Effects of heat treatment, starter culture, plant coagulant and ripening on in vitro ACE inhibitory and antioxidant activity of goat cheese

The objective of this study was to determine effects of heat treatment, starter culture addition, coagulant origin and ripening time on antioxidant and angiotensin-converting enzyme-inhibitory (ACE-I) activities of goat cheese. The bioaccessibility of the cheeses was tested in the low molecular weight (< 3 kDa) fractions (LP) of in vitro digested samples containing bioactive peptides. The antioxidant activity of the cheeses was tested with ABTS [2,20-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid)] radical scavenging and CUPRAC (Cupric reducing antioxidant capacity) assays. The interaction of heat treatment and starter culture addition affected the bioaccessibility of the cheeses just as ripening process, while different coagulants had no effect. The highest ACE-I activities observed in heat-treated + starter-added milk cheeses on the 1st day and starter-free raw milk cheeses on 30th, 60th, 90th days of ripening. Starter-free raw milk cheeses exhibited better antioxidant activities in the ABTS assay on the 1st and 30th days, and CUPRAC assay throughout all ripening days. Observations indicated that raw milk cheeses fermented by natural microbiota may exhibit an antihypertensive effect with over 50% ACE-I activity and reduce oxidative damage thanks to their bioactive peptides, demonstrating potential positive impacts on human health and suggesting their possible use in functional diets.