Study On Preparation And Stability Of Saccharomyces Boulardii Powder

Saccharomyces boulardii is the only yeast probiotic,it usually grows well at 37?(physiological temperature of the host),while the optimal growth temperature of common yeast is around 30?.Meantime,Saccharomyces boulardii has unique biological activity,it's suitable for the use of human and animals.At present,Saccharomyces boulardii is widely used in the treatment of infantile diarrhea,the domestic Saccharomyces boulardii preparation is mainly dependent on imports,and there are few reports about its culture and preparation.In this experiment,the laboratory preserved Saccharomyces boulardii was used as test strain,we studied the culture medium composition and fermentation condition of the yeast,and the technical process,the activity and stability of the powder prepared by freeze-drying and spray drying were researched.The results are as follows:1.The optimal culture conditions of Saccharomyces boulardii were determined by single factor experiment and response surface methodology,the results were as follows: broth content 52 mL/250 mL,shaking speed 181 r/min,inoculum size 3.1%,the initial pH value of medium 6.4.Under these conditions,the viable counts in the culture solution were 1.86×108 CFU/mL,which was increased 14.1% than before optimization.2.In the above conditions,the main factors were selected by single factor experiment and Plackett-Burman design: glucose,yeast extract powder,fructo-oilgosaccharides,Na2HPO4,CaCl2 and peptone.Especially,glucose,yeast extract and fructo-oilgosaccharides were major influence factors.Finally,the results of steepest ascent experiment and Box-Behnken design showed that the optimal medium compounds were: glucose 4.83%,yeast extract 0.18%,fructo-oilgosaccharides 0.18%,Na2HPO4 0.45%,CaCl2 0.2% and peptone 2%.Using this culture medium,the viable counts reached 3.91×108 CFU/mL,and the dry cell weight was 5.1911 g/L,which was increased 2.1×108 CFU/mL and2.0811 g/L compared with control group.3.The results of batch culture and fed batch culture of Saccharomyces boulardii in 5 L ventilating fermentation tank showed that fed batch culture was more conducive to the growth,the viable counts and dry cell weight reached7.3×108 CFU/mL and 12.7644 g/L.Compared with batch culture,the viable counts increased by 1.5 times,the dry cell weight was increased by nearly 2times.Logistic and DoseResp models were used to establish the nonlinear fitting dynamic model of the yeast growth and substrate consumption in batch culture:478.2.These models were well fit with the experimental data.4.The optimal freeze-dried protective agent formula was determined by response surface methodology: inulin 0.6%,xylooligosaccharide 0.4%,NaHCO3 0.3%,Mg SO4 0.75%,lactose 21.41%,trehalose 21.98%,sodium glutamate 4.02%,skim milk 22%,and the ratio of the amount of phosphate buffer to the weight of the yeast mud was 1.2:1.Under this condition,the survival rate and viable counts of freeze-dried powder reached 72.55% and1.32×1010 CFU/g.The thermal protective agent formula of Saccharomyces boulardii was optimized by water bath simulation experiment: skim milk15.12%,gelatin 1.8%,trehalose 9.72%.The verification test showed that the survival rate was 17.82%,similar to the predicted values.And then Saccharomyces boulardii powder prepared by spray drying under above conditions,the survival rate was 26.12%,the viable counts of spray dried powder was 1.018×109 CFU/g.5.The accelerated storage testing suggested that,the inactivation rate constant of the freeze-dried powder and spray dried powder for Saccharomyces boulardii were k-18F=8.04×10-6 and k-18S=1.04×10-5,respectively.Obviously,the stability of freeze-dried powder was better than that of spray dried powder.In addition,the accelerated storage testing of goat milk containing freeze-dried powder suggested that the inactivation rate constant under 4? and 25?were:k4=4.48×10-4?k25=9.72×10-3,respectively.The optimized culture medium and fed batch culture could significantly increase the concentration of Saccharomyces boulardii.Meanwhile,the freeze-dried protective agent and thermal protective agent formula were used to prapared the Saccharomyces boulardii freeze-dried powder and spray dried powder,which could significantly improve the survival rate of the powder.This provides a reference and technical support for the development of Saccharomyces boulardii preparation.