COWPEA POWDERS DRIED WITH METHIONINE: PREPARATION, STORAGE STABILITY, ORGANOLEPTIC PROPERTIES, NUTRITIONAL QUALITY

Abstract

ABSTRACT Cowpea ( Vigna sinensis ) was soaked, dehulled, ground, supplemented with various levels of DL‐methionine, drum dried and the powders evaluated fresh and after storage. Chemical determinations indicated that the protein, amino acid composition, available lysine, methionine retention and thiamine content of the cowpea powders, compared to raw cowpeas, were not appreciably affected by the processing and storage conditions, including 24 wk at temperatures up to 37°C. Fresh and stored powders supplemented with up to 0.6% methionine were evaluated in a traditional main‐moin recipe by a taste panel of members from several African countries and well rated in terms of color, flavor, consistency and overall acceptability. Nutritional studies indicated that drum drying eliminated trypsin inhibitors and that methionine supplementation produced a concentration dependent effect on protein quality as gauged by weight gains of rats and PER values, which increased from 1.64 without methionine supplementation to 2.65 at the 0.6% addition 1eveL At the 0.6% level, however, fatty infiltration of rat livers occurred. This was also evident but much less pronounced at a level of 0.4% added methionine. Cowpea powders stored 24 wk showed reductions in PER values but even at 37°C protein quality, as measured by PER, was largely retained in methionine‐supplemented powders.