Improving the in vitro protein digestibility of sorghum with reducing agents

Proc Natl Acad Sci U S A. 1987 February; 84(3): 626–628.

PMCID: PMC304267

Improving the in vitro protein digestibility of sorghum with reducing agents

B. R. Hamaker,^*^† A. W. Kirleis,^*^‡ L. G. Butler,^§ J. D. Axtell,^¶ and E. T. Mertz^*

^*Department of Food Science, Purdue University, West Lafayette, IN 47907

^§Department of Biochemistry, Purdue University, West Lafayette, IN 47907

^¶Department of Agronomy, Purdue University, West Lafayette, IN 47907

^†Present address: Instituto de Investigacion Nutricional, La Molina, Lima, Peru.

^‡To whom reprint requests should be addressed.

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Abstract

We have shown in previous reports that cooked sorghum protein is less digestible than other cooked cereal proteins. The pepsin-indigestible proteins in sorghum were found to be mainly prolamin proteins. Cooking sorghum in the presence of 2-mercaptoethanol increased protein digestibility (in vitro with pepsin or trypsin/chymotrypsin) to a level comparable with other cereals. At a concentration of 100 mM, other reducing agents (dithiothreitol, sodium bisulfite, and L-cysteine) were equally effective in improving sorghum digestibility. When maize was cooked in the presence of 2-mercaptoethanol, protein digestibility increased 5% compared to 25% for sorghum. Cooking barley, rice, and wheat with 2-mercaptoethanol had no significant effect on protein digestibility. The addition of reducing agents appears to prevent the formation of protein polymers linked by disulfide bonds.

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Selected References

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