CRITERIA FOR FUNCTIONAL QUALITY ASSURANCE
The criteria currently used to select probiotics define the optimal
quality control of probiotic strains in industrial practice. Probiotics
are often used in fermented foods and fermentation acts to
retain and optimize microbial viability and productivity while
simultaneously preserving the probiotic’s properties. During fermentation,
several metabolic products appear in the food product,
including acetic acid, lactic acid, and possibly bacteriocins, and
the pH of the product is lowered. Such changes may affect the stability
of probiotic bacteria and may alter the bacteria’s functional
properties. Also, long-term industrial use of the starter culture for
production purposes may influence both viability and functional
properties. Important quality-control properties that must be constantly
controlled and optimized are the following: adhesive properties;
bile and acid stability; viability and survival throughout the
manufacturing process; effects on carbohydrate, protein, and fat
utilization; and, especially, colonization properties and immuno.genicity. Most of these properties are related to the physiologic
properties of the strain, but long-term industrial processing and
storage conditions may influence probiotic properties. Thus, in
addition to technologic properties, functional properties should
be considered in quality-control measures.