Modified 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic Acid (ABTS) Method to Measure Antioxidant Capacity of Selected Small Fruits and Comparison to Ferric Reducing Antioxidant Power (FRAP) and 2,2‘-Diphenyl-1-picrylhydrazyl (DPPH) Methods

Abstract

The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.

Bioactive compounds and quality characteristics of five apples cultivars

“…Although statistical differences among cultivars vary between the two methods, the assay results were generally similar for different cultivars because these methods are based on electron transfer mechanism. Due to these variations, it is recommended to have at least two antioxidant methods with different modes of actions in study to accurately reflect the antioxidant activity (OZGEN et al, 2006).…”

Shelf life extension and antioxidant activity of ‘Hayward’ kiwi fruit as a result of prestorage conditioning and 1-methylcyclopropene treatment

“…The absorbance at 450 nm was recorded against a reagent blank. (Apak et al 2004;Preshita et al 2013;Ozgen et al 2006). …”

Phenolic compounds, bioactive content and antioxidant capacity of the fruits of mulberry (Morus spp.) germplasm in Turkey

“…Trolox equivalent antioxidant capacity (TEAC) was determined with ABTS (2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radical cation by dissolving ABTS in an acetate buffer using potassium persulphate (Ozgen et al 2006). Three replicates including 30 fruits per replicate were used.…”