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Fermentation Characteristics of Streptococcus thermophilus Coupled with Different Lactobacillus Strains in Reconstituted Skim Milk

XU Ai-cai1,MA Cheng-jie1,HUA Bao-zhen1,DU Zhao-ping1,LIU Jun2,*   

  1. 1. Huazhong Institute of Technical Center, Bright Dairy & Food Co. Ltd., Wuhan 430040, China;
    2. School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
  • Online:2013-08-15 Published:2013-09-03
  • Contact: LIU Jun

Abstract:

The fermentation characteristics of Streptococcus thermophilus coupled with Lactobacillus casei, Lactobacillus
helveticus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus acidophilus, Lactobacillus lactis or Lactobacillus
plantarum in reconstituted skim milk (RSM) were studied. Changes in pH during 24 h of fermentation, and viscosity,
acidification speed and viable cell number of Lactobacillus in fermented milk stored at 4 ℃ were analyzed. The results
showed that the combination of Streptococcus thermophilus and Lactobacillus acidophilus had the quickest fermentation
speed. The pH was lowered to 4.19 from 6.45 after 24 h of fermentation. The combination of Streptococcus thermophilus
with different Lactobacillus had unique fermentation characteristics. Within the shelf life, all six combinations exhibited
post-fermentation acidification, especially the combination with Lactobacillus helveticus. The viable cell number of
Lactobacillus was significantly increased except when combined with Lactobacillus acidophilus. The change in yoghurts
viscosity among different combinations also revealed a significant difference.

Key words: probiotics, yoghurt, post-fermentation acidification, fermentation curve

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