MICROBIOLOGICAL AND SENSORY EVALUATION OF COOKED ROAST BEEF PACKAGED IN A MODIFIED ATMOSPHERE

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Abstract
Sliced cooked roast beef was packaged in a modified atmosphere (MA) consisting of 75% CO2, 15% N2 and 10% O2 and stored at 4.4.degree. C for 42 days to evaluate the MA''s effectiveness at controlling the outgrowth of Pseudomonas fragi, Clostridium perfringens, Staphylococcus aureus and Salmonella typhimurium after inoculation. Additionally, a taste panel was conducted to monitor the effects of modified atmosphere packaging (MAP) on sensory parameters of uninoculated samples. P. fragi was able to grow only to a limited extent in the MA, but grew to high numbers in air. The three pathogens were unable to grow in the MA, probably due to the effects of temperature. Numbers in S. typhimurium and C. perfringens declined more rapidly in the MA than in air but S. aureus numbers did not decrease in either atmosphere. High numbers of molds were recovered from the uninoculated samples stored in air but none were recovered from MAP samples. Sensory analysis indicated that most product deterioration occurred within the first 7 days of storage.