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The study aim was to determine the shelf life of yogurt sinbiotik at several temperatures with the addition of Dioscorea esculenta modified flour. Lactic Acid Bacteria used for yoghurt making consist of Lactobacillus acidophilus, Bifidobacterium longun, Streptococcus themophillus. The method used Accelerated shelf life test (ASLT) with the characteristics observed namely pH, total acid value using titration method, and total lactic acid bacteria with TPC method. The concentration level of modified flour of Dioscorea esculenta was 2%. The shelf life of yogurt can be determined from the critical factor based on most rapid damage to the Arrhenius equation y = -3504,1x + 9.1043 and R2 = 0.5125. Yogurt sinbiotik stored at room temperature shelf life is 9.5 days. At 4 ° C storage temperature, shelf life is 23.2 days. At 40 ° C storage temperature, shelf life is 5.4 days. The addition of Dioscorea esculenta tuber starch in yogurt sinbiotik affect viability of LAB in the yogurt, since viability of lactic acid bacteria during storage has decreased, but the numbers are still within the range of CFU / ml on the final day of storage

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This study investigated the influences of steam-cooking on (poly)phenolic compounds and colors in purple yam (Dioscorea alata L.) and purple sweet potato (Ipomoea batatas) tubers cooked at the household level. Steam-cooking did not significantly change the contents of total phenolic compounds, flavonoids, anthocyanins and antioxidant capacity measured by ABTS radical scavenging assay in purple yam (P≥0.05), but lowered the antioxidant capacity measured by Crocin assay (P<0.05). The liquid chromatograph– mass spectrometer–Ion Trap–Time of Flight (LCMS-IT-TOF) indicated the degradation of high MW alatanin B to lower MW alatanins due to the loss of glucose units. Purple sweet potato, however, responded to steam-cooking differently from purple yam (P<0.05). Steam-cooking drastically increased total phenolic compounds, flavonoids, anthocyanins, antioxidant capacities, and retained the vivid reddish-purple color of cooked purple sweet potato (P<0.05). The stability of polyphenolic compounds in starchy tubers against steam-cooking at the household level was, in part, due to the different contents of indigenous phenolic compounds in the raw tubers.

The study aims to determine the effect of CMC in preventing yoghurt separation in 7 days with the addition of 2% Dioscorea esculenta flour. Organoleptic test using quality hedonic was conducting to find out yoghurt with addition of CMC that had accepted characteristic by panelists. Research was carried out using regression method to determine the total titrated acid, pH and separation level of yoghurt during storage. The concentrations of CMC were added at 0.2%, 0.4%, 0.6%, 0.8%. The analysis showed the addition of 0.6% CMC showed the lowest separation with high viscosity grades of DPAs 40.25. Yoghurt storage for 7 days shows a graph of the pH value and total titrated acid were parabolic where increasing in total titrated acid value would lower the pH value. Yoghurt was damaged on the 7th day of storage at room temperature characterized by the increasing in the pH value and damage to the organoleptics properties, namely yoghurt flavor and aroma.