Study On The Effect Of Glycerol Monolaurate And Complex Preservative On The Preservation Of Chilled Pork

Chilled meat, also named fresh meat, cold meat, is produced from strictlyquarantined slaughtered animals. The carcasses are immediately chilled down to therecommended meat temperature of-1℃~7℃, andthis chilling temperature ismaintained throughout the subsequent processing, storage, transportation, and sale.Just because chilled meat is safe, nutritious, sanitary, and of fresh taste, it has becomethe main selling form of meat in developed country, and this is going to be the meatconsuming tendency in china as well. Thus，to develop safe and effective preservativeto extend the shelf life of chilled meat has become a popular research field in recentyears.This study selected several meat-borne typical putrid bacteria, includingGram-positive and Gram-negative, and then the antimicrobial properties of GML andother commonly used preservatives in meat on the selected bacteria were assayed.Furthermore, GML and its compound with other preservatives were applied in thechilled meat to investigate the preserving effect.The main research findings are as follows:(1) A microtiter plate assay was employed to systematically assess the MinimumInhibitory Concentrations (MIC) of GML and many other preservatives (Nisin,Sodium dehydroacetate, Sodium diacetate, Potassium sorbate, Lactic acid, SodiumLactate, Gly, EDTA). Results showed that GML exhibited effective inhibitoryactivities against gram-positive bacteria (Listeria monocytogenes, Staphylococcusaccrues, Beta-hemolytic streptococcus, Bacillus cereus, Streptococcus faecalis), andthe MICs are all below25ug/mL under neutral pH (pH7.2). On the contrary, GMLdid not completely inhibit growth of the gram-negative bacteria (Ps.fluorescens,E.coli, Salmonella typhimurium), but there was some increase of the inhibitioryactivity when the pH decreased to5.7. The organic acid preservatives exhibited widerantibacterial spectrum in acidic than in neutral environment.(2) The microtiter plate assay method was also used to assess the interactionbetween GML and other common preservatives against strains of Listeriamonocytogenes, Streptococcus faecalis, Salmonella enteritidis, and Pseudomonasfluorescens. The results showed that low levels of lactic acid acted synergisticallywith GML against all strains. Other combination forms were strain-dependent, forexample, sodium dehydroacetate synergistically enhanced the activity of GML againstListeria monocytogenes and Salmonella typhimurium but not Pseudomonasfluorescens and Streptococcus faecalis.(3) According to NY/T632-2002and GB/T9959.2-2008, the preservation effectsof different treatments were evaluated seperatedly on the ripening and thesegmentation stage of the meat, while common treatment used in the industry andtreatment without any antimicrobial were added as positive and negative control separately. Results showed that0.5%GML+1%lactic acid spray treatment canextend the shelf life of the chilled meat to5days and to7days respectively.