Microbial quality of foods produced by an enhanced cook-chill system in a hospital

Abstract

A total of 1,137 samples representing 77 cook-chill food products were analyzed during a 27-month period. Vacuum-packaged food samples from the same production batch of regular diets or products modified for low sodium, low fat, diabetic, or strained diets were analyzed before and after storage at 1 ± 1 °C for up to 21 days in a hospital's food bank. Samples were analyzed for aerobic counts at 26°C and 35°C and for coliforms, staphylococci, Bacillus cereus, Clostridium perfringens, Escherichia coli, E. coli O157:H7, Listeria spp., Salmonella spp. and Staphylococcus aureus. None of the samples contained C. perfringens, E. coli. E. coli O157:H7, or Salmonella. Listeria was isolated from one production batch of asparagus which had been inadequately heated and cooled due to overloading of the vat. S. aureus was isolated (< 100 CFU/g) from 2 samples (beef roast, stewed tomatoes) and B. cereus was isolated (<100 CFU/g) from several pasta and bean products. Low-fat products had higher (P < 0.05) aerobic populations than products modified for low sodium, low fat, diabetic, or strained diets. No differences were obtained between the before- and after-storage populations. Over 92% of the samples had aerobic populations of 3 log CFU/g or less and 98% had populations of 4 log CFU/g or less. All except 2 samples had coliform populations of 1 log CFU/g or less and all samples had staphylococci populations of 3 log CFU/g or less. Under the conditions of this study, the microbial quality of vacuum-packaged foods properly produced by an enhanced cook-chill system was acceptable after food storage at 1± 1°C for up to 21 days.