Effects of modified atmosphere on Listeria monocytogenes and Salmonella typhimurium during storage of meat, sucuk and white cheese

In this research effect of modified atmosphere (MA) on Listeria monocytogenes in meat, sucuk and white cheese stored at 4°C, and Salmonella Typhimurium in meat and sucuk stored both 4 and 12°C have been studied. These two pathogens were studied at separate time periods. During S. Typhimurium and L. monocytogenes counts at manufacturing and storage periods, Aerobic bacteria (AB), Lactic acid bacteria (LAB) and mold and yeasts (MY) were also counted. Head space gas analysis, pH and aw values of sucuk dough, meat and cheese have been also recorded during storage period. Numbers of S. Typhimurium and AB increased at all packages in both of meat and sucuk stored at 12°C. Numbers of S. Typhimurium decreased in sucuk and meat packaged by vacuum and 100 % CO2 at 4°C. Numbers of AB were increased in meats stored at both 4 and 12°C, and the increase was higher at 12°C than 4°C. AB numbers in sucuks increased in sucuks stored at 12°C, but decreased in sucuks stored at 4°C. In meats packaged with CO2 at 4°C L. monocytogenes survived without increasing the growth, but in the presence of low CO2 (30% CO2) the number of counts of L. monocytogenes have been increased slightly. AB counts have been increased at 4°C in meat packaged by vacuum and 100 % CO2 at 4°C by 3 and 2 logs, respectively. In sucuks, numbers of L. monocytogenes and AB were decreased but this decrease differed according to the atmospheric conditions of the packages. In packages containing CO2, inhibition was observed more. LAB counts of sucuks have been increased during the fermentation period, and become constant at further storage. Similar microbiological results have been seen at cheese samples, both AB and L. monocytogenes numbers decreased during 22 days storage and the highest decrease was observed in 100% CO2 packages by approximately 3 logs. Sucuks were also produced without S. Typhimurium and L. monocytogenes and sensory analyzed for quality parameters like color, odor, taste, cutting (texture) and general acceptance quality (GAQ) by panelists. And all parameters except cutting property gave scores as 7/10. Color analyses of meats packaged with MA in this research were made during storage, meats packaged with 100% CO2 darkened during storage and contaminated meats have lost their acceptable appearance because of microbial spoilage. Head space gas analysis was observed in sucuk and CO2 amounts in 100 and 60% CO2 packages decreased due to the dissolution of CO2. Amount of O2 in air packages was decreased due to the consumption of O2 by microorganisms.Presence of CO2 in package atmosphere has an inhibition effect on bacteria (both pathogens). The results of this research show that; meat, sucuk and cheese packed with CO2, pathogen bacteria can be inhibited. The shelf life of these products (meat, sucuk and cheese) can be increased by using MA packaging.Keywords: Modified atmosphere packaging, vacuum packaging, Listeria monocytogenes, Salmonella Typhimurium, meat, sucuk,white cheese