The objective of this study was to investigate the effect of hot water extract of Welsh onion root (HEWO) on growth of lactic acid bacteria and fermentative characteristics of yogurt. The physiochemical characteristics of HEWO such as pH, soluble solid, reducing sugar, total polyphenol content and DPPH radical scavenging activity were studied. The lactic bacterial count in brain heart infusion (BHI) broth with HEWO was about 1 log cycle higher than in control for 24 h at 37℃. The pH of yogurt prepared with HEWO (WY100) and 50% HEWO (WY50) was gradually decreased significantly but increased the viscosity of yogurt with increasing HEWO concentration during fermentation. The viable cells of lactic acid bacteria after fermentation for 24 h were 8.03 (control), 8.77 (WY50), 8.84 (WY100) log CFU/mL, respectively. The DPPH radical scavenging activity of yogurt increased with increasing HEWO concentration. Sensory quality of yogurt prepared with HEWO was higher than that of control. The pH and lactic acid bacteria of all tested yogurts decreased during storage for 10 days at 4℃ but lactic bacterial count of yogurt prepared with HEWO maintained 108 CFU/mL during storage. These results indicated the potential use of HEWO as a valuable resource to improve fermentation and functionality of yogurt.

• 김민정(대구가톨릭대학교 식품공학과) | Min-Jeong Kim (Department of Food Science and Technology, Catholic University of Daegu, Gyeongsan 38430, Korea)
• 이신호(대구가톨릭대학교 식품공학과) | Shin-Ho Lee (Department of Food Science and Technology, Catholic University of Daegu, Gyeongsan 38430, Korea) Corresponding author