菌株性能及球杆菌比例对酸奶品质的影响

Effects of strain properties and proportion of Streptococcus thermophilus to Lactobacillus delbrueckii subsp.bulgaricus on the quality of yoghurt

分析测定了从某直投式发酵剂中分离的两株嗜热链球菌(Streptococcus thermophilus)S.t S1、S.t R1和一株保加利亚乳杆菌(Lactobacillus delbrueckii subsp.bulgaricus)L.bL1的发酵性能,并将球菌与杆菌以不同比例组合发酵,比较酸奶发酵时间、粘度、乳清析出、后酸化和感官评价差异。结果表明,嗜热链球菌S.tS1生长速度略慢于S.tR1,酸化速度相当,但S.tS1的胞外多糖产量和发酵乳粘度明显高于S.tR1,保加利亚乳杆菌L.bL1的上述性能均比两株球菌差。S.tS1与L.bL1菌株以100:1的比例进行组合发酵时,粘度达0.549Pa·s;乳清析出仅2.5mL/10g;4℃冷藏保存15d后,酸度上升12°T,酸奶产品各项指标优于其他菌株组合。菌株性能和组合方式对酸奶产品的品质具有显著的影响。

Fermentation properties of individual strains and combination fermentation of S.t S1,S.t R1（Streptococcus thermophilus）and L.b L1（Lactobacillus delbrueckii subsp.bulgaricus）with different proportion were performed.The differences of fermentation time,viscosity,syneresis,postacidification and sensory evaluation of yoghurt with different combinations were analyzed.The results indicated that the growth rate of S.t S1 was slower than that of S.t R1,and the acidic rate was similar between each other,but the exopolysaccharide production and yoghurt viscosity of S.t S1 were better than that of S.t R1.The above mentioned properties of strain L.b L1 were inferior to that of S.t S1 and S.t R1.The yoghurt combinatively fermented by S.t S1 and L.b L1 with proportion of 100：1 was better than other combinations,the viscosity and syneresis of which was 0.549Pa·s and 2.5mL/10g respectively,and the acidity rose only 12°T after 15 days at 4℃.The properties and combination modes of strains are with significant influence on the quality of yoghurt.