ABSTRACT
Lben is a dairy fermented food that is largely consumed in Tunisia for its numerous health benefits that are related to the existence of probiotics. Lactic Acid Bacteria (LAB) are well known for their beneficial probiotic properties for humans, especially when administered in adequate amounts. The aim of this study was to isolate and investigate the probiotics properties of Lacticaseibacillus paracasei L2 from Lben. The isolated strain was identified by 16S r-RNA gene sequences and MALDI- TOF MS. To evaluate the probiotic potential of the isolated bacterium, in vitro tests were performed, including adhesion ability to HCT-116 cells, survival in acid and bile salt conditions, lysozyme resistance, biofilm formation, hemolytic activity, antioxidant activity, and antimicrobial activity. Our results revealed that the selected Lacticaseibacillus paracasei L2 strain expressed a high adherence to HCT-116 cells (45.03%), survived under acidic conditions (pH3), and showed a resistance to bile salts. The strain was considered as safe (α-hemolysis). L. paracasei L2 showed a high biofilm-formation ability (OD 570 > 1.7) after 24 h of incubation. It also demonstrated an important antioxidant activity in the range of 85.31% for the intact cells. However, an antimicrobial activity against pathogens, namely Staphylococcus aureus, was detected with an IZ that was above 19 mm. In conjunction with the results obtained and the technological properties of Lacticaseibacillus paracasei L2 (proteolytic property, autolytic activity, acidifying activity, and EPS production), this strain may be used as a probiotic for manufacturing fermented foods.
ABSTRACT
Flavonoids are compounds characterized by antioxidant activity, and their intake in the human diet is considered useful for health and nutrition. Non-anthocyanic flavonoids in 4 different types of Tunisian figs belonging to the smyrna-type Ficus carica varieties known as Kholi, Tchich Asal, Himri, and Bidhi were studied by liquid chromatography/high-resolution mass spectrometry UHPLC-QqTOF. Twenty-two compounds belonging to the classes of flavanones (naringenin and eriodictyol), flavones (3 apigenin and 5 luteolin derivatives), and flavonols (2 kaempferol and 7 quercetin derivatives) were identified. Three O-methoxy flavonols (tamarixetin, syringetin, and isorhamnetin-3-O-glucoside) were found in figs for the first time. Total content of non-anthocyanic flavonoids found in dark varieties (between 410 and 830 mg/kg) show that these F. carica are fruits qualitatively and quantitatively rich of dietary polyphenols.