Evaluation of the addition of Moringa oleifera L. and Salvia hispanica L. on the antioxidant activity and viability of lactic acid bacteria in yogurt during refrigerated storage

Abstract Moringa oleifera L. and Salvia hispanica L. are plants known to possess nutritional and medicinal properties, especially in bioactive compounds (antioxidants), which could be used to generate functional foods. The present study investigated the effect of M. oleifera leaves and S. hispanica seeds on yogurt’s antioxidant activity and microbial viability during 21 days of storage at 4 °C. Peptide content, pH changes, lactic acid content, and the microbial viability of lactic acid bacteria were analyzed on days 0, 7, 14, and 21. Antioxidant activity was determined by the 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods. Total phenolic compounds were determined by the Folin-Ciocalteu technique. During storage, treatments showed post-acidification, with lactic acid accumulation (1.30 to 1.80 lactic acid percentages) and pH values close 4.0. Compared to the other treatments, the mix treatment showed significantly (p < 0.05) elevated antioxidant activity, with 97.03 ± 1.2% free radical scavenging capacity in the ABTS assay at the end of storage. Regarding phenolic compounds, the Mix treatment obtained a concentration of 313.80 ± 15.71 mg GAE/100 g of yogurt, compared to the other treatments, which presented lower concentrations at the end of storage. In the DPPH assay, the treatment added with M. oleifera presented higher antioxidant activity on day 14 of cold storage with a free radical scavenging capacity of 23.15 ± 0.92% compared to the other treatments. The highest peptide concentration shown during cold storage of the treatments was in the Mix treatment during days 7, 14, and 21, with values of 26.86 ± 2.19, 37.34 ± 5.94, and 34.71 ± 1.33 mg leucine/100 g yogurt, respectively. The added treatment with M. oleifera showed increased lactic acid bacteria viability up to day 14 of refrigerated storage with a maximum value of 4.75 × 107 (CFU/ml) compared to the other treatments. These findings indicate that M. oleifera and S. hispanica influences the physicochemical properties of yogurt during storage for 21 days at 4 °C, affecting parameters such as pH, titratable acidity, LAB viability, peptide content and antioxidant capacity. These modifications can impact the stability and functionality of yogurt, making it a potential candidate studies in the field of functional foods.