The Effect of Refrigerated Storage on Anti-Diabetic and Antioxidant Potency of Probiotic Yogurt Treated with Some Medicinal Plants

This research aimed to evaluate the effect of the inclusion of Codonopsis pilosula (CP), Illicium verum (IV), Lycium barbarum (LB), and Psidium guajava (PG) water extracts in yogurt (Y) on phenolic antioxidant-linked α-amylase and α -glucosidase inhibitory activities. Four types of herbal yogurt (CP-Y, IV-Y, LB-Y, and PG-Y) and plain-Y (control) were prepared and stored in disposable plastic containers at 4 °C for 28 days. All samples were analysed for peptide concentration using O-phthaldialdehyde, total phenolic content (TPC), 1,1-Diphenyl-2-Picrylhydrazyl radical scavenging activity, and α-amylase and α-glucosidase inhibitory activities (IC50). LB-Y showed the highest peptide concentration and TPC (p < 0.05) among all the yogurts during storage. IV-Y showed the highest (p < 0.05) radical scavenging activity among all herbal yogurts. The best α-amylase and α-glucosidase inhibitory activity (IC50) for all herbal yogurt was on days 7 and 14 of storage. In conclusion, all herbal yogurts could be considered as a potential functional food with antioxidant and anti-diabetic properties.