Ultrasound-assisted enhancement of microbial, physicochemical, and bioactive properties in Lactobacillus helveticus-fermented milk

This research assessed the impacts of ultrasound on fermentation dynamics and bioactive properties in milk fermented with <i>Lactobacillus helveticus</i>. Ultrasound was applied to milk (MU + L), bacterial culture (M + LU), both (MU + LU), or the inoculated mixture [(M + L)U], and samples were analysed during a 24 h fermentation. Results demonstrated that ultrasound significantly enhanced microbial viability, especially in MU + LU. Acidification occurred more rapidly in ultrasound-treated samples, with MU + LU achieving the lowest pH(3.31). Ultrasound also improved antioxidant potential, with DPPH radical scavenging and ascorbate oxidation inhibition reaching 79.8 % and 28.4 %, respectively, in MU + LU. Furthermore, inhibitory activities against α-amylase, α-glucosidase, ACE, and lipase were significantly higher in ultrasound-treated samples, again with MU + LU showing the most pronounced effects (47.2 %,43.4 %,42.9 %, and 34.6 %, respectively). These findings highlight the synergistic advantages of applying ultrasound to milk and culture, offering a promising green, non-thermal approach to accelerate fermentation and improve microbial viability, antioxidant activity, and functional health-promoting properties in fermented dairy products.