A rapid assay for determining peroxidase activity in wheat and flour. D.W. HATCHER and W. Barker. Grain Research Laboratory, Canadian Grain Commission, Winnipeg, MB, Canada.
Peroxidase catalyzes the oxidation of a number of substrates making it of interest to cereal scientists. Peroxidase oxidation of arabinoxylans in wheat and rye increases dough viscosity, carotenoid bleaching during mixing and is suspected to be responsible for undesirable discoloration in oriental noodle products. A rapid, multiple sample assay for peroxidase was developed using ABTS as the substrate. Wheat meal or flour samples (0.5 g) were extracted 30 min at 4°C prior to centrifugation and filtration. The use of a microplate reader allows 16 samples to be read in triplicate within 1 min against a standard calibration (r(^2) > 0.995). Stock solutions of calibration standards were viable for 5 working days. The assay's coefficient of variation (CV) for a single extract replicated three times was 1.60%. The CV of 5 separate extracts was determined to be 1.92% while the assay's CV on samples extracted and analyzed on 3 separate days was 4.35%. The technique highlighted statistical differences in enzyme activity of different Canadian wheat varieties, the influence of environment on activity and the ability to quantify activity within individual millstreams.