The storage life of non-muscle offals packaged under vacuum or carbon dioxide***

Beef livers and sweetbreads and pork livers and kidneys were collected from commercial slaughter operations, packaged under vacuum or CO 2 , and then stored at −1·5°C. Offals were microbiologically and organoleptically assessed at intervals of 3 weeks until they were grossly spoiled. After 6 weeks storage, vacuum-packaged livers had a low pH and were spoiled by autolytic and microbial activities. Carbon-dioxide packaging delayed the fall in tissue pH and the development of microbial spoilage, but did not obviously retard the autolytic deterioration of livers. After 6 weeks storage, vacuum-packaged kidneys were spoiled by lines of white granules (presumably tyrosine crystals) on organ surfaces and, after 12 weeks storage, by offensive odours and flavours of microbial origin. Carbon-dioxide packaging delayed the appearance of blemishes for a further 9 weeks and microbial spoilage of kidneys for a further 3 weeks. After 12 weeks storage, vacuum-packaged sweetbreads were spoiled by green discolouration and spoilage odours and flavours as results of microbial activities. Carbon-dioxide packaging prevented the development of green discolouration and extended the time before spoilage odours and flavours were evident to 18 weeks. However, after storage for 9 weeks the appearance of sweetbreads packaged under CO 2 deteriorated because of staining of surfaces with blood pigments.

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