Comparative Protein Quality as Measured by Human and Small Animal Bioassays of Three Lines of Winter Wheat

Abstract

Incomplete information on factors contributing to apparent protein quality and to value of food products as sources of protein and how these factors interact necessitate the use of bioassay procedures. Ideally bioassay procedures should be done using the animal speciesfor which the protein is intended. Practical considerations dictate the use of small animal bioassay rather than human bioassays for routine use in protein product evaluation. To be of real value for assays of food products designed for human use, animal bioassays must accurately predict human performance. Surprisingly little information is available on this topic.

In the current project three Nebraska winter wheats of similar genetic backgrounds were evaluated for protein value and for value of the wheats as sources of proteins. Chemical, weanling mouse, adult human and growing human bioassay techniques were employed. Rankings of the grains were similar regardless of species used for protein quality evaluations. Similar rankings were found regardless of species used for protein quality/quantity evaluations. However, ranking varied between methods designed to evaluate protein quality and those designed to measure protein quality/quantity interrelationships. The results stress the importance of matching appropriate methodology with information desired. In a latter project, wheats of dissimilar genetic background were not as uniformily evaluated. This suggests that other factors known to affect protein quality and value were more variable in these wheats.

The research was supported in part by funds from the Agency for International Development, U.S. Dept. of State, Washington, D.C. Contract No. AID/csd-1208 and by Nebraska Agricultural Experiment Station Project 91–007. Published as Paper No. 3633, Journal Series, Nebraska Agricultural Experiment Station