Determination of Total Procyanidins in Selected Chocolate and Confectionery Products Using DMAC
A simple, specific, high-throughput colorimetric method based on the reaction of 4-dimethylaminocinnamaldehyde (DMAC) with flavan-3-ols was developed to determine total procyanidins in selected cacao-based products. Extracts of defatted samples were dispensed into a 96-well plate and
reacted with DMAC. The absorbance of the reaction products was measured at 640 nm and compared to commercially available procyanidin B2 as a standard. The use of the 96-well plates and a plate reader dramatically improved sample throughput. A standard protocol was established and used for
further studies. The calibration was found to be linear from 1100 ppm. The DMAC reagent reacted relatively specifically to ()-epicatechin, (+)-catechin, epigallocatechin, gallocatechin, the gallates of catechin, epicatechin, gallocatechin, and epigallocatechin, oligomeric procyanidins of cocoa
up to n = 4, and A-type procyanidins. Little or no reaction occurred with cyanidins and representative compounds of phenolic acids, flavones, flavanones, flavonols, anthocyanidins, isoflavones, and stilbenes. Sample precision studies were carried out on 10 different test materials over
several weeks, and yielded RSD values of 4.0 to 9.5. The method was ring-tested in three laboratories using blinded test materials including cocoa beans, cocoa powder, chocolate liquor, dark chocolate, and milk chocolate. There was excellent agreement of the results between laboratories.
Document Type: Research Article
Hershey Center for Health and Nutrition, The Hershey Co., 1025 Reese Ave, Hershey, PA 17033.
Brunswick Laboratories (USA), 50 Commerce Way, Norton, MA 02766.
Brunswick Laboratories (China), 218 Xing Hu Rd, Suzhou Industrial Park, China 215125.
Publication date: January 1, 2010
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The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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