PROCESS FOR ENRICHING THE PROTEIN CONTENT OF FOOD AND FEEDSTUFF AND PRODUCTS THEREOF

Abstract: A method for producing a protein enriched food or feed product and products thereof. The method entails forming a mixture of water and a food or feed product, sterilizing the mixture, inoculating the sterilized mixture with a spawn culture of the genus Pleurotus, maintaining the inoculated mixture in the presence of air at a temperature of from about 5 to about 46`C so as to enable the mycelium of the spawn culture to grow, and later terminating the growth of the mycelium. The food or feed product resulting from this process has an increased protein content.

Description: FOODANDFEEDSTUFFANDPRODUCTSTHEREOF BACKGROUND OF THE INVENTION This invention relates generally to food or feed products and processes. More particularly, this inven¬ tion relates to a process for enhancing the protein content of food or feed products. Additionally the invention relates to food and feed products having an increased protein con¬ tent as produced by the subject process. One of the most serious problems which the world faces is supplying nutritionally adequate protein to meet the demands of a population which is expanding by approximately 55 million people annually. If the average protein require¬ ment for an individual is about 52 pounds per year, this means that there must be produced an additional 2.8 billion pounds of protein each year just to keep pace with the popula- tion increase. This does not take into account the fact that much of the present world population does not have suf¬ ficient protein in their diet to be healthy enough to lead meaningful lives. Thus, there is a very pressing need for ways of increasing the total protein production of the world. A problem associated with the need to supply adequate protein for the world population is the fact that cereal grains and cereal grain products make up a high percentage of the diet of most of the developing nations. Unfortunately, these grains and grain products usually contain 10% or less protein which is very often deficient in some of t essential amino acids. Since the average person requir at least 65 grams of high quality protein per day for good health, this means that an intake of 650 grams of cereal grains would be required to supply this quantity of protein. Ingesting this much cereal grain would sup too much carbohydrate relative to the amount of protein Furthermore, the protein contained within these cereal grains is generally of relatively poor quality. The present invention is directed to a soluti to the above-described problems by increasing the ratio of protein to carbohydrate in cereal grains and product thereof while concominantly improving the overall amino acid balance for the treated grain. Much of the grain grown in the world is fed t monogastric animals (swine, chickens, etc.) who have roughly the same nutritional requirements as man. Acco ingly, the present invention would lead to economy in feeding these animals since it would not be necessary t add protein supplements to these grains (soy bean meal, cotton seed meal, fish meal, etc.) if the animals were fed grains treated by the process of the present inven¬ tion. Studies have been made in the past to dev¬ elop processes for treating various foods containing carbohydrates with lower fungi so as to increase their protein content. The process suggested in such studies, however, are less desirable than O P fa IP the process of the present invention because these other processes either require "fixed" inorganic nitrogen, produce nutritionally deficient protein, or require separation of the protein to produce an acceptable food or feedstuff. On the other hand, the present process suffers from none of these drawbacks. A food or foodstuff such as a cereal grain (wheat, corn, and the like) treated by the instant process may be dried to the customary moisture levels and processed by conventional methods to provide food and feed products such as bread, dry cereal products, dog and cat foods and the like which contain enough high quality protein to be nutritionally well balanced and have a flavor which is highly acceptable. Another aspect of the present invention is the fact that agricultural waste products such as peanut hulls, corn residue, grain straws and the like may be mixed with cereal grains and treated by this process to give products which are particularly well suited for animal feedstuff. Materials such as corn silage could also be treated by the present process. Additionally concepts have previously been disclosed relating to the art of cultivating mushrooms from a mycelium of the genus Pleurotus including Pleurotus ostreatus, Pleurotus u3...ariums, Pieurotiu. sapi us, Pl_eurot_ι_3 cor_ nicopiae, and p]eurotus florida. At least one publication suggests that mushrooms may be cultivated in a culture medium comp ising, for example, ■ f - O PI - corn fibers and rice bran (or corn bran) and subsequently the cultivation medium may be used as feedstuff. At least one other previously known publication dis¬ closes that a nutrient substance which comprises one or more cellulose-containing agricultural waste products may be crushed, mixed with water and placed into a ventilated con- tainer which is sterilized. The sterilization is carried out either by heating to 70 to 80°C for 5 hours or by intro¬ ducing propylene oxide. After the mixture is placed inside the sterilized container, it is injected with a mycelium of the fungus Pleurotus ostreatus. The nutrient substance is preferably wheat, barley, rye, peas, rice shells, sun flower stalks and seeds. The container is kept at a constant temperature betwee 16 and 20°C after seeding. When the nutrient is permeated with " the mycelium, the temperature is lowered to between 5 and 16°C. After the onset of the crop of mushrooms, the container is opened and illuminated with light. Still another theorist suggests that a substrate such seed oil residues (e.g., cottonseed meal, coconut meal, peanut meal, etc.) which are advantageously mixed with a cereal material such as wheat or the like may be innoculated with a mycelium of mushrooms including, among others, Pleurotus ostreatus. The substrate (e.g., peanut meal) is first acid hydrolyzed by treating it with mineral acid. The calcium carbonate is added and the pH is adjusted to between U J 6 and 8. This mixture is then innoculated with the mycelium of mushrooms (e.g., Pleurotus ostreatus) which has been grown on a medium of the same composition. Although the above noted disclosures have at least a degree of conceptual appeal in the art of growing mushrooms, little if any attention has been directed to developing a protein enriched food or food stuff using a spawn culture of the genus Pleurotus. In none of these publications has any mention been made of the fact that Pleurotus will grow in the presence of materials already containing protein (cereal grain and the like) without substantially altering the protein already present, and at the same time produce additional protein by fixing nitrogen which is in the air and using the grain as a source of carbon. OBJECTS AND SUMMARY OF THE INVENTION Accordingly, a general object of the present invention is to provide a novel process for preparing a food or feed product which has an enhanced protein content. A more specific object of the present invention is to provide a novel process for increasing the protein content of food or feed products . Another object of the invention is to provide a novel process for increasing the protean content of a food or food- stuff utilizing nitrogen from the atmosphere. OMPI IPO A further object of the invention is to prov a novel process for increasing the protein content of eal grains while concomitantly improving the overall a acid balance for the treated grain. A still further object of the invention is t provide a novel process for increasing the protein con of agricultural waste products to produce a product pa cularly suited for animal feedstuff. Still another object of the present inventio to provide a protein enriched food or feed product pro by this process. Other objects and advantages of the inventio will become apparent from the following summary and des cription of the preferred embodiments of the present i vention. Summary In one aspect, the present invention provides process for increasing the protein content of a food o feed product which contains carbohydrates. This process comprises 1 : (a) forming a mixture of the food or feed pr duct with water; (b) sterilizing the mixture in order to sub¬ stantially eliminate the growth of sub- stances which would compete with a spawn culture of the genus Pleurotus; (c) innoculating the mixture with a spawn culture of the genus Pleurotus; (d) maintaining the innoculated mixture in t presence of air at a temperature of fro ( about 5 to about 46°C so as to enable the mycelium of the spawn culture * to grow, and (e) terminating the reproduction of the mycelium so as to form a food or feed product which has an increased protein content. In another aspect, the present invention comprises the product produced by the above described process. DESCRIPTION OF PREFERRED EMBODIMENTS The process of the present .invention involves treating a food or feed product with a spawn culture of the genus Pleurotus. The food products useful in this process include any carbohydrate containing food product on which Pleurotus mycelium will grow in the presence of air. Such products include, for example, cereal grains such as corn, rye, oats, milo, rice, barley, soybeans, manioc, yams, and sweet potatoes; products of the milling industry that con¬ tain carbohydrates such as wheat bran and rice bran; other carbohydrate containing food products such as lima beans, pinto beans , and pulses including white acre peas , black- eyed peas, and the like, and agricultural wastes such as pea¬ nut hulls, corn residue, grain straws, cottonseed hulls, bi- gasse, corn silage. Mixtures of two or more food or feed products may also be used. The first step in the subject process comprises mixing the food or feed product with water. Water is needed so that when the food or feed product is innoculated with Pleurotus it will have a sufficiently moist environment in which to grow. The mixture should contain generally from about 20% to about 80%, typically from about 30% to about 70% and preferably from about 40% to about 60% by weight food or feed product, and correspondingly generally from about 20% to from about 40% to about 60% by weight water. These ~~- percentages are based upon the total weight of the mixture. In a preferred embodiment of the present inventio calcium carbonate may be added to the mixture of the food product and the water. The purpose of the calcium carbonat is to increase the pH of the mixture to a value in the rang of from about 6 to about 8 for the purpose of providing the preferred pH for the growth of Pleurotus. The calcium car¬ bonate is also added for the purpose of supplying nutrient to the mixture. Although calcium carbonate is preferred, any com- pound which is non-toxic and which will supply required nu¬ trients is useful in the growth of the leurotus mycelium. Such compounds include calcium hydroxide, calcium sulfate, dicalcium phosphate, organic calcium salts such as calcium citrate, and the like, and other mineral nutrient materials such as nutrient compounds of potassium, magnesium iron, phosphorus, zinc, copper, boron, sulfur, and the like. Mix tures of two or more nutrient compounds may also be used. These nutrient compounds must be in a form such that they are not toxic to the mycelium. Harvested grains usually contain sufficient quantities of these nutrients and their addition is not required for efficient growth when harvested grains are employed. The second step of the present process comprises sterilizing the mixture so as to substantially eliminate the w ta ces whic om with th P tus. This mixture may be sterilized by any means known to those skilled in this art. For example, the mixture may be sterilized by heating or by pretreating the substrate with chemical compounds such as propylene oxide or anhydrous ammoni . If the mixture is sterilized by means of heat, it should be heated to termperatures in excess of 120 β C for a sufficiently long period of time to allow the entire mix¬ ture to attain a minimum temperature of 120°C. The sterilized mixture is next innoculated with a spawn culture of the genus Pleurotus at temperatures which are generally from about 5 β C to about 46°C typically from 10 β C to about 30°C and preferably from about 20°C to about 30°C. Mixtures of two or more members of this genus may al- so be used. As used herein, the term "spawn culture" refers to a living culture of the mycelium growing on any substrate which will support its growth. The mixture may be innoculated with the spawn cul- ture by adding a small amount of the culture as finely divided as possible and mixing this culture into the new substrate as thoroughly as possible. The amount of Pleurotus used to innoculate the food product mixture may be generally from about 0.5% to about 20%; typically from about 1% to about 5%, and preferably from about 1% to about 3% by weight based upon the total weight of the innoculated mixture. The innoculated mixture is then maintained in the presence of a mixture of nitrogen and oxygen at a temperature of generally from about 5°C to about 46°C, typically from about 10°C to about 35°C, and preferably from about 20°C to about 30°C. These temperature ranges are important in they represent those temperatures at which Pleurotus will grow. At temperatures substantially below about 5°C or su stantially above about 46°C Pleurotus does not experience substantial growth. The innoculated mixture must be maintained in the presence of a mixture of nitrogen and oxygen in order to produce an increase in protein content of the food product Any ratio of nitrogen to oxygen may be employed in the process of the present invention although the mixtu shall preferably contain more than 10% by weight oxygen an more than 10% by weight nitrogen. The amount of gas mixtu which is employed is important only in that substantial protein increase may not_ occur if there is insufficient nitrogen and/or oxygen present during the growth period. Other gases may also be included in this mixture. Air whi is at or near the surface of the earth is a preferred gas mixture since it contains oxygen and also contains approxi mately 78% molecular nitrogen by volume. The innoculated mixture should be maintained in contact with the gas mixture for a period of time long enough to effect sufficient growth of the mycelium but not for too long a period of time since there is no advantage doing so and since contamination with other fungi or bacte mav occur. The ' innoculated mixture should be kept in contact with the gas mixture for generally from about 2 days to about 80 days, typically from about 14 days to about 56 days, and preferably from about 21 days to about 35 days. If the innoculated mixture is kept in contact with the gas mixture for a time period substantially less than about 2 days, then the protein increase is comparatively in¬ significant. On the other hand, if the innoculated mixture is kept in contact with the gas mixture for a time period sub- stantially in excess of 80 days, the amount of protein increase over and above that attained up until that time is also comparatively insignificant. After sufficient mycelium growth has taken place, the growth of the mycelium is terminated. Growth may be terminated, for example, by dehydrating the mixture to a moisture content of generally less^ than about 20%, typically less than about 18%, and preferably less than about 12% by weight based upon the total weight of the innoculated mixture. Growth may also be terminated by chemical steriliza- tion or heating. Prior to treatment according to the process of the present invention, the food product has a protein content of generally less than about 25 percent, by weight, based upon the weight of the food product as determined by nitrogen analysis. After treatment according to the process of the present invention, the food product has a protein content • which is generally at least about 30 percent to 65 oercent by weight higher; based upon the weight of the food product. The following Examples are given as specific illust tions of the claimed invention. It should be understood, however, that the invention is not limited to the specific details set forth in the Examples. All parts and percentage in the Examples as well as in the remainder of the specifica tion are by weight unless otherwise specified. ■Examples 1 - 7 These Examples illustrate the preparation of the enriched protein food product of the present invention. The following general procedure applies to each of these Example One hundred twenty five (125) grams of the food product, one hundred (100) grams of water, and two point fiv (2.5) grams of finely divided calcium carbonate are mixed in a glass container. The container is closed with a cotton plug and the mixture is sterilized by heating in a steam autoclave. The mixture is then cooled to room temperature and innoculated with a Pleurotus ostreatus spawn culture. T innoculated mixture is then maintained in the presence of atmospheric air at 21°C. The specific details of each Example are given in Table I below. fa TABLE I EXAMPLES Wheat 50% White Food Product Corn Rye Oats Rice Wheat Corn 50% Acre By Weight Peas Amount P .0. (grams) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Initial Pro¬ tein Content 11.3 14.3 14.0 8.0 15.5 12.8 22.5 Protein Con¬ 15.7 17.74 18.8 8.7 ____>«• tent After 3 weeks " Protein Content —, — — — 19.2 18.9 32.5 After 4 Weeks Protein Content After — 23.9 — 10.8 — — — 5 Weeks The protein content of each example was determined by the well known technique of nitrogen analysis. The above examples illustrate that the present invention provides a process whereby protein content of a food product is substantially increased by innoculating the food product with mycelium of the genus Pleurotus. By means of this process, the ratio of protein to carbohydrate in cereal grains and other food products may be increased, thus alleviating to some degree the problems associated with the lack of protein in the diet of much of the world population. Comparative Example Example 2 was repeated except that Agaricus bisporus mycelium was used instead of Pleurotus ostreatus. Sub¬ stantially no increase in protein content was measured. The above-described Examples illustrate that when the process of the present invention is employed, there is pro¬ duced a food product having an increasedprotein content. On the other hand, when the same process is carried out using Agaricus Bisporius rather than Pleurotus, there results sub- stantially no protein increase. The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Varia¬ tions and changes may be made by those skilled in this art without, departing from the spirit of the invention. WHAT IS CLAIMED IS:

Claims: 1. A process for increasing the protein content of a food product which contains carbohydrates comprising: a) forming a mixture of said food product with water; b) sterilizing said mixture in order to substantially 5 eliminate the growth of substances which might compete with the growth of a spawn culture of the genus Pleurotus; c) innoculating said mixture with a spawn culture of the genus Pleurotus; 20 d) maintaining the innoculated mixture in the presence of a mixture of nitrogen and oxygen at a- temperature of from about 5°C to about 46°C so as .to enable the mycelium of said spawn culture to reproduce; and e) terminating the reproduction of said mycelium so • j _5 as to form a food product which has an increased protein content. 2. The process for increasing the protein content of a food product as defined in claim 1 wherein said Pleurotus spawn culture comprises: a member selected from the group consisting of Pleurotus 5 ostreatus, Pleurotus ulmarius, Pleurotus sapidus, Pleurotus corninicopiae and Pleurotus florida. 3. The process for increasing the protein content of a food products as defined in claim 1 wherein: the innoculated mixture formed in step (c), is maintained in the presence of air at a temperature of from about 10°C 5 to about 46 e, C for from about 2 days to about 80 days - oτ O*-MEPI WIΪO 4. The process for increasing the protein content of a foo product as defined in claim 1 wherein the food product comprises: a mixture of an agricultural waste product and a cereal grain. 5. The process for increasing the protein content of a foo product as defined in claim 1 wherein the food' product comprises: at least one member selected from the group consisti of corn, rye, oats, rice, wheat and white acre peas. 6. The process for increasing the protein content of a foo product as defined in claim 1 wherein: from about 0.5% to about 20% by weight y Pleurotus is added to the food product mixture based upon the total weig of the innoculated mixture. 7. A process for increasing the protein content of a food product which contains carbohydrates comprising: a) forming a mixture of from about 20% to about 80% by weight food product and from about 20% to abou 80% by weight water; b) sterilizing said mixture in order to substantiall eliminate the growth of substances which might compete with the growth of a spawn culture of the* genus Pleurotus; c) innoculating said mixture with from about 0.5% to about 20% by weight of at least one member selected from the group consisting of Pleurotus ostreatus, Pleurotus ulmarius, Pleurotus sapidus, Pleurotus corninicopiae, and Pleurotus florida; d) maintaining the innoculated mixture in the presence of a mixture of nitrogen and oxygen at a temperature of from about 5°C to about 46°C so as to enable the mycelium of said spawn culture to- reproduce; and e) terminating the reproduction of said mycelium so as to form a food product which has a protein content which is about 30% to 65% by weight higher than it had been prior to said innoculation. 8. The process for increasing the protein content of a food product as defined in claim 7 wherein: said mixture of food product and water comprises from about 30% to about 70% by weight food product and from about 30% to about 70% by weight water. 9. The process for increasing the protein content of a food product as defined in claim 8 wherein: said mixture of nitrogen and oxygen comprises air. 10. The process for increasing the protein content of a food product as defined in claim 9 wherein: said mixture is sterilized by pre-treating the food product with a chemical compound which removes substances which would grow and compete with Pleurotus. 11. The process for increasing the protein content of a fo product as defined in claim 9 wherein: the food product comprises a mixture of an agricultu waste*product and a cereal grain. 12. A process for increasing the protein content of a food product which contains carbohydrates comprising: 1 a) forming a mixture of from about 40% to about 60% by weight food product and from about 40% to abou 60% by weight water, b) sterilizing said mixture in order to substantiall eliminate the growth of substances which might .compete with the growth, of a spawn culture of the genus Pleurotus, c) innoculating said mixture with from about 1% to about 5% by weight of at least one member selecte from the group consisting of Pleurotus ostreatus, Pleurotus ulmarius, Pleurotus sapidus, Pleurotus corninicopiae, and Pleurotus florida, d) maintaining the innoculated mixture in the presen of air at a temperature of from about 10°C to abo 46°C, for from about 21 to about 35 days so as to enable the mycelium of said spawn culture to reproduce, and e ) terminating the reproduction of said mycelium so to form a food product which has a protein conten which is about 30% to 65% by weight higher than i had been prior to said innoculation. 13. The product produced by the process of claim 1. 14. The product produced by the process of claim 7. 15. The product produced by the process of claim 12.

Inventors: HARPER J
Applicants: HARPER J
Application year: 1979
Main classification: A23J1
IPC codes: A01G1, A23K1, A23L1