Abstract
We hypothesize that the Ferric Reducing Antioxidant Power (FRAP) assay that follows the reaction of Fe(3+)-TPTZ at 593 nm underestimates the antioxidant capacity of fruits, since the standardized time of the reaction (4 min) is not enough to titrate all the reducing compounds available. We measured FRAP, total phenolics and anthocyanins content in a variety of Chilean berry fruits (blueberries, blackberries, raspberries and strawberries) and apples (cv. Fuji, Granny Smith, Pink Lady, Red Delicious and Royal Gala). Taking into account the dependence of FRAP on the time course of the reaction, we propose to measure FRAP indexes after 1 min (FRAP-1), 30 min (FRAP-30) and 120 min (FRAP-120) of incubation. Most fruit extracts showed significant correlations between the antioxidant capacity and the incubation time, although in some cases the FRAP indexes did not correlate with the total phenolics and/or anthocyanins content. In fact, in apples and berries the correlation between anthocyanins content and FRAP indexes decreased with the incubation time. It is concluded that the fruit extracts analyzed require an incubation period higher than the established in the original experimental protocol to reach the equilibrium, due to the presence of a complex mixture of antioxidant compounds. In addition, a kinetic profile should be realized in each sample studied to establish the most suitable incubation period to titrate all the reactive antioxidant species.
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Claims 6
Claim · model-written summary
FRAP indexes should be measured after 1 min (FRAP-1), 30 min (FRAP-30) and 120 min (FRAP-120) of incubation.
Verbatim
t0“Chilean apples and berries”
e0“we propose to measure FRAP indexes after 1 min (FRAP-1), 30 min (FRAP-30) and 120 min (FRAP-120) of incubation”
Claim · model-written summary
Most fruit extracts showed significant correlations between antioxidant capacity and incubation time.
- Taxon
- apples and berriest0
- Treatment
- incubation timee1
- Outcome
- antioxidant capacitye1
- Qualifier
- Most fruit extractse1
Not reportedDirection
Verbatim
t0“Chilean apples and berries”
e1“Most fruit extracts showed significant correlations between the antioxidant capacity and the incubation time, although in some cases the FRAP indexes did not correlate with the total phenolics and/or anthocyanins content”
Claim · model-written summary
In some cases FRAP indexes did not correlate with total phenolics and/or anthocyanins content.
Verbatim
t0“Chilean apples and berries”
e1“Most fruit extracts showed significant correlations between the antioxidant capacity and the incubation time, although in some cases the FRAP indexes did not correlate with the total phenolics and/or anthocyanins content”
Claim · model-written summary
In apples and berries the correlation between anthocyanins content and FRAP indexes decreased with incubation time.
Verbatim
t0“Chilean apples and berries”
e2“In fact, in apples and berries the correlation between anthocyanins content and FRAP indexes decreased with the incubation time”
Claim · model-written summary
Fruit extracts require an incubation period higher than the established protocol to reach equilibrium.
Verbatim
t0“Chilean apples and berries”
e3“It is concluded that the fruit extracts analyzed require an incubation period higher than the established in the original experimental protocol to reach the equilibrium”
Claim · model-written summary
A kinetic profile should be established for each fruit sample to select the incubation period.
Verbatim
t0“Chilean apples and berries”
e4“a kinetic profile should be realized in each sample studied to establish the most suitable incubation period”