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A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey.
Food Chem. 2015 May 01; 174:119-23.FC

Abstract

The ferric reducing antioxidant power (FRAP) assay was recently adapted to a microplate format. However, microplate-based FRAP (mFRAP) assays are affected by sample volume and composition. This work describes a calibration process for mFRAP assays which yields data free of volume effects. From the results, the molar absorptivity (ε) for the mFRAP assay was 141,698 M(-1) cm(-1) for gallic acid, 49,328 M(-1) cm(-1) for ascorbic acid, and 21,606 M(-1) cm(-1) for ammonium ferrous sulphate. The significance of ε (M(-1) cm(-1)) is discussed in relation to mFRAP assay sensitivity, minimum detectable concentration, and the dimensionless FRAP-value. Gallic acid showed 6.6 mol of Fe(2+) equivalents compared to 2.3 mol of Fe(+2) equivalents for ascorbic acid. Application of the mFRAP assay to Manuka honey samples (rated 5+, 10+, 15+, and 18+ Unique Manuka Factor; UMF) showed that FRAP values (0.54-0.76 mmol Fe(2+) per 100g honey) were strongly correlated with UMF ratings (R(2)=0.977) and total phenols content (R(2) = 0.982)whilst the UMF rating was correlated with the total phenols (R(2) = 0.999). In conclusion, mFRAP assay results were successfully standardised to yield data corresponding to 1-cm spectrophotometer which is useful for quality assurance purposes. The antioxidant capacity of Manuka honey was found to be directly related to the UMF rating.

Authors+Show Affiliations

School of Biomedical Sciences, Faculty of Life and health sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.School of Biomedical Sciences, Faculty of Life and health sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.School of Biomedical Sciences, Faculty of Life and health sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.School of Biomedical Sciences, Faculty of Life and health sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK. Electronic address: r.owusu-apenten@ulster.ac.uk.

Pub Type(s)

Evaluation Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25529660

Citation

Bolanos de la Torre, Amparo Angelica S., et al. "A Universally Calibrated Microplate Ferric Reducing Antioxidant Power (FRAP) Assay for Foods and Applications to Manuka Honey." Food Chemistry, vol. 174, 2015, pp. 119-23.
Bolanos de la Torre AA, Henderson T, Nigam PS, et al. A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey. Food Chem. 2015;174:119-23.
Bolanos de la Torre, A. A., Henderson, T., Nigam, P. S., & Owusu-Apenten, R. K. (2015). A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey. Food Chemistry, 174, 119-23. https://doi.org/10.1016/j.foodchem.2014.11.009
Bolanos de la Torre AA, et al. A Universally Calibrated Microplate Ferric Reducing Antioxidant Power (FRAP) Assay for Foods and Applications to Manuka Honey. Food Chem. 2015 May 1;174:119-23. PubMed PMID: 25529660.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A universally calibrated microplate ferric reducing antioxidant power (FRAP) assay for foods and applications to Manuka honey. AU - Bolanos de la Torre,Amparo Angelica S, AU - Henderson,Terence, AU - Nigam,Poonam Singh, AU - Owusu-Apenten,Richard K, Y1 - 2014/11/07/ PY - 2014/07/20/received PY - 2014/10/25/revised PY - 2014/11/01/accepted PY - 2014/12/23/entrez PY - 2014/12/23/pubmed PY - 2015/7/28/medline KW - 2,4,6-Tripyridyl-s-Triazine (PubChem CID: 77258) KW - Ammonium ferrous sulphate (PubChem CID: 197097) KW - Antioxidant capacity KW - Ascorbic acid (PubChem CID: 54670067) KW - FRAP KW - Ferric reducing antioxidant power KW - Gallic acid (PubChem CID: 370) KW - Manuka honey KW - Microplate assay SP - 119 EP - 23 JF - Food chemistry JO - Food Chem VL - 174 N2 - The ferric reducing antioxidant power (FRAP) assay was recently adapted to a microplate format. However, microplate-based FRAP (mFRAP) assays are affected by sample volume and composition. This work describes a calibration process for mFRAP assays which yields data free of volume effects. From the results, the molar absorptivity (ε) for the mFRAP assay was 141,698 M(-1) cm(-1) for gallic acid, 49,328 M(-1) cm(-1) for ascorbic acid, and 21,606 M(-1) cm(-1) for ammonium ferrous sulphate. The significance of ε (M(-1) cm(-1)) is discussed in relation to mFRAP assay sensitivity, minimum detectable concentration, and the dimensionless FRAP-value. Gallic acid showed 6.6 mol of Fe(2+) equivalents compared to 2.3 mol of Fe(+2) equivalents for ascorbic acid. Application of the mFRAP assay to Manuka honey samples (rated 5+, 10+, 15+, and 18+ Unique Manuka Factor; UMF) showed that FRAP values (0.54-0.76 mmol Fe(2+) per 100g honey) were strongly correlated with UMF ratings (R(2)=0.977) and total phenols content (R(2) = 0.982)whilst the UMF rating was correlated with the total phenols (R(2) = 0.999). In conclusion, mFRAP assay results were successfully standardised to yield data corresponding to 1-cm spectrophotometer which is useful for quality assurance purposes. The antioxidant capacity of Manuka honey was found to be directly related to the UMF rating. SN - 1873-7072 UR - https://www.unboundmedicine.com/medline/citation/25529660/A_universally_calibrated_microplate_ferric_reducing_antioxidant_power__FRAP__assay_for_foods_and_applications_to_Manuka_honey_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0308-8146(14)01734-8 DB - PRIME DP - Unbound Medicine ER -