The effect of storage temperature and inoculum level on the time of onset of 'blown pack' spoilage.

AIMS: To examine the effect of storage temperature and inoculum level on the time of onset of 'blown pack' spoilage (BPS) caused by psychrotolerant bacteria in vacuum-packed (VP) meats.

METHODS AND RESULTS: Gas-producing species and strains (n = 11), recovered in our laboratory or reported as associated with BPS, were inoculated onto beef or lamb meat pieces at final levels of <10, 10, 10(2) and 10(3) CFU cm(-2), VP and stored at -1.5, 1 or 4 degrees C. Six strains produced observable amounts of gas within 42 days and a further four strains produced gas within 100 days. BPS was observed earliest in VP meats inoculated with Clostridium estertheticum ssp. estertheticum at all inoculum levels/storage temperature combinations examined. Storage temperature and inoculum level significantly affected (P < 0.001 and P < 0.05 respectively) the onset of BPS in all cases.

CONCLUSIONS: Controlling contamination levels and lowering the storage temperature delay the onset of BPS.

SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates the positive effects of low contamination-low temperature as control interventions preventing/delaying BPS in VP chilled meats and identifies some of the contaminants most likely to cause BPS in chilled stored VP meat products.