Analysis of Antioxidant Activities of Common Vegetables Employing Oxygen Radical Absorbance Capacity (ORAC) and Ferric Reducing Antioxidant Power (FRAP) Assays:  A Comparative Study

• Published in: Journal of agricultural and food chemistry Vol. 50; no. 11; pp. 3122 - 3128
• Main Authors: Ou, Boxin, Huang, Dejian, Hampsch-Woodill, Maureen, Flanagan, Judith A, Deemer, Elizabeth K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 22.05.2002
• Subjects: Antioxidants - analysis; Autoanalysis; Biological and medical sciences; Ferric Compounds - chemistry; Food industries; Freeze Drying; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General pharmacology; Medical sciences; Oxidation-Reduction; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Extracts - analysis; Species Specificity; Spectrometry, Fluorescence - methods; Time Factors; Vegetables - chemistry; Vegetables; Oxidant; Antioxidant; Oxygen ion; Biological activity; Free radical; Ferric ion; Health food; Vegetable crop; Quality; Peroxides; Measurement method; Comparative study
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0116606

A total of 927 freeze-dried vegetable samples, including 111 white cabbages, 59 carrots, 51 snap beans, 57 cauliflower, 33 white onions, 48 purple onions, 130 broccoli, 169 tomatoes, 25 beets, 88 peas, 88 spinach, 18 red peppers, and 50 green peppers, were analyzed using the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant capacity (FRAP) methods. The data show that the ORAC and FRAP values of vegetable are not only dependent on species, but also highly dependent on geographical origin and harvest time. The two antioxidant assay methods, ORAC and FRAP, also give different antioxidant activity trends. The discrepancy is extensively discussed based on the chemistry principles upon which these methods are built, and it is concluded that the ORAC method is chemically more relevant to chain-breaking antioxidants activity, while the FRAP has some drawbacks such as interference, reaction kinetics, and quantitation methods. On the basis of the ORAC results, green pepper, spinach, purple onion, broccoli, beet, and cauliflower are the leading sources of antioxidant activities against the peroxyl radicals. Keywords: ORAC; FRAP; antioxidant activity; chain-breaking antioxidant; free radical; hydrogen atom transfer; single electron transfer