FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (18): 172-179.doi: 10.7506/spkx1002-6630-20190724-320

• Bioengineering • Previous Articles     Next Articles

Fermentation and Probiotic Properties of Lactic Acid Bacteria Isolated from Dairy Products in Yili, Xinjiang and Optimization of Their Mixtures for Mixed-culture Fermentation

CAI Jingjing, ZHANG Yachuan, LI Xu, ZHANG Yan, NI Yongqing   

  1. (Food College, Shihezi University, Shihezi 832000, China)
  • Online:2020-09-25 Published:2020-09-18

Abstract: The acidification ability and aroma-producing ability of seven strains of lactic acid bacteria preserved in our laboratory for yogurt fermentation and the texture properties of yogurt made with each of the strains were measured. The probiotic characteristics of these strains were evaluated by their antibacterial properties, gastrointestinal juice tolerance and antibiotic susceptibility. Strains with better performance were selected and combined to obtain the optimal mixed starter culture. The results of single-strain fermentation showed that the coagulation time of yogurts made separately with Leuconostoc lactis XKN1-5 and Lactobacillus delbrueckii subsp. bulgaricus BSTS6-4 was shorter (about 7 h), and the acidity reached around 96 °T; their acidification abilities were better than those of other strains. The yogurts fermented separately by L. delbrueckii subsp. bulgaricus BSTS6-3 and Streptococcus thermophilus XSXN1-2 had excellent texture characteristics. L. delbrueckii subsp. bulgaricus BSTS6-1 and S. thermophilus XSXN1-1 had the best aroma-producing ability and the yogurt fermented by strain XSXN1-1 contained 2.02 mg/L of diacetyl and 16 mg/L of acetaldehyde, indicating significantly improved flavor. The results of probiotic properties showed that L. fermentum BST2-3 and L. delbrueckii subsp. bulgaricus (BSTS6-1, BSTS6-3, and BSTS6-4) could inhibit the growth of pathogenic bacteria, and Lactobacillus fermentum BST2-3, L. delbrueckii subsp. bulgaricus BSTS6-1, BSTS6-4) had greater adhesion ability; the number of viable L. fermentum BST2-3 was 106 CFU/mL after 9 h of simulated gastrointestinal juice treatment. All the seven strains showed sensitivity to most tested antibiotics and were of high safety. Based on the ability to produce acids and aroma compounds, yogurt texture and probiotic properties, the optimal strain combination for mixed-culture fermentation was obtained as L. delbrueckii subsp. bulgaricus (BSTS6-4 and BSTS6-3) + S. thermophilus XSXN1-1 + L. fermentum BST2-3.

Key words: yogurt; lactic acid bacteria; fermentation characteristics; probiotic characteristics; mixed-culture fermentation

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