Sensory and microbiological assessment of foods stored in packaging from different European countries

As the increment of commercial globalization and consumers’ awareness of food safety and environment, active packaging is introduced as new concept to satisfy these demands. Mostly active packaging approaches aim to add substances with the properties, such as: modifying the ratio of carbon dioxide and nitrogen, oxygen scavenger, and moisture absorber, antimicrobial and antioxidant activity [1]. Due to the fact that one of the main factors to define the shelf-life of one food product is the food bacterial concentration, the overgrowth of spoilage microbes may cause the inflation of the package, undesirable changes in flavor, aspects and quality of food during storage, thus make the food unacceptable for consumption. Besides, the existence of pathogenic microorganisms in food may pose risks to people’s health. Therefore, many studies focused on the active packaging techniques that can control or inhibit microorganisms overgrowth. This research is part of GRAFOOD project that aims to develop an active package based on paper and polylactic acid film modified by graphene oxide. Graphene oxide is effective in inhibiting the growth of bacteria by causing damages on cell membrane or producing Reactive Oxygen Species (ROS) [2]. The specific objectives of the present task are to analyze the currently used packaging concepts for cheese and meat storage. The present study evaluated organoleptic and microbiological changes of “ricotta” cheese and chicken breast meat deposited in currently in use packages from four different European countries (Italy, Spain, Romania and Slovenia) during a cold storage period of 14 days. All four countries used polyethylene bags as packaging material for cheese. However as for meat storage, Romanian package was made by paper laminated with polyethylene on one side (in contact with food), waxed paper on both side was used in Spanish one. Slovenia paper is modified with oxidized starch on food contact surface. Italian meat package material was made by a polystyrene tray and a flexible polyethylene film. “Ricotta” was packed in polyethylene bags, once cheese were produced by a local company, then were stored at 4°C until analysis. Slices of chicken breast meat were purchased from local market and packaged in different packaging materials and stored in fridge. The sensory evaluation was performed on the aspect, color, odor, taste at different time points during storage (day 0, 3, 6, 9, 14) assessing 31 attributes. The measurement of bacterial cell counts was conducted by viable count method, using both selective and non-selective culture media for differentiating bacterial species, the colonies were counted and the numbers were registered after incubation time. Also the changes of pH values of meat and cheese was measured at the same time points of microbiological analysis, all experiments were carried out in triplicate. The results showed that generally the microbial counts are arising from day 3 in “ricotta” cheese deposited in almost packaging. There are some statistical differences (p<0.05) for the counts of Enterobacteriaceae, Staphylococcus spp. and Pseudomonas spp., between the Italian vs the Spanish, and between Romanian vs Slovenian. The sensory analysis showed changes in form maintenance, compactness, specific color and taste, that are more evident in “ricotta” cheese deposited in Slovenian packages then the others. All packages show that chicken breast meat has an increase of microbial cell counts till day 9. Statistically significant differences (p<0.05) between Italian vs Spanish are from day 3 for total mesophiles, psychrophiles, Pseudomonas spp. Romanian vs Slovenian present a significant difference in Staphilococcus spp. from day 3, while one time point only is significant different, day 3 for total mesophiles and lactic acid bacteria and day 6 for total coliform, psychrophiles and Pseudomonas spp. The sensorial profile of chicken breast meat in Romanian and Slovenian packages is almost the same. While the meat deposited in the Italian and Spanish packages presented high score of differences for all the appearance descriptors. In particular the Spanish, showing sudden changes at day 3 and a peculiar complete absence of “slime” descriptor always present in all the others, with the “compactness” increasing during time. These results represent the baseline data that will be used to assess the new composites during their usage.