Fermentation of Yam (Dioscorea batatas Decne) by Lactic Acid Bacteria and Sensory Evaluation of the Fermented Yam Mixed with Plant Juice Concentrates

Abstract

Yam (Dioscorea Batatas Decne) contains high contents of starch. In the present work, a dry yam tuber extract was hydrolyzed by α-amylase, pullulanase, and malt enzyme extract and fermented with lactic acid bacteria (LAB) to develop a fermented Yam beverage retaining the health benefits of a probiotic culture. The starter culture strain was selected by comparing the viable cell counts of the various LAB during the fermentation of the enzyme treated yam extracts (ETYE). L. bulgaricus showed a high growth rate in ETYE media and was therefore chosen as the fermenting microorganism. The sensory value of the fermented yam beverage was optimized by response surface methodology (RSM). Eighteen formulations of beverage with different ingredients were prepared: jujube extract (1-10%), blueberry extract (1-10%), mango juice (1-10%) and a group of 30 panelists responded to the sensory evaluation. The formulation optimizing both sweetness and sourness was composed of 6.53% of jujube, 7.41% of blueberry, and 10% of mango.