title: Determination of antioxidant activity in foods and beverages by reaction with 2,2'-diphenyl-1-picrylhydrazyl (DPPH): collaborative study First Action 2012.04.
abstract: 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 quantified 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 micromole 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 first 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.
authors: Medallion Laboratories, 9000 Plymouth Ave North, Minneapolis, MN 55427, USA. david.plank@medlabs.com
authors: David W
authors: DW
authors: Plank
authors: John
authors: J
authors: Szpylka
authors: Harry
authors: H
authors: Sapirstein
authors: David
authors: D
authors: Woollard
authors: Charles M
authors: CM
authors: Zapf
authors: Vong
authors: V
authors: Lee
authors: C Y Oliver
authors: CY
authors: Chen
authors: Rui Hai
authors: RH
authors: Liu
authors: Rong
authors: R
authors: Tsao
authors: André
authors: A
authors: Düsterloh
authors: Steve
authors: S
authors: Baugh
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D001713:Biphenyl Compounds / Q000737:chemistry*; D002839:Chromans; D005504:Food Analysis / Q000379:methods*; D005638:Fruit / Q000737:chemistry; D007202:Indicators and Reagents; D010851:Picrates / Q000737:chemistry*; D027861:Prunus / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D017365:Spices / Q000032:analysis; D013662:Tea / Q000737:chemistry; D014675:Vegetables / Q000737:chemistry; D014920:Wine / Q000032:analysis; D015014:Yogurt / Q000032:analysis
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D002839:Chromans; D007202:Indicators and Reagents; D010851:Picrates; D013662:Tea; C004931:1,1-diphenyl-2-picrylhydrazyl; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid