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Updated: Jun 4, 2026
A Generalized Method for Determining Free Soluble Phenolic Acid Composition and Antioxidant Capacity of Cereals and Legumes
Published on: June 10, 2022
Simple and rapid method for the analysis of phenolic compounds in beverages and grains
1Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture , 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, United States. marjorie.medina@ars.usda.gov
Abstract:
A new method for the detection of phenolics in food systems was developed. This method is based on interactions of phenolics with Fast Blue BB diazonium salt in alkali pH, forming azo complexes, with the absorbance measured at 420 nm after 60 min. The linear regression correlations (R(2)) of gallic acid calibration standards were >0.99. The phenolic content (gallic acid equivalent) of samples analyzed yielded higher ratios (1.7-6.6) of the total phenolics by Fast Blue BB to Folin-Ciocalteu methods in most beverages and grain samples, but in flaxseed and some juice blends, the ratios were <1. The lower ratios suggest the presence of non-phenolic reducing constituents measured with the Folin-Ciocalteu method as "total phenolics". This method is simple and inexpensive and can be used to rapidly assess the total phenolics of foods and beverages.
