CA2114315A1

CA2114315A1 - Cooking apparatus using electron and molecular excitation mode

Info

Publication number: CA2114315A1
Application number: CA002114315A
Authority: CA
Inventors: Eugene R. Westerberg; Robert I. Ii Beaver
Original assignee: Individual
Current assignee: Quadlux Inc
Priority date: 1991-07-30
Filing date: 1992-07-29
Publication date: 1993-02-18
Also published as: JPH07500179A; AU2417292A; EP0613543A1; EP0613543A4; WO1993003310A1; AU667823B2

Abstract

An oven using one or more quartz halogen tungsten lamps or quartz arc bulbs (16, 18) capable of producing 4KW of radiant energy of which a significant portion is in the visible light range of the electromagnetic spectrum and substantially forty to fifty percent of the radiation is in the visible and near visible range impinges visible, near visible and infrared radiation directly onto a food item (32). Radiation sources (16, 18) can be positioned above and below the food item (32) and the inner walls (12) of the oven are preferably highly reflective to reflect light energy onto the food (32). The intensity of the radiation light source (16, 18) is automatically controllable and can be varied throughout the cooking cycle.

Description

WO g3/03310 PCr/lJS92/~266 3 ~ ~

t:OORING AppARA~ru8 U~:ING E:LECq!RON AND
~O~:C:U~R E~:KCITA~IO~N ~ODE

Cross Re~erences to Related Ap~lications This application is a continuation-in-part of V.S.
Patent application number 195,967 filed on May 19, 1988, (now abandoned), a continuation-in-part of U.SO
Patent application number 664,494 filed on March 5, 1991, and a continuation-in-part of U.5. Patent application number 07/350,024 filed on May 12, 1989, which are incorporated herein by reference.

Field of the Invention This invention relates to the field of cooking apparatuses. More particularly, this invention relates to baking and cooking processes that are substantially fa~ter than such processes in conventional ovens, and I offer sensory improvements in quality for many ¦ foodstuffs.

. Back~round of the Invention Ovens Por cooking and baking food have been known and used fcr th~ousands of years. Basically, oven types can be categ~rized in four different forms. The simplest and probab~ly the oldest cooking resulted when l man put some vegetable or grain products on a hot rock J next to a fire~, and cooked them essentially by the heat 2 5 transf er me~hod of conduction. With a little more refine~ent, an enclosure surrounding the heating ~ element entrapped the heated air gi~iny rise to cooking '` by convective heat transfer. This was the prototype ,' f or the modern g~s or electric oven . In the past century, radiant energy from infrared radiation sources has been used to heat and cook f oodstuf f s directly .
Within the past f ew decades, micrc)wave radiation has .

W093/03310 PCT/~S9 /0~26~

.
~ 21,1431S

proved useful in allowing very short cooking times for many types of food.
There are subtle diferences between c09~ing and baking~ Cooking just requires the heating of the food.
Baking of a product from a dough, such as bread, cake, crust, or pastry, re~uires not only heating of the product throughout but also a chemical reaction coupled : with driving the water from the dough in a predetermined fashion to achieve the correct consistency of the final product and finally browning the outside. Following a recipe when baking is very important. An attempt to decrease the baking time in a conventional oven by increasing the temperature results in a damaged or destroyed product.
~`( 15 In general, there are problems when one wants ~o cook or bake foodstuffs with high-quality results in the shortest times. Conduction and convectioSn provide the necessary quality, but both are inherently slow energy transfer methods. Infrared radiation can provide faster heating rat~s, but it only heats the surface area of most foodstuffs, leaving the internal heat energy to ~e:transferred by much slower . conduction. 'Microwa~e radiation heats the foodstuff very quickly in depth, but during baking the loss of ~;, 25 . water near the surface.stops the heating process before .i any satisfactory browning occurs. Consequently, ~, microwave ovens cannot produce quality baked ~, foodstuf~s, such as bread.

~6,` SummarY of the Invsntion 1':'`
An oven for the high-speed, high-quality cooking . and baking of~food items includes a means for impinging ~` ~ high-int nsity:~isible, near-visible, and infrar~d radiations ontoS a food item, thereby cooking the item at accelerated rates comparable to microwave cooking, Y'' ~ .

.. .. . .

~ WO93/0331~ PCT/~S92/062~6 ~119L315 .. . . . .

while maintaining the browning of infrared cooking and the quality of conduction-convection cooking.
It has generally been believed that radiation with wavelengths much shorter than 1.35 ~m is not of much value in cooking or baking processes. This presupposition is based on the fact that water is the major constituent of most foodstuffs and water is essentially transparent for wavelengths of electromagnetic radiation less than about 1.35 ~m.
This region of low energy absorpti~n in water includes th~ visible (.39 to .77 ~m) and the short infrared ~.77 to 1.35 ~m) which we term "near-visible". The absorption characteristic of water in the visible and ne~r-visibl~ regions of the spectrum i5 illustrated in the graph of Figure 1 using data compiled from the Handbook of Optics. Because of the low absorption, radiation at these wavelengths provides very povr energy transfer to the water, especially in the visible ra~ge where less than one percent o~ the radiant power is converted to heat in a one centimeter depth of water. For this reason, one of ordinary skill in the art would be predisposed to cook with the longer -- infrared wavelengths to heat the water in various foods. - ~
Accordingly, another mode of cooking must be utilized in ~e present invention. The foodstuff molecules themselves have very definitQ handc of absorption in both the visible and near-visible : xegions~ In the visible regio~ this~absorption shows up as food color. For example, tomatoes absorb all of the blue and gr n components of the white light that illuminates t~em, and they reflect the red portion back to the eye. Hence we see a "red" tomato~ This color absorption is due to the excitation of specific electrons that make up the molecules in a particular W093/03~10 PCT/US92/Q626~

'2i.1,~31~

foodstuf~, and it is this absorption that makes it possible to use intense visible and near-visible radiation to heat the foodstuff molecules directly. If one provides a su~ficiently intense source of visible and near-visible radiation in conjunction with the ~ longer infrared radiation, a novel and very effective :' cooking apparatus results. The low absorption of . visible ~nd near-~isible radiation allows the energy to penetrate the foodstuff and heat it deeply like ~, 10 microwave energy. ~y contrast the longer infrared radiation does not penetrate very deeply and acts as a very effective browning agent. By combining these sources of radiation into a single cooking process it 1 is possible to produce a very rapid and highly 1 15 e~ficient method of cooking and baking a wide variety ;~ of foodstuffs.
As an illustration of the effectiveness of this ~ combined direct:heating pro~ess one ran consider a :~ simple example.: A cup~(8 oz.~ of pure water in a ~ 20 transparent ¢ontainer can:be heated~to boiling in a .' time of 35 secondæ in our oven using ~ KW of power.
This can be~compared to the 210 seconds that it takes to.heat-the same:cup of water in a standard 600 watt microwave oven. Since water is transparent to the l 25 visible and::near-visible~radiations, virtually all of .1 khe heating is~produced by the infrared longer than 1035 ~m. If that cup of water is replaced by an ! identical cup of water, but with a teaspoon of instant coffee added~:to color it, the boiling time is reduced ~o 25 seconds in our oven, while the microwave oven ~` still requires 2~0 seconds. The coffee r;olecules themseIves are directly absorbing the impinging energy, and the visible and near-visible radiations are ~ contributing to the heat rise.
,~

; , ' W093/033~0 PCT/US92/06266 3 ~ ~
i . .

Radia~t cooking methods can be classified by the manner in which the radiation interacts with the foodstuff molecules. This interaction i8 illustrated for ~arious wavelengths in Fig~re 2. For exampl~, f 5 starting with the longest wavelengths for cooking, the ~ microwave regisn, most of the heating occurs because of ¦f the coupling of radiant energy into the bipolar water ~ molecule causing it to rotate and thereby absorb energy ,l to produce heat. Decreasing the wavelength to the ~l 10 infrared regime, we find that the molecules and their !~ component atoms resonantly absorb the energy in well-~ defined excitation bands. This i5 mainly a vibrational f energy absorption pro~ess. In the near-visible and visible regions of the spectrum, the principal absorption mechanism is excitati~n of the electrons that c~uple the atoms to form the molecules. These interactions are easily discerned in the visible band of the spectra, where we identify them as "colorl' absorptions. Finally, in the ultraviolet, the ~JI 20 waveleng~h is short enough, and the energy of th~
~l radiation is su~ficient to actually remoYe the . ~ electrons:from their component atoms, thereby creating ionized:~states. This short wavelength ultraviolet, while it finds uses in sterilization techniques, ~l 25 probably has little use in foodstuff heating~ because it pr~mo~es chemical reactions and destroys food molecules.
Using intense visible, near-visible, and infrared radiation to cook food has a number of significant adYan~ages. First of all, the cooking process is very fast. Baker~ products, like pizza crust ~or example, ~: can be ba~ d 5 to 10 times faster than ovens tha rely on con~entional convection and conduction processes only. Second, the quality of the cooking process is enhanced for many foodstuffs. For example, crusts , r l`
~;
~,1 ~ WOg3/03310 PCT/~92/0~26~

~1431.5 become fully cooked with crispy exteriors and moist, ch~wy interior~. Vegetables are cooked so fast that they are virtually stzamed in their own water vapor, leaving them hot, but with very little lois of any of their nutriti~e values. Third, the process is very energy efficient. Because the oven has reflective inner walls, most of the energy produced by the sources is used to cook the food rather than heat the oven. A
pizza can be fully baked for about $.01 o~ ~lectrical energy.
Ordinarily, in the preferred oven configuration, the visible, near-visible and infrared impinging means , is one or more guartz-halogen tungsten lamps, or equivalent means such as quartz arc lamps~ Typic~l quartz-halogen lamps of this type, operating at 3000 degrees Kelvin, convert electrical energy into black body radiation having a range of wavelengths from .4 ~m to 4.5 ~m with a peak intensity at .965 ~m. Each lamp can generally~provide from 1 to 2 KW of radiant energy ii 20 with a signif icant portion of the energy in the visible `' light spectrum.
.~1 Typical con~igurations can use one to as many as ten lamps operated in unison, and larger ovens could use even ~ore:lamps. One or more of the radiation source lamps may be used in the cooking process as necessary. ~These radiation sources are ordinarily ~ positioned above and below ths food item. Certain ;I applications~may require that radiation sources surround the food item. The walls of the surrounding food chamber are preferably treated to be highly reflective to~this radiation. The visible and infrared ~i ~ waves from the radiation sources impinge directly on the food item and are also reflected on this inner surface of the oven to strike the food item many times ~ 35 and from many angles. This reflecting action results ';

~ WO93/03310 PCT/US92/06266 r 211~3315 in a greater unif ormity of cooking, and ince very ; little of the radiation is absorbed in the surrounding reflecting surface, almost all of the radiant energy is converted into heat upon and within the foodstuff.
Hence, this process is a very efficient mode of , transferring energy to the foodstuff ~or cooking, and ,~l operation is very economical.
For certain cooking applications, the food item may be placed on a radiant energy absorbing and h~at . 10 conductive support platter. The platter can be :. selectively heated by means of the bottom set of lamps to increase its temperature to a point where it can aid the cooking process by conductive heating, if desired.
The platter may be perforated in such a m~nner so as to facilitate the removal of internal water vapor and , gases from the bottom sf the foodstu~f.
l The in~ensity of the radiation from the lamps is ql controllable~ Each lamp can be individually controlled or the lamps can be operated in uni~on to provide the desired cooking result. It is necessary that this ~, control be performed quickly, because of the inherent speed of the cooking process. For certain food products, it is necessary that the intensity be varied throughout the~:cooking cycle. Such fast and variable intensity control is preferably managed through aut~matic means,:~such as computer or microprocessor circui~s.
In general, this is a new mode of cooking. The potentialit:ies of using this enhanced range of ~i 30 wavelengths for:cooking and baking are just starting to be explored, and a whole new range of cooking : techniques should resu~t from the invention.

.
! ~ :
:~"

~`1 t i~.
.

~ WO93/03310 PCT/USg2/06~66 '2,1 14315 . -8-~rie~ Description of the Drawinas Figure 1 is a graph showing the ab~orption of water at various wavelengths of electromagnetic . radia~ion.
i 5 Figure 2 is a schematic representation showing various modes of electromagnetic absarption.
Figure 3 shows a front cross section of a preferred embodiment o~ the present inventisn.
Figure 4 is a graph showing the depth of penetration of electromagnetlc radiation into watsr versus wavelength.
.~ Figure 5 is a graph showing cooking time versus ; diameter-squared of a pizza.
Figure 6 sh~ws a side cross section of the preferred embodiment of the present invention.
Figure 7 is a graph showing the approximately ~ inverse linear relationship between cooki~g power and ;' - cooking time.
. : Figure 8 is a graph showing the constant ; 20 power-time~product for baking a pizza in the oven of j : the preferred embodiment.

;
::. Det~ailed Description_of the Preferr~d: EmbQdiment Fig~ 3 is a front ~ross section of the preferred : ~mbodiment of the present invention. The oven in ~-Fig.: 3 includes~an outer enclosure 10. The enclosure has an inner wall 12 coupled to the outer wall 10~
~$, ; Ordinarily, an insulating layer 14 is formed between the outer enclosure~lO and the inner wall 12. Because of the~inherent:speed of the cooking cycle, the insulating layer~l4 may be a layer of air.
l .
The present~invention has been used to cook pizzas :reasonably continuously for an hour in an oven with : onl:y air as an insulator. While the exterior of the oven did warm up, it never became too warm to touch ~ . W~93/03310 P~T/US92/06266 ~ t~ 3 1 ~

_g_ comfortably. This is true because the interior walls of the oven are re~lective so that most of the energy i~ used to cook the food, not heat the oven. Second, a f an is used to pull hot air out of the oven. Though some air is heated directly by the radiation, most of the air is heated by convection from the cooked food.
In prior art convection ovens, hot air is forced onto a ~ood product and acts to cook the food. Commercial ! pizzas are o~t~n cooked this way. Because the cooking times are so short with the present invention, the hot air is removed to prevent further cooking after the radiation source is turned off.
The energy for cooking is supplied by the lower radiation heating lamps }6 and the upper radiation ; 15 heating lamps 18. Thes~ lamps are generally any oX the quartz body, tungsten-halogen or quartz arc lamps commercially available, e.g., 1.5KW 208V quartz-halogen lamps. The oven according to the preferred e~bodiment utiliæes ten such lamps and cooks with approximately 1 20 40% to 50% of the energy in the visible and near-: visible light portion of the spectrum, which is significant. Quartz xenon-krypton arc lamps have been used as an alternate source in which 95~ of the radiation is below l~m and good cooking re~ults have been achieved with their shorter wa~elengths.
There is no precise definition for the range of wavelengths for ~isible light because the perceptive ranges of each human eye is different. Scientific definitions typically encompass the range of 0~39 ~m to `~ 30 0~77 ~m. An engineering shorthand for visible light: specifies the range of 0.4 ~m to 0~7 ~m. The tQrm ~! near-visible has been coined for radiation that has ~ wavelengths longer than the visible range, but less -l than the water absorption cut-off at 1.35 ~m.

, "
, .

!
I WO93/03310 PCT/VS92/06~

211431~

, Figure 4 is a graph showing depth of penetration of electromagnetic radiation into water relative to the wavelength. Please note that the vertical scale is logarithmic. The d~pth o~ penetration for the visible light range is in excess of 100 cm (1 m~ter) which is substantially larger than any ordinary food product.
Because food is mostly water, one would expect the shorter wavelength radiation of visible light to simply pass through food. In fact, it is the color absorption bands of most foods that absorb the radiation and convert the radiant energy into heat and the high penetration provides heating deep into the foodstuff.
Alternately, the long infrared has a very small penetration (less than ~ mm) and this provides high surface temperatures and good browning characteristics.
The inner surface of the inner wall 12 is preferably a highly polished, poorly absorptive surface, so that it appears to~be very reflective to the wide spectrum of wavelengths from the radiant - 20 lamps. ;Polished Aluminum~and;stainless steel have been successfully~used~for the inner wall 12. Plating the inner~wall~l2,~ such ~as with~gold, increased the ef~iciency~of~the~reflector~for visible light by about 10% ovér the~polished~Aluminum or~stainless steel : : :
walls.~
The oven efficiently uses the generated radiant energy. Figure 5 shows a graph relating cooking time to diameter-squared of a pizza. The pizzas were all loaded with~similar ingredients to approximately the ~ same dépth so that area (which is~proportional to the diameter-squaredj is proportional to volume. As expected,~as the~volume of pizza to be cooked increased, the coo~ing time also increased. This graph ~shows two surprising results. First, the graph is 3s linear. In other words, the cooking time is directly ~/U~ g 2 / li b 2 6 6 211~31~ ~ ~ 7 ~E~ ?g~3 proportional to volume (all pizzas were of the same height). This indicates tha~ nearly all o~ the radiant energy goes into cooking the pizza. Second, the graph passes approximately th~ough zero. In conventional ovens one would expect a displacement of the line up the vertical axis to account for inefficiencies in th~ -cooking proc~ss.
Two radiation transparent plates 20 and 24 are used to isolate the cooking chamber from the radiant sources making the oven easier to clean as shown in Figure 3. These plates can be formed from s~ch materials as quartz or a glass that transmits visible, near~vi~ible and infrared radiations. The lower transparent plate 20 is supported by brackets 22a and ~5 22b and is positioned above the }ower lamps 16. The upper transparent plate 24 is support~d by bracke~s 26a and 26b and is positioned below upper lamps 18.
Brackets 28a and 28b support platter 30. The platter 30 is positioned above th~ lower transparent plate 20 and below th2 upper glass plate 24. A food item 32 is positioned on platter 3~: to be cooked~ The sontrol circuit 34, shown as a circuit block, controls the operation:o~ lamps 16 and 18.
The platter 30 may formed o~ a material similar to tha transparent plates 20 and 24 to allow even cooking over ~he surface of the ~ood item 32. However, in some circumstances it m~y be desirabl~ to crisp the bottom o~ the ~ood item 32. As a particular example, when cooking a pizza, it is desirable that the crust be light and crispy, rather soggy and doughy. In such an application, the cooking platt~r 30 can be fsrmed of a radiation absorbing, heat conducting mat~rial, such as ~ ~ bl~ck anodized aluminum. In this way, the lower lights i 16 would rapidly heat the platter 30 to a high temperature in order to crisp and brown the bottom of SUBSTITUTE SHEET

WO93/~3310 PCT/V~92/06266 . . 5 3l~

.

the pizza. It may also be desirable to perforate the platter 30 in order to allow steam to escape ~rom the cooking pizza ~ough. Platter 30 should touch the support brackets 28a and 28b over very limited areas, so that the heat delivered to platter 30 is not lost by conduction.
The lamps 16 and 18 produce very high intensity visible and in~rared radiation. Prior art uses of radiant energy heat sources teach cooking using radiation in the infrared portion of the electromagnetic spectrum. For example, see Malick U.S.
Patent 4,481,405 and Bassett U.S. Patent 4,486,639.
Burkhart, in U.S. Patent 4,516,486t discloses a radiant I energy cooker for the exclusive purpose of charring the surface of foods, particularly meats.
I The use of high intensity vi~ible radiation f provides a very rapid method of high quality cooking and baking both alone or in combination with infrared radiation.~ The radiant energy from the lamps 16 and 18 radiates from each bulb in all directions.~ ~A portion : of the energy radiates directly onto the food item 32.
The remainder of the energy will be reflected off the surface of~t~:e preferably metal inner wall 12 and then strike~the food item 32 for more e~ficient cooking.
-. It is possible to control the lightæ 1~ and 18 independently with the control circuit 34. The control circuit 34, shown as a circuit block in Fig. 3, may include a mi~roprocessor or a microcontroller and ~l a~sociated~memory to stoxe individual cooking r cipes ~: 30 to control proper heating of the food produ~t.
: For example, in cooking a pizza, it may be de~irable to run the upper lamps 18 at a reduced power level for a time. For a pizza having fresh vegetables, this would prevent ~he overcooking of the vegetables ~: 35 making them mushy~ The lower lamps 16 might be ; ` .

,j :

WO93/03310 PCT/US92/062~
, operated at a higher powsr level to make the pizza crust light and crispy.
Figure 6 shows a side CrOS5 section of the preferred embodiment of the present invention. In the prefPrred embodiment, there are 5 lower lamps 16a through 16e and 5 upper lamps 18a though 18 By appropriately selecting the lateral spacing between the lamps relative to the food, even cooking can be achieved over the entire surface. A door 40 is also shown.
Experimental results show that cooking with one s l.SKW lamp above and one below, i.e. impinging a ~ maximum of 3KW of radiant energy onto a pizza, does not ;l achieve the dramatic improvem~nt in speed that is possible according to the present invention. The oven in the preferred embodiment includes 5 lamps above and 5 lamps below. This number provides for a maximum of lSKW of cooking ener~y.
Pizza has been success~ully cooked using a l 20 modification of the present invention with more -~ powerful bulbs using total power in the range of 4KW to . approximately ~OKW. There appears to be no reason preventing the power ranges in excess of 20XW.. This i5 a significant advantage of the present invention.
Cooking times can be reduced by increasing power. The only way to increase power in a conventional o~en is to ~' increase temperature which damages the fQod. In a `, ~ microwave, severe federal restrictions prevent i increasing the power that can be-delivered to food : 30 because of the~potential for leakage of the dangerous ~waveS, While cooking a pizza using total power in excess of about 4KW an approximately inverse linear relationship develops between time and cooking power.
In other words, as the power delivered to the pizza is W093/0331~ PCT/US92/06266 ~1 14~1~

~, doubled, the time to cook a pizæa is cut in half. This result is totally unexpected in view of conventional oven baking where increasing oven temperature to achieve a higher energy transfer rate results in a j 5 burnt product which may ha~e an uncooked interior.
¦ Figure 7 is a graph showing the relationship between cooking time and cooking power for baking four pizzas at 3.8, 6, 9 and 12~W of power. The raw pizzas I were essentially identical. While the quality of a ,J 10 pizza is subjective, the four finished pizzas from thisexperiment were all of similar satisfying quality.
Figure 8 is a graph showing the power-time product versus power for baking a pizza in the oven of the preferred embodiment. Note that in the preferred o~en the power-time product is constant and has a value of ~,~ about 470KW-sec.
This cooking:in the linear range of the power-time product appears to be a function of both the wavelength~of radiation and the amount of power : 20 applied. :T~us,~ he specific mecha~ical configuration of the oven in the preferred embodiment is not critical . to the invention.~ Rather, it is the combination of the lamps tha~ provide~at~least a significant portion of ` radiati'on in the v~isible light range in excess of 4KW
2~ (total radiant;~:power)~and impinging the radiation directly onto:the:~food item of energy which provides the dramatic speed increase of the present invention.
For exampl~e,:an oven having a reflecti~e inner surface could~operate according to the present , : 30 invention with~a~single;arc lamp capable of producing suf~icient power in the desired frequency ranges. In certain circumstances it may be desirable in such a single source oven to place the food product, such as a pizza, on a highly thermally conductive pla~ter with the lamp positioned above the food item. The amount of !

!, ' /
211 ~13I5 ,, --15--heating to the bottom of the pizza can be regulated by heating the platter and by adjusting the ratio o~ the si.ze of the pizza to the size of the pan. In other words, the amount of exposed area of the pan would control the amount o energy absorbed by the pan used to ~eat the bottom of the pizza.
Microwave ovens cannot be used in cooking high quality freshly prepared pizza. The commercially ;l available frozen pizzas for microwave ovens are precooked and then frozen. The pizza is merely heated ;~ to the proper serving temperature in the microwave ' oven, but the result is usually unsatisfactory. A
! higher quality pizza can be baked in a commercial grade conductionJconYection oven. There, the pizza is placed directly on the hot floor of the oven to properly crisp the bottom of the crust (up to 900F in a brick oven~r ~' Unfortunately, the ovens have various "hot" spots and re~uire constant operator attention to aYoid over or under cooking the pizza, i.e., consi~tency is a major problem. Such ovens cook a pizza in 5 to 20 minutes.
~? Conveyorized infrared and hot air convection ovens can cook a pizza in 5-to 15 minutes, but have great difficulty in properly crisping the bottom of the pizza .
A pizza can be cooked using the present invention in as little as 30 to 45 second~. This sp~ed is vexy important in the commercial pizza market because it i~, enables:pizza to be produced in a manner that would `,~ qualify it as a true fast-food.
: 30 -~ The energy efficiency of the present invention is illustrated by~the fact that the energy cost to ook : such a pizza is about $0.01. The majority of the radiant energy produced by the oven is utilized in cooking the pizza and after the cooking process is completed the energy is turned off~ In contrast, ., WOg3/03310 PcT/uS92/06266 , 7,1 1~315 conventional commercial pizza ovens must be preheated to desired cooking temperatures. Ordinarily, the oven in a pizza restaurant is left on all day, whether cooking a pizza or not, making the energy consumption S significant.
Another way of considering this new mode of cooking, especially for pizza, is determining the ! amount of radiant energy necessary to cook a pizza, per ~ unit time and mass. By impinging approximately 20 j 10 watts/gram of radiant energy in an oven of the preferred embodiment, a minimal nine inch cheese pizza can be cooked in about 30 seconds, and a combination pizza with extra large portions of toppings can be baked in around 50 seconds. A typical twelve inch pizza takes about 70 seconds. Because of the inverse dependence of power and cooking time, a nine inch pizza I could be cooked in two minutes or less by impinging about 10 watts of radiant power/gram of ingredients from the oven~of the preferred embodiment. The inventors believe that improving the reflective efficiency of the oven would reduce this cooking time.
The inventors~know of no other~pizza oven capable of baking a quality piz7a of this diameter in times of Iess than 5 minutes.
The oven~of; the present invention is not limited ~ ~ to cooking pizzas.~ Certain foods are cooked with more `~ consistent and reliable results than with conventional ~l techniques. For example, ~ooking vegetabl~s, such as!
broccoli, so that they retain good texture is difficult ~, ~ 30 using prior art techniques~ Generally, such items are `j~ preferred;al dente. The short cooking t,mes of the ~; present invention, about 20 seconds for broccoli, bring the product to serving temperature so rapidly that the vegetable maintains its crisp, firm texture.
:
'~
:~

,i :

; WO93/03310 PCT/US92/06266 ~114'315 Popcorn is another interesting food that can be prepared in the oven. If the popcorn kernels are completely surrounded with a water-filled shield, all of the long infrared can be removed leaving only the visible and near-visible wavelen~ths to heat the kernels. Even with all of the direct water-heating radiation removed the corn will pop in less than 20 I seconds (3 or 4 times ~aster than hot air poppers).
I This is another example showing the efficacity of the ; lO visible and near-visible radiation for rapidly cooking food. It is interesting *o note that when the corn pops, its very low absorbing white color automatically terminates the radiant heatiny, and the popcorn does not burn.
Even TV dinners can be defrosted and hPat~d in the oven. Generally, heating times are one-half to one-i third of the times required in microwave ovens, .~ depending on the foodstuff. For example, darkly colored items like salisbury steaks heat very fast, while lightly colored items like mashed pctatoes heat at a slower rate.
The oven o~ the present invention may also be used cooperatively with other cooking sources. For example, I the oven of the present invention may include a `, 25 microwave radiation source. Such an oven would be ideal for cooking a thick highly absorbing food item such as a roast beef. The microwave radiation would be u~sd to cook the interior portions o~ the meat and the infrared and visible light radiation of the pres~nt invention would cook the outer portions. Further, the ; oven according to the present invention could be used with a con~ection oven or with both convection oven and .
microwave oven cooking sourcesO
The present invention was described in relation to a preferred embodiment. However, it will be apparent , .

~ WO93/03310 PCr~US92/~626~
:; i , ~11431~
-18- .
to one skill~d in the art that one can change the parameters and ~till practice an invention within the ¦ spirit and scope of the present invention.

;l ~1 , :: :

;~
,'.i '' '' . 1 , ` ' , , ~ , ~i .
~ ~ , `i:
`''`

~`:

Claims

C L A I M S

What is claimed is:

1. An oven for cooking a foor item in a food location comprising:
a. a food cooking chamber having reflective inner walls;
b. means for generating in excess of 4KW of radiant power within said walls and having a significant portion of the radiant energy in the visible light range of the electromagnetic spectrum; and c. means for directing the energy to impinge directly on the food location.

2. The oven according to claim 1 having an approximately inverse linear relationship between cooking time and cooking power.

3. The oven according to claim 1 wherein the portion of radiant energy in the visible light range is at least eight percent.

4. The oven according to claim 1 wherein the portion of radiant energy in the visible and near visible light range is at least forty percent.

5. The oven according to claim 2 wherein the means for generating energy includes a plurality of sources of energy positioned spatially around the food.

6. The oven according to claim 5 wherein the food item has an upper surface and a lower surface, and further wherein the plurality of sources is comprised of a first group of sources positioned above the upper surface and a second group of sources positioned below the lower surface.

7. The oven according to claim 1 wherein the means for generating radiant energy is comprised of a quartz body tungsten halogen lamp.

8. The oven according to claim 6 further comprising means for differentially controlling each of the plurality of sources by time and by intensity.

9. The oven according to claim 1 wherein the means for generating radiant energy is comprised of a quartz arc lamp.

10. The oven according to claim 1 wherein at least 10 Watts of power is generated per gram of the food item.

11. An oven for cooking and baking food comprising:
a. a food cooking chamber having reflective inner walls;
b. means for generating in excess of 4KW of radiant power within said walls and having a significant portion of the radiant energy in the visible light range of the electromagnetic spectrum, the means for generating positioned inside the cooking chamber for impinging the radiant energy directly on the food; and c. a container for holding the food while cooking which is transparent to the radiant energy.

12. The oven according to claim 11 having an approximately inverse linear relationship between cooking time and cooking power.

13. The oven according to claim 11 wherein the portion of radiant energy in the visible light range is at least eight percent.

14. The oven according to claim 11 wherein the portion of radiant energy in the visible and near visible light range is at least forty percent.

15. The oven according to claim 11 wherein the means for generating radiant energy comprises a quartz body tungsten lamp.

16. The oven according to claim 11 wherein the means for generating radiant energy comprises a quartz arc lamp.

17. The oven according to claim 11 wherein at least 10 Watts of power is generated per gram of the food item.

18. A pizza oven for cooking and baking a pizza and forming a cooked pizza therefrom, the pizza having a crust formed of dough and toppings formed of any variety of foodstuffs comprising:
a. a pizza cooking chamber having reflective inner walls;
b. a plurality of quartz body tungsten lamps for generating in excess of 4KW of radiant power within said walls having a significant portion of the radiant energy in the visible light range of the electromagnetic spectrum, the lamps having a first group of lamps inside the cooking chamber positioned above the pizza and a second group of lamps inside the cooking chamber positioned below the pizza for impinging the radiant energy directly onto the pizza;
c. a plurality of plates which are transparent to radiant energy positioned between the pizza and the lamps; and d. means for controlling the first group of lamps and the second group of lamps differentially by time and intensity.

19. The oven according to claim 18 wherein the pizza is placed upon a radiation absorbing platter for absorbing radiation from the lower lamps for improved crisping of the pizza bottom.

20. The oven according to claim 18 having an approximately inverse linear relationship between cooking time and cooking power.

21. The oven according to claim 18 wherein the portion of radiant energy in the visible light range is at least eight percent.

22. The oven according to claim 18 wherein the portion of radiant energy in the visible and near visible light range is at least forty percent.

23. The oven according to claim 18 wherein at least 10 Watts of power is generated per gram of the pizza.

24. A method for cooling and making food comprising:
a. generating in excess of 4KW of radiant power in the electromagnetic spectrum having a significant portion of the radiant energy in the visible light range; and b. directing the energy to impinge directly on the food.

25. The method according to claim 24 having an approximately inverse linear relationship between cooking time and cooking temperature.

26. The method according to claim 24 wherein the portion of radiant energy in the visible light range is substantially eight percent.

27. The method according to claim 24 wherein the portion of radiant energy in the visible and near visible light range is at least forty percent.

28. The method according to claim 24 wherein the step of generating further comprises patlally positioning a plurality of energy sources around the food.

29. The method according to claim 24 further comprising the step of controlling the sources differentially by time.

30. The method according to claim 24 further comprising the step of controlling the sources differentially by intensity.

31. The method according to claim 24 wherein at least 10 Watts of power is generated per gram of the food.

32. A method for cooking and baking a pizza in a cooking chamber having reflective inner walls comprising the steps of:

a. generating in excess of 4KW of radiant power having a significant portion of the radiant energy in the visible light range of the electromagnetic spectrum by using a plurality of quartz body tungsten lamps, the lamps having a first group of lamps inside the cooking chamber positioned above the pizza and a second group of lamps inside the cooking chamber positioned below the pizza for impinging the radiant energy directly onto the pizza;
b. positioning a plurality of plates which are transparent to radiant energy between the pizza and the lamps; and c. controlling the first group of lamps and the second group of lamp defrayal by time and intensity.

33. The method according to claim 32 having an approximately inverse linear relationship between cooking time and cooking power.

34. The method according to claim 32 wherein the portion of radiant energy in the visible light range is at least eight percent.

35. The method according to claim 32 wherein the portion of radiant energy in the visible and near visible light range is at least forty percept.

36. The method according to claim 32 wherein at least 10 Watts of power is generated per gram of the food.

37. An oven for baking a pizza, the oven having a food location for holding a pizza, the oven comprising:

a. a pizza cooking chamber having reflective inner walls;
b. means for generating at least 10 Watts of power per gram of pizza of radiant energy having a significant portion of the radiant energy in the visible light range of the electromagnetic spectrum; and c. means for directing the energy to impinge directly on the food location.

38. The oven according to claim 37 having an approximately inverse linear relationship between cooking time and cooking power.

39. The oven according to claim 38 wherein the portion of radiant energy in the visible light range is at least eight percent.

40. The oven according to claim 38 wherein the portion of radiant energy in the visible and near visible light range is at least forty percent.

41. The oven according to claim 39 wherein the means for generating energy includes a plurality of sources of energy positioned spatially around the food.

42. The oven according to claim 41 wherein the food item has an upper surface and a lower surface, and further wherein the plurality of sources is comprises of a first group of sources positioned above the upper surface and a second group of sources positioned below the lower surface.

43. The oven according to claim 38 wherein the means for generating radiant energy is comprised of a quartz body tungsten halogen lamp.

44. The oven according to claim 43 further comprising means for differentially controlling each of the plurality of sources by time and by intensity.

45. The oven according to claim 37 wherein the means for generating radiant energy is comprised of a quartz arc lamp.