Lactiplantibacillus plantarum enhances the texture of fermented milk by facilitating protein gelatinization through the action of a novel coagulation-promoting protease

Enzymatic modification can effectively improve the gel properties of protein -based food matrices. However, how bacterial proteases influence milk gels has been rarely reported. In the current study, the proteases isolated from two strains of Lactiplantibacillus plantarum , namely YM13 -8.1 and YN22 -3.1, demonstrated significant improvement in the textural properties of acid -induced gels characterized by increased hardness and a more compact, dense and fine -pored structure. The inclusion of milk -coagulating proteases resulted in a significant augmentation of hydrophobic interactions and disulfide bonds within the protein gels. Furthermore, both proteases exhibited rennet -like characteristics through kappa-casein hydrolysis, with key hydrolysis sites identified as Tyr25-Ile26, Ala65-Ala66 and Lys112-Asn113. By utilizing MALDI-TOF-MS, whole genome sequencing and RTqPCR analysis, we successfully identified the gene responsible for encoding the proteases as prtA , which has not been previously characterized. In conclusion, our findings demonstrate that the newly characterized protease prtA exerts a positive influence on milk gelling.