Preparation And Bioactivity Evaluation Of Lactobacillus Helveticus Starter And Its Fermentation

The key technology of concentrated Starter of Lactobacillus helveticus was studied in this paper,including filtration of the culture medium and fine freeze-dry protestant,Optimizing the condition of cell cultivation,concentration and the technology of lyophilization.The effects of Lactobacillus helveticus and its fermentation product on reductions in mean systolic blood pressure and immune function in mice were also studied, the biological mechanism of Lactobacillus helveticus was explored and the best dose-effect relationship was determined.The optimum medium was prepared as:enzyme hydrolysed 11%RSM,0.5.0%lactose, 0.5%peptone,0.3%yeast extract and 0.1 mol/L KH₂PO₄-NaOH,culture time 14 h.The viable counts was 5.87×10⁹,100 and 15.4 fold higher than fermented in 11%RSM and enzyme hydrolyzed 11%RSM.Fermented liquor of Lactobacillus helveticus was centrifuged(4000 r/min×20 min),the components and dosage of the cryoprotective agents were ascertained.The results indicated that the cryoprotective agents showed significant effect on increasing the survival rate of Lactobacillus helveticus.When using the combination of 10%trehalose and 4%sodium glutamate and 11%skim milk,the cryoprotective agents showed the most positive effect.Compared with spray drying,the effect of freeze drying was more obvious with the survival rate of 83%.The effects of Lactobacillus helveticus fermented milk and its whey on blood pressure, heart rate and blood lipid were evaluated in spontaneously hypertensive rats(SHR).The SHR were each given Lactobacillus helveticus fermented milk and its whey by gastric intubations in six weeks.The cholesterol and triglyceride in serum were ameliorated and the systolic blood pressure of rats decreased since fourth week,Compared with control group,the systolic blood pressure of rats was decreased significantly:11.4±1.7 mmHg (P＜0.05).Th0s result testified that the Lactobacillus helveticus fermented milk and its whey containing bioactive peptides,in daily use,does have a blood pressure-lowering effect in hypertensive subjects and is thus a potential for the dietary treatment of hypertension,arteriosclerosis and hyperlipidemia.For its mechanism,it should be further studied in clinic.The effects of Lactobacillus helveticus and its fermentation product on immune function in mice was also studied.It is discovered that L.helreticus-living bacteria liquid could improve the growth of thymus,promote functions of macrophage and the proliferation of B lymphocyte,the best number of active microorganism is 2×10⁹cfu/mL,the best dosage is 20 mL/kg b.w;L.helreticus-whey could promote functions of macrophage and increase the levels of serum IgG,the best dosage is 25 mL/kg b.w.It may suggest that the L.helreticus-living bacteria liquid can remarkably enhance immune function in mice such as cellular immunity and non-specific immunity.L.helreticus-whey can more remarkably enhance immune function in mice such as cellular immunity and humoral immunity with high dose.Compared with L.helveticus cell lysis buffer and common yoghurt,the L.helveticus living bacteria liquid and its whey enhance immune function more remarkably.The immunoactive constituents of Lactobacillus helveticus include its cell wall constituents and metabolites.In conclusion,Lactobacillus helveticus and its fermentation product had apparent effects on depressing blood pressure,ameliorating blood lipid and improving immunologic function.It is a potential novel bioactive substance.