Quality Characteristics and Inhibition Activity against Helicobacter pylori KCCM 40449 of Liquorice Yogurts Manufactured by Exopolysaccharide Producing Lactic Acid Bacteria

Exopolysaccharide 생성 유산균을 이용한 감초 추출물 첨가 Yoghurt의 품질특성 및 Helicobacter pylori KCCM 40449 억제활성

  • Jung, Seung-Won (Department of Food Science & Biotechnology, Dongguk University) ;
  • Kim, Cheol Woo (Korea Advanced Food Research Institute) ;
  • Lee, Su Han (Department of Food Technology and Services, Eulji University)
  • 정승원 (동국대학교 식품생명공학과) ;
  • 김철우 (한국식품공업협회) ;
  • 이수한 (을지대학교 식품산업외식학과)
  • Received : 2011.10.12
  • Accepted : 2011.11.01
  • Published : 2011.11.30


This study was carried out to fortify the antimicrobial activity of yoghurt by adding liquorice extract to it. The liquorice extracts (1 mg/mL) showed relatively high antibacterial activity against H. pylori KCCM 40449 (p < 0.05). The solvent liquorice extracts of minimal inhibitory concentrations (MIC) against H. pylori KCCM 40449 were 25- 100 ${\mu}g$/mL. Lactobacillus amylovorus DU-21 with high EPS production ability were inoulated to milk after the addition of different amounts of liquorice extracts (0.0%, 0.05%, 0.1% and 0.2%). The physico-chemical characteristics of yoghurts added with liquorice extracts were examined. The initial pH, titratable acidity, viscosity and viable cell counts of the yoghurt added liquorice extracts were 3.41-3.51, 1.021-1.091%, 1,686-1,930 cp and 9.41-9.38 Log CFU/mL, respectively. The viscosity and syneresis of yoghurt were better than that of the control. Antimicrobial activity against H. pylori KCCM 40449 increased with increasing addition of liquorice extract. However, the sensory score of yoghurt added with different amounts of liquorice extracts was lower than that of the control (p < 0.05). As a result of the sensory evaluations, the flavor, taste, texture, color and overall acceptability of the yoghurt with 0.05% liquorice extract were found to be much better than those of the other groups (p < 0.05). Overall, the optimal amount of liquorice extract added in the manufacture of yoghurt was 0.05% of the total weight. Further studies on increment of antimicrobial activity and palatability of liquorice extract added yoghurt are necessary.