Predicting Protein Quality of Corn‐Soy‐Milk Blends After Nonenzymatic Browning

CSM, a corn‐soy‐milk high‐protein supplement for children, was exposed to high temperatures. Various degrees of nonenzymatic browning occurred, and product color ranged from yellow to dark brown. Progressively greater deterioration of protein quality as measured by protein efficiency ratio (PER) occurred with increasing color change as measured by Hunter color values. Protein quality was also estimated by the Tegrahymena pyriformis W bioassay and essential amino acid analysis. Linear relationships between PER, available lysine, and Hunter “L” values provided rapid methods for predicting protein quality. Correlation with PER was 0.95 using Hunter “L” and 0.88 using available lysine values. A color standard plate was developed to provide rapid field screening.