Effect of starch spherulites on survival of bifidobacteria in the presence of acid or bile
Open Access
- Author:
- Chittiprolu, Srilatha
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 16, 2008
- Committee Members:
- Robert F Roberts, Thesis Advisor/Co-Advisor
Robert F Roberts, Thesis Advisor/Co-Advisor - Keywords:
- Adhesion
Bifidobacteria
Spherulites - Abstract:
- Probiotics are live microorganisms which have been shown to confer a health benefit on the host, when administered in sufficient amounts. Many of the probiotic bacteria currently used in foods and dietary supplements are members of Lactic Acid Bacteria. Strains of the genus Bifidobacterium are widely used as probiotics for human consumption. Bifidobacteria are often sensitive to stresses encountered during production and storage of food and during passage through the gastrointestinal tract. Thus, the overall purpose of this research was to determine if adhesion of bifidobacteria to starch-based spherulites can improve their survival when exposed to acid or bile. The first objective of this work was to develop a procedure to prepare spherulites in adequate quantities for use in adhesion and survival studies. Spherulites were prepared successfully in a Parr reactor (pressure vessel) using potato starch, high amylose maize starch (Hylon VII) and purified potato amylose. Conditions were developed to dry spherulites using vacuum filtration and solvent dehydration. Spherulites were characterized with respect to size (particle size analysis) and shape (optical microscopy). Similar morphology and size were observed for both washed and dried spherulites. The second objective was to determine if a variety of bifidobacterial strains could adhere to potato amylose spherulites and high amylose maize starch granules. The strains differed in their ability to adhere to spherulites and Hylon VII with adhesion to spherulites significantly higher (p = 0.001) than Hylon VII for the majority of the strains. The final objective was to investigate the protective effect of adherence of bifidobacteria to spherulites or Hylon VII on their survival when exposed to acid or bile. Adhesion to spherulites or Hylon VII did not improve the survival of bifidobacteria. The number of bifidobacteria surviving after 3 h exposure to acid (pH 1.8, 2.9 and 7.2) or bile (0, 0.5 and 1% oxgall) was significantly affected by type of strain used, pH and bile concentration. The strains analyzed were not tolerant to pH 1.8 whereas survived well at pH 2.9 and 7.2 and in bile solutions containing 0, 0.5 and 1% oxgall.