STORAGE CHARACTERISTICS OF SOUS VIDE COOKED ROAST BEEF

The technological, microbiological, and sensory storage characteristics of low temperature sous vide cooked roast beef were investigated. The effect of two heat treatments, 59 degrees C (P(70)(10)in core 8.4) and 62 degrees C (P(70)(10)in core 15.9) on the stability of spiced roast beef made from Musculus semitendinosus with a high initial microbial load were compared as well as storage temperatures of 2 and 10 degrees C. Although chilling baths with circulating water were used, recommended chilling rates for sous vide products could not be attained. Yield was significantly higher at 59 degrees C and at a storage temperature of 2 degrees C but decreased during storage. At 62 degrees C the meat became significantly more tender than at 59 degrees C as measured by shear force. No differences in microbiology were observed between heating regimes. At low storage temperature products were microbiologically stable over a 35-day period. At 10 degrees C, however, a rise in psychrotrophic aerobic counts and occasional pack swelling was observed. In a commercial scale experiment conducted with sous vide cooked (62 degrees C) beef with low initial counts, no increase in aerobic counts was observed at 2, 5 and 10 degrees C while swelling occurred in 28% of the packages stored at 10 degrees C and in none at 2 and 5 degrees C. The swelling was due to different types of gas-producing clostridia. Warmed-over flavour (as TEARS) showed no development during storage in intact packages, while slicing and serving the roast beef under commercial conditions resulted in a marked increase to > 100 mu mole kg(-1). In spiced roast beef only minor changes in off-odour and off-flavour of the product were observed during 23 days of storage at 2 degrees C.