Search

An ultrasound, a non-thermal technique, can be employed to increase a probiotic’s biomass and its fermentation products. The effects of high-intensity ultrasounds (20%, 30%, and 40% amplitudes for 3 min) on the growth and fermentative profile of Lactobacillus acidophilus and helveticus were studied. The use of an ultrasound decreased the Lag phase and increased the maximum growth potential; however, the effect depended on the amplitude used. For both probiotics, the β-galactosidase activity increased in the treatments with a 20% amplitude—3 min and 30% amplitude—but decreased in the treatment with a 40% amplitude—3 min in comparison to the values found in the control treatment. The two probiotics showed a decrease in the protein concentration when compared with the control treatment. Both probiotics presented the lowest values of proteolysis in the treatments with a 30% amplitude—3 min. Lactic, acetic, and citric acids were the organic acids that were present in the highest concentration and formic acid was not detected in either of the two probiotics. It can be concluded that the ultrasound amplitude has a noticeable influence on the growth and fermentation profiles of both probiotics. The results from this study could be used in subsequences investigations to enhance the postbiotic production of Lactobacillus acidophilus and Lactobacillus helveticus.

Sonoporation stimulates cell growth as it improves the permeability of the membrane and increases the uptake of impermeable molecules in the extracellular matrix. We evaluated the effects of substrates (whey, whole, and skim milk) and ultrasonic treatments (ultrasonication and thermosonication) on the antioxidant activity (AA) of water-soluble kefir postbiotics (WSKPs). The samples were evaluated in terms of antioxidant activity (ABTS, DPPH, FRAP, and ORAC), water-soluble protein content, proteolysis (SDS-PAGE profiles), and cell membrane permeability. The levels of AA in all WSKPs depended on the substrate and method of obtaining them. However, the WSKPs from whey had higher antioxidant activity with DPPH (11.11 mg TE/100 mL), ABTS (12.77 mg TE/100 mL), and FRAP (5.18 mg TE/100 mL). Also, the WSKPs from whey had the highest values for water-soluble protein (1.45–1.32 mg/mL) and proteolysis degree and the lowest percentage of dead cells (11.4–28%). These results suggest that the production of WSKPs from whey might add value to whey production. Furthermore, WSKPs have potential as a functional ingredient in the production of beverages or foods with antioxidant activity.