US2653096A - Puffed wheat and method of making same - Google Patents

Description

Patented Sept. 22, 1953 NITED STAT TENT QFF ICE PUFFED. WHEAT AND METHOD. OF MAKING SAME No Drawing; ApplicationlJune 12, 1953,

Serial No. 361,411

15' Glaims; 1,

This invention relates to" a; puffed cereal and method of preparing same, and particularly'to puffed wheat;

Thepresent application is a continuation-inpart of my copending application, Serial No. 296,963; filed July'2, 1952, nowabandoned, which in turn is a continuation-in-part of my applications, Serial No; 40,630 filed July 24, 194:8, now abandoned, and copending Serial No. 189;679; filed October 11', 1950', now abandoned. My application; Serial No; 189 ,679", filed October 11, 1950,- was a continuation-in-part of my following applications: Serial No. 34,821, now abandoned; Serial No. 34,822 now abandoned; and Serial No; 34-3823; now-abandoned, all filed July 23; 1948; Serial No. 231869, filed April 28, 1948, now abandoned; SerialiNo. 38;l79; filed July 10, 1948'; now abandoned; and Serial No. 40,636, filed July 24, 1948; now abandoned.

Reference is had to the related cases of John M: Beer and Frank B. Doyle, Serial No. 62,984, filed December 1, 1948; Allison and Carman, Serial No. 1 615744, filed May 12; 1958; now abandoned Carman. and Allison, Serial No. 259,313, filed November 30; 1951, now abandoned; and Gar-man and Allison, Serial No. 275,458, filed March 7; 1952, now abandoned.

The-problem" ofpuflihg organic cellular mate'- riai" such as wheat involves a large number of interlocking variables. as'will trap expanding gas andthus provide the pressure differential necessary for puffing. A suddendrop in pressure must be provided'of such amount to'produce-thepressure difference necessaryno't only'to expand the cell walls-but to do so; in spite of theleakage that necessarily occurs. On the other hand, thepressure difference must be great enough to exceed the elastic limit ofthe" material before puffing has occurred. The

expansibility" oi the cell wall normally depends upon the moisture content of the product, the condition oi that moisture as to being free or combined, thetemperature of the article and-its chemical condition; particularly as to-wh'ether it itco'olied or uncookedi Likewise, there-must not only be the pressure diiierencerequired to institute pufiihg, but there must bear volumetric increase of the gases in- VOIVB'Q sun'icientto maintain it.

l? have now found that anotl'ier factor involved, which'has hitherto'been completely overlooked but; the accomplishment of which is inherent in theopera-tion described in my previous applications referred to, is that once'tlie wheat has been puff-ed; the puffed condition must" be The wheat cells are such maintained even afterv the pressure" difference has been removed. One of the difiiculties encountered" in many instances. of: puifing in the prior art was that the wheat could be puffed; but after puffi'n'g would collapse because of'the weakened condition of the walls following the leakage out of the gas which. produced puffing. This was particularly trueif, after puffing; the pressure outside: of the: puffed wheat wasincreased.

I have now found that by suddenly cooling and dehydrating the product? so that its final temperature is below 150'F. and preferably well below F.as2 for example,. from. 32 F. or

' lower up to, say, 100 thatithe' cell. walls. of

the product on puffing are cold set so that on standing or on the application of pressure, even of a greatly increased amount, collapse does not occur.

These results are obtained. automatically by following the procedures already outlinedin my previous applications. In these procedures, the following'points-are'important':

l. Substantially all of the air should be removed from the product and replaced'byan atmosphere-of steam prior to pufiing.

2. The product should'be cooked or moistened by steam or otherwise, preferably by the addition of substantially air-free steam at higher pressure and temperature until the condition of the material is proper for pufling and its moisture' content is within the desired range. The use. of theprocess permits the introduction of substantially-more moisture than waspermissible under the old processes.

3. It is preferred that thesudden release of pressure be into a maintained vacuum zone which is initially'below 8 inches of mercury absolute. The conditions of the resulting explosion should be such as to cause" cold setting of the puffed wheat. This means that in actual practice, employing commerciallypracticable vacuum equipment, the pressure may ride up somewhat during the puffing step. It" is preferred to continue evacuation of the vacuumzone during the pufiing'step so as to cause cold setting of the pu-fied-- wheat. Theexpansion. of air-free steam into a vacuum of 4 inches of mercury absolute will automatically reduce the temperatureof the product to approximately F. 1 Reduction of the pressureto-Z inches reduces the temperature approximately to- 100 F. Reduction to 1 inch reduces it to about." 79- F. and reduction to-0.2 inch reduces it toapproximately 3r F- Furthermore; by pufiing into a maintained vacuum, it is possible to obtain a greater temperature drop in number of degrees between the maximum and minimum than was ordinarily obtainable heretofore. The result of this greater temperature drop was to permit the evaporation of more water from the product by boiling into steam. This boiling not only maintained the pressure difference for pufiing, but the removal of the water helped to cold set the cell walls by reducing plasticity and elasticity. The combination of the moisture reduction plus chilling, particularly below 100 F., has produced results not heretofore obtainable.

In a vacuum process, this reduction of temperature is of particular significance, since the lower the vacuum used the greater is the increase in pressure after the completion of the puffing operation when the material is taken back into the atmosphere. If it were not for the cooling and drying eifects, many products would not be able to maintain their puffed condition when the pressure is increased, for example from 2 inches absolute to 30 inches absolute-an increase of fifteenfold.

The removal of the air from inside the wheat grains in the first instance has a number of advantages. In the first place, the oxygen of the air has a deleterious effect on the wheat grains, particularly when they are heated. Secondly, the removal of non-condensable gases increases the permeability of the wheat grains to heat and to steam so that heating will occur uniformly and the steam will penetrate equally to all portions of the wheat grains.

Thus, when it comes to introducing steam for increasing the moisture content of the product and for cooking it to the necessary chemical and physical conditions, the fact that air is not present inside the wheat grains produces a rapidity and uniformity of steaming and cooking not otherwise possible. Because of this greater uniformity and speed, it is possible to go to higher temperatures and pressures than would otherwise be possible. Normally, however, it permits the use of lower temperatures and pressures than otherwise required. As an example of this, raw wheat having a weight of 188 grams per unit of volume (one cup) approximately, was subjected to a series of tests. Various portions of the wheat were cooked for fifteen minutes at thirty-five pounds gauge of steam pressure, in each case after removing substantially all of the air from inside the grains.

In the first group of tests, pressure was then increased to 100 pounds with steam held for fifteen seconds and the product then puffed to the full chamber vacuum of approximately 0.2 inch of mercury absolute. The weight of the wheat grains per cup dropped from an average of 188.5 grams (average of five samples) to 18.7 grams (average of five samples) The following Table I shows the weights before and after puffing of five samples of wheat.

TABLE I Raw Wheat Grams Grams for fifteen seconds and then the material puffed to the same full chamber vacuum. In this, the five original samples had the same average weight as before but the average weight per cup after pulling, instead of being 18.7 grams was 150 grams for the five samples.

On the other hand, wheat cooked in the same manner for the same time and then having the pressure raised to 115 pounds with steam airfree, held for fifteen swonds and then puifed to atmosphere showed an average final weight per cup of 60.1 grams for five samples as compared to the 18.7 when pufi'ed to the vacuum. 115 pounds was used here in order to have the same pressure differences as in the first one in which the pound pressure was puffed to full vacuum.

The Doyle patent, No. 2,627,221 which issued February 3, 1953, shows a pufiing apparatus particularly suitable for carrying out the processes herein described. In such an apparatus a steaming chamber is provided within which the product may be placed. This steaming chamber is connected by a triggered door to an expansion chamber. The expansion chamber is preferably kept at a very low pressure, means being provided to maintain a low pressure during the pufiing. The steaming chamber is provided with evacuating means, steaming means, and usually with a purge line through which non-condensable gases can be eliminated as Well as some condensed steam which is developed during steaming.

As an example of the process, durum wheat was introduced to the steaming chamber. Air and other non-condensable gases were removed from the wheat grains by reducing the pressure in the steaming chamber to about 0.2 inch of mercury absolute while withdrawing the generated steam, the wheat being at a temperature of not less than about 40 F. Saturated steam was then introduced and the pressure increased to 35 pounds gauge, and held at this point for 15 minutes to substantially completely cook the material without loss of cellular identity. The steam pressure was then raised to 100 pounds per square inch gauge, held for 15 seconds, following which the wheat was fired into the expansion chamber which in this instance was at a pressure of 0.2 inch of mercury absolute. This firing is done by suddenly releasing the triggered door of the expansion chamber and the resulting explosion ejects the wheat into the expansion chamber. The potentiometer indicated a temperature at the moment of the puff of slightly below 32 F. indicating an actual super-cooling of the material. This was done by opening the triggered door of the p uning apparatus and firing the wheat into the expansion chamber. The pressure within the expansion chamber was maintained at a low point by continuing the evacuation during the pumng and normally the pressure in that chamber was not permitted to exceed 4 inches of mercury absolute and preferably not permitted to exceed 2 inches of mercury absolute. In some instances, however, I have operated successfully with the pressure in the expansion chamber following the explosion riding up to as high as 4 to 8 inches of mercury absolute as measured on a standrad mercury manometer, but in most instances the pressure was reduced below 4 inches of mercury absolute within a few minutes and before reimposition of atmospheric pressure.

The actual values of the variables in the cooking-pufling-cycles ofthis-method:dependjuponithe condition and type of wheat. being used, aswell asthe degree-.ofpufimgdesiredz; T

The wheat grains in their normal dry state may be employed. withoutmoistening. However, inv some: instances, it maybe desiredzto supply flavor, and/or moistening, and/or nutritional values to, the grain, prior to, during, or after pu-inng. This may-be; doneby-theuse: of a liquid carrier;. such waten; under. highptemperature and. pressure which is exploded into the. vessel maintaining the product under high vacuum in an atmosphere-of: steam. Byusing water under a pressure and temperature corresponding to that, of; say, we pounds gauge of steam, theparticles.

- may be exploded into a. fine mist which will. penetrate the grains, particularly after; they have been puffed. In this way moisture, sugar, salt, certain vitamins, and nutritional. salts may be supplied to the material with or without other flavoring agents. This may be. done-immediately following the initial evacuation (i. e., during cooking) or immediately following thepufling. It is, less economical to do it at some intermediate stage.

The wheat should be thoroughly cooked, for desirable pulling. I have found that cooking at from about 35 to 100 pounds-steam pressure gauge for a period of from about 1 /2 to l5 minutes produces satisfactory results. Following, cooking in the steaming chamber, the steam pressure was adjusted to from about. 50 to 100 pounds gauge, after which the pressure was then immediately reduced to sub-atmospheric, preferably below 8 inches of mercury absolute and particularly to about.v 0.2. inch, of; mercuryabsolute.

The resulting vacuum puffedwheat has a volume of from about 4, to 10 times the original grains. as determined by their cup weights. Put conversely, the specific. gravity as determined by cup weights is from about 10% to of, the specific gravity of the originalwheat grains. The vacuum pufied, wheat particles are everted, substantially pure white except for the-brarr particles adhering thereto, and are entirely clinkerent inshape from the original wheat grains. The cellular structure is vitreous in appearance. On cross-section, the puffed. grains have a large number of relatively large cavities substantially uniformly distributed throughout the These cavities While by no-rneans spherical are generally rounded at their protuberances;

The vacuum puffed-wheat grains are immediately. wettahle by water, except in those portionsprotected by the bran fragments and when immersed in water at 65 F., for a period of 10 minutes, they-retain their entity and shape and do not break down even when mashed on a microscopic slide.

Examplesof applying the method-of this invention are:

Emmple 1- Red durum wheat was placed in a steamchamher which was then evacuated to an absolute pressure of about 0.2 inch of mercury absolute, the temperature of the wheat being not less than about 4.0 E, to remove substantially all of the.

interior.

sionchamber was, continued during the. pufi until the grains were cold set.

Example 2 Red durum wheat (15 pounds) was placed in the. steam chamber and the pressure reduced to about 0.2 inchoi' mercury absolute for 2 minutes, the wheatbeing at atemperature'of not: less than 40 F., to remove substantially all of the noncondensable gases. The wheat was then steamed to a pressure of'lOO pounds per square inch gauge, held there for 2' minutes accompanied by continualpurging of the steam, and then fired into the expansion chamber which was at a pressure of 0.12 inch of mercury absolute. Evacuation. of the.- expansion chamber was continued during the puif until. the grains were cold set.

Example 3 Red durum wheat; (5 pounds) was: placed in the steam chamber and the pressure reduced to 0.2. inch of. mercury absolute for 2 minutes; the wheat being at a temperature-not less than about 46 FL, to remove substantially all of the noncondensable gases. The wheat Was then steamed to 75 pounds per square inch gauge in minlite-,1 held; there; for 1 minutes accompanied. by continual purging of the steam, and then fired into the expansion chamber which was at a pressure of 0.2 inch of mercury absolute. Evacuation of the expansion chamber was continued during the puff until the grains were cold set.

Example 4 Wheat (5 pounds) was placed in the steam chamber and the pressurereduced to-0.2 inch of mercury absolute for 2 minutes, the wheat being at atemperature not less than 40 F., to remove substantially all of the non-condensabie gases. The-wheat was then steamed to a pressure of 75 pounds per square inch gauge, held there for a minutes accompanied by continual purging of thesteam, and then fired into the expansion chamber which was at a pressure of 02 inch of mercury absolute. Evacuation of the expansion chamber was continued until the grains were cold set. r r

Example 5 Red durum wheat (20 pounds) was placed in the steam chamber and the pressure reduced to about 0.2 inch of mercury absolute for 2 min utes, the wheat being at a temperature not less than about 49 to remove substantially all of the non-condensable gases. The wheat was then steamed to a pressure of 109 pounds per square inch gauge. held there for 5- minutes, following which the steam pressure was quickly reduced to 50 pounds per square inch gauge, and then the wheat was fired into the expansion chamber which was at a pressure of 0.2 inch of mercury absolute. Evacuation of the expansion chamber Wascontinued during the puff until the grains were coldset.

Ercamplc 6 Wheat was treated in the same manner as in Example 1 exeeptthat in the step of removing the; non-condensable gases from the Wheat grains priorto steaming, the period of evacuationat. 0.2 inch ofmercury absolute pressure was 1' minute instead of 2 minutes.

Example 7 Wheat was treated in the same manner as in Example 1 except that in the step of removing the non-condensable gases from the wheat grains prior to steaming, the period of evacuation at 0.2 inch of mercury absolute pressure was 5 minutes instead of 2 minutes.

Example 8 Wheat (20 pounds) was placed in the steam chamber and the pressure reduced to 0.2 inch of mercury absolute for 2 minutes, the wheat being at a temperature not less than about 40 F., to remove substantially all of the non-condensable gases from the wheat grains. The wheat was then steamed at a pressure of 100 pounds per square inch gauge in 95 seconds, held there for 5 minutes and then fired into the expansion chamber which was at a pressure of 0.2 inch of mercury absolute. The pressure in the expansion chamber was kept below 4 inches of mercury absolute during the puff until the grains were cold set.

The puffed wheat grains from Examples 1 to 8 were very satisfactory, having the above described characteristics. Samples of the vacuum puffed wheat from the examples showed from 11% to 15% thiamine retention and 78% to 87% lysine retention. A standard commercial puffed wheat showed thiamine retention and 35% lysine retention. The sample from Example 6 had the 11% thiamine retention determination and that from Example 7 had the 15% thiamine retention determination.

The lysine retention was likewise greater for the vacuum puifed wheat product which had been evacuated for minutes before steaming, i. e., Example 7.

The puffed wheat product produced by the process of this method showed 51% nitrogen efficiency by a feed test compared to a negative efficiency for a corresponding commercially puffed wheat.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom for some modifications will be obvious to those skilled in the art.

I claim:

1. The method of pufiing wheat which comprises: freeing wheat grains from air and replacing the air with an atmosphere of steam, cooking the wheat grains for a period sumcient to soften the cell walls and adapt them for puffing, then subjecting the wheat grains to a sudden change from a high super-atmospheric pressure to a low sub-atmospheric pressure whereby they are puffed.

2. The method as set forth in claim 1 in which the wheat grains are cooked under a pressure of steam of approximately 35 to 100 pounds per square inch gauge.

3. The method as set forth in claim 1 in which the wheat grains are cooked under a pressure of steam of approximately 35 to 100 pounds per square inch gauge, the pressure adjusted to from 50 to 100 pounds per square inch gauge, and then instantaneously reducing the pressure by shooting the wheat grains into a low sub-atmospheric pressure whereby they are puffed.

i. The method as set forth in claim 1 in which the wheat is cooked for a period of from 1 /2 to minutes at a pressure of from 35 to 100 pounds per square inch gauge.

5. The method which comprises cooking wheat in an atmosphere of steam, suddenly re- 8 ducing the pressure below 8 inches of mercury absolute to puff the wheat and then drying the pulled. wheat under the sub-atmospheric pressure.

6. The method as set forth in claim 5 in which the drying is accomplished while supplying heat to the wheat.

"I. The method which comprises pufling Wheat by a sudden reduction in pressure in an atmosphere of steam and concluding the operation at an absolute pressure substantially below 8 inches of mercury absolute, and then introducing a volatile liquid at a temperature sufficiently high to have an internal vapor pressure markedly above atmospheric, said mist containing additive fiavoring or nutritive ingredients, whereby the liquid explodes into a fine mist and penetrates the wheat.

8. In the puihng of wheat, the steps of heating the wheat in the presence of moisture to produce a super-atmospheric steam pressure thereon and then pumng the product into a maintained vacuum sufficiently low to cold set the product by evaporation of moisture from and consequent cooling of the product and reimposing atmospheric pressure upon the product while in cold set condition.

9. The process of claim 8 in which the pumng operation is carried out as a batch process, the pumng being into a vacuum which is initially at substantially absolute zero pressure and which rises during the puiiing operation to a point not above an average pressure of 4 inches of mercury absolute.

10. The process of claim 8 in which the pufling operation is carried out as a batch process, the puffing being into a vacuum which is initially at substantially absolute zero pressure and which rises during the pufhng operation to a point not above an average pressure of 2 inches of mercury absolute.

11. The method of claim 8 in which the product is dried after the puffing operation is complete but before reimposition of atmospheric pressure.

12. The method of claim 8 in which the temperature of the product is reduced below F. before reimposition of atmospheric pressure.

13. The method of claim 8 in which the temperature of the product is reduced below 50 before reimposition of atmospheric pressure.

14. The method of claim 8 in which the temperature of the product is reduced below F. before reimposition of atmospheric pressure.

15. A cold set, vacuum puffed wheat product produced by the process set forth in claim 8.

. JOHN M. BAER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,933,158 Bohn et a1 Oct. 31, 1933 2,246,528 Musher June 24, 1941 2,261,456 Warren Nov. 4, 1941 2,278,464 Musher Apr. 7, 1942 2,295,116 Kellogg Sept. 18, 1942 2,358,250 Rogers Sept. 12, 1944 2,438,939 Ozai-Durrani Apr. 6, 1948 FOREIGN PATENTS Number Country Date 494,085 Great Britain of 1937

Claims (1)

1. THE METHOD OF PUFFING WHEAT WHICH COMPRISES: FREEING WHEAT GRAINS FROM AIR AND REPLACING THE AIR WITH AN ATMOSPHERE OF STEAM, COOKING THE WHEAT GRAINS FOR A PERIOD SUFFICIENT TO SOFTEN THE CELL WALLS AND ADAPT THEM FOR PUFFING, THEN SUBJECTING THE WHEAT GRAINS TO A SUDDEN CHANGE FROM A HIGH SUPER-ATMOSPHERIC PRESSURE TO A LOW SUB-ATMOSPHERIC PRESSURE WHEREBY THEY ARE PUFFED.