MICROBIOLOGICAL QUALITY OF FILLED PASTA IN RELATION TO THE NATURE OF HEAT-TREATMENT

The microbial population present in 49 samples of Italian industrially processed filled pasta was characterized and its changes during refri gerated storage were evaluated. The most frequently isolated species b elonged to the genus Bacillus. No pathogenic organisms were isolated f rom the processed industrial pasta. As a consequence of the diversity of composition and thermal treatment a wide variability was observed ( from less than 3 days to more than 1 month) in the shelf life at 4 deg rees C of the industrial ''fresh filled pasta.'' However, the results obtained suggested that the shelf life of the processed products depen ded not only on the number of surviving cells but also on the textural or microstructural changes induced by the heat treatment. Challenge t ests using Staphylococcus aureus showed that even pasteurization value s (P-70(10), expressed as an equivalent process time, in minutes, nece ssary to obtain at 70 degrees C the same lethal effect as during the a ctual process) not exceeding 2 were able to remarkably reduce the cell load of this organism. Subsequent growth of the surviving S. aureus c ells occurred only at temperatures >7 degrees C, particularly when the water activity (a(w)) Values were higher than 0.97.