Chapter 7. A SPECIAL SHELTER RATION

Part 1.

Development of a wheat wafer

Choice of Materials and Methods

Cereals offer certain unique advantages as the basis for a shelter ration. They are perhaps the lowest cost, most abundant raw material available; additionally, they are regularly present in some form in the daily diet of most of the U.S. population regardless of ethnic origins, religious beliefs, or diet habits. Wheat, since it enjoys the widest acceptance in Americans diets, appears to be the logical choice as a starting material. However, the other common cereal grains -- rice, oats, corn, barley, and rye would probably lend themselves to the same end if desirable.

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Cereals appear in diets in many forms; baked products such as bread, crackers, and cookies; paste products such as spaghetti and noodles; in whole grain form such as rice, bulgur, and pearled barley; flakes or granules such as rolled oats and wheat, farina, and corn meal; and precooked dry doughs, namely the numerous ready-to-eat breakfast cereals. All of these familiar forms, because of their low bulk density, fragility, short storage life, a need for cooking, or other reasons, appear to be unsuitable as all-purpose shelter rations.

An approach to the problem of developing a cereal food for shelter stockpiling was suggested by a characteristic of parboiled rice noted several years ago (40). Parboiled rice ( 8 to 12% moisture content) expands several fold in volume when exposed for periods of a few seconds to air blasts at temperatures of 250° to 300° C. The resultant product is fully cooked, has a crisp friable structure and, because of the numerous small voids created by the expansion process, readily absorbs either hot or cold liquids. Bulgur (20) which is a pregelatinized or parboiled wheat, can also be expanded to give a similar product. Limited experiments indicate other pregelatinized grains react in like manner. The expanded bulgur is firm enough to withstand rigorous handling without breaking or crumbling and, in fact, can be ground and compressed without losing its desirable characteristics.

Pregelantinized grains have already undergone some processing involving major energy expenditures; as raw materials their cost is well above that of raw grains. Accordingly, some effort was expended on development of simpler and cheaper processes that would achieve the same ends. Two processes to date

have shown enough promise to justify further investigation. These are the hot-air treatment of moisture-conditioned wheat, and steam treatment followed by hot-air treatment of moisture conditioned wheat. Both techniques yielded products with some of the physical characteristics required and with a smaller energy demand than that required for expansion of dry parboiled wheat.

Compression and binding.

Pelleting is an economical and familiar commercial process for compressing bulk materials. Experimental pellets were made from ground expanded bulgur and evaluated for their usefulness. Their lack of flexibility in menu uses, and their unfamiliar form as a human food militated against this method of compression. In fact, the pellet form might actually cause complete rejection of a food because pellets are so frequently associated with animal feeds or pest control poisons. Compression into a more familiar

wafer shape and size appears to be most desirable.

In order to form wafers firm enough to withstand handling, but friable enough for easy chewing and crumbling, some binding material had to be used. Water is an effective binder, but organoleptic and stability requirements dictate moistures of 4 to 5 percent in the finished product. Attempts to dry wafers to such a low moisture level resulted in either flaking or a rock-like hardness. The choice of a binder was markedly limited because it was necessary to use an essentially dry material and one that is acceptable under Food and Drug laws. Fatty materials were found to be most satisfactory because of their plastic flow characteristics over a wide range of temperature-pressure conditions. Materials investigated ranged from liquids to high melting point solids and included natural animal and vegetable fats, hydrogenated fats, fatty acids, and fatty acid monoglycerides. Fatty materials have the added advantage of markedly increasing the caloric density of the product.

The higher the melting point of the fat the better are its binding characteristics. However, fats with melting points well above body temperature are reported to be poorly absorbed in the digestive tract. Therefore, fats with melting points above 120°F. were avoided. Because emulsification is a factor in fat digestion, use of a surface-active agent might offer some advantage. vestigation of this possibility was carried out.

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Some sugars (of low sweetening power) such as lactose and maltose and sugar-containing materials such as malt extracts or malt flours are also effective binders, though over a much narrower range of conditions. They also increase caloric density but to a lesser degree than would fats.

Formulation

Many possibilities exist for varied formulation of the wafer. Numerous flavoring materials, such as cheese, fruit, or bacon bits, could be added to form an assortment of snack-type products. Complete meals requiring only the addition of water could be made by incorporating powdered milk and sugar or various combinations of spices, herbs, and dehydrated vegetables and meat. Such an approach, however, would add serious complications to the already complex picture of product stability, procurement and standardization, and surveillance sampling procedures and costs.

The more desirable approach appears to be formulation of wafers of pleasantly bland flavor, palatable enough to be eaten plain yet neutral enough in flavor to blend well with a wide variety of possible flavor adjuncts. This tends to simplify many of the problems just mentioned and, additionally, allows wider flexibility in adapting to individual or group preferences.

Technological details

The material used to prepare cereal wafers was commercial bulgur made from California-grown soft white wheat. Bulgur processing consists essentially of raising the moisture content of whole wheat to at least 40 percent, gelatinizing the starch completely by steaming under pressure (usually 20 psi. or higher), drying the product to approximately 10 percent moisture, and milling slightly to remove a portion of the bran (20). Crude fiber content is normally in the range of 1-1/2 to 2 percent. This could be lowered by harder milling at this stage of production. Finally, the grain is cracked and screened into various grades of

coarseness.

For making the cereal wafer, either cracked or whole kernels can be expanded with equal facility. Moisture content prior to expanding was in the range of 9 to 11 percent; optimum conditions, however, have not been accurately determined. Expanding was done by passing the grain on a moving belt through a stream of hot air at 265° C.; the air velocity was sufficient to keep the particles bouncing slightly on the belt. Residence time in the air stream was 20 seconds, though this could be varied somewhat to alter the amount of toasting given the grain. The grains should come off the puffer at approximately 2-1/2 to 3 percent moisture.

Equipment for continuous expanding of bulgur consists essentially of a moving continuous woven wire belt on which the grain travels through the air stream. The belt is powered by a variable speed drive so that residence time of the grain in the air stream can be varied from 10 to 120 seconds. Air is delivered by a

squirrel-cage blower from the bottom through the two layers of belt which act as baffles to distribute the air uniformly. Air velocity is variable from essentially 0 to 900 feet per minute, controlled by a damper on the intake side of the blower. Heat is supplied to the air by a gas burner positioned near the intake side of the blower and temperature is controlled by modulating gas flow to the burner through automatic controls. The whole equipment is enclosed in an insulated box and the amount of recirculation of heated air can be controlled between approximately 0 and 85 percent by means of an adjustable opening on the box near the burner.

After expanding, the grain was coarsely ground (or it could be left whole). Then it was placed in the heated bowl of a planetary-type mixer equipped with a wire whip or paddle and the other ingredients uniformly blended in. The formulation (at the current stage of development) is 79.5 percent bulgur, 10 percent fat (hydrogenated peanut oil, melting point 116° 118° F., iodine value 50), 10 percent dry malt extract, and 0.5 percent salt. Fat was added in a liquid state and bowl temperature maintained high enough to retain the liquid state. The malt and salt were added after dissolving them in sufficient hot water to raise bulgur moisture content to 4 to 5 percent. Mixing continued for 20 minutes to allow uniform distribution and adsorption of the additives. Any further additives such as anti-oxidants or flavoring could be added at this stage.

Textural adjustments can be made by further grinding after the materials are blended. The degree to which the material is ground alters wafer characteristics markedly. If no grinding is used, higher pressures are required to form wafers of sufficient strength; the wafers are harder to chew and the material absorbs liquids very slowly. As the proportion of fines are increased due to grinding, lower pressures are required to form wafers, crunchiness of the wafers diminishes, and the rate of absorption of liquid increases. A wide range of particle sizes, obtained by grinding after incorporation of all additives, appears most desirable. Binding is improved, a measure of crispness is retained, and liquid adjuncts are quickly immobilized because the fines absorb the liquid rapidly, yet the product is rice-like in texture.

Wafers were pressed at pressures over a range of 7500 to 10,000 psi. and at temperatures from 40° to 70° C., with residence time of approximately 2 minutes. In commercial production, residence time could probably be reduced to a few seconds by feeding preheated material to the press. These conditions will vary with formulation, melting point of fat, and moisture content. If fat alone is used as a binder the determining factor is its melting point, whereas if malt is added moisture content also must be considered.

Each wafer contained 20 grams of material. No effort was made to determine the optimum size and shape for the wafers. They were pressed to approximately 1/3 inch thick and either 2x2 inches square or circular with 2.25-inch diameter; these are sizes and shapes common in commercially produced crackers and cookies. The circular wafers have better handling characteristics, i.e. less tendency for edges to crumble; square wafers could be packaged better and would require less cubage for storage of a given weight.

The conditions and formulations described above were based on subjective evaluations; time did not permit development or use of objective measurements related to flavor preference, wafer strength, or crumbling and chewing characteristics. A light toasting was given the grain during the expansion process to enhance the flavor. Both fat and malt were used because the combination gave desirable flavor and binding qualities. The use of both may also contribute to storage stability (see next section). Salt was added for the usual organoleptic reasons.

Storage stability

As with other cereal products, storage stability of the cereal wafers will depend on several factors. Undesirable changes over long periods of time can be minimized by proper formulation, control of moisture, use of antioxidants, proper packaging, and inert storage atmosphere. Adequate study of the effect of these variables has not been possible as yet.

Of the changes leading to deterioration, oxidative changes in the lipid fraction are most likely to occur first. Wheat contains approximately 2 percent of a highly unsaturated natural fat markedly susceptible to oxidative rancidity. Removal of this fat before or during processing offers perhaps the best possibility of eliminating or minimizing the problem. By treatment of the raw grain with dilute alkali combined with wet scouring to remove all or most of the germ, approximately 50 percent of this troublesome fat was removed.

A storage study of canned dry puffed bulgur was conducted to evaluate the effects of six different formulations, nitrogen compared with air as the package atmosphere, and three levels of storage temperature. The observations were made after the material had been stored for 47 days. This test indicated that a formulation containing both malt and fat may delay development of rancid odors. Rancidity was detected in most samples formulated with either malt or fat alone. But even after storage at 110° F., no rancid odor could be detected in any of the samples formulated with both malt and fat whether they contained antioxidant or not.