RAPID EVALUATION OF PROTEIN QUALITY OF FOODS USING Clostridium perfringens

A 1‐day protein quality evaluation procedure was developed utilizing the anaerobic microorganism, C. perfringens strain 3624. The food sample required no pretreatment except for particle size reduction. Culture development was measured manometrically. Contaminating microorganisms were inhibited by cultural conditions which included anaerobiosis, 46°C incubation and a large initial inoculum. Culture response was expressed as Relative Slope Ratio (RSR) which compared the response slopes of the test nitrogen source with that of a standardized mixture of synthetic amino acids. A preliminary study comparing RSR values with Protein Efficiency Ratios (PER) for 2.5 foods showed a linear correlation coefficient of 0.74. A study comparing RSR and PER values for 15 foods representing a wide variety of protein sources indicated that the RSR method cannot be substituted for the PER method, but there was an indication that foods may be grouped for improved analysis. The RSR assay was sensitive to thermal treatment variations and responded to sulfur containing amino acid supplementation of heated products. Further evaluation of the technique for rapid assessment of protein quality changes resulting from processing variables seems warranted.