مشخصات پژوهش

Kefir, a traditional fermented milk product, is considered as a rich source ofbiofunctional compounds like peptides that are beneficial to human health. Theobjective of this study was to extract water-soluble peptides from cow and ewemilk kefir (produced by local kefir grains of Semnan, Iran) and investigate theirantioxidant and antimicrobial activities. Evaluation of the chemical compositionof the cow and ewe pasteurized milk and kefir showed a decrease in protein, total 1 1✉ 1 2/20/2021 e.Proofing https://eproofing.springer.com/journals_v2/printpage.php?token=bmbqIE9J77YnKnQVDGQCSnlst-kvrYTAUMNKeMxRHW8DjBOg25wJ7w 2/23 carbohydrate, and lactose content. There was no difference between the mineralprofile of fresh milk and kefir. The count of lactic acid bacteria was almost stableduring the 28 days of storage period. From the 1st to the 28th day of storage, thepopulation of Lactococci (LC) was 11.5–12.1 and 11.4–12.2 log10 CFU/mL forcow and ewe milk kefir, respectively. A great antioxidant potential (DPPH andABTS assay) was observed for the peptides extracted from cow and ewe kefir (ata concentration of 1.25 mg/mL) on day 28 storage. Also, ewe kefir peptides hadhigher antioxidant activity than peptides of cow kefir. The antimicrobial activityof water-soluble peptides of ewe milk kefir was superior to those of cow milkkefir (at the same concentration of 20 mg/mL). The results of this work expressedgreat functional properties of peptides derived from ewe milk produced by localkefir grains of Semnan.