessary because ex-tremely high local temperatures may occur on the insert due to direct contact with the cooking vessel. Even if aluminium foil is used for the insert, which in itself has good heat-resistance and good heat-conductivity, it is difficult to fit this to the shape of the cooking vessel so that no pockets of air, steam or water are formed between the vessel and the insert. This gives con-siderably reduced heat-conductivity and thus less economic heating. Further-more, unless coated with for instance a plastics material, aluminium foil is scarcely corrosion-resistant and is also sensitive to mechanical action. If a hole appears in the foil due to corrosion or mechanical action, liquid will leak out between cooking vessel and insert, resulting in the expulsion of steam and air mentioned above. If, on the other hand, the foil is coated with plastics, it loses its heat resistance and the plastics may burn because of the high temperatures which may occur.
According to one aspect of the invention there is provided a method of cooking foodstuffs by boiling and/or steaming including the steps of plac-ing the foodstuff in a disposable, liquid-tight film or foil insert which is maintained open at the top by a stiff flange that is thicker than the main body of the insert, positioning the insert in a perforated spacer within a cooking vessel so that the insert is spaced from the bottom and walls of the cooking vessel, so that a gap is formed between them, and heating the food-stuff placed in the disposable insert through the action of steam or water and steam in said gap, the insert closely fitting the inside of the perforated spacer.

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According to another aspect of the invention there is provided an apparatus for cooking foodstuffs by boiling and/or steaming including a cook-ing~vessel and an insert that is open at the top to contain the foodstuff, said insert being disposable and made of a liquid-tight foil or film material of similar shape to the vessel, and having a stiff flange at its open end that is thicker than the main body of the insert~ and perforated spacer means ar-ranged to maintain said insert supported and spaced from the bottom and walls of the cooking vessel, with the shape of the insert being such that it closely fits the inside of the perforated spacer means.
According to a further aspect of the invention there is provided a disposable bowl shaped container for use in heating solid and liquid food-stuffs either separately or together, said container comprising: a liquid tight plastic member having an open upper end and a bowl shaped body portion having an unpleated wall and integral bottom, said body portion being thermo-formed to be sufficiently thin and flexible so as to be capable of being fold-ed and crushed by hand to facilitate disposal of said container; an annular semi-rigid flange integrally formed at said open upper end of said plastic member and extending generally outward and away from said side wall of said . body portion; and said flange having an inner edge integrally formed with said side wall about the entire circumference of said side wall of said body portion at said open upper end of said plastic member and having a downwardly extending free end surrounding at least a major portion of the curcumference of said flange, and said flange being sufficiently strong and cooperating with said body portion to maintain the integrity of said bowl shaped body por-tion when a foodstuff is deposited in said container.

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When preparing food by boiling, for instance, water is poured into the cooking vessel up to a suitable level. If the vessel is placed on a hot-plate the water in the bottom of the vessel will be brought to a boil. Steam will be produced and at least some of this steam ;:

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- will condense on -the outer surface of the insert, the heat being transmitted through the wall of the insert to the foodstuff. If the level of the water is suf- -- ficiently high in the cooking vessel for it to come into contact with the bottom of the unit, heat may also be conducted directly through the casing and the insert.
Some of the steam produced by the boiling water may also be directed over the upper edge of the insert so that - the steam condenses directly on the foodstuff.
If water or other liquid leaks through a hole in the insert into the space between the insert and cook- ~ ¦
ing vessel, there is no risk of explosion. Furthermore, the material of the insert need not be especially heat-resistant since the holder is separated from at least the bottom of the vessel and the temperature of the insert walls will not therefore exceed 100C during cooking. -The invention will be more clearly understood from the following description which is given by way of example only with reference to the accompanying drawings - 20 in which:-Figure 1 is a section through a first embodi~
ment of apparatus of the invention;
Figure 2 is a view from above of the appara-tus shown in Figure l;
Figure 3 is a section through a second embodi-ment of apparatus of the invention;
Figure ~ is a section through a third embodiment of apparatus of the invention;
- Figure 5 shows the apparatus according to Figure S6~;~

4 as seen from above.
. ~ Figure 6 shows an enlargementof a part of the supporting holder shown in Figure 4 Figure 7 is a section of a serving dish designed to receive an insert the m~ans and holder o~ apparatus -of the invention;
Figure 8 shows a section through a fourth embodiment of apparatus of the invention;
Figure 9 is a temperature-time chart of a cook-ing process using apparatus as shown in Figure 4 Figure 10 is a temperature-time chart in resp-ect of experiments performed using apparatus substantially in accordance with that in Figure l;
;. Figure 11 is a view of a bagshaped insert;
Figure 12 shows the insert of Figure 11 arra~
nged ln a casing, Figure 13 shows a detail of the collar of the casing of Figure 1~; and -~- Figure 14 shows a detail of the arrangement of .
~0 an insert in the casing. . . ~- .
In Figure 1, numeral 1 designates a conventional cooking vessel with a handle 2a The cooking vessel is provided with a lid 3.
A unit 4 is placed in the coo~ing vessel, this unit ~5 comprising a thin liquid-tight and heat-conducting insert

5 surrounded by a supporting holder or casing 6. The casing 6 is relatively rigid and in the embodiment shown ., in Figure 1 it is placed on a spacer 7 which in turn rests on the bottom of the vessel 1. Both casing 6 and insert 5 - ' ' .' ', . .

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are substantially cylindrical and are open at the tup, i.e. towards the lid 3. The casing 6 has a reinforcing ring 8 around its upper edge. A number of apertures 9 -are provided in the casing 6. In the embodiment shown the casing consists of the upper ring 8 and a perforated cylindrical surface and bottom. In use, water 10 is fil-led to a suitable level in the vessell~for instance to the level of the spacer 7 as shown. Suitable lateral spacers are arranged so th~ the unit 4 is centered symm-etrically in relation to the vertical axis of symmetry of the vessel 1, i.e., so that the space between the inner wall of the cooking vessel and the unit 4 is substantially the same all around the wall of the cooking vessel 1.
Water 11 is placed in the insert 5 to a certain level so that it at least partially covers foodstuff/to be cooked in the insert 5.
To boil the foodstuff, the cooling vessel 1 is placed on a hot-plate or some other source of heat. As with traditional boiling, the water 10 in the lower space of the vessel should preferably be brought to the boil rapidly, that is to say with the hot-plate set at maxi-- mum heat. During the heating process steam will gradually be produced by the water 10. Initially, the steam will come into contact with the cooler wall of the insert 5 ?
whereupon the steam will condense thus liberating heat through the thin insert 5 to the water 11 and the food~
stuff 12.
As heat is supplied to the foodstuff 12 its temperature increases and a certain amount of excess ~1065~i3~ ~
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steam passes through the space 13 between insert 5 and the wall of the vessel. In the apparatus illustrated, some of the steam can pass over the upper edge of -the unit 4 and will also partially condense on the exposed surface of the water 11 and the foodstuff so that heat is also transferred in this manner. Furthermore, as with tradit-ional boiling, there will be a certain amount of conden~
- sation on the lid 3, which is preferably and as shown pro-vided with a drip edge 14 in known manner~ As the heating process continues excess steam will find its way to the surroundings, as with traditional boiling, either by pas-sing between the upper lip 15 of the coo~ing vessel and the corresponding edge of the lid or through apertures pro-- vided in the vessel or the lid for this purpose.
As with traditional boiling, an increasing quantlty of excess steam reaching the surroundin~ indic-ates that the heating up stage is almost over and that . .
it is advisable to reduce the heat supplied. By setting this at a lower level the quantity of excess steam can be kept down. As described earlier, the quantity of water - 10 in the bottom of the cooking vessel 1 is small so that the surface of the water is below the bottom of -the casing. In this case the effect wiil he that of a heat pipe, steam from the water 10 will condense on the surface of the insert 5 and the condensate will then run back into -the vessel 1 where it will once again ~ -be vaporised and the process repeated. Assuming that the insert has good heat-conductivity, being made of a suitable thin material, considerable heat can be rapidly .

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-transferred from hot-plate to foodstuf~. However, it has also been ~ound tl~at the water level at the bottom of the vessel may be so high that the unit is partially immersed without the heating and cooking processes deteriorating. However, if the water leve]
is too high the thin insert may be disturbed by vig-orously boiling water and start vibrating in the casing which may be a drawback in certain cases.
As shown in Figure 1, the process takes place under a lid in order to reduce the heat losses, especially if the space between the unit`4 and the wall of the cook-ing vessel is large.
When cooking is complete the unit 4 may be lifted out of the cooking vessel 1, for instance with the ~- 15 help of a separate handle which can be fitted on -to the ring 8 at an attachmen ieans 17. The unit consisting of the insert 5 and the casing 6 may now be placed dir-ectly on the table for serving. However, -the insert 5 alone or the unit ~ may also be placed inan outer bowl which can have a lid and is shaped to receive the insert - or the unit. If the food is not all consumed, either the insert 5 alone or the complete unit ~ may be used as a storage container for the left-over food, for inst-ance in a refrigerator or freezebox. Leftovers stored in this manner can then be placed in the cooking vessel and reheated to serving temperature, using a smaller quantity of water 10, upon a later occasion.
Since the insert consists of a thin-walled mat-erial which in itself need not have particularly good _ g _ 3L~65~3'~

mechanical properties such as st:Lffness, or even have high heat-resistance, it is possible to mass-produce the inserts inexpensively. Since also an inexpensive material such as plastics or aluminium foil can be used, inserts manufactured in this way can be readily dis-posed of after use. The insert 5 may be given an appr-opriate shape in relation to the casing at the time of manufacture. In one embodiment the insert is made of aluminium foil preshaped as a bowl to fit the shape of the casing. Another suitable construction of the insert 5 is in the shape of a bowl or trouyh manufactured by means of hot-forming, for instance vacuum-forming of plastics foil. Such inserts have the advantage that they can be made relatively stiff, at least at the top, to facilitate handling. In a third embodiment the inse-rt 5 may be made of a plastics film in the form of a bag or the li~e, shaped to fit inside the casing~ This latter embodiment has the advantage that it can easily be folded flat for storage. Bagshaped inserts, an exa-mple of which is shown in Figure 11 can be made accord-ing to the known techniques for making li~uid-tight plastics bags such as shopping bags or bags utilised for storing deep frozen vegetables. Such a bag made of a thin flexible material placed in the casing as shown in Figure 12 and filled with for instance the liquid to be boiled, wlll, due to its flexibility, assume a shape conforming to the shape of the casing. The upper edge -of the bag can be folded over the edge of the casing and ;
fixed in position by a separate holding ring or a ring ' . , - . ,, ~:, :
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attached or connected to the open end of the bag.
Irrespective of wllether the insert 5 and casing

6 are to be used for ~reparing food, storing food or heating up food,therefore, the insert can be thrown away after use since it can be made so cheaply. The cooking utensils need not therefore be cleaned after use, nor of course the serving dish in which the insert or the unit is placed for serving or keeping the food.
According to the invention it has been found that many cooking operations can be performed in the same cooking vëssel without the vessel having to be washed. This is a great help in the housework, particularly when preparing dishes which tend to leave deposits on the walls of the cooking vessel which are difficult to remove.
As will be described below, the cooking time and energy consumption is approximately the same when using the apparatus accoxding to Figure 1 as compa-red with traditional cooking. Burning does not occur, presumably because the surface temperature of the insert never exceeds 98-99C or thereabouts. As is ]~nown, burning - is usually caused by the foodstuff being heated locally - to a high temperature. It has been found that milk, drinking chocolate, vegetables and fish boiled by the method of the invention do not boil over. It has also been found that eggs have less tendency to crac~.
Furthexmore, it has been found -that by using the apparatus of Figure 1, vegetables and fish, for instance, can be steamed. The foodstuff is in this , :~
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case placed in the insert without water and cooked with - the lid on. Steam will then finds its way between the unit and the wall of the cooking vessel and pass over the upper edge of the unit to condense on the walls and the surface of the foodstuff. Thus, not only is the advantage gained that the cooking vessel is not dirtied by using the insert, but at the sanetime the advantages _ associated with steaming certain foodstuffs are also obt- ;
ained, namely that the flavor is retained better. Steam-ing generally takes somewhat longer than boiling in acc- ~ -ordance with the method described above, however~ -The insert 5 shown in Figure 1 is preferably provided with a pouring lip. Figure 2 shows the appar-atus shown in Figure 1 seen from above with the lid rem-oved. The insert 5 has in this case been provided with a pouring lip 16. This fits over the ring 8 of the casing and also preferably bridges the gap between the edge 8 and the lip of the cooking vessel 15. This pouring lip 16 enables the contents of the inserts to be poured ~
- out while the insert is still inthe cooking vessel, with~ ~ ;
out cooked food dirtying -the vessel or the casing 6.
Even if the unit ~ is lifted up out of the vessel 1, the lip 16 provides protection against dirtying if the contents are poured out of the casing 6, for instance with the help of the detachable handle mentioned above, or in some other way. The pouring lip 16 shown in Figure 2 is only one example. The pouring lip 16 may of course be constructed in other ways. Another pouring edge may for instance be placed opposite the one shown in Figure 2. However, it is .
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advisable for the pouring lips 16 to be arranged to per-mit a certain passage of steam from the space 13 to the inside of the insert 5. As mentioned earlier, a det-achable handle may also be arranged for application on the casing 6. An attachment means 17 to take such a handle has been indicated in Figure 2. Similar attach-ment means 17 may suitably be distributed around the peri-phery of the ring 8, possibly serving at the same time as spacers between the casing 6 and the walls of -the cooking vessel 1.
Figure 3 shows a second embodiment of the inve-ntion. Here the cooking vessel is designated 18 and a support means 19 having an upper edge 20 is arranged there-in. The support means 19 may comprise a number of legs made of sheet-metal, for instance, which are bent upwardly and inwardly as shown in Figure 3. The casing, preferably consisting of a wire basket or a perforated material, is designated 21. The casing 21 has a flange directed out-wardly and downwardly, this flange being designated 22.
The flange is arranged to rest on the edge 20 of the sup-port leg. The flange 22 of the casing 21 is also perfor-ated or consists of mesh so that steam can pass through it. The casing 21 with its flange is positioned centrally in the vessel 18. An insert 23, for use once only, is placed in the casing 21. In the embodiment according to Figure 3 the insert 23 has a flange 24 which fits at least partially over the flange 22 of the casing 21. A lid 25, prefera~ly provided with a drip edge 26 is placed on the cooking vessel 18. In this case also the thin insert 23 is ~06563;~:
suitably provided with one or more pouring lips~ One such pourin0 lip is designated 27 in Figure 3. Since the ~
insert 23 is made of a thin, yielding material, the pour -ing edge 27 can be shaped to fit the drip edge 26 of the lid 25 to form a seal between the flange 28 of the cooking vessel and the corresponding outer edge of the lid 25.
As with the embodiment shown in Figures 1 and 2, water is poured into the vessel 18 to a suitable level.
Here also heating up and boiling occurs both by means of heat transfer by steam condensing and also possibly by heat conducted directly from the water at the bottom - of the cooking vessel 18 to the unit comprising casing 21 and insert 23 suspended in the vessel 18. The embodiment . . . .
according to Figure 3 has certain advantages over that shown in Figures 1 and 2. When preparing purees and sauces it is often necessary to beat the mixture either --during or after cooking. Difficulties may arise in the embodiment according to Figure 1, especially if the dis posable insert is very thin and yielding as when it is made of aluminium foil. In such a case the insert with its contents may be drawn in during beating so that it 'loses contact with the casing. This may result in the insert folding down into the mixture which then spreads over the edge of the insert, thus being sp~iled and dirty-ing the casing and the cooking vessel. The embodiment according to Figure 3 has the advantage that the flange ; 24 holds the top of the insert in contact with the flange .
22 of the casing 21 thus permitting vigorous stirring or beating. In both the embodiments shown so far it is .' ' , , : .

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preferable for the inser~s and also the casings to be designed so that they can be s-tacked one inside the other~
Thus, in the embodiment according to Figure 3 it is advis-able for the flange 24 to be shaped so that the inserts ~--~ 5 can be stacked.
Figure 4 shows another embodiment of the invention.
A casing 29 is arranged in a cooking vessel 28, the upper part 30 of the casing 29 fitting over the upper part 31 of the vessel 28. A disposable insert 32 is placed in the - 10 casing 29. The insert 32 also has an upper flange 33 which fits over the flange 30 of the casing 29. The casing 29 - is perforated and at least the lower part preferably con- sists of a mesh basket of suitable materail.
The protuding part 30 of the casing 29 may con-slst of homogenous material but in this case steam apert-ures 34 are provided at least at certain points in the collar. Holes or slits 35 are suitably arranged in the same manner in the disposable insert 32, this also being designed so that the slits 35 can easily be positioned over the steam apertures 34.
Figure 5 shows the apparatus of Figure 4 from above. The upper flange 30 of the casing 29 forms two projections 36 and 37, which protude over the flange 31 of the cooking vessel 28 and provide handles for lifting the casing 29. Suitably, and as shown in Figure 4 the `
handles are provided with a heat-insulating section 38.
The insert 32 can be similarly extended from the flange 33 so that the handle 36 is covered by the thin material of the disposable insërt (see 39, Fig. 4). The embodiment ', '' '.

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accordin~to Figure 4 and 5 has certain advantages o~er the embodi~lents shown previously. Due to the shape of the '' ' casing 29 no separate support means or centering means is required to position the casing 29 in the vessel 28. ~,' With the aicl of the protruding handles 36, 37, which con- ¦ "
~ stitute e,xtensions of the casing 29, the casing can easily - be lifted out of and into the vessel 28 without the nec-essity of a separate handle. With the aid of the flanges -30 and 33 on casing 29 and insert 32, respectively, the insert 32 will be retained at the upper edge of the cas-ing 29 during stirring. Since the insert 32 fits over the flange 30 of the casing 29 and also over the flange , ~
of the cooking vessel 28, the contents can be poured ~' out without risk of dirtying the vessel 28. ,,-The flange on the insert also stiffens the ~
~ , . ' upper part of the insert making it easier to handle and , lift into and out of the casing when it contains the foodstuff. In certain cases, therefore, the in,sert with ~,.
, the foodstuff can be placed on a suitable,sur-face without the casing being used. In this case the extending parts 39 of the insert can be used as handles. , Figure 6 sho~s a detail of the casing 29. The upper edge, with the flange 30, is provided with steam apertures 34 as mentioned previously. The rest of the casing consists of a mesh 40 of suitable material, rel- , atively stiff in comparison with the insert. Since the ,insert 32 is also provided with protruding parts 39 -corresponding to the handle 36 in the casing it is easy ; to guide the insert to such a position that the apertures '.' , - 16 - ' ;

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35 in the insert 32 communicate with corresponding steam apertures 34 in the casing 29. The apparatus according to Figures 4 and 5 can be provided with a lid in suit-able manner.
As mentioned earlier, it is important that at least-the casings 29 are shaped so that they can be stacked into each other for storage. Since the disposable inserts with their casing can be used not only forcoo~ing, but also for storing and serving food, there must be several casings to fit one si~e of saucepan in every house-~
- ' hold. According to a preferred feature of the invention the casings are designed so that they can be stacked in-side each other to require a minimum of space. As shown in Figures 1, 3 and 4, both insertand casing have been made slightly conical to facilitate stacking.
The disposable inserts can also be used for -~
storing food prepared earlier, as mentioned above. Fig-ure 7 shows a means for serving or storing food using the same disposable insert as previously used for preparing the food. The disposable insert 32 shown in Figure 7 with the casing 29 or 40 has the same shape/that pre-viously shown in Figures 4 and 5. The insert 42 with casing 40 is i~ Figure 7 placed in a bowl-shaped outer ~-dish 41. Because the bowl is suitably shaped, the insert 32 with its casing will remain suspended and centred in relation to the bowl wall so that a space 42, 43 is formed. This provides good heat-insulation. A lid ;
44 is placed on the vessel 41, prefera~ly having a handle ' . , , : ' ' ' , ''' ~:
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45. The dish 41 lS preferably al,so shaped so that sev-eral dishes can be stacked one into the other~ The lid 44 should also preferably be stackable. In the embodiment shown, furthermore, another dish 41 with its contents can be stacked on top of a simi~r serving dish wi-th lid 44 if the bottom of the dish is provided with a raised sect-ion 46 fitting into the handle 45 of the lid below. Of course, the method of stacking sho~n here is only one example out of many possible embodiments. In many cases it is convenient for the insert without a casing to be pla-ced in a dish with lid, designed to fit the shape of the insert, for instance for serving or storing after cooking.
- This dish may be double walled to provide good heat insu-lation. The inner wall of the storage dish may possibly be perforated or consist of mesh.
Thus in a complete system according to the inv-ention for preparing, keeping, serving and reheating food, one and the same disposable insert can be used.
- The system is exemplified in the following manner refer-ring tothe apparatus of Figures 4, 5 and 7.
A suitable cooking vessel for preparing food - is taken, together with an appropriate casing and dispos- ;
able insert. The disposable insert is lowered into the --casing in such a way that the steam apertures cover each -~ 25 other. The unit consisting of casing and insert is placed in thecooking vessel after a suitable quantity of water has been poured thereinto. The food to be cooked is pla-ced in the insert. The lid is then placed on the cooking vessel and the boiling process is initiated, being performed ~
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as described above. The quantity of heat is thus regul-ated according to how much exceæs steam escapes between the edge of the lid and the vessel or through specia~
holes in the lid.
In the embodiments according to Figures 4 and 5 cooking may also be performed without the lid since the steam losses will be relatively small assum~ng that the steam apertures are not too large.
When the food is ready it can, of course, be served`straight from the cooking vessel. However, for many reasons it is preferred to use the storage and serving system proposed. In this case the unit is for instance lifted out of the cooking vessel 28 according to ~-Figure 4 and placed in the ~orage an~ serving dish 41 according to Figure 7.... If the food is not to be consumed immediately it should be covered withthe lid 44, The lid - 44 may possibly be provided with extra heat insulation.
It has been found that newly cooked food can be kept hot for a relatively long time in the outer dish 41 described in Figure 7. '' ' If the food in the dish 41 is only partially consumed, the dish together with unit and contents can be ,' - used for ætorage in a refrigerator or deep-free2e. If ~, the food i~ to be reheated, the unit is lifted out of the ;;-outerdish and once again placed in,a cooking vessel, after `
which the food can be quickly reheated as described earl- ; ' ier. The unit can then once more be lifted out of the - , cooking vessel and placed in the serving dish. When ~' the food is consumed the disposable insert is removed - 19 - .

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from the casing and -thrown away.
Thus, as described above, within the scope o~
the invention, the thin, disposable insert has protected the cooking vessel from becoming dirty during preparation of the food as well as protecting the storage dish from becoming dirty during serving and if stored. The invention thus also covers a method, using inexpensive, thin, dis-posable inserts which are strengthened and stiffened by being combined with a casing permeable to steam and water, - 10 of ut~ising the disposable insert so that the foodstuff -will be kept in the same insert during preparation, storage and serving. This not only avoids cleaning the cooking vessel, but also the storage vessel~ Further-more, there is less waste since thefoodstuff does not have to be transferred from one vessel to another.
So far, apparatus according to the invention has been described in which water is poured into the - bottom of a traditional cooking vessel in order to cook foodstuff by steaming when heat is applied. The invention also covers other methods and mea~sfor cooking ` ;
using disposable inserts. It is, for example, possible to use means other than those described for applying .
heat and producing stea~. The invention can thus be ~-used to cook food in special cooking apparatus which ~n -be automated to a certain extend in order to facilitate the cooking process. Figure 8 reveals such a device.
- In this figure numeral 47 designates a cooking vessel placed on a hot plate 48. Numeral 49 designates a casing similar to that described previously. A -.
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disposable insert 50 is placed in the casing 49. A lid 51 fits over the vessel ~7. The base 52 of the cooking arrangement according to Figure 8 includes a means for producing steam. This is not shown in Figure 8 but may comprise an electric coil of the type employed in auto-matic coffee-making machines. A container 53 for liquid is placed above the steam generator. A steam channel 54 - provided with a suitable connection at 55 directs steam to the space between the wall of the vessel 47 and the casing 49. The steam produced is condensed while at the same time transmitting heat to the outer surface of the - insert 50. Steam also passes through apertures in the insert to heat the food to be cooked.
The condensate run,s down to the bottom of the vessel 47 and is vaporised again by the heat Erom the plate 48. The device is preferably provided with a dispensing means for the continuous supply of water and ~;
steam in adjustable quantities. The device is alsop~e-ferably provided with a timer and thermostat. The latter can be set in suitable manner so that a suitable rate of vaporisation is obtained from the bottom of the cooking vessel. Among the advantages obtained with an arrangement like the one shown in Figure 8 include the fact that the cooking process can be automated by using the thermostat and time-setter. Furthermore, the water is brought to the boil quickly since the quantity of water is adjusted ~-to the capacity of the vaporiser and vigorous prodvction of steam will be obtained shortly after the machine is started. The water supply to the vaporiser may be controlled ,. ., ' : ': '' ,., ,' ;:

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by a timer. The use of a thermostat com~lned with the vaporiser prevents boiling clry. Instead of a timer `
to control the water~supply, the quantity of water poured into the container 53 may be adjusted to the desired cooking time. This can easily be achieved since the water container 53 is preferably transparent and marked with graduations 53a.
The device shown in Figure 8 is only one example of the many ways within the scope of the invention of mak-ing use of the great advantages gained by the use of thin, disposable inserts of the type described earlier, combined with the reinforcing casing.
It has been mentioned earlier that the dispos-able inserts should be liquid-tight and have good heat-conductivity. In some cases a metal foil, such as lumin-- ium, is a suitable material and the thickness may be 0.01 to 0.04mm, 0.02 to 0.03 mm being preferred.
In other cases, however, drawbacks have been found to be associated with the use of aluminium foil. It is for `
instance difficult to shape aluminium foil other than by pleating it to provide the vertical walls of the insert.
However, the wall of the insert then has poorer heat-conductivity than the bottom. Thus aluminium foil which -~ per se has excellent heat-conductivity, has certain other drawbacks. If the foil is thin, small holes may easily be caused by corrosion, steam or by acids in, for example, vegetables. It is therefore preferable, though not essential to coat the foil by lacquering or laminating it with a film of plastics in order to improve the anti-: ' . ` , :

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, corrosion properties. At the same time the foil is also strengthened. ~owever, such materials are rel-atively expensive and there remains the problem of shaping the foil, particularly in the case of inserts having a flange as shown in Figure 4.
Careful studies have shown that in certain cas-es a plastics film or foil is suitable for making the disposable inserts, assuming o~ course that the material ` is suitable for contact with foodstuff. Although plast- ¦
ics such as polyolefins, polystyrenes, styrene/butadienes, PVC, all of which are suitable for hot-moulaing, have ¦ ~ `
; considerably poorer heat trans~ission coefficient than .,. :'.' aluminium, for instance, it has been found that satisfact- ;
ory results can be obtained using disposable inserts made of such materials under the assumption that good heat- ;
conductivity is obtained by making the insert sufficiently thin. Disposable inserts have been made from HD-polythene by means of hot moulding, for instance, with very good results. It has been found that a special type of HD-polythene, namely, a so-called HD-HM-polythene has ;
given extremely satisfactory results since the material is suitable for hot moulding and the walls can be made extremely thin so that the insert can easily be bunched - up after use so that the used mould does not take up much 25 ~ space. An insert can be made in this materail which has a wall-thickness of about 0.01 mm at the thinnest part.
Conventional moulding technique of course enables adjust-ment of the wall-thickness of the inser-t to its function so that the upper parts of the insert are slightly thicker ,':
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- 23 _ . :

~L06563'~

to provide a certain stiffness. A wall-thickness as thin as 0.01 - 0.06mm offers great advantages in t~le form of good heat-conductivity,little consumption of material and easy compressibility upon disposal~ On the other hand such an insert may be difficult to handle in certain cases, not least during manufacture, and it is therefore sometimes preferable for the insert to have considerably greater wall-thickness~ Greater thickness is also to be preferred if the inserts are to be used without a suppor-t-- 10 ing casing. The foil used may in such cases have a thick-- ness of up to 2mm, although this is not deslrable, partly for reasons of cost.
Good heat-conductivity is also obtained in - inserts manufactured by means of hot-moulding since the vertical walls of the insert are smooth and better ;
heat-conductivity is obtained than with a pleated aluminium foil wall. The advantage of a thin dîsposable insert is of course not only that of good heat-conductivity.
It is important that the disposable insert is inexpensive `
and since the cost of material are a major part of the - manufacturing costs for disposable inserts, a thin insert is also desirable from the cost point of view. A third advantage is also gained, as mentioned, and that is that if the disposable insert is thin it can easily be crushed when thrown away, so that it occupies very little ~pace in the refuse bin. '~^
HD-polythene has previously been mentioned by way of example as suitable for inserts made by means of hot-moulding. This is, however, only one example. Many :

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~6~63'~

.
other plastics materials suitable for moulding to the desired dimensions can also be used within the scope of th~ invention. When vacuum-forming a thin plastics film or foil, for example, , it may also be advis- ;
able for the insert to have greater thickness at the upper edge than at the bottom and the lower portions of the sides. In this case the advantages of good heat-conductivity, low weight and easy crushability are obta-ined while at the same time the upper edge is given a ' ;
10 certain stiffness since the material is thicker there as well as being reinforced by the formation of a flange.
The stiffness in the upper edge facilitates handling of the disposable inserts. ' - As emphasised previously, it is important that 15 the disposable inserts do not weight too much, not the least from the cost point of view. It may be mentioned ~-that disposable inserts having a volume of 1 liter which were manufactured for various materials were found to have the following weights:
-Material Initial ThicX- Weight, g ness'_mm _ Aluminium 0.025 3.5 ;~
- Vacuum-formed polypropylene 0.4511.0 Vacuum-formed polythene 0.18 4.5 Vacuum-formed polythene 0.15 3.7 Vacuum-formed polythene 0.09 2.3 Polythene bag having a stiff 0 0~ 1.5 ,-upper edge As the table shows, a disposable insert of poly-thene, for instance, can bemade with substantially the ' ''~. ' ; , .

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~1)6~ii63'~ `
same weight as a corresponding insert of aluminium foil.
As mentioned earlier, extensive studies have been made in preparing food by boiling in accordance with the invention. The studles have also covered - comparison with boiling in water in the traditional manner. Steaming has also been tried, that is to say without liquid inthe insert~ The following examples are of experiments perEormed, cooking in various ways in accordance with the invention and comparing the results with traditional boiling. The cooking process - is described in the form of a temperature-time chart.
- In all the examples the process has been divi-ded into a stage in which the water was-brought to a - 15 boil with maximum heat in the form of electrical heating and, after a certain time, a stage with less heat suppl-ied, this being the same for all the examples given below.
Example 1:
In this example measurements were taken when boiling water in a normal cooking vessel with a lid, us-ing 9.5 dl of water. Water was afterwards heated in a - disposable insert corresponding to the apparatus of Fig-ure 4, by way of comparison. The quantity of water in the insert was 7 dl and in the bottom of the vessel 2.5 - foil dl. The disposable insert was made of aluminium/having a thickness of 0.025 mm. A third experiment was performed using the same quantity of water and the same disposable insert, but with the bottom of the insert somewhat ~ 26 ~

~ ~ ~ - --r . ~. .1.

~.

10-i56;~

immersed in the water at the bottom of the cooking vessel. ~ thermometer was secured to the lid of the vessel with the operative portion at the same level 1below the surface o~ the liquid in all the ~xperiments.
In all three experimen-ts the heat supplied during the boiling up stage comprised 1200 Watts from an electric hot plate for a period of 8.5 minutes, after which the heat was reduced to 600 Watts. Figure 9 reveals the temperature-time chart. From t~s it is clear that the boiling up stage was slightly different for traditional - boiling and for the two methods according to the invent-ion. After approximately 12-13 minutes tobal cooking time a constant state is obtained. As is clear from the example shown, a negligibly higher temperature is obtained for traditional boiling than for boiling in an insert of aluminlum foil. On the other hand, apart from the - boiling up stage, the same temperature was obtained whe~
her the disposable insert is immersed in the liquid at the - bottom of the cooking vessel or not. As mentioned, the boiling up stage took slightly less time with traditional boiling. The same is true for boiling up with an immersed insert. This is probably because better heat-conductivity .-:
is obtained during the first stage of the heating through direct contact than if the insert is not immersed. How-ever, the difference in heating rate only applied up to 70-80, after which it is probably immaterial which of the embodiments is used.
- Example 2~
: .
Figure 10 illustrates the results of another ~ ~
';'-, ~;563Z

series of experiments by means of a temperature-time - chart. In this case boillng has been performed using - inserts o~ three different types as well as traditional boiling. As in example 1, the total quantity of water - 5 in each case was 9.5 dl. The temperature-time chart is shown in Figure 10. The means used correspond substant-ially to that shown in Figure 1 but without a lid. The heat supplied and the time interval during boiling were the same as in the experiments described earlier in con-nection with Figure 9. It may be seen that there is a slightly greater temperature difference between the curve for traditional boiling (70) and that according to the in~ention. It can also be established that the curves are different for different materials.
The dot-dash-line curve 71 illustrates an -experiment using aluminium fo:il for the insert having a thickness of 0.025 mm. The curve 73 shown as a dotted line illustrates a vacuum-formed insert of HD-polythene having an initial thickness of 0.1~ mm. The broken-line curve 72 shows an insert made of vacuum-moulded polypropy-lene having a thickness of 0.45 mm. It can be seen that the aluminium foil and the polythene have very similar curves whereas the polypropylene shows a more deviating course.
As also mentioned, extensive studies have been made in preparing foodstuff in accordance with the invent-ion and comparisons have been made with boiling in water in a traditional manner. In all cases the foodstuff was cooked using the same boiling programme for traditional - ' ~, .

~o~S~i3'~ ::

boiling as in accordance with the invention. Samples were then taken and the result tested. Testing was both visual and by taste. Sampling was performed by -a jury who gave their verdicts without knowing the man-ner in w~lich the food had been cooked. The result showed that potatoes, vegetables, meat and fish, i.e., food re~uiring relatively long cooking times, did not differ in the cooking time according to the invention or for traditional cooking. In the preparation of food requiring only a short period of heating up, such as ready-made soups or boiling eggs, slight differences in cook-ing time have been observed, i.e., it has taken slightly long~r with the method according to the invention.
-However, the~differences are such that they must be con-sidered lnsignificant in comparison with the great advantages gained by the method according to the invent-ion. It has been found that deep-frozen foods can be thawed by placing them in the insert and then heating `
- them by means of steam from the water in the bottom ~ of--the-cooking---vessel,-for-instance. An extra high ~ supply of heat should be used for quick thawing. Due to the great temperature differences between the cold food and the steam, considerable quantities of steam will be condensed, thus resulting in rapid thawing~
Also included in the system for preparing, ser-ving and storing food is the deep-freezing goods in a ~' mould shaped to fit the insert, so that when placed in the insert, preferably having removed wrapping applied for deep-freezing, the deep-frozen product has good contact ~. .

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; with the walls of the insert to facilitate thawing.
In certain cases, the food can be frozen and stored directly in inserts which can then be placed in the casing for thawing and possibly also preparing, serv-ing and keeping in the saneinserts.
The insert proposed according to the invention may also suitably be made in the form of a bag, preera-bly kept substantially flat until required for use~ In the foregoing it was mentioned that the bag may be folded over the edge of the casing in fixed in position by a separate or fixedly attached ring. In Figure~ 13 and 14 details of such ring means are shown.
In Figure 13 a detail of another embodiment of the invention is shown. ~ccording to this embodiment the upper collarshaped part 56 of the casing consists of a ring which lies on the upper edge 57 of the cooking vessel. In cross-section the ring preferably has such a profile that it has an opening 58 inwardly directed towards the centre of the ring. The ring i5 attached to a basket 59 preferably consisting of a net or the like.
The disposable insert 60 has an upper part 61 which is arranged as a collar over the part 56 of the casing~
Steam passages 62 in the shape of apertures or the like are arranged in the disposable insert. A lid 63 of the cooking vessel rests on the upper collarshaped part.
The embodiment of the invention shown in Figure 13 has several advantagese Steam may pass from the bottom of the cooking vessel to the foodstuff to be boiled in the disposable insert without an arrangement of correspond-' 106S63'~

ing steam apertures in the upper part of the casing.
The steam may thus pass through the upper part of the net basket via the space which is formed by the wall 56 and the upper part of the disposable insert and through the apertures 62 of the wall of the disposable insert as suggested by the arrows in Figure 13, which give the direction of the steam flow. Another advantage - of the embodiment of the invention shown in Figure 13 is that the lower, flat part of the ring resting 1 against the edge 57 of the cooking vessel may be made so wide that it closes tight all way -round even if cooking vessels having different diameters are used. By applying -:~
suitable dimensions of the ring and the insert special means for centralizing ~he casing are not needed. Even if the casing is placed unsymmetrically in the cooking vessel the net basket 59 will always keep the casing in such a position that a cloæ fit is obtained all way round between the lower flat part of the ring 56 and the upper flat part 57 of the cooking vessel. The absence of special means for centralizing makes the handling of the cooking equipment easier, as a single size of the ;~
casing fits cooking vessels of different diameter. This is important as in this way the mass production of cas-ings is facilitated. The embodiment of the ring shown in Figure 13 is moreover adapted for mass production as the ring may be produced from a preshaped band, which means that no excess material has to be disposed of and, as already mentioned above that no special steam apertures have to be arranged in the ring. A handle ~ -, . '. :.
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106563~

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may also be arranged very easily in the outer wall of the ring. By making the ring rather high, disposable inserts which are relatively deep compared with the cooking vessel may be used. The însert may be produced as a bag which is applied to the upper rim of the casing with o~ without using a ring.
One type of ring may thus be separate and be brought to surround and retain the folded upper part of the bag after the bag has been placed in the casing. In another embodiment a ring e.g. in the form of a band, is attached to the upper rim of the bag. If the bag ~ i should consist of a thin foil of thermoplastic material the band may consist of a similar material having larger wallthickness, which band is fixed to the bag e.g. by lS means of heat welding to the upper rim of the bag.
In Figure 14 a detail of an embodiment is shdwn wherein a bag having a thicker upper rim in the ~ ~.
form of a band has been placed in a casing of the same kind as shown in Figure 13. The upper wall of the cooking vessel has been denoted 64, the collarshaped part of the s casing is denoted 65 and a net basket is denoted 66~ The upper thin part of the bag is denoted 67 and the band-shaped upper part of the bag is denoted 68.
The ~and 68 has been folded over the collar 65 It can be ~een that the bag having been folded over the collar is locked in position, due to the fact that the thicker, ringshaped band which has been folded, is relat-ively stiff. In this way the bag is prevented from slid-ing off and down into the casing during handling of the - 32 ~

106S63~:
foodstuff, e.g. by stirring or whipping.
Experiments have unexpectedly shown that when iising inserts of extremely thin plasticslfilm, a temperature-time chart can be obtained which, with respect to the cooking process, coincides with the cor-responding temperature-time chart for traditional boiling.

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Claims (31)

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

1. A method of cooking foodstuffs by boiling and/or steaming including the steps of placing the foodstuff in a disposable, liquid-tight film or foil insert which is maintained open at the top by a stiff flange that is thicker than the main body of the insert, positioning the insert in a perforated spacer within a cooking vessel so that the insert is spaced from the bottom and walls of said cooking vessel, so that a gap is formed between them, and heating the foodstuff placed in said disposable insert through the action of steam or water and steam in said gap, the insert closely fitting the inside of the perforated spacer.

2. Apparatus for cooking foodstuffs by boiling and/or steaming including a cooking vessel and an insert that is open at the top to contain the foodstuff, said insert being disposable and made of a liquid-tight foil or film material of similar shape to the vessel, and having a stiff flange at its open end that is thicker than the main body of the insert, and perforated spacer means arranged to maintain said insert supported and spaced from the bottom and walls of the cooking vessel, with the shape of the insert being such that it closely fits the inside of the perforated spacer means.

3. Apparatus as claimed in claim 2 wherein said insert is made from a plastics film or foil having a thickness of between 0.01 - 2mm.

4. Apparatus as claimed in claim 3, wherein said plastics foil consists of a polyolefin taken from the group consisting of polypropylene, HD-polythene, HD-HM-polythene or polystyrene, styrene/butadiene or PVC.

5. Apparatus as claimed in claim 3 or 4, wherein said plastics insert is formed by a heat-moulding or vacuum-forming technique.

6. Apparatus as claimed in claim 2, wherein said insert consists of a thin metal foil.

7. Apparatus as claimed in claim 6 wherein the foil is aluminium coated with a plastics material.

8. Apparatus as claimed in claim 2, 3 or 6 wherein said insert is generally conical in shape to facilitate stacking.

9. Apparatus as claimed in claim 2, 3 or 6 wherein the insert is provided with at least one pouring edge.

10. Apparatus as claimed in claim 2, 3 or 6 wherein the thickness of said insert is such that it can easily be crushed up and flattened to facilitate disposal.

11. Apparatus as claimed in claim 2, 3 or 6 wherein the flange is outwardly directed to position the insert in the cooking vessel and/or the supporting holder.

12. Apparatus according to claim 2 wherein the insert is bag shaped and can be stored flat prior to use.

13. Apparatus as claimed in claim 12 wherein the flange section is designed at least partially to cover the gap between the insert and the wall of the cooking vessel to enable foodstuff to be poured out without spilling into the cooking vessel.

14. Apparatus as claimed in claim 2, 3 or 12 wherein the insert is provided with apertures or slots at selected positions near its upper edge to allow the passage of steam from the gap.

15. Apparatus as claimed in claim 2 or 12 wherein said perforated spacer means maintaining the insert spaced from the vessel includes a supporting holder surrounding the bottom and walls of the insert and provided with perforations comprising a plurality of passages for steam.

16. Apparatus as claimed in claim 15 wherein spacers are provided in the cooking vessel to position the supporting holder spaced from the cooking vessel wall.

17. Apparatus as claimed in claim 15 including spacers in the vessel, each spacer having an upper edge cooperating with a flange protruding from the supporting holder.

18. Apparatus as claimed in claim 15 the supporting holder is provided with an upper flange arranged to abut the upper edge of the cooking vessel so that the supporting holder with its insert is suspended in the cooking vessel.

19. Apparatus as claimed in claim 15 wherein the supporting holder consists at least partially of a wire mesh basket.

20. Apparatus as claimed in claim 15 wherein opposed flanges are provided on the supporting holder to serve as handles.

21. Apparatus as claimed in claim 15 including an outer container, the unit comprising the disposable insert and the supporting holder being adapted to be fitted into said outer container which can act as a serving dish.

22. Apparatus as claimed in claim 15 including steam producing means and means for connecting the cooking vessel to said steam-producing means arranged to introduce steam in the gap formed between the supporting holder and the walls of the vessel.

23. Apparatus as claimed in claim 15 the supporting holder is provided with feet on its lower side which rest on the bottom of the cooking vessel.

24. Apparatus as claimed in claim 15 wherein the supporting holder is provided at its upper edge with apertures or slots to facilitate the passage of steam to the space above the foodstuff.

25. A disposable bowl shaped container for use in heating solid and liquid foodstuffs either separately or together, said container comprising:
a liquid tight plastic member having an open upper end and a bowl shaped body portion having an unpleated wall and integral bottom, said body portion being thermoformed to be sufficiently thin and flexible so as to be capable of be-ing folded and crushed by hand to facilitate disposal of said container; an annular semi-rigid flange integrally formed at said open upper end of said plastic member and extending generally outward and away from said side wall of said body portion; and said flange having an inner edge integrally formed with said side wall about the entire circumference of said side wall of said body portion at said open upper end of said plastic member and having a down-wardly extending free end surrounding at least a major portion of the circum-ference of said flange, and said flange being sufficiently strong and cooper-ating with said body portion to maintain the integrity of said bowl shaped body portion when a foodstuff is deposited in said container.

26. The disposable bowl shaped container of Claim 25 wherein said liquid tight plastic member is formed of a film or foil having a thickness of between 0.01-2.0 mm.

27. The disposable bowl shaped container of Claim 25 wherein said un-pleated side wall is generally conical in shape to facilitate stacking.

28. The disposable bowl shaped container of Claim 25 wherein the open upper end of said plastic member including at least said flange has a thick-ness greater than said side wall and integral bottom to further strengthen said plastic member.

29. The disposable bowl shaped container of Claim 28 wherein the thinnest part of said bowl shaped portion has a thickness no greater than 0.06 mm.

30. The disposable bowl shaped container of Claim 25 wherein said liquid tight plastic member is formed from a plastic material taken from the polyolefin group.

31. The disposable bowl shaped container of Claim 25 wherein said liquid tight plastic member is thermoformed from a sheet of plastic material whose thickness is not greater than 0.18 mm.