Introduction: Evaluation of the quality of food proteins have great biological and economical importance. However, biological, microbiological, chemical and combined methods have been used and introduced for determining quality of proteins. Among the existing methods, NPR, RNPR, TPD and PER have been suggested as appropriate methods for determining quality of proteins. This study was conducted to evaluate the quality of wheat flour and soya protein mixture using the mentioned methods in 2003.

Methods: Forty-eight male Wistar rats, aged 21-23 days were randomized into bundles of 8, and each group was assigned one of the 6 diets. Three groups were used to study RNPR and PER for wheat flour and soya mixtures, casein+methionine and control (free Protein). The conditions of studying of RNPR and PER were the same with the exception that the duration of study on PER was 28 days and without limitation on Protein intake. To study TPD, the remaining 3 groups were fed the same diets. The period of the study for NPR was 14 days. Protein intake and weight gain were determined for calculating NPR. The period of the study for TPD was 9 days, and nitrogen intake and fecal nitrogen were determined for calculating TPD. Protein intake and change in weight of animals were determined. Rate of NPR, RNPR, TPD and PER were compared by t- test.

Results: NPR values were calculated as 2.7.3 and 4.3.48 for wheat flour and soya mixture and casein+methionin, respectively (P<0.0001) with RNPR=64.1. TPD values were 82.75.3 and 93.42.2 for wheat flour and soya mixture and casein+methionin, respectively (P< 0.0001). PER amounts were 1.15.12 and 3.04.24 for wheat flour and soya mixture and casein+methionin, respectively (P< 0.0001).

Conclusion: Wheat flour and soya mixture protein has low quality as compared with casein.

 Hakim Research Journal 2007 10(1): 20- 25.