فهرست مطالب مریم قره ئی

Food processing conditions such as heat, mechanical or osmotic stress can lead to considerable losses of probiotics’ survival in food. Recently, the addition of probiotics into edible films has been proposed as an emerging technology for the delivery of probiotic cells. In this study, Lactobacillus acidophilus and Lactobacillus casei cells were incorporated into sodium caseinate matrix to develop a probiotic-based film which can improve food safety.
Material and Probiotic cells were separately added to the film forming solutions and the active films were prepared by casting method. The physical, optical and mechanical characteristics of the films were examined. Color properties were determined using a colorimeter and the mechanical properties of the films were evaluated by an Instron Universal Testing Machine. The viability of Lactobacillus acidophilus and Lactobacillus casei in the films was determined during a period of 12 days. The antibacterial activities of the films were also tested against Listeria monocytogenes on Trypticase Soy Agar medium at 4°C.
Results and Results demonstrated that lactic acid bacteria cells remained viable during a storage period of 12 days (> 4 Log CFU cm-2). The incorporation of lactic acid bacteria cells into the film polymer had no significant effect on tensile strength (p>0.05) whereas it significantly improves the appearance of films. Indeed, samples covered with the lactic acid bacteria film displayed higher anti-listerial activity than the control group on day 6 of preservation (p≤0.05). These findings show that the sodium caseinate film containing lactic acid bacteria cells can be used as a new effective packaging method for improving food safety.

Casein-based edible films due to high nutritional value have potential to protect the food products. The purpose of this investigation is to prepare sodium caseinate film containing Lactobacillus acidophilus and Lactobacillus casei and determine the antibacterial activity of the film against Listeria monocytogenes inoculated into the silver carp fillet.
In this survey, Lactobacillus acidophilus and Lactobacillus casei bacteria in the form of solution were added to sodium caseinate film and dried at 40°C for 24 hours. The effect of the film to control Listeria monocytogenes was determined on silver carp fillets and culture media during 9 days at 96 hour intervals. The viability of the LAB bacteria within 12 days in culture medium and fish fillet were studied at 96 hours intervals. The effects of incorporated bacteria on the physical and mechanical properties of the film were also examined.
The viability of lactic acid bacteria in fillets was increased. Both bacteria caused reduction in the Listeria count as compared to the control group. Lactic acid bacteria had a significant effect on the solubility percentage, moisture, L index and color difference, however there were not significant differences in tensile strength and elongation percentage.
Due to a significant decrease in L. monocytogenes viable count on culture media, it seems that the incorporation of LAB cells into films could be a useful method to control food pathogens.