Abstract
This study investigated angiotensin-converting enzyme (ACE) inhibitory activity (ACE-IA), antioxidant activity (AnOxA), and bioactive peptides in novel probiotic fermented sheep and bovine milks, along with their storage stability and sensory properties over 28 days at 4 °C. Milks fermented by Lactobacillus delbrueckii MF55 exhibited strong ACE-IA and AnOxA, whereas Lacticaseibacillus paracasei MF48 produced only pronounced AnOxA. After ultrafiltration, QExactive identification, in silico analysis, and molecular docking simulations, four novel peptides with antihypertensive and antioxidant potential (ITVDDKHYQK, AMKPWTQPK, YPVEPFTER, KYNVPQLEIVPK) were screened from the <3 kDa fractions. Among them, AMKPWTQPK and KYNVPQLEIVPK were uniquely detected in fermented sheep milk. During cold storage, MF55 fermented sheep milk (MF55-FSM) maintained significantly higher ACE-IA and water-holding capacity than MF55 fermented bovine milk (P < 0.05), while the latter showed superior viable cell counts and sensory properties. Overall, MF55-FSM demonstrated potent functional performance, highlighting sheep milk as a promising matrix for functional dairy products.