Minimally processed lettuce is sensitive to microbial attack caused by the loss of natural resistance and their high water content and nutrients. The use of natural anti-microbial agents such as the lactoperoxidase system (LPS) represents an interesting alternative to the use of chemical treatments. This study focused on the importance of LPS and its efficiency as a bioprotective agent. The effect of washing with LPS, at two different concentrations (4 and 5 IU) and four different treatment times (1, 2, 3 and 4 h) on microbial growth in fresh-cut lettuce, was determined at 30˚C and compared with a 80 ppm chlorine at 4˚C for 20 min. The results deduced that both doses of LPS showed significant reductions in microbial growth when applied during 4 h, but the highest dose proved to be more effective. No significant differences were found between the LPS treatment and chlorine considering native microflora reduction and quality markers during storage.

This study aimed to produce probiotic ‘Testouri’, traditional Tunisian sheep cheese, by direct-to-vat inoculum of probiotic adjuncts.The potential of Testouri sheep cheeses was evaluated by an assessment of gross composition and proteolytic, antibacterial, antidiabetic and antioxidant activities during storage at 4 °C for 28 days. Results highlighted that no significant differences were observed in compositional parameters of the samples at day 0. Probiotic counts in cheeses remained at 8 log CFU g−1 during storage. Probiotic cheeses exhibited measurable antibacterial activities with the maximum value (diameter of 12 ± 0.07 mm) on Staphylococcus aureus strain. Also, α-glucosidase and α-amylase inhibitions ranged from 42 ± 0.77 to 58 ± 0.88% and 20 ± 0.9 to 47 ± 1.3%, respectively, during storage. Additionally, cheeses inoculated with probiotics exhibited significant increases in proteolytic and antioxidant activities compared to the control sample.Therefore, Testouri cheese can be considered a good carrier of probiotics and can be promoted for commercial uses.

Milk is a natural product secreted by mammals. Both food and drink, it is of great nutritional interest and lends it-self to many therapeutic, technological and industrial applications. Indeed, the importance of milk in the human diet has been well established and its regular consumption has been recommended. In addition, several studies have shown that milk represents an important source of probiotic lactic acid bacteria [1]. The study of this biological fluid could be a challenge to obtain a possible diversity of probiotic lactic acid bacteria.The colonization of the gut by probiotic bacteria prevents growth of many bacteria by competitive exclusion and by the production of organic acids and antimicrobial compounds. In addition, studies suggest that functional foods containing probiotics minimize the risk of heart disease and therefore, the characterization of the active ingredients and the type and number of the probiotics is important [5]. Also, antioxidant activity is an important effect of probiotics which consists in the protection of cells from oxidation problem [6]. Thus, the aim of this study was to evaluate the co-existence behaviour of probiotic strains between them, antagonistic power against pathogens, cholesterol assimilation and antioxidant properties.Three probiotic Lactobacillus plantarum strains such as BA12, CT28 and OSO47, isolated respectively from cow, goat and sheep Tunisian raw milks, were identified and characterized in UR 13AGR 02, ESIAT, Tunisia. The cultures were stored at 20% of glycerol at -80°C. For this study, the probiotic cultures were activated for three times in de Mann Rogosa Sharpe (MRS) broth (Biokar Diagnostics) using 1% of inoculum and incubated at 37°C for 18h.Identifying and characterizing bacteria all over the world are essential in the study of human health. The term "probiotic" was de- Materials and Methods Growth of probiotic strainsThe strains were streaked perpendicular to each other on MRS agar and incubated was done at 37°C for 48h to observe their coexistence at the crossing points of the streaks [7].

The present work focused on the effects of the Modified Atmosphere Packaging (MAP) 1 (5% O 2 and 10% CO 2) or 2 (2% O 2 and 5% CO 2) and the previous addition of Lactoperoxidase System (LPS) and Oregano essential oil or chlorine washing on the quality of fresh-cut lettuce during refrigerated storage at +4˚C. Our results showed the significant effect of this combined treatment on quality improvement during storage. Thus, mesophilic bacteria was reduced in treated samples compared to those untreated with number which not exceeded the critical of 5 × 10 7 UFC•g −1 (p < 0.05). In addition, the elevated O 2 and CO 2 levels created by both atmosphere were not significantly different between the two treatments (p > 0.05). Brightness of lettuce samples was significantly reduced during storage. Thereafter, the PCA data showed the effect of combined treatment on the preservation of hygienic, physico-chemical and sensory quality up to the 7 th day of refrigerated storage of these treated samples. The results obtained draw attention to modified atmosphere packaging lettuce and the addition of bio-preservatives which could be an alternative of choice to replace chlorine to preserve the sanitary quality of green products.

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