1562 Plank et al.: Journal of aoaC InternatIonal V ol. 95, no. 6, 2012 Determination of Antioxidant Activity in Foods and Beverages by Reaction with 2,2′-Diphenyl-1-Picrylhydrazyl (DPPH): Collaborative Study First Action 2012.04 DaviD W. Plank Medallion Laboratories, 9000 Plymouth Ave North, Minneapolis, MN 55427 John SzPylka General Mills, Inc., 9000 Plymouth Ave North, Minneapolis, MN 55427 harry SaPirStein University of Manitoba, Department of Food Science and Nutrition, Winnipeg, Manitoba, MB R3T 2N2, Canada DaviD WoollarD New Zealand Laboratory Services Ltd, 35 O’Rorke Rd, Penrose, Auckland 1642, New Zealand CharleS M. zaPf McCormick & Co., Inc., Technical Innovation Center, 202 Wight Ave, Hunt Valley, MD 21031 v ong lee POM Wonderful, LLC, 5286 S. Del Rey Ave, Del Rey, CA 93616 C-y. oliver Chen Tufts University, Jean Mayer USDA Human Nutrition Research Center on Aging, 711 Washington St, Boston, MA 02111 rui hai liu Cornell University, Department of Food Science, 108 Stocking Hall, Ithaca, NY 14853 rong t Sao Guelph Food Research Centre, Agriculture and Agri-Food Canada, 93 Stone Rd West, Guelph, Ontario N1G 5C9, Canada anDré DüSterloh DSM Nutritional Products, Ltd, Bldg 205, Rm 6, Wurmisweg 576, 4303 Kaiseraugst, Switzerland Steve Baugh AOAC INTERNATIONAL, 481 N. Frederick Ave, Suite 500, Gaithersburg, MD 20877 Collaborators: A. Begelman; M. Camire; C. DeRito; J.W. DeVries; M.P. Dougherty; M. Hanson; R. Liu; M. Marquard; A. Ser; M. Stringer Submitted for publication July 24, 2012. The method was approved by the Expert Review Panel on Strategic Foods Analytical Methods as First Action. See “Standards News,” (2012) Inside Laboratory Management, March/April issue. The AOAC Stakeholder Panel on Strategic Foods Analytical Methods (SPSFAM) invites method users to provide feedback on the First Action methods. Feedback from method users will help verify that the methods are it for purpose and are critical to gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author. Corresponding author’s e-mail: david.plank@medlabs.com DOI: 10.5740/jaoacint.CS2012_04 ANTIOXIDANTS A colorimetric method for the determination of total antioxidant activity in a variety of foods and beverages was validated in both a single-laboratory validation and a collaborative laboratory validation study. The procedure involved extraction of the antioxidants directly into a methanol–water solution containing a known amount of 2,2′-diphenyl-1- picrylhydrazyl (DPPH), thus promoting the rapid reaction of extracted materials with DPPH. The reaction was monitored by spectrophotometric measurement of the absorbance loss at 517 nm. Antioxidant activity was quantiied relative to a dilution series of vitamin E analog standards (Trolox ® ), which were analyzed in parallel simultaneously with the food and beverage samples. The antioxidant activities of the samples ranged from 131 to 131 000 µmole Trolox equivalents/100 g. Statistical analysis of the results showed that nine of the 11 matrixes gave acceptable HorRat values, indicating that the method performed well in these cases. The acceptable matrixes include pomegranate juice, blueberry juice, carrot juice, green tea, wine, rosemary spice, ready-to-eat cereal, and yogurt. Two samples failed the HorRat test: the irst was an almond milk that had an antioxidant level below the practical LOQ for the method; the second was a sample of canola oil with added omega-3 fatty acid that was immiscible in the reaction medium. O n March 28, 2011, the AOAC Board of Directors approved an alternative path to achieve Oficial First Action status for methods selected. Following this process, selected methods are reviewed and approved by an expert review panel (ERP) for AOAC Oficial First Action status. This process follows selected methods for a period of approximately 2 years as First Action methods, allowing an opportunity for methods to be used in laboratories and to generate additional information. The ERP will monitor the method’s performance, and after about