Editing Antioxidant (section)

=== Measurement and invalidation of ORAC ===
Measurement of polyphenol and carotenoid content in food is not a straightforward process, as antioxidants collectively are a diverse group of compounds with different reactivities to various reactive oxygen species. In [[food science]] analyses in vitro, the [[oxygen radical absorbance capacity]] (ORAC) was once an industry standard for estimating antioxidant strength of whole foods, juices and food additives, mainly from the presence of [[polyphenol]]s.<ref>{{Cite journal |vauthors=Cao G, Alessio HM, Cutler RG |date=March 1993 |title=Oxygen-radical absorbance capacity assay for antioxidants |url=https://zenodo.org/record/1258621 |journal=Free Radical Biology & Medicine |volume=14 |issue=3 |pages=303–11 |doi=10.1016/0891-5849(93)90027-R |pmid=8458588}}</ref><ref>{{Cite journal |vauthors=Ou B, Hampsch-Woodill M, Prior RL |date=October 2001 |title=Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe |journal=Journal of Agricultural and Food Chemistry |volume=49 |issue=10 |pages=4619–26 |doi=10.1021/jf010586o |pmid=11599998|bibcode=2001JAFC...49.4619O }}</ref> Earlier measurements and ratings by the [[United States Department of Agriculture]] were withdrawn in 2012 as biologically irrelevant to human health, referring to an absence of physiological evidence for polyphenols having antioxidant properties ''[[in vivo]]''.<ref name="USDAx">{{Cite web |date=16 May 2012 |title=Withdrawn: Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 (2010) |url=http://www.ars.usda.gov/services/docs.htm?docid=15866 |access-date=13 June 2012 |publisher=United States Department of Agriculture, Agricultural Research Service}}</ref> Consequently, the ORAC method, derived only from ''in vitro'' experiments, is no longer considered relevant to human diets or [[biology]], as of 2010.<ref name="USDAx" />

Alternative in vitro measurements of antioxidant content in foods – also based on the presence of polyphenols – include the [[Folin-Ciocalteu reagent]], and the [[Trolox equivalent antioxidant capacity]] assay.<ref>{{Cite journal |vauthors=Prior RL, Wu X, Schaich K |date=May 2005 |title=Standardized methods for the determination of antioxidant capacity and phenolics in foods and dietary supplements |url=https://naldc.nal.usda.gov/Policy.pdf |url-status=dead |journal=Journal of Agricultural and Food Chemistry |volume=53 |issue=10 |pages=4290–302 |doi=10.1021/jf0502698 |pmid=15884874 |bibcode=2005JAFC...53.4290P |archive-url=https://web.archive.org/web/20161229203509/https://naldc.nal.usda.gov/Policy.pdf |archive-date=29 December 2016 |access-date=24 October 2017}}</ref>