239Soy proteins appear to be the only commercial protein ingredients that will be used in the foreseeable future for both nutritional and functional purposes as replacements for traditional animal proteins. Of various soy protein forms, isolates are the most expensive, but often offer the greatest savings and best performance functionally plus, consumer acceptance.

This chapter reviews a wide variety of alternatives to traditional animal protein (meat) ingredients. Ideal protein ingredients offer easy digestibility, high quality, safety, absence of microbial contamination, and a wide range of functional properties, including desirable organoleptic properties, low cost and wide availability.

This thorough analysis considers non-traditional animal sources, such as blood proteins and fish protein concentrate, and other plant proteins such as leaves, cottonseed, sunflower, rapeseed, winged bean, coconut, peanuts and wheat gluten. Single cell proteins hold a small position in the market, primarily as health foods and flavoring ingredients.

In addition to soy protein isolate, commonly used and widely accepted protein food ingredients include egg albumin and the milk derivatives, nonfat dry milk and sodium caseinate.

Meat proteins have established standards of nutritional and functional properties, and are the measure against which most vegetable protein food ingredients are compared. The protein food ingredients surveyed here are compared on the basis of such attributes as essential amino acid content, digestibility, safety, economics, availability, production feasibility, and functional properties such as solubility, viscosity enhancement, emulsification, cohesion-adhesion, health characteristics, flavor, texture and color.

Functional properties are critical in manufacturing and in consumer acceptance of food products containing vegetable protein ingredients.

Because of increasing costs of traditional animal proteins, such as meat and milk, and because of increasing health concerns related to these traditional products, the food industry has investigated and developed a variety of alternative sources of protein. Most of the viable alternatives are plants.

Among the non-traditional animal proteins, blood proteins have limitations of color, amino acid composition and cost. Fish protein concentrate, developed and used in Japan, is expensive, subject to fluctuations in supply, contains residual ethanol from processing, and is insoluble, thereby having limited functional value.

In their limited applications, single cell proteins are very expensive. Some yeasts have excessive nucleic acid content.

240Peanuts and wheat are used commercially, but are not major factors in the protein ingredient market. Peanuts are too expensive to compete with soybeans and do not have a good balance of essential amino acids. Wheat gluten serves a special market, supplying desired baking characteristics in bread items and chewy texture in meat analogs.

Other plant protein sources—leaf protein, cottonseed, sunflower, rapeseed, winged bean and coconut—remain potentially valuable sources, but near-term commercial development is uncertain. The uncertainties include questions of safety, quality, availability and economics.

Soybeans are clearly the most promising alternative source of protein food ingredients. They meet virtually all of the desired performance and economic requirements. The soybean industry is well established and a wide range of products is available in the form of flours, protein concentrates and isolates.

isolates are the most highly refined and most expensive form, but are widely available and have the greatest versatility. They often offer the greatest savings because they can be added to foods at higher levels and still retain all their performance advantages.