Acid, Bile, and Heat Tolerance of Free and Microencapsulated Probiotic Bacteria

• Published in: Journal of food science Vol. 72; no. 9; pp. M446 - M450
• Main Authors: Ding, W.K, Shah, N.P
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.11.2007; Institute of Food Technologists; Wiley Subscription Services, Inc
• Subjects: acid tolerance; Alginates; Analysis of Variance; Bacteria - drug effects; Bifidobacterium longum; Bile; Bile - microbiology; bile salts; bile tolerance; Biological and medical sciences; Body fluids; Colony Count, Microbial; Food industries; Food science; Fundamental and applied biological sciences. Psychology; Glucuronic Acid; Heat; heat tolerance; Hexuronic Acids; Hot Temperature; hydrochloric acid; Hydrochloric Acid - pharmacology; Hydrogen-Ion Concentration; Lactobacillus rhamnosus; Lactobacillus salivarius; Microbial Viability - drug effects; microencapsulation; Microspheres; mortality; Probiotics; Probiotics - metabolism; strain differences; strains; Temperature; Temperature effects; Time Factors; Probiotic; Biological fluid; acid tolerance; Tolerance; Survival; Heat; Bile acid; pH; Bacteria; Microencapsulation; Bile; bile tolerance; probiotics
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2007.00565.x

Eight strains of probiotic bacteria, including Lactobacillus rhamnosus, Bifidobacterium longum, L. salivarius, L. plantarum, L. acidophilus, L. paracasei, B. lactis type Bl-O4, and B. lactis type Bi-07, were studied for their acid, bile, and heat tolerance. Microencapsulation in alginate matrix was used to enhance survival of the bacteria in acid and bile as well as a brief exposure to heat. Free probiotic organisms were used as a control. The acid tolerance of probiotic organisms was tested using HCl in MRS broth over a 2-h incubation period. Bile tolerance was tested using 2 types of bile salts, oxgall and taurocholic acid, over an 8-h incubation period. Heat tolerance was tested by exposing the probiotic organisms to 65 °C for up to 1 h. Results indicated microencapsulated probiotic bacteria survived better (P < 0.05) than free probiotic bacteria in MRS containing HCl. When free probiotic bacteria were exposed to oxgall, viability was reduced by 6.51-log CFU/mL, whereas only 3.36-log CFU/mL was lost in microencapsulated strains. At 30 min of heat treatment, microencapsulated probiotic bacteria survived with an average loss of only 4.17-log CFU/mL, compared to 6.74-log CFU/mL loss with free probiotic bacteria. However, after 1 h of heating both free and microencapsulated probiotic strains showed similar losses in viability. Overall microencapsulation improved the survival of probiotic bacteria when exposed to acidic conditions, bile salts, and mild heat treatment.