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The protein quality of 34 samples of commercially prepared foods was determined using the Tetrahymena pyriformis W and rat Protein Efficiency Ratio (PER) bioassays. ANRC Reference Casein was used as the reference protein in both assays. The regression equation relating the Tefrahymena Relative Nutritive Value (RNV) and PER was: PER = 0.286 + 0.022 (RNV), r = 0.90 (P < 0.01). This relationship could be used to predict the protein quality of food samples. The use of the Coulter particle counter instead of the direct microscopic counting procedure increased the efficiency of the Tetrahymena assay by reducing counting error and the length of time required. In addition, quantitative information on cell size in relation to quality and quantity of protein in the test sample was obtained. The results of these studies suggest that the Tetrahymena pyriformis W assay may be adapted to provide a rapid, low cost assay for estimation of protein quality of commercially prepared foods.

A chemical method for the quantitative measurement of fungal chitin was used to estimate the level of mold contamination in tomato products. The alkaline degradation of chitin results in a polyglucosamine which is measured calorimetrically and the results expressed as c(g of fungal glucosamine. Addition of fungal mycelium to tomato products gave recoveries of 97 + 3% of the expected level of glucosamine. Analysis of various types of tomato products showed a significant correlation (P < 0.01) between fungal glucosamine content and the Howard mold count.

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