title: The effect of alginate and chitosan concentrations on some properties of chitosan-coated alginate beads and survivability of encapsulated Lactobacillus rhamnosus in simulated gastrointestinal conditions and during heat processing.
abstract: BACKGROUND
  In this study, chitosan-coated alginate beads were produced with different concentrations of chitosan and alginate to evaluate the survival of encapsulated Lactobacillus rhamnosus GG during exposure to adverse conditions in gastrointestinal simulated juice and heat processing.
  
  
  RESULTS
  The encapsulation yield of different encapsulation treatments was between 25 and 53.2%. Although there was a drastic decrease in pH within 48 h of incubation in MRS medium inoculated with free and encapsulated bacteria, no significant changes (P > 0.05) in bacterial count were observed among different encapsulation treatments. Moreover, the survival rate after gastrointestinal juice exposure of all prepared beads was 10-87 times greater than that of free cells and was significantly enhanced by increasing chitosan and alginate concentrations. The encapsulated bacteria survived significantly (P < 0.05) better than the free cells during heat exposure at 55, 60 and 65 °C: free cells experienced about 5 log cycles reduction after heat treatment at 65 °C for 30 min, whereas 40 g L(-1) alginate/10 g L(-1) chitosan-encapsulated L. rhamnosus was reduced by only 2.55 log cycles.
  
  
  CONCLUSIONS
  Encapsulation effectively protected L. rhamnosus against heat treatment and gastrointestinal conditions, and this effect is important in delivering sufficient numbers of viable probiotic bacteria to the gastrointestinal tract.
authors.affiliation: Department of Food Hygiene, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Abbaszadeh
authors.forename: Hassan
authors.initials: H
authors.lastname: Gandomi
authors.forename: Ali
authors.initials: A
authors.lastname: Misaghi
authors.forename: Saeid
authors.initials: S
authors.lastname: Bokaei
authors.forename: Negin
authors.initials: N
authors.lastname: Noori
mesh_terms: D000464:Alginates; D002214:Capsules; D048271:Chitosan; D004339:Drug Compounding / Q000379:methods; D005750:Gastric Juice / Q000737:chemistry; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000382:microbiology*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006358:Hot Temperature; D006801:Humans; D052201:Lacticaseibacillus rhamnosus; D050296:Microbial Viability; D008863:Microspheres; D019936:Probiotics / Q000008:administration & dosage*
chemical_list: D000464:Alginates; D002214:Capsules; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D048271:Chitosan
keywords: Encapsulation; Lactobacillus rhamnosus; acidifying ability; alginate; chitosan; gastrointestinal survival; heat treatment