Ispitivanje uticaja različitih načina pakovanja na rast Salmonella spp. u mlevenom mesu / The influence of different ways of packaging on the Salmonella spp. growth in the minced meat

Foodborne diseases present a major health and economic problem worldwide. Foodborne disease is any disease which is transmitted by food consumption, or when pathogens which cause disease entered into organism through food. More than half of foodborne diseases are caused by pathogenic bacteria. One of the most common causes of food poisoning are Salmonella spp. Clinically, salmonellosis occurs in the form of a gastrointestinal syndrome with diarrhea. According to the World Health Organization occurrence of intestinal disease is result of improper handling of food, including food preparation, inadequate cooling and insufficient thermal processing of food, carriers of bacteria. In order to increase safety requirements for meat and meat products, extending the shelf life of retail products and satisfy consumer expectations related to practicality and quality, fresh meat is packaged and thus prevents contamination and disposed of spoilage. Modified Atmosphere Packaging (MAP) is one way of extension of sustainability and preserving the quality of fresh minced meat, which is becoming more common method of packaging meat for retail sale in the last two decades. The gases which are commonly used in this type of packaging, in different combinations, are carbon dioxide, oxygen and nitrogen. The carbon dioxide, as a potent inhibitor of bacteria from the family Enterobacteriaceae, inhibits the growth of Salmonella spp. extending the lag phase of the reproduction, wherein the proportion of gas is very important in packaging because its inhibitory effect was pronounced at a concentration higher than 10%. The aim of the research in the framework of this dissertation was to determine the impact of different ways of packaging (vacuum and modified atmosphere) on the X growth of Salmonella spp., microbiological status (total number of bacteria, the number of lactic acid bacteria and Enterobacteriaceae family of bacteria), pH value, content total volatile nitrogen and sensory properties of ground meat. Pork and beef were provided in a local facility for slaughtering pigs and cattle, are ground to a meat grinder (size of the opening in the plate 4 mm) and mixed in a 50:50 %. Half of the ground meat was contaminated by strains of Salmonella Enteritidis (ATCC 13076), Salmonella Typhimurium (ATCC 14028), Salmonella Arizona (ATCC 13314) and Salmonella Infantis (ATCC 51741). Half of the minced meat was contaminated and was used as a control. All samples, experimentally contaminated and control were packed in a vacuum, the modified atmosphere with 20% O2, 50% CO2 and 30% N2 (MAP1) and the modified atmosphere with 20% O2, 30% CO2 and 50% N2 (MAP2). After packaging, the samples were stored for 13 days at a temperature of the refrigerator 3 ± 1 ° C. Reducing the number of Salmonella spp. was observed in all groups of experimentally contaminated samples of ground meat to seventh days of storage, while the seventh and thirteenth days of strage the number was not significantly changed. The most significant reduction in the number of Salmonella spp. was observed in samples packaged in modified atmosphere. The number of Enterobacetriaceae during all days of storage in control samples was not significant changed, while number of Enterobacteriaceae in the experimentally contaminated samples of ground meat grew up on the senventh day of strage, from the seventh to the tenth day of strage decreased, then the thirteenth day of the re-grow. In experimentally contaminated samples of the control and ground meat number of aerobic mesophilic bacteria and the number of lactic acid bacteria, regardless of the manner of packaging, is increased from zero to the thirteenth day of storage. During all days of storage the aerobic mesophilic bacteria and the number of Enterobacteriaceae in experimentally contaminated samples was higher than the number of aerobic mesophilic bacteria and the number of Enterobacteriaceae in the control samples, which did not always observed when comparing the number of lactic acid bacteria in experimentally contaminated and control samples of packaged ground meat. The content of total volatile nitrogen in experimentally contaminated samples grew more intense by the seventh day of storage when the number of XI Salmonella spp. decreased, and the number of Enterobacteriaceae in experimentally contaminated samples was greatest. Also, the content of total volatile nitrogen was higher in experimentally contaminated samples compared to control samples, and the samples packed in a vacuum as compared to the samples packed in modified atmosphere. In experimental contaminated samples content of total volatile nitrogen, tenth day was higher than limits of acceptability, while in the control groups of samples content of total volatile nitrogen was higher limits of acceptability on thirteenth day of the experiment. During storage period pH value in experimentally contaminated samples of minced meat increased, while in control samples was not significantly changed regardless of the method of packing. Sensory evaluation of the acceptability of odour in experimentally contaminated and control samples of ground meat was less than the limits of acceptability on the tenth day, and on the thirteenth day of storage, respectively. Based on the results of this PhD thesis, it was concluded that the package of ground meat in the modified atmosphere has advantages over the package in a vacuum in terms of bacteriological status, and in terms of indicators of meat spoilage.