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

Abstract

Beef livers and sweetbreads and pork livers and kidneys were collected from commercial slaughter operations, packaged under vacuum or CO2, 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 CO2 deteriorated because of staining of surfaces with blood pigments.