Peanut sprout yogurt: Increased antioxidant activity and nutritional content and sensory evaluation by fuzzy mathematics

Peanut sprouts contain abundant bioactive substances including resveratrol and other natural polyphenols, which have strong antioxidant activity. Herein, we describe the formulation of peanut sprout yogurt, which combines the antioxidant activity of a fermented product with the added activity afforded by peanut sprouts. A fuzzy mathematical model was developed for the sensory evaluation of the peanut sprout yogurt based on three indexes: the color, taste, and texture of yogurt. Using the fuzzy mathematical model, the optimal parameters of peanut sprout yogurt were 0.4% lactic acid bacteria, 8% white sugar, and 2% peanut sprout freeze-dried powder. Subsequently, the antioxidant activity of the yogurt was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity assays. Peanut sprout yogurt had higher antioxidant activity (25.07 ± 0.05%, DPPH; 24.75 ± 0.01%, ABTS) as compared to plain yogurt (17.10 ± 0.05%, DPPH; 17.03 ± 0.02%, ABTS). Interestingly, the Colony-Forming Unit (CFU) of lactic acid bacteria in plain yogurt versus peanut sprout yogurt differed, 1.9 × 109 CFU/g and 3.6 × 109 CFU/g, respectively. The two yogurts also differed in protein, fat, carbohydrate, and caloric content with peanut sprout yogurt determined as 6.3 g/100 g, 4.2 g/100 g, 18.0 g/100 g, and 559.0 kJ/100 g, respectively, versus plain yogurt determined as 3.3 g/100 g, 3.9 g/100 g, 13.0 g/100 g, and 422.0 kJ/100 g, respectively. Novelty impact statement Yogurt containing peanut sprouts had higher content levels of lactic acid bacteria. The addition of peanut sprout increased the antioxidant activity of yogurt. Optimum concentration of peanut sprout in the yoghurt was 2%.