Optimasi Formulasi Yogurt Kedelai pada Skala Laboratorium

Abstract

Functional food trend progress is very rapidly and the majority of the growing functional food claims are intended to create a healthy digestive tract. Therefore, probiotic food products ranked second most popular after energy food and drink products. Yogurt is one type of probiotic food products that much favored by consumers due to having delicious flavor and providing many benefits for human health. Until now the raw materials used in the process of making yogurt is dairy cow, however, soymilk is one of the raw materials that potentially can replace cow's milk in the manufacture of yogurt. The use of soymilk as raw material for making soy yogurt has not been used optimally. This study aims to optimize the use of soymilk and fresh milk in the manufacture of soy yogurt in order to obtain the optimal cost of raw material response, objective responses (pH, viscosity, and total lactic acid bacteria), and subjective responses (texture, aroma, flavor, and color). Soy yogurt was developed using lactic acid bacteria (1:1 mixture of Streptococcus thermophilus and Lactobacillus acidophilus) and fermented for 8 hours at 43-45°C. The recommended optimum formula by design expert version 8 is the formula with the composition of soymilk and fresh milk ratio of 68.384% and 16.416% with a desirability value of 0.450. The optimum formula has a yellowish white color, taste sour and slightly sweet, sour aroma typical of soy yogurt, smooth texture, a bit of liquid viscosity, and no beany flavor in the final product. Soy yogurt optimum formula has 4.47 pH value, viscosity 200 cP, raw material cost Rp 978.0838, water content 84.70%, ash content 0.73%, protein content 3.06%, fat content 0.79%, carbohydrate content 10.62%, total titratable acidity 0.52%, average content of total lactic acid bacteria in the product 1.8x109 CFU/ml or 9.2553 log CFU /ml, there were no molds and yeasts, and the result of coliform test is <3 MPN/g in the final product. Soy yogurt optimum formula is still suitable for consumption up to 25 days of storage in the refrigerator at 10°C and there were no growth of molds and yeasts.