POTENTIAL APPLICATION OF LASER MICROBE BIOASSAY TECHNOLOGY FOR DETERMINING WATER-SOLUBLE VITAMINS IN FOODS

A microbiological technique was developed for quantitating niacin by d etermining microbial growth rates in response to the amount of vitamin available. Unlike the current official AOAC method, the new procedure for niacin measured the growth rates during the early exponential gro wth phase rather than during the stationary phase. Lactobacillus plant arum was used to determine niacin to a lower limit of 1 00 pg/mL. The assay time was approximately 6 h, compared with 16-24 h for the curren t AOAC method. The extent of microbial growth was determined by differ ential light scattering of a LASER beam. Multiple photodetectors were integrated with a computer system to collect and analyze the data. The use of differential light scattering to determine 8 water-soluble vit amins under stationary phase conditions demonstrated the potential app lication of the new technology for microorganisms and foods.