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Four hundred strains isolated from Tunisian sheep and goat raw milks were initially screened for their ability to survive the GastroIntestinal Tract (GIT). Forty-three among the four hundred bacteria were resistant to pepsin, pH 2, pancreatin and bile salts at 0.3%, even after 5 hours of incubation. Identification using 16S rRNA gene sequencing was established and we obtained as a species Lactobacillus plantarum (29 isolates from sheep milk and 11 from goat milk) and Lactobacillus pentosus (2 isolates from sheep milk and 1 from goat milk). We showed the ability for auto-aggregation and/or hydrophobicity properties. Finally, both M63 and C78 strains showed an important level of adhesion to three intestinal epithelial cells Caco-2 TC7, HT29-MTX, and HT29-CL.16E. Taken together, these properties allow the lactobacilli strains to be considered promising beneficial strains for developing functional foods for consumers.
 

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This research aimed to analyze the influence of probiotic bacteria on the microbiological, physico-chemical, technological, and sensory characteristics of goat yogurt during 28 days of refrigerated storage. Results revealed that the incorporation of two probiotic bacteria did not significantly influence (P> 0.05) the physico-chemical characteristics such as pH, lactic acidity, total solids, syneresis, water holding capacity and protein, color, viscosity and texture parameters and sensory properties of the inoculated samples, compared to the control. Similarly, the probiotic viability was maintained at all stages of storage at the rate of 10⁸ CFU g^-1. Therefore, this research shows that yogurt is an appropriate vehicle for probiotic bacteria and provides new insights regarding their impact on the metabolism of this functional food while preserving its quality.

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This work aimed to study the antibacterial activity of various Essential Oils (EOs) against food borne pathogens as well as the effect of their incorporation at different concentrations on vacuum-packed ground ovine meat, experimentally inoculated with Listeria monocytogenes, during 12 days of storage at 4°C. In summary, pathogenic bacteria, particularly L. monocytogenes, Salmonella enteritidis and Escherichia coli, showed high sensitivity towards citrus, rosemary, thyme, cinnamon and oregano EOs due to their richness in bioactive compounds. The Minimum Inhibitory Concentrations (MICs) of various EOs against L. monocytogenes and E. coli were about 0.5% for oregano and thymus EOs and 0.7% for cinnamon EO. Besides, addition of EOs at different concentrations resulted in the improvement of biochemical and microbiological qualities of ground vacuum packed sheep meat, during refrigerated storage. High concentrations of oregano (1%) and cinnamon (1.4%) EOs had the most efficient antilisterial activities compared to the control and other meat samples. The treatment of ovine meat with oregano or cinnamon EOs preserved a better content of proteins, a high ratio of PUFAs and a favorable balance between w-6 and w-3 PUFA, resulting in the production of healthier meat.

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This study aimed to evaluate the effect of Artemisia absinthium L. Essential Oil (EO) incorporation at various concentrations on the properties and oxidative stability of butter during 2 months of refrigerated storage. The obtained results on peroxide value, acidity, fatty acids, antiradical scavenging activity, and physical and microbiological properties confirmed the effectiveness of Artemisia EO incorporation in fat rich dairy foods. New produced butters can be classified as functional products due to their strong antioxidant activity, better oxidative stability, and richness in essential unsaturated fatty acids when compared to the control. All quality parameters were improved with Artemisia EO enrichment, however, descriptive sensorial analysis showed that the lowest concentration of about 45 ppm of the product was the most preferred in terms of color, odor, taste, firmness and overall acceptability. Due to its positive effects on all butter properties, Artemisia absinthium EO can be used as natural antioxidant and antimicrobial agent in food industries.

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The current research aimed, first, to valorize Tunisian cork oak acorn starch extracted by water soaking method in dairy industry. The effect of its incorporation into milk on the evolution of rheological, sensorial and microbiological properties of stirred yogurt during refrigerated storage was, also, evaluated. No significant effect was observed on fermentation parameters of the acorn starch added product. During 28 days of refrigerated storage, the incorporation of acorn starch did not affect the post-acidification and the viability of the lactic starter cultures. Moreover, the treated stirred yogurt exhibited a lower syneresis value and a higher consistency when compared to the untreated control and that incorporated with industrial modified starch. The findings revealed that acorn starch incorporation extended the shelf life of the final product by about 6 days. Despite its less appreciated color (3.67±0.5), acorn-starch-added yogurt product gained the highest overall acceptability scores (4.11±0.6) by the panel.

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This study aimed to evaluate the sensorial, physicochemical, rheological, and microbiological properties of yoghurt fortified with Artemisia absinthium leaf powder during refrigerated storage. The valorization of this plant in food industry was realized by the incorporation of its dried leaf powder at various concentrations in order to produce a new functional yoghurt. It is interesting to note that the fortified yoghurt with the lowest Artemisia dose (2%) was the most preferred by the panel. Furthermore, this fortification did not affect the fermentation parameters nor the viability of lactic starter. During storage, the incorporation of Artemisia powder reduced syneresis and improved the microbiological properties of fortified yoghurts. Besides, at the end of storage, it was noted that yoghurt fortified with 2% of Artemisia powder presented the highest consistency (8.98±0.04 Pa sⁿ) and antioxidant activity (60.08±3.61%) when compared to the control yoghurt. Finally, the accelerated shelf-life test showed the efficiency of Artemisia absinthium powder incorporation by increasing the shelf life of yoghurt by about 4 days.