Analysis for determining the amount of added niacin by means of the microbiological microtiter plate test
This analysis is suitable for NAB, juice and other foods.
The VitaFast® microbiological assay for niacin is carried out on microtiter plates and is suitable for the determination of total amount of niacin in foods and beverages.
The beverage is sterile-filtered and diluted with sterile water for the determination of added niacin.
The diluted sample and the niacin assay medium are added to the wells of the microtiter plate, which are coated with Lactobacillus plantarum. Lactobacillus plantarum requires niacin to grow. After an addition of niacin, the microorganism exhibits growth until the vitamin is completely utilized. The plates are incubated at 37 °C for 44–48 h.
The growth of Lactobacillus plantarum is dependent upon the concentration of niacin and is determined through measuring the turbidity. These results are compared with those obtained from a series of standard concentrations. The measurement is performed with a microtiter plate photometer at 610–630 nm (alternatively at 540–550 nm).
Analysis for determining the content of added niacin using HPLC
This analysis is suitable for NAB, juice, beverage bases and vitamin powder.
Niacin is separated by ion-pair RP-HPLC, detected using UV absorption and quantified through comparison with external standards. If necessary, the identity of the substances can be confirmed via spectra comparison.