title: Effect of complexation conditions on microcapsulation of Lactobacillus acidophilus in xanthan-chitosan polyelectrolyte complex gels.
abstract: BACKGROUND
  Lactobacillus acidophilus has become increasingly popular because of their beneficial effects on health of their host, and are called proboscis. In order to exert beneficial effects for probiotics, they must be able to tolerate the acidic conditions of the stomach environment and the bile in the small intestine. Microencapsulated form has received reasonable attention, since it can protect probiotic organisms against an unfavourable environment, and to allow their release in a viable and metabolically active state in the intestine. The aim of this study was to investigate some factores, such as chitosan solution pH and concentration, xanthan concentration, cell suspension-xanthan ratio, mixed bacteria glue liquid-chitosan ratio, which impacted the process of microencapsulation of L. acidophilus.
  
  
  METHODS
  In this study, L. acidophilus was immobilized with xanthan⁄chitosan gel using extrusion method. The viable counts and encapsulation yield of L. acidophilus encapsulated in different chitosan solution pH (4.5, 5, 5.5 and 6), in different chitosan concentration (0.5%, 0.7%, 0.9% and 1.1%), in different xanthan concentration (0.5%, 0.7%, 0.9% and 1.1%), in different cell suspension-xanthan ratios (1:5, 1:10, 1:15 and 1:20), in different mixed bacteria glue liquid-chitosan ratios (1:3, 1:4, 1:5 and 1:6), have been investigated by single factor experiment method.
  
  
  RESULTS
  The optimum conditions of microencapsulated L. acidophilus have been observed. The optimum chitosan solution pH for L. acidophilus was 5.5; the optimum chitosan concentration was 0.9%; the optimum xanthan concentration was 0.7%; the optimum cell suspension-xanthan ratio was 1:10; the optimum mixed bacteria glue liquid-chitosan ratio was 1:3.
  
  
  CONCLUSIONS
  These results will be helpful to further optimize the process of L. acidophilus microencapsulation, and provide reference for obtaining higher viable counts and entrapped yield of L. acidophilus microcapsules.
authors.affiliation: College of Life Science and Engineering, Shaanxi University of Science and Technology, China.
authors.forename: He
authors.initials: H
authors.lastname: Chen
authors.affiliation: College of Life Science and Engineering, Shaanxi University of Science and Technology, China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Song
authors.affiliation: College of Life Science and Engineering, Shaanxi University of Science and Technology, China.
authors.forename: Nina
authors.initials: N
authors.lastname: Liu
authors.affiliation: Shaanxi Yatai Dairy Co., Ltd. Xianyang, China.
authors.forename: Hongchang
authors.initials: H
authors.lastname: Wan
authors.affiliation: College of Life Science and Engineering, Shaanxi University of Science and Technology, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Shu
authors.affiliation: College of Life Science and Engineering, Shaanxi University of Science and Technology, China.
authors.forename: Na
authors.initials: N
authors.lastname: Liao
mesh_terms: D000268:Adhesiveness; D058491:Bacterial Load; D018914:Cells, Immobilized; D002681:China; D048271:Chitosan / Q000737:chemistry*; D005503:Food Additives / Q000737:chemistry*; D005524:Food Technology; D005782:Gels; D006863:Hydrogen-Ion Concentration; D007779:Lactobacillus acidophilus / Q000254:growth & development* / Q000302:isolation & purification; D050296:Microbial Viability; D009994:Osmolar Concentration; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D019936:Probiotics / Q000737:chemistry*
chemical_list: D005503:Food Additives; D005782:Gels; D011135:Polysaccharides, Bacterial; D048271:Chitosan; C002563:xanthan gum
keywords: Lactobacillus acidophilus; chitosan; extrusion; microencapsulation; xanthangum