Evaluation of Factors Affecting the Use of Tetrahyrrzena pyriformis W to Determine the Relative Nutritive Value of Foods

Abstract

This study was conducted to evaluate the effects of alterations in sample preparation procedures on the growth of Tetrahymena pyriformis W as they relate to the use of this organism to determine the protein quality of foods. The effects of altering the sources of papain used to hydrolyze samples, homogenizing samples prior to papain hydrolysis and autoclaving the protein suspensions were studied. The effects of salt and faton growth by T. pyriformis were also determined.As the purity of papain was increased, the minimum concentrations needed for optimum growth decreased. Homogenization of samples prior to papain digestion did not improve growth relative to control samples. Autoclaving the test protein suspensions reduced organism counts for samples with high carbohydrate contents, and slightly increased growth for samples low in carbohydrate when compared to the same samples that were not autoclaved. Adding salt to the media did not noticeably affect growth. Fat reduced organism growth, and the growth depression corresponded to the amount of fat added, and to the area of the liquid-air interface.