Study On Microencapsulation Process Of Lactobacillus And It's Heat Resistance

Lactobacillus is a spore-free Gram-positive bacterium that is one of the important physiological flora in the gut of humans and animals.Lactobacillus have physiological functions such as resisting pathogen colonization,maintains intestinal flora balance,controls inflammatory response,enhances innate immunity and reducing serum cholesterol.As a feed additive,Lactobacillus can improve the animal's poduction performance,immune function and intestinal mucosal morphology.This experiment aims to study the microencapsulation of Lactobacillus rhamnosus GG?LGG?microencapsulation and heat resistance.Sodium alginate and chitosan were selected for wall materials,LGG microcapsules were prepared by double-layer embedding with extrusion,and The heat resistance of LGG microcapsules was studied by adjust five factors including sodium alginate concentration?0.5%,1%,2%?,Ratio of LGG bacterial liquid to sodium alginate?1:0.5,1:1,1:2,1:4?,pH value of chitosan solution?pH 4.0,pH 5.0,pH 6.0?,chitosan concentration?0.5%,1%,2%?and CaCl₂ concentration?0.5%,1%,2%?.Specific steps:using the physiological saline suspension liquid as the embedding bacterial solution,the bacterial liquid and the sodium alginate solution are uniformly mixed in proportion,the mixed solution is added to the CaCl₂ solution to be solidified,stirred to fully solidified,then added particles into chitosan solution Forming Double layer LGG microcapsules..A mixture of sodium citrate and NaHCO₃ was used as the opening reagent for microcapsules.Free LGG as the control group,testing the survival rate of microencapsulated LGG after heating at a high temperature of 80°C for 15 min.The results showed that:1)The heat resistance of microcapsules prepared by pH value of chitosan at pH 4.0and pH 6.0 was significantly higher than that of pH 5.0?P<0.05?.2)The microcapsules prepared by the volume ratio of LGG to sodium alginate solution was 1:0.5,which has the best heat resistance,was significantly higher than other ratios?P<0.05?.3)Under the condition of 2%sodium alginate concentration,the heat resistance of microcapsules prepared was higher than that of other groups,however,there was no significant difference?P>0.05?.4)Under the conditions of0.5%chitosan concentration,the heat resistance of the prepared microcapsules was lower than that of other groups?P<0.05?,the chitosan concentration of2%is just over 1%?P>0.05?.5)When the concentration of CaCl₂ was 1%or 2%,the heat resistance of the prepared microcapsules was significantly higher than that of the 0.5%group?P<0.05?.Based on the single factor test combined with the comprehensive analysis of the use efficiency of the coated materials,the optimal microencapsulation conditions for LGG/SA/CS microcapsules are:2%SA concentration,the ratio of V_LGG to V_SA is 1:0.5,2%CS concentration,pH 4.0 of CS,CaCl₂ concentration 1%,the heat resistance of LGG was significantly improved by microcapsules.In the orthogonal test,the orthogonality of the five factors of CS pH,V_LGG:V_SA ratio,SA concentration,CS concentration and CaCl₂ concentration was investigated in the heat resistance of LGG/sodium alginate/chitosan microcapsules.The orthogonal test of 5 factors and 3 levels was mainly based on the heat resistance of LGG microcapsules,and the particle size of microcapsules was supplemented.As an indicator for examining the quality of microcapsules,L₁₈?3⁵?orthogonal scheme was selected to determine the orthogonal test.The optimal solution was chosen:2%SA concentration,the ratio of V_LGG to V_SAA is 1:0.5,2%CS concentration 2%,pH5.0 of CS,CaCl₂ concentration 1%,Microcapsules were prepared by three LGG microcapsule preparation schemes including the optimal scheme.Among the three heat resistance results,the heat resistance of the optimal group,the fifth group and the thirteenth group of LGG microcapsules were measured.They were 72.8%±5.6%,71.9%±8.8%,and 69.1%±3.2%?Mean±SD?,respectively,and the thermal survival rates of the three groups were not significantly different from each other?P>0.05?.It is proved that the protection of lactic acid bacteria is better by the orthogonal LGG microcapsules.Compared with the heat treatment test of other microcapsule products,the preparation of LGG/SA/CS has the characteristics of high treatment temperature and long treatment time,and the microcapsules have good heat resistance,which provides a method for using the lactic acid bacteria like LGG in feed.