Cereal Chem 64:327-332   |  VIEW ARTICLE

A Protein Quality Assessment of Wheat and Corn Distillers' Dried Grains with Solubles.

F. M. Dong, B. A. Rasco, and S. S. Gazzaz. Copyright 1987 by the American Association of Cereal Chemists, Inc. 

The protein quality of distillers' dried grains with solubles (DDGS) made from either soft white winter wheat, hard red wheat, or corn was assessed by amino acid analysis, protein efficiency ratio (PER), and net protein retention bioassays. The amino acid profiles of the whole grain flours and DDGS were similar, indicating that the amino acid profiles of the whole grains were retained throughout the fermentation process. Chemical scores of DDGS revealed that lysine was the most limiting amino acid. Both the PER and net protein retention assays ranked the different types of DDGS in the same order. The PER was less than 1.0 for DDGS. The in vitro protein digestibilities of red wheat DDGS and white wheat DDGS were significantly lower than in the unconverted whole grains. The much improved growth rates and food intake of rats fed a diet containing supplemental crystalline amino acids added to the white wheat DDGS basal diet indicated that the main reason for retarded growth in rats fed DDGS as a sole protein source was deficient intake of essential amino acids.