The influence of vacuum-packaging and marination on the behaviour of total Enterobacteriaceae on chicken breast fillets

Poultry meat is a highly perishable food and the time it takes to deteriorate varies from 4 to about 10 days after slaughter, in spite of having been stored under chill systems (Marenzi, 1986). Deterioration depends on the microbiological quality of the poultry carcasses, which is a direct reflection of sanitation during slaughtering and handling practices (Moreno Garcia, 1988). Chicken and other types of poultry meat have higher pathogenic and spoilage bacterial counts than almost any other food (Snyder, 1998). For the verification of the effectiveness of HACCP-based system in abattoirs, microbiological testing of carcasses is commonly used. The indicator organisms include aerobic colony count and Enterobacteriaceae count in the European Union, or E. coli count in the USA (Anonymous, 2005). After chilling, carcasses are cut into different parts. Meat cutting and deboning operations involve relatively intensive manipulation and handling of meat which markedly increases risk of microbial contamination due to: a) microbial cross-contamination via hands and utensils (knives, saws, conveyers, etc.); b) transfer of bacteria from the meat surface to the internal parts. Packaging methods for extending the storage time of poultry meat have been thoroughly surveyed. Vacuum-packaged poultry breasts have generally shown a longer conservation time than poultry breasts packaged in air. Traditionally, meat has been marinated to improve flavor and tenderness and increase product shelf-life. Commercial marination involves addition of a solution of water, salt, phosphate and sometimes flavorings and other ingredients, by means of soaking, blending, tumbling or injecting (Smith at al., 2001). Marination with acids or phosphates may cause pH changes and unfolding of secondary protein structure to allow more water to be absorbed and bound to the protein molecules. Marinades containing phosphates tend to reduce rancidity development and warmed-over flavor, increase shelf- life and improve color of poultry meat. Weak organic acids, such as citric acid, are components of flavored marinades used with meats in limited quantities. The aim of this study was to evaluate the effectiveness of marination and vacuum-packaging on the behaviour of total Enterobacteriaceae in chicken breasts fillets.