Nutritional Value of Proteins from Different Food Sources. A Review

The nutritional value or quality of structurally different proteins varies and is governed by amino acid composition, ratios of essential amino acids, susceptibility to hydrolysis during digestion, source, and the effects of processing. To optimize the biological utilization of proteins, a better understanding is needed of the various interrelated parameters that influence their nutritive value. This review attempts to contribute to this effort. It discusses methods used for protein quality evaluation, research needs to facilitate labeling foods for protein quality, and factors influencing protein quality including amino acid analysis, digestion, food processing, antinutrients, and protein-energy relationships. Recent studies on the nutritional quality of more than 50 common and uncommon protein sources including cereals, legumes, other seeds, meat, seafood, insects, leaves, mushrooms, and potatoes are reviewed. Also described are advantages of consuming low-quality proteins fortified with essential amino acids, nutritional benefits of mixtures of complementary protein sources, plant genetic approaches to improving the nutritive value of foods, problems associated with liquid diets for adults and infants, socioeconomic aspects of new protein foods, and the influence of protein type and quality on lactation, the immune system, and serum lipids. This integrated overview is intended to stimulate interest in the introduction and use of new protein sources for feeding the ever-growing world population. Keywords: Amino acids; digestibility; food protein sources; health; malnutrition; mixed proteins; nutritional quality; protein quality