Effect of Co2 or vacuum packaging on normal and high pH meat shelf‐life

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Abstract
In order to extend meat shelf‐life, normal‐pH and high‐pH beef steaks were packaged under vacuum or in 100% C 0 2 atmosphere. Microbiological, colour (L*, a*, b*)and reflectance (R630‐R580 values) characteristics were measured.After packaging under vacuum, Enterobacteriaceae, Brochothrix thermosphacta and Pseudomonas numbers were 10‐ to 100‐fold greater on high‐pH meat than onnormal‐pH meat.Packaging under C 0 2 improved the shelf‐life of meat, particularly that of high‐pH meat up to 42 days. For both high‐ and normal‐pH meats, the bacterial flora wascomposed only of lactic acid bacteria. Normal‐pH meat in C 0 2 atmosphere and vacuum packaging had a purple colour. After C02‐pack opening the meat colourbecame bright red and R630‐ R580 measurements were high, whereas after opening of vacuum packaging R630‐R580 decreased rapidly with increasing aerobic exposure.High‐pH meat became paler with increasing storage time in C02. Simultaneously R630‐R580 values increased and the pH fell. In addition it lost less exudate andoxidized less in air than the normal‐pH meat under the same conditions.