Probiotic fermentation enhances the technological properties and health-promoting potential of skyr-type yogurts

Skyr-type yogurt (STY) has emerged as a promising carrier for probiotics and functional components with health benefits. This study evaluated the technological properties and health-promoting potential of STY formulations fermented with probiotics: Lactobacillus acidophilus LA5 (S1), Lactiplantibacillus plantarum 299v (S2), and Lactiplantibacillus plantarum LPLDL (S3), alongside a control. Analyses included proximal composition, physicochemical and sensory profiles, probiotic viability, enzymatic activity assays, and cellular tests for immunomodulatory and antioxidant properties. Probiotic fermentation preserved the moderately high-protein (5.73–5.88 g/100 g) and low-fat (2.31–2.53 g/100 g) profile of STY while reducing syneresis (38–40 %) and enhancing viscosity due to increased exopolysaccharide production. The sensory evaluation confirmed that STY formulations maintained comparable acceptability to the control and a commercial skyr product. Probiotic viability exceeded 7 log colony forming units/mL after in vitro digestion, ensuring effective delivery to the gut. Regarding functional properties, S3 showed the strongest α-amylase inhibition, while S2 excelled in α-glucosidase inhibition after in vitro digestion. Both S2 and S3 also exhibited the highest bile salt hydrolase activity, indicating potential cholesterol-lowering properties. Immunomodulatory effects included a 32 % reduction in tumor necrosis factor alpha (TNF-α) production by S2 and S3. Additionally, S3 demonstrated the greatest anti-inflammatory activity, reducing nitric oxide production by 44 %. All formulations increased anti-inflammatory interleukin-10 (IL-10) levels (14–18-fold), enhanced phagocytic activity (1.7–1.9-fold), and reduced oxidative stress (14–18 %). These results highlight the potential of STY formulations, especially those fermented with L. plantarum 299v and LPLDL, as innovative dairy-based functional foods.