PENGARUH PENAMBAHAN EKSTRAK KULIT BUAH NAGA MERAH DAN LAMA FERMENTASI TERHADAP SIFAT FISIKOKIMIA, MIKROBIOLOGIS, DAN ORGANOLEPTIK SOYGHURT

Soymilk is a form of soybeans processed. Soybeans has many nutrients such as high protein, high in unsaturated fatty acids, betalain, and flavonoids. The benefit of flavonoids as a functional food are being proliferation inhibitor, antibacterial, and as antioxidant. Soymilk has unpleasant aroma and not durable, therefor it needs further processing so that it can be stored longer, one of the processing of soymilk is soyghurt. Dragon fruit peel extract has a bright red color and various of functional food coumpounds in it such as anthocyanins and flavonoids, it is useless if the peel of dragon fruit is not used. The length of the fermentation process in making soyghurt affects the number of total bacteria in it. So it is needs to do research on the effect of the addition of dragon fruit peel extract and fermentation length of soyghurt. The research method used was Randomized Block Design (RBD) with 2 treatment factors, the first one was the addition of dragon fruit peel extract in 10, 20%, and 30% (v/v), while the second factor is the length of fermentation process in 12, 18, and 24 hours. The results showed that there were interactions between the addition of dragon fruit peel extract and fermentation time on physicochemical properties (Antioxidant and viscosity), microbiological, and organoleptic properties (Aroma and viscosity). The addition of dragon fruit peel extract significantly affected the physiochemical properties (Total dissolved solids, titrated total acid, fat, color intensity (a+), color intensity (b), and brightness (L)), microbiological, and organoleptic viscosity. The fermentation time has signifanctly effect on physiochemical properties (pH, total titrated acid, and fat), microbiological, and organoleptic properties (Taste and appearance) of soyghurt