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Physicochemical, microbiological, and sensory properties of low-lactose yogurt using Streptococcus thermophilus with high β-galactosidase activity.

  • 2023-07-24
  • Journal of the Science of Food and Agriculture 103(15)
    • Ling Li
    • Ling-Hua Zhou
    • Xuemin Liu
    • Jinyan Gong
    • G. Xiao

Abstract

Background: Lactose maldigestion or intolerance affects a large number of individuals worldwide. If lactose is hydrolyzed by the β-galactosidase enzyme during the fermentation process, lactose-intolerant individuals can consume milk products without experiencing diarrhea, flatulence, or other symptoms.

Results and conclusion: We isolated and characterized Streptococcus thermophilus, which exhibits high β-galactosidase activity. This was then used as a starter culture with Lactobacillus delbrueckii subsp. bulgaricus in yogurt to determine the effects of different starter ratios and fermentation temperatures on its organoleptic and physical properties. The β-galactosidase activity of the isolated strain was 2.60 units mg-1 . The optimal temperature was 42 °C for St. thermophilus to acidify yogurt faster than at other temperatures and it was effective in hydrolyzing the lactose in the media and yogurt. The lactic acid bacteria (LAB) population in 37 °C fermented yogurt was higher than in the other samples, but the starters St. thermophilus and Lb. bulgaricus with a ratio of 2:1 used lactose more effectively than other sample ratios. The lactose content decreased significantly at 37 °C, where it was ~50% hydrolyzed. The acceptability of the sensory properties of yogurt was unaffected by relative lower fermentation temperatures (30 and 37 °C), despite using different ratios of St. thermophilus and Lb. bulgaricus as starter cultures. © 2023 Society of Chemical Industry.

Keywords: Streptococcus; fermented temperature; starter ratio; yogurt.

Research Insights

SupplementHealth OutcomeEffect TypeEffect Size
Streptococcus thermophilus MAK34S24TImproved Symptom Relief for Lactose IntoleranceBeneficial
Moderate
Streptococcus thermophilus SD-5207Reduced Lactose Content in YogurtBeneficial
Moderate
Streptococcus thermophilus SL-21Enhanced Yogurt Acidification RateBeneficial
Moderate
Streptococcus thermophilus SL-21Improved Lactose DigestionBeneficial
Large
Streptococcus thermophilus UASt-09Reduced Lactose-Related SymptomsBeneficial
Large
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