Antioxidant Activity, Physicochemical Characterisation and Antibacterial Properties of Caspian Sea Yoghurt Enriched with Ginger and Sappanwood Extracts

Abstract

Caspian Sea yoghurt has lower acidity and is thicker than common yoghurt. Caspian Sea yoghurt contains probiotic bacteria that improve the balance of intestinal microflora. This research aimed to determine the antioxidant activity of Caspian sea yoghurt enriched with two different herbs, ginger and sappanwood, at concentrations of 5, 10 and 15% w/v. The pH, total phenol, antioxidant, total LAB, and antibacterial activity of the enriched yoghurt were measured to determine the best of the two products. The results showed that the enrichment of the yoghurt with sappanwood and ginger extracts increased lactic acid bacteria (LAB) growth compared with the control (yoghurt without plant extracts). Further analysis showed that the product that contains 15% sappanwood extract was judged to be the best formulation with a pH of 5.01 and a total LAB of 3.78 x 107 CFU/mL. It also exhibited antibacterial activity against B. cereus and E. Coli with zones of inhibition of 8.00 mm and 8.39 mm, respectively. The total phenol content was 5.48 mg GAE/g of the sample and 50.08% antioxidant activity. In conclusion, Caspian sea yoghurt enriched with herbs showed increased antioxidant and antibacterial activities and may have better potential in health maintenance.