EFFECTS OF PURPLE SWEET POTATO RATIOS ON ANTIOXIDANT AND SENSORIAL QUALITY OF JELLY YOGURT

Abstract

Purple sweet potato yogurt is a novel product developed to enhance both the nutritional and economic value of yogurt. The study aimed to evaluate the effects of different ratios of milk to purple sweet potato juice (0; 1:0.5; 1:0.75; and 1:1) on antioxidant properties, including total polyphenol content (TPC), total flavonoid content (TFC), and free radical scavenging activities (DPPH and ABTS assays), with IC50 values over fermentation periods of 2, 4, 6, and 8 h. The results showed that the yogurt with a 1:0.75 ratio after 6 h of fermentation exhibited the best sensory quality and achieved high levels of antioxidants, including a TPC (53.54 mg GAE/g db), TFC (27.23 mg QE/g db), DPPH (58.51 µmol TE/g db), ABTS (63.32 µmol TEAC/g db), and an IC50 value of 9.51 mg/mL. The results showed that the addition of purple sweet potato to the yogurt production process not only enhanced the antioxidant activity of the product but also improved the sensory quality of the jelly yogurt.