Abstract 040
Evaluation of a Colorimetric Method for Determination of Ascorbates in Beer
J. Amer. Soc. Brew. Chem. 47: 57-61, 1989
J.J. Kelley and K.J. Siebert
A colorimetric method for routine detn. of reduced ascorbates in beer based on a kit from Boehringer Mannheim (Indianapolis, USA) was evaluated. [In this assay, ascorbates in the sample reduce the tetrazolium dye, 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl-tetrazolium bromide to a formazan that absorbs visible light at 578 nm.] With slight modification, the assay was found to be well-suited for determining reduced ascorbates in beer. Limit of detn. in beer was 1.09 mg/l vs. 0.31 mg/l for a liquid chromatographic electrochemical detection method (LCEC). The 95% sample confidence interval at 10 mg/l was ±0.94 mg/l compared with ±1.99 mg/l for the LCEC method. The slope of a standard curve was within 2% of the theoretical value and statistically not significantly different. The method utilizes common laboratory equipment, does not suffer interference from beer constituents, is rapid and reproducible, and does not require the preparation of reagents or a standard curve.
Back to K.J. Siebert home page | Back to publication list