PENGARUH VARIASI PENAMBAHAN SARI BUAH NAGA MERAH (Hylocereus polyrhizus) DAN LAMA FERMENTASI TERHADAP KARAKTERISTIK YOGHURT SUSU KAMBING

Processed dairy products, especially yogurt, have become a popular trend in society due to their delicious taste and abundant nutritional content. Yogurt made from goat's milk still requires various efforts to be more widely accepted by the public. Therefore, this research aims to enhance public acceptance of goat's milk yogurt by exploring the potential addition of natural flavors and colorings such as red dragon fruit. Additionally, red dragon fruit is known for its high antioxidant activity, which can elevate the nutritional value of goat's milk yogurt products. This research aims to analyze the effects of two main factors, namely variations in the addition of red dragon fruit extract and fermentation time, on the characteristics of goat's milk yoghurt. The study used a Completely Randomized Factorial Design (CRFD) method, with the first factor being the concentration of red dragon fruit extract, which included F1 (5%), F2 (10%), and F3 (15%), and the second factor being the
fermentation duration treatment, which included P1 (8 hours) and P2 (10 hours). The results of the research indicate that the addition of red dragon fruit extract significantly affects antioxidant activity, viscosity, color intensity (L, a, and b), as well as color and taste organoleptic characteristics. On the other hand, the fermentation
duration significantly affects protein content, total titratable acidity, pH value, total lactic acid bacteria (LAB), antioxidant activity, viscosity, as well as color and taste organoleptic characteristics. The best combination of physicochemical and organoleptic results is the treatment F3P2 (15% red dragon fruit concentration and 10 hours of fermentation time) with results including a protein content of 3.38%, total titratable acidity of 3.95%, a pH of 3.89, a total LAB count of 5.38 x 10^9 cfu/ml, antioxidant activity of 55.39%, a viscosity of 221.66 cP, and L, a, and b color intensity values of 56.13; 36.50; and -14.00, respectively.