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Abstract
The effects of wrapping
product in polyvinylidene chloride (PVDC) film,
load size (150, 600 and 1200
g loaves), microwave output power (713 ± 5 W and 356 ±
3 W at 2450 MHz) and processing time on bacterial survival were evaluated in
beef loaf. Specifically the survival of aerobic flora, and inoculated Staphylococcus
aureus (ATCC 6538) and Escherichia coli (0157:H7)
were assessed. Results showed that beef loaf wrapped in PVDC film had lower
levels of survival for aerobic bacteria, S. aureus
and E. coli than unwrapped beef loaf. When beef loaf was
exposed to the same microwave dose (watts x minutes processed/grams of food),
the percent of survival remained the same, regardless of load size or
microwave output power. Exposed microwave dose, which correlated highly to
percent of bacterial survival (R2=0.8-0.83) and endpoint
temperature (R2=0.84), is suggested in place of output power, time
or temperature as a predictor of microbial quality in foods that have been
microwave processed.
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