The effect of storage temperature on shelf life of vacuum-packed lamb shoulders

摘要

Enquiries from importing countries on the shelf life of lamb primals prompted storage trials of vacuum-packed lamb shoulders in chillers at seven plants in Australia. After around 30 days (typical for delivery to short-distance markets) storage at four plants, sensory quality was excellent and the microflora were dominated by lactic acid bacteria (LAB), mean log 3-4 cm/cm2. However, some counts were either close to, or greater than, log 5 cfu/cm2, a level set arbitrarily by some importers as the maximum to ensure sufficient shelf life through the retail chain. To simulate long-distance markets, product was stored at three plants and withdrawn at intervals 60-90 days after packing. Sensory attributes were acceptable for 80 days at one plant and at least 85 days at the other two. Temperature of storage had a great effect on Aerobic Plate and LAB counts. In product stored at 0°C counts reached log 7 cfu/cm2, dominated by LAB, while in product stored at -0.5°C and -2.4°C the count reached log 5 cfu/cm2 and log 2 cfu/cm2 respectively. The results indicate that vacuum-packed lamb primals have a much longer shelf life than the 60 days usually claimed by the trade. It is believed this reflects improvements in microbial levels at packing, and particularly in temperature control in the commercial cold chain.