Comparison of in vitro antioxidant activities of kefir, yogurt, and cheese produced from goat milk

This study compared the physicochemical characteristics and in vitro antioxidant activities of kefir, yogurt, and cheese produced from the same batch of goat milk using specific starter cultures. The physicochemical properties of the samples, as well as the antioxidant capacity (CUPRAC and FRAP) of the in vitro digested samples were analyzed. Additionally, low molecular weight (<3 kDa) peptide fractions were isolated to evaluate their contribution to antioxidant capacity. The highest antioxidant activities (mM Trolox/g protein) based on the CUPRAC assay were observed in yogurt (123.30), followed by kefir (116.05) and cheese (89.35). In contrast, the highest FRAP values were in cheese (22.74), followed by kefir (14.22) and yogurt (14.12). Low molecular weight (<3 kDa) peptide fractions generally showed antioxidant activity similar to or higher than that of the corresponding complete digest samples. Findings highlight the antioxidant potential of fermented goat milk products, especially cheese and kefir, for functional dairy applications.