Comparison of organoleptic, protein, lipid and flavonoid content of commercial starter and isolated culture red dragon fruit peel yogurt

Abstract

Red dragon fruit peel can be processed into yogurt. Yogurt is a coagulated milk product obtained from the lactic acid fermentation-yogurt made from various milk, whether fresh milk, skim milk, or even full cream milk. The additions of red dragon fruit peel may enhance the taste and the therapeutical values. This study was aimed to compare the organoleptic properties, protein, lipid, and flavonoid content of commercial starter and isolated culture red dragon fruit peel yogurt. Red dragon fruit peel yogurt was made with amounts of red dragon fruit peel (25% w/v), full cream milk, sucrose and, commercial starter (Lactobacillus bulgaricus, Lactobacillus acidophilus, Streptococcus thermophilus, Bifidobacterium) or isolated culture (L. bulgaricus and S. thermophilus). Hedonic scale test form was used for measuring organoleptic properties. Protein content was used Kjeldahl method, lipid content was used Soxhlet method, and flavonoid content was used chromatography. This research showed that protein and lipid contents in red dragon fruit peel yogurt with commercial starter were higher than red dragon fruit peel yogurt with isolated culture. Flavonoid content in the isolated culture yogurt was higher than commercial starter yogurt. Organoleptic properties between groups were significantly different (p<0.05). Red dragon fruit peel yogurt used isolated culture has a good chance of getting a positive reception from the public and has potential as a functional food.