Proteolytic lactic acid bacteria for food safety and One Health: Degradation of cow's milk allergens and prospects for hypoallergenic dairy development.

Background and Aim: Cow's milk allergy (CMA) is one of the most common food allergies, particularly in infants and young children, caused mainly by β-lactoglobulin (β-LG) and caseins. Conventional methods to reduce milk allergenicity, including heat and pressure treatments, often compromise nutritional quality or lack industrial feasibility. Safe, natural approaches to allergen reduction are essential for both food safety and One Health perspectives, as CMA contributes to nutritional deficiencies and impacts global health. This study aimed to isolate and characterize proteolytic lactic acid bacteria (LAB) from Chinese dairy products and fermented foods, evaluate their ability to degrade major cow's milk allergens, and assess their probiotic and safety profiles for application in hypoallergenic dairy products. Materials and Methods: Seventy-six LAB isolates were obtained from dairy and fermented foods and screened for proteolytic activity using skim milk agar and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The most active isolates were identified by phenotypic characterization and 16S ribosomal RNA sequencing. Probiotic potential was evaluated through in vitro gastrointestinal tolerance, bile salt hydrolase (BSH) activity, antimicrobial activity, and antibiotic susceptibility. Safety was assessed through hemolytic activity and screening for virulence-associated genes. Results: Seventy isolates exhibited proteolytic activity, of which 7 (S30, S44, S46, S52, S63, S67, and S76) showed strong hydrolysis of β-LG and β-casein. These were identified as Conclusion: Proteolytic LAB strains, particularly