Abstract

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 Streptococcus thermophilus, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus casei, Lactobacillus rhamnosus, and Lactobacillus paracasei. Notably, L. rhamnosus S46 achieved complete degradation of β-LG while maintaining high survival (>83%) under simulated gastrointestinal conditions, with BSH activity and broad antimicrobial effects. Most isolates lacked virulence genes and hemolytic activity, except L. paracasei S67.

Conclusion: Proteolytic LAB strains, particularly L. rhamnosus S46 and L. plantarum S52, exhibited strong allergen-degrad­ing activity, probiotic potential, and safety profiles, supporting their application in hypoallergenic dairy production. From a food safety and One Health perspective, these strains represent natural, functional alternatives for reducing milk allerge­nicity, improving consumer health, and supporting sustainable dairy innovation. However, in vivo validation and pilot-scale trials in real dairy systems are necessary to confirm industrial feasibility and consumer acceptance.

Keywords: cow’s milk allergy, food safety, lactic acid bacteria, One Health, probiotics, proteolytic activity.