Preparation And Properties Of Lactobacillus Plantarum Microcapsules

With the increasing demand for functional foods,probiotics have become one of the most important foods to promote health in recent years.However,the survival rate of probiotics is greatly reduced after the processing,storage,and passage through the gastrointestinal tract.Therefore,maintaining the number of viable bacteria in probiotic has become a major challenge for the food industry.Currently,microencapsulation technology has been proven to be an effective way to protect probiotics.In this paper,the effects of different packaging and storage temperatures on the quality of probiotic powder were first discussed,and then the microencapsulation of Lactobacillus plantarum LN66 was carried out by complex coacervation method,double emulsion-complex coacervation method and SPG(Shirasu Porous Glass)membrane emulsification method.Finally,the viability of Lactobacillus plantarum LN66 under simulated gastric fluid,intestinal fluid and storage under different packaging conditions was explored.The specific research contents are as follows:(1)Lactobacillus plantarum LN66 powder,galactose oligosaccharide,fructooligosaccharide,whey powder and inulin were formulated to prepare probiotic powder,and the effects of ordinary aluminum foil bag,vacuum aluminum foil bag,brown glass bottle and storage at 4℃,25℃ and 37℃ on the quality of probiotic powder were investigated.The results showed that the number of viable bacteria decreased with the increase of storage time.During the storage period of only 28 days,the number of viable bacteria at 37℃ decreased by about2%,which had a great impact on the shelf life of probiotic powder which was usually 1～2 years.Correlation analysis showed that there was a significant negative correlation between viable bacteria count and storage temperature and water activity.Therefore,in the storage process,low temperature,vacuum aluminum foil bags and brown glass bottles are conducive to improving the viability of probiotic powder.(2)Lactobacillus plantarum LN66 microcapsules were prepared by complex coacervation method,double emulsion-complex coacervation method and SPG membrane emulsification technology,and the embedding rate of different microencapsulation technologies was explored.The results showed that the complex coacervation method was usually more effective for hydrophobic compounds,and the embedding rate of Lactobacillus plantarum LN66 was75.26%.The embedding rate was 97.89% after the optimization of double emulsion-complex coacervation method,and the protection effect against Lactobacillus plantarum LN66 was significantly improved after the combination of double emulsion technology.The microcapsules prepared by the complex coacervation method and the double emulsion-complex coacervation method can be freeze-dried into powder form.The SPG membrane emulsification method is suitable for the preparation of liquid microcapsules,and has the advantages of mild processing conditions and high embedding rate.The embedding rate of SPG film emulsification method is always stable above 95%,and the shortcomings of manual operation such as poor repeatability are avoided by SPG equipment operation.(3)Probiotics play a probiotic effect in human intestines,so the viability rate of unembedded and embedded Lactobacillus plantarum LN66 dry powder was explored after 4hours in the simulation of gastric juice and intestinal juice.The results showed that the viability rates of unembedded Lactobacillus plantarum LN66 powder in simulated gastric fluid and intestinal fluid were 45.45% and 8.59%,respectively.The viability rates of microcapsules by complex coacervation method were 71.33% and 70.39%,respectively.The viable bacteria rates of the microcapsules with double emulsion-complex coacervation method were 80.90% and79.33%,and the viable bacteria rates of the simulated gastric fluid and intestinal fluid were increased by 35.45% and 70.74%,respectively,compared with the unembedded Lactobacillus plantarum LN66 dry powder.The results showed that the combination of complex coacervation and double emulsion technology was more beneficial to maintain the activity of Lactobacillus plantarum LN66 during digestion.(4)To investigate the viability of Lactobacillus plantarum LN66 microcapsule dry powder in brown glass bottles,aluminum foil bags and stored at 4℃,25℃ and 37℃.The results showed that after 28 days of storage in brown glass bottles and aluminum foil bags,the number of viable bacteria at 4℃ did not decrease significantly,and the survival rate remained above80%.The viability of bacteria at 25℃ was 62.11% and 42.81%,respectively.The viable bacterial rates at 37℃ were 6.37% and 0%,respectively.The viability rate of microcapsules with double emulsion-complex coacervation method in brown glass bottles and aluminum foil bags at 4℃ is about 90%.The viability rates of bacteria at 25℃ were 71.04% and 60.03%,respectively.The viable bacterial rates at 37℃ were 12.06% and 4.98%,respectively.Compared with the complex coacervation method,the viable bacteria rate was increased by about 10%,which significantly improved the storage activity of Lactobacillus plantarum LN66.In addition,the results also showed that Lactobacillus plantarum LN66 microcapsules in glass bottles had higher viable bacteria count.This paper explores the protective effect of new microencapsulation technology on Lactobacillus plantarum LN66,improves the number of viable bacteria during production,storage and consumption,and provides a certain theoretical basis and guiding significance for the embedding of Lactobacillus plantarum by complex coacervation method and SPG membrane emulsification technology.