Assessment of the shelf-life of meat packed in various protective atmospheres with addition of lysozyme

anglais. The objective of this research was to evaluate the impact of diifferent protective atmospheres, with or without the addition of lysozyme, which were used to pack swine longissimus muscles kept in cold store conditions for the period of up to 3 weeks. The employed atmospheres comprised: vacuum, modified atmosphere with carbon oxide (70 percent CO2, 29.5 percent N2, 0.5 percent CO) MAP-CO and with oxygen (79 percent N2, 20 percent CO2, 1 percent O2) MAP - O2. The evaluation of the shelf life of packed meat was performed on the basis of microbiological examination determining the total number of aerobic bacteria, Enterobacteriaceae family bacteria, enterococci as well as lactic acid bacteria (LAB). Measurements of hydrophobicity of muscle centrifugal drip protein were employed as a method allowing to compare the microbiological status of the meat during its storage in the chilled room. The atmospheres applied were found not to differ with regard to the degree of aerobic microorganisms development in the stored meat. The application of vacuum or MAPűO2 was found as a best way to inhibit the development of LAB. Samples with the addition of lysozyme were characterised by a slower development of microorganisms than these without its addition only in the case of samples packed in MAPűO2 and stored for 21 days. Storage time exerted a significant influence on the hydrophobicity of meat, which was lower in vacuum conditions than when protective gases were applied. The inclusion of lysozyme resulted in an increase of hydrophobicity

polonais. Atmosfery ochronne stanowily: proznia, modyfikowana atmosfera z tlenkiem wegla (70 proc. CO2, 29,5 proc. N2, 0,5 proc. CO) - MAP-CO oraz modyfikowana atmosfera z tlenem (79 proc. N2, 20 proc. CO2, 1 proc. O2) - MAP-O2. Mieso przeznaczone do badan bylo normalnej jakosci. Stwierdzono, ze poszczegolne atmosfery ochronne w rownym stopniu hamowaly rozwoj drobnoustrojow tlenowych w przechowywanym miesie. Zastosowanie prozni (z lizozymem lub bez) oraz MAP-O2 bylo czynnikiem najlepiej hamujacym rozwoj bakterii fermentacji mlekowej. Proby z dodatkiem lizozymu charakteryzowaly sie wolniejszym rozwojem drobnoustrojow niz proby bez jego dodatku tylko w wypadku prob pakowanych w MAP-O2, przechowywanych 21 dni. Czas przechowywania wplywal istotnie na zmniejszenie hydrofobowosci bialek wycieku z miesa pakowanego niezaleznie od zastosowanej atmosfery ochronnej. Istotne statystycznie roznice wystapily pomiedzy probami przechowywanymi 48 h i 7 dni a analizowanymi po 3 tygodniach. W warunkach prozniowych hydrofobowosc byla nizsza niz przy stosowaniu mieszanin gazow ochronnych. Dodatek lizozymu powodowal z reguly wzrost tego wskaznika