Evaluation of Microbiological Methods Used for the Examination of Precooked Frozen Foods12

The increasingly wide acceptance of precooked frozen foods has led to the establishment throughout the United States of new frozen food plants devoted entirely to the precooked products. Among the problems facing this rapidly expanding industry is the development of adequate quality control standards for flavor, attractiveness, stability, and wholesomeness. As early as 1947 the question of wholesomeness was raised by Fitzgerald, who pointed out the importance of high quality raw materials, adequate cooking, careful plant sanitation during processing and packaging, rapid handling, and quick-freezing. Food sanitarians and public health officials presently are focusing their attention on the potential health hazards resulting fron unsanitary operations and improper handling durinig the production and distribution of these foods. For effective sanitary control in the industry, processors may find it desirable to employ a standardized bacteriological testing program as an adjunct to rigidly supervised measures of cleanliness. The purpose of this report is to describe and evaluate laboratory methods used for estimating levels of bacterial populations surviving in the precooked frozen products. When frozen meals were introduced into the U. S. Air Force in-flight feeding program in 1951, a military specification for these foods was published by the U. S. Army Quartermaster Corps. The sanitary requirements specified for their production included a provision for continuous plant inispection by the Veterinary Corps and imposed bacterial standards for the finished product. At present the specifieation (MIL-M-13966) provides for a standard plate count not to exceed 100,000 organisms per g, and a coliform plate count not to exceed 10 per gram. The two counts serve as an index of ade(uate cooking. Since the relatively heat-labile colon-aerogenes group of organisms cannot survive the