The Preparation Of Chitosan/Xanthan Probiotic Microcapsule And Its Application

Probiotics have been regarded as a kind of health food, because of its much important healthy function. However, most of the probiotic strains were vulnerable to the external environmental, and the probiotic hardly against the gastrointestinal tract environment, thus it is difficult for probiotic to remain activity. The application of microcapsule technology has provided a way to solve this problem, wall material is an important part of microcapsule technology, alginate has been regarded as wall material by most of the research. But in the presence of a chelating agent, alginate has given rise to unreliable embedding effect. Chitosan and xanthan gum are biological macromolecules, and they have good biocompatibility. Therefore, the gel which was formationed by the polyelectrolyte complexation was used as the wall material in this issue, and the probiotic were microencapsulated by extrusion method.In this study, the preparation technology of monolayer Lactobacillus acidophilus or Bifidobacterium BB01 microcapsules was optimized by single factor and response surface method. On the above basis, the double xanthan/chitosan/xanthan microcapsules of probiotics were prepared.The effect of deoxidation agent and prebiotics on Bifidobacterium BB01 microencapsulation was investigated, and these factors were screened and optimized. Finally, the characteristics and application in yogurt, pure milk of monolayer, double microcapsules was studied, the results were shown as follows:The effects of different embedding conditions on Lactobacillus acidophilus and Bifidobacterium BB01 microencapsulation was investigated by single factor test. Plackett-Burman screening test results showed that chitosan concentration, xanthan concentration and chitosan-water ratio were main elements for xanthan/chitosan Lactobacillus acidophilus microcapsule; chitosan concentration, chitosan-water ratio and stirring time were main elements for xanthan/chitosan Bifidobacterium BB01 microcapsule. Box-Behnken test and response surface analysis showed that the optimum preparation conditions on xanthan/chitosan Lactobacillus acidophilus microcapsule were with chitosan 0.68%, p H5.5, xanthan 0.76%, bacterial suspension with xanthan ratio 1:10, chitosan-water ratio 1:2.56, stirring time 32 min, the encapsulation yield and the number of live bacteria was 86% and 1.31×1010CFU/g. For xanthan/chitosan Bifidobacterium BB01 microcapsule, the optimum preparation conditions were that, chitosan 0.87%, p H 4.24, xanthan 0.5%, bacterial suspension with xanthan ratio 1:3.8, chitosan-water ratio 1:7.7, stirring time 47 min, the encapsulation yield and the number of live bacteria was 90% and 1.25×1010 CFU/g.The effects of different deoxidants and prebiotics on Bifidobacterium BB01 microencapsulation was investigated by single factor test. Plackett-Burman screening test results showed that sodium erythorbate, ascorbic acid and xylooligosaccharide were main elements for xanthan/chitosan Bifidobacterium BB01 microcapsule. Box-Behnken test and response surface analysis showed that the optimum sodium erythorbate content of 2.4%, ascorbic acid content of 3.1%, xylo-oligosaccharide content of 2.4% for Bifidobacterium BB01 microcapsule, the microencapsulation yield and the number of live bacteria was 91% and 1.33×1010CFU/g.Comparing with without any deoxidizer and prebiotics microcapsule, viable count and encapsulation yield of Bifidobacterium BB01 microencapsule were improved.Based on the monolayer microcapsules, double microcapsules of probiotics were prepared with xanthan gum. The number of live bacteria of xanthan/chitosan/xanthan double Lactobacillus acidophilus and Bifidobacterium BB01 microcapsule were 1.32×1010CFU/g,1.02×1010CFU/g, respectively.The characteristics test of Lactobacillus acidophilus and Bifidobacterium BB01 microcapsule showed that, free Bifid bacterium BB01 and Lactobacillus acidophilus decreased rapidly in acid and bile salt tolerance test, living bacterias were not detected in 104 after 2h.The viable counts of monolayer microcapsules, double microcapsules decreased by four magnitudes, two magnitude respectively. Comparing with free probiotics, embedded probiotics had better acid, bile salt resistance, and double microcapsules better than monolayer microcapsules. In the enteric test, double and monolayer Lactobacillus acidophilus and Bifidobacterium BB01 microcapsules could get a lot of cracking release in 40 min.Application of Bifidobacterium BB01 microcapsule show that, viable counts of free bifidobacterium, single-layer, double-layer embedding of Bifidobacterium BB01 decreased in pure milk and yogurt, whether it is under 4℃or ambient temperature. the optimum storage time was 7d, 14 d, 21 d under 4℃, the optimum storage time was 3d, 7d, 14 d under ambient temperature. In the optimum storage period of pure milk and yogurt, viable counts of Bifidobacterium BB01 were maintained 106cfu/m L. Lactobacillus acidophilus microcapsule application test show that, viable counts of free Lactobacillus acidophilus, single-layer, double-layer embedding of Lactobacillus acidophilus decreased in commercial dairy drinks and yogurt, whether it is at 4 ℃ or ambient temperature. For yogurt, the optimum storage time was 7d, 14 d under 4℃, the optimum storage time was 3d, 7d, 14 d under ambient temperature. In the optimum storage period of yogurt, viable counts of Lactobacillus acidophilus were maintained106CFU/m L. Commercial dairy has the best effect at 4℃storage condition.In this subject, chitosan and xanthan gum were used to embedding probiotics, it maked up for the shortcomings of the common wall material, and improved the protection effect of microencapsulation technology for probiotic.