Production of α-glucosidase inhibitory peptides during milk fermentation using indigenous lactic acid bacteria Lactiplantibacillus plantarum subsp. plantarum Dad-13

α-glucosidase inhibitor (AGI) peptides from various food sources have been widely studied. This study aimed to determine the optimal incubation period for producing peptides with high AGI activity in fermented milk commonly used as a protein source. After sterilization, milk was inoculated with Lactiplantibacillus plantarum subsp. plantarum Dad-13 and incubated for 6, 12, 14, 16, 18, and 24 h. Various parameters such as proteolytic activity, peptide content, degree of hydrolysis, protein pattern, and α-glucosidase inhibition were studied during incubation. Milk fermentation caused hydrolysis of milk proteins, resulting in more ϒ-casein and small molecular mass peptides monitored by SDS pages. The highest protein hydrolysis occurred after 24 h of fermentation, as observed from the degree of hydrolysis (24.05) and peptide content (1.53 mg/mL). The highest AGI activity was obtained after 18 h of milk fermentation (36.12). Milk fermentation using L. plantarum Dad-13 produced potential AGI peptide. Peptide fractions with a molecular mass of >2 kDa had high α-glucosidase inhibitory activity in fermented milk. Milk fermentation using L. plantarum Dad-13 produced AGI peptides that have the potential to be further developed as antidiabetic functional foods. © 2025 The Authors.