EFFECTS OF MODIFIED ATMOSPHERE AND VACUUM PACKAGING ON THE GROWTH OF SPOILAGE AND INOCULATED PATHOGENIC BACTERIA ON FRESH POULTRY

Fresh chicken breast meals inoculated with Yersinia enterocolitica and Aeromonas hydrophila were packaged in glass jars either containing di fferent compositions of modified atmospheres (MA) (100% CO2; 80% CO2/2 0% N-2), or in vacuo or containing air, and were stored at 3 +/- 1 deg rees C and 8 +/- 1 degrees C. The changes in gas composition as well a s Y. enterocolitica, A. hydrophila, total aerobic bacterial, total psy chrotrophic, Lactobacilli and Enterobacteriaceae counts were determine d after 0, 1, 3, 7, 9, 11 and 14 days of storage. The results show tha t while the growth of Y. enterocolitica and A. hydrophila were retarde d following MA storage, the pathogens were capable of growth in MA and vacuum storage al both temperatures, for the inoculation levels studi ed. For total aerobic bacterial counts, there were no differences betw een the values for chicken breast meats kept in different atmospheres. Being packaged in CO2 had the greatest inhibitory effect on the growt h of psychrotrophic aerobic bacteria during the first 3 days. Lactic a cid bacteria levels of samples stored in MA conditions and in vacuo in creased rapidly when compared to those levels of samples stored in air . It was also found that the effect of MA storage increased at 3 +/- 1 degrees C.