The Fast Blue BB chemical method was developed to measure total plant phenolics through direct coupling interactions. Optical density (420 nm) of the azo complex formed was proportional to the phenolic concentrations. The microassay was optimized for the 96-well plates utilizing 200 �L samples or standards and 0.04% to 0.06% Fast Blue BB.  Linear correlations (R) of gallic acid (0 � 500 �g/mL) were 0.9996 (+/-0.0002 SD) in 58 assays. Total phenolics in the samples expressed as gallic acid equivalent (GAE) by the microassay was 95% of the original test tube method (R=0.9980) in 28 juice samples and 101% in eight fruit samples. Gallic acid and catechin calibration standards were compared in 50 samples.  Total phenolics in tea, coffee and fermented beverages will also be presented.  The Fast Blue BB method is simple, robust and has <10% RSD reproducibility.  The microassay method is faster than the original tube method with reduction of materials and labor cost.

Fast Blue BB microassay method for determination of total phenolics in beverages and fruits

244th National Meeting (2012)

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