Antioxidant peptides produced by <i>Pediococcus acidilactici</i> YKP4 and <i>Lacticaseibacillus rhamnosus</i> BD2 in fermented soymilk made from germinated soybeans

Abstract Soybeans contain antioxidants and are a rich source of proteins. Germination of soybeans improves the bioavailability of nutrients and reduces the content of antinutritional compounds. Moreover, lactic acid fermentation of high-protein foods, such as soybeans, can produce bioactive peptides. Therefore, this study aimed to produce bioactive peptides through fermentation of soymilk prepared from germinated soybeans using Pediococcus acidilactici YKP4 and Lacticaseibacillus rhamnosus BD2 and to identify the antioxidative properties of the resulting peptides. Results demonstrated that the &amp;lt;2 kDa fraction of germinated soybean milk, fermented by P. acidilactici YKP4 and L. rhamnosus BD2, had the lowest IC50 values of 471.16 and 556.93 μg/ml, respectively. Furthermore, the resulting peptides of &amp;lt;2 kDa were mainly derived from glycinin and β-conglycinin. Some of the identified peptides exhibiting antioxidant activities were GKHQQEEENEGGSI, VNPESQQGSPR, IGINAENNQRN, and FVDAQPQQKEEG. Moreover, fermentation of germinated soybean milk produced peptides that act as inhibitors of dipeptidyl peptidase-4, angiotensin-converting enzyme, and dipeptidyl peptidase-3.