[Supplementary effect of 3 sources of soy protein on various corn products]

The purpose of the study was to demonstrate that the supplementary effect of soybean protein to corn depends on the protein quality of the soybean product and of the corn products used. Four types of corn flour of different protein quality were used, which included two whole corn flours produced from common corn, one from Opaque-2 corn, and one from degerminated corn. Likewise, three soybean products were tested, including a solvent-extracted soybean flour, a texturized soybean product and a soybean protein isolate. The study was carried out with weanling rats and the effects were measured by PER assays. The results corroborated the hypothesis that the protein quality of the ingredients controls the response observed. The supplementary effects were more evident for low-quality corn flours. Furthermore, large increments in quality were observed with additions of 5% soy protein, which became smaller as this level increased, independent of the corn flour used.