Enhancement of the lactic acid bacteria population, chemical and organoleptic properties of soygurt with nutraceuticals from purple sweet potato (Ipomoea batatas L) paste

Soygurt is a type of probiotic beverage that is made from soy milk fermented by lactic acid bacteria (LAB). Purple sweet potato-PSP ( Ipomoea batatas L) contains various nutraceutical compounds which may amplify the health benefits of soygurt once added at optimum level. The aim of this experiment was to evaluate the impact of PSP at various concentrations on LAB population, chemical and organoleptic properties of soygurt. The purple sweet potato paste (PSPP) was added at six different concentrations i.e. 0%, 3%, 6%, 9%, 12%, and 15% (w/v) of the total mixture. Statistical analysis with ANOVA at α of 5% showed that the addition of PSPP caused an increase in the total plate count of LAB cells (from 7.9900 to 9.7459 log cfu/g), pH (from 4.735 to 4.298), and total lactic acid (from 0.267 to 0.466%). Based on the organoleptic evaluation preferences, soygurt at 3% and 6% PSPP have been accepted by the panelists in terms of its taste preference at 5.35 (sufficient) and its mouthfeel at 5.88 (like). Notwithstanding, soygurt with 12% PSPP was the optimum concentration with respect to its color at 5.40 (sufficient). In conclusion, PSPP concentrations affect significantly the LAB population, chemical, and organoleptic properties of soygurt.