Digestion : Selection Criteria for Probiotics

By Dr. S.K. Dash

The use of probiotics in dietary supplements, food and beverages has increased from $10 million to $31 billion as consumer awareness has grown from 5% to 81%. The need for selecting the right probiotics is more important now than ever.

Strain Selection

Selection of the proper probiotic strains is the key to functionality and safety. Probiotic effects are strain specific, dose specific and condition specific. Considerations for strain selection include safety (must be GRAS), ability to survive intestinal transit, manufacturing and distribution, and the final application. Identity of strains must be confirmed for every batch using genetic typing techniques. Sources for probiotics include humans (intestine and breast milk), animal and food. Human isolates are more likely to be safe, compatible with the human digestive system and more able to colonize.

Probiotic Screening

Microorganisms with probiotic potential can be screened using a range of in vitro tests and confirmed using animal testing and/or human clinical studies. Typical in vitro tests include:
  • Bile and Acid Resistance (probiotics must resist natural defenses at the introduction site to remain viable and provide health benefits)
  • Adherence to mucus or human epithelial cells and cell lines (in order to produce enzymes, vitamins, lactic acid and antimicrobials, probiotics must adhere to the digestive wall and reproduce)
  • Antimicrobial activity against possible pathogens
  • Ability to reduce pathogen adhesion to surfaces
  • Bile sale hydrolase activity
  • Resistance to spermicides
  • Effects on immune expression (probiotics have the ability to stimulate components of the immune system as well as the ability to minimize production of certain inflammatory cytokines)
Probiotic Stability

Probiotics must stay viable in food, feed, and dietary supplements. Probiotic stability is affected by high temperature, oxygen, humidity and high water activity in culture and excipients. Stability is also strain specific. Nitrogen packaging and use of University of Wisconsin technology has enhanced stability. Antimicrobial Activities of Probiotics The inhibition of pathogenic microorganisms is done by the selected probiotic strains due to their:
  • Production of antibiotic like substances – acidophilin
  • Lowering of pH by producing lactic acid
  • Production of hydrogen peroxide
  • Decreasing the redox potential
  • Consumption of available nutrients.
Probiotic Formulation

Multi-strain and multi-species probiotics have improved functionality as compared to single strain. However, special attention should be given to avoid combination of probiotic strains showing inhibitory properties against each other. All quality control testing should be done on the final formulation, not just individual strains for strain identification, potency and pathogens.. Storage, Handling and Shipping

Storage of probiotic supplement at 400 F is recommended to maintain the viability of the microorganisms. Probiotics that claim to be shelf stable must provide stability data for shelf-stable status.

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