Effect of oxyrase~TM on the metabolic processes of lactic acid bacteria in frozen yogurt mix~1

摘要

The effect of Oxyrase~TM (a bacterial cell material containing oxygen-reducing membrane fractions) on the metabolic processes of lactic acid bacteria during fermentation of a frozen yogurt mix was studied. Frozen yogurt mixes that were treated with 0.5 units of Oxyrase~TM per gram were inoculated with commercial culture organisms of Bifidobacterium bifidum, Lactobacillus acidophilus, and a mixed culture of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus and incubated at 40C for 8 h. Results showed that Oxyrase~TM significantly affected the development of titratable acidity (TA) and pH as well as the rates of bacterial growth. The TA increased from 0.23 to 0.87 with Oxyrase~TM during 8 h, whereas it increased only to 0.52 without Oxyrase~TM. In the same period, pH decreased from 6.8 to 5.15 with Oxyrase~TM but only to 6.12 without Oxyrase~TM. In all cultures, Oxyrase~TM enhanced the bacterial growth rate (#mu#) and reduced generation time (g) (P < 0.05). The greatest effect of Oxyrase~TM on growth was observed with B. bifidum, followed by the mixed yogurt culture and L. acidophilus.