Inhibition of Growth of Escherichia coli O157:H7 and Salmonella in ground beef using modified atmosphere packaging systems

This study determined if selected strains of E. coli O157:H7 and Salmonella could grow under extreme temperature abuse conditions in a carbon monoxide MAP packaging environment.

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Objectives

The objectives of this study were to determine if E .coli O157:H7 and Salmonella growth was inhibited under extreme temperature abuse conditions in various modified atmosphere packaging (MAP) packaging environments compared to traditional PVC overwrap packaging.

Conclusions

The results demonstrate higher numbers of E. coli O157:H7 in PVC compared to other packaging types under all abuse condition; and no significant difference between vacuum bags (VAC), high oxygen blend (80%O2/20% CO2) (HO), low oxygen packaging with carbon monoxide (0.4% CO/35% CO2/64.6% N2) (CO) and low oxygen packaging without carbon monoxide (35%CO2/65% N2) WOCO). A temperature of storage and a day of sampling effect were observed. Packages stored at 2.8ºC had significantly lower E. coli O157:H7 compared to those at 35ºC, but both were statistically the same as packages stored at 21ºC (P<0.05 and P> 0.05, respectively).  Additionally, days 6 and 14 were significantly less than days 9 and 11. Salmonella recovery were not significantly different in the packaging type nor the storage temperature (P>0.05). However, Salmonella concentrations were higher on days 6 and 9, regardless of storage temperature and packaging type.  Packaging type by day interaction was highly significant (P<0.0001) but all other interactions were not significant (P>0.05). When the data is sliced to determine the simple main effects within the study packaging type PVC was significantly different amongst sampling days and on day 11 and 14 of storage there were significant difference amongst packaging types (P<0.05).

Deliverable

Overall, it was evident that packaging other than overwrap has a positive impact on reducing E. coli O157:H7. Samples packaged under these conditions had significantly less E. coli O157:H7 growth during temperature abuse and under no abuse conditions, while Salmonella counts was significantly different on sampling days 11 and 14 within packaging types and within PVC packaging throughout study.   These data suggest packaging types may result in a safer ground beef supply.