Peanuts protein quality

Cottonseed, peanut, sesame seed, and soybean flours, when used as supplements, add to the quality of the protein. The improvement of protein quality was due to the flours compensating for limiting amino acids. Supplementation using various flours improved total protein, amino acid content and some physical characteristics in akamu, yeast bread and sugar cookies. 

Soybean is a good source of lysine but is deficient in methionine. Cottonseed protein is deficient in lysine and peanut protein in methionine and lysine. The protein of potato although present in small quantity (Table 3-1) is of excellent quality and is equivalent to that of whole egg. 

Mixtures of legumes and cereals have a protein quality which comes close to that of meat, milk, and other animal proteins. The highest protein quality is usually achieved in mixtures comprised of 50% legume protein and 50% cereal protein because the amino acid patterns of the two types of foods complement each other. Some examples of food combinations utilizing this principle are corn tortillas and refried beans, baked beans and brown bread, peanut butter sandwiches, and macaroni products fortified with soy protein. 

Follow-up studies utilized finely-milled legume flours and the addition of soybean flour as a fat-control agent in an effort to improve doughnut quality (5). The legume products and doughnuts prepared from them are shown in Figure 5. On a dry weight basis, peanut flour from solvent extracted peanuts (PF-SE) contained 0.9% fat and 54.4% protein while cowpea flour (CF) contained 1.4% fat and 25.5% protein. Peanut flour from partially defatted untoasted peanuts (PF-PD-U) contained 34.5% fat and 34.9% protein while peanut flour from partially defatted peanuts toasted at 160°C contained 34.4% fat and 37.6% protein. 

Table II, Quality characteristics of peanut butter cookies prepared with navy bean hull (20%) and protein (30%) substitutions for wheat flour.

Lin et al. (15) showed that sunflower meal was superior to soybean and sunflower concentrates or isolates In emulsion capacity. McWatters and Cherry (9) compared select functional properties of defatted soybean, peanut, field pea, and pecan flours and showed that major seed storage proteins were important in emulsifying and foaming properties. Protein solubility was related to the quality of the emulsions and foams. Behavioral characteristics contributed by nonprotein components that occur naturally In the seeds, especially carbohydrates, were Implicated. 

A new process for peanut flour production has been developed that requires treatment of the seed with both heat and moisture prior to oil extraction. The flour end product is white and bland, contains 65% protein, and is devoid of peanut flavor. This allows the addition of this product to a variety of food products without dismrbing color, flavor, or texture. A high-quality flour has been used in the treatment of hemophiliac patients (67). 

Eight major oilseed crops traded in international markets account for more than 95% of the world s vegetable oil. These include soybean, cottonseed, peanut, sunflower, rapeseed, flaxseed, copra and palm kernel. Soybean is unique among these oilseed crops in that it also contains about 40% dry weight protein. Because of the large amounts of both oil and protein, soybean has dominated world oilseed production. The US, Brazil and China produce most of the world s soybean crop and as a widely traded commodity it is available throughout the world as a cheap source of quality protein and oil. 

Javanmard, M. Effect of whey protein edible film packaging on the quality and moisture uptake of dried peanuts. J. Food Process Eng. 31, 503-516 (2008)... 

Apart from price and availability considerations, the composition of an oil is only one of the factors that enter into decisions to choose one oilseed over another in world markets. Two other important considerations are the proportion of meal in the seed and the quality of the meal. For example, soybeans contain only 18% oil hence a much higher proportion of their total value lies in the high protein meal than in the oil. Conversely, rapeseed peanuts, sunflower, and cottonseed contain 30-40% oil, therefore oil is the more valuable component. Then the quality of the meal becomes a very critical factor in determining the commercial value of one oilseed versus another. Sunflower seed, for example, produces an inferior meal, which is high in fiber and low in protein (23%) meals from cottonseed and peanut are of medium quality. 

Growth studies using laboratory animals show that breads made from cassava starch and peanut flour, and from cassava starch and soy flour, contain higher quality protein than a standard bread made from wheat flour alone. An acceptable bread may be made from 70% wheat flour and 30% cassava flour. 

Protein supplements—The sources of extra protein are usually corn flour and soybean flour or meal, although other ingredients such as nonfat dry milk, fish flour, and derivatives of oilseeds (usually peanut, safflower seed, or sunflower seed) also may serve this purpose. These supplements raise both the quantity and quality of protein so that the macaroni and noodle products may be substituted for part of the dietary animal protein. 

These products must contain at least 20% protein with a quality at least 95% that of case in (a major protein in cow s milk). The supplemental protein may be supplied by flours or meals made from nonwheat, cereals or oilseeds such as soybeans, peanuts, sunflower seeds, and cottonseeds. 

Protein Quantity and Quality. Like legumes, nuts contain about twice as much protein as the common cereal grains, and have amino acid patterns that generally complement those of the cereals. However, nuts contain less of the amino acid lysine than legumes. Hence, the age-old practice of combining nut milks with cooked cereals made a lot of sense when animal protein was scarce. The American version of these complementary protein mixtures is peanut butter sandwiches, which children should eat with milk to offset the mild deficiency of lysine in the sandwich. 

Blends of peanut/chickpea, wheat/chickpea, rice/chickpea, peanuVsoybean, sunflower/maize, and cowpea/rice have all shown improved nutritional qualities with supplementation of sesame meal. Even more significant, however, is the finding that a simple blend of one part sesame and one part soy protein has about the same protein nutritive value as casein, the main protein of milk. The high-lysine and low-methionine content of soy protein is complementary to sesame protein. 

Maturity of peanuts has been shown to be important to many quality factors including flavor and shelf life (1, 2). Because of the indeterminate flowering pattern of peanuts, at harvest pods of various maturity are found on the plants. Research has been conducted to deftne many of the oil, carbohydrate and protein physiological changes that take place during maturation (3-6). Arginine (7), proteins (6) and peptides (5) have been related to maturity in peanuts. Williams and Drexler (P) found that pod mesocarp color changes in a defined manner with maturation. 

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