Nonprotein constituents

Proteins and Meals. Nutritional properties of the oilseed protein meals and their derived products are deterrnined by the amino acid compositions, content of biologically active proteins, and various nonprotein constituents found in the defatted meals. Phytic acid (3), present as salts in all four meals, is beheved to interfere with dietary absorption of minerals such as 2inc, calcium, and iron (67) (see Food toxicants, naturally occurring Mineral nutrients). ... 

For products of dissimilar composition, e.g., isolates, concentrates, and flours, changes in the chemical environment undoubtedly elicit different responses from the various constituents of an ingredient, i.e., protein, carbohydrate, etc. Perhaps the properties of the protein can best be examined in the isolate because of its relatively low concentration of nonprotein constituents. Unfortunately, isolates usually have been subjected to the most extensive processing, which also affects the response of the protein. 

A protein-containing biological catalyst. Many enzymes also include prosthetic groups, nonprotein constituents that are essential to the enzyme s catalytic activity, (p. 1190)... 

Whey Protein Isolate occurs either as a liquid or as a dry product. It is the substance obtained by the removal of sufficient nonprotein constituents from whey so that the finished dry product contains not less than 90% protein. Removal of nonprotein constituents is accomplished by separation techniques such as precipitation, membrane filtration, and/or ion exchange. The acidity of Whey Protein Isolate maybe adjusted by the addition of safe and suitable pH-adjusting ingredients. The final product is pasteurized. 

In meat emulsions, a specific soluble fraction of proteins was shown to function as the key emulsifier (22). However, Lin et al. (15) showed that sunflower meal was superior to soybean and sunflower protein concentrates or isolates in emulsification capacity. These authors suggest that nonprotein constituents of seeds may contribute to the formation of emulsions and aid in the formation of whipped foams. 

The total concentration of protein may be measured by nitrogen, or by specific gravity or refractive index. The method is generally applicable to sera and to serum protein solutions. Care should be taken to check the possibility of absorption by nonprotein constituents of serum which in some diseases such as cirrhosis of the liver may be considerable. The presence of such substances is shown by a marked fall in absorption of the serum after dialysis. 

Table 4. Average values of experimental partial specific volumes of the main nonprotein constituents of glyco- and lipoproteins. From [89D1].

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