Understanding Antioxidant Capacity: Insights from the Folin–Ciocalteu Assay


A recent review article published in the Journal of Agriculture and Food Chemistry explored how the Folin–Ciocalteu (F–C) assay quantifies total polyphenols in food (1). In this study, lead author Maria Perez from the University of Barcelona and her team examined the F–C method’s mechanism and provided important discernments into interpreting its results.

The F–C assay method follows the principle of the reduction of a yellow phosphotungstate–phosphomolybdate complex by antioxidants to form a distinctive blue chromogen (1). In the review, Perez's team emphasizes the importance of understanding the structural characteristics of (poly)phenolic compounds, as these properties closely correlate with their antioxidant capacity (1). To accurately estimate the antioxidant potential using the F–C method, Perez and her team emphasize in their article that a thorough understanding of the structural features is important (1).

Perez’s study focuses most of the review evaluating the phenolic intake with adherence to the Mediterranean diet. The Mediterranean diet is widely accepted for its health benefits, containing many polyphenol-rich foods, including fruits, vegetables, nuts, legumes, and whole grains, to name a few (1).

Although the F–C assay stands as a widely acknowledged method for measuring total phenolic content (TPC) in foods or extracts, the method does have some key limitations. While the Mediterranean diet is replete with (poly)phenol-rich foods potentially contributing to its health advantages, the F–C assay primarily quantifies TPC without considering variations in bioactivity among different phenolic compounds (1).

When using the F–C assay for quantification of polyphenols, the individual polyphenols in the sample under study are connected to the results of the F–C assay (1). However, the issue is that not all phenolic compounds exhibit health impacts equally; as a result, to discover the specific effects within the Mediterranean diet, or any other diet, more research is needed (1).

This review addresses the importance of a nuanced understanding of (poly)phenolic compounds' structures and their influence on antioxidant capacity (1). Although the F–C assay remains a cornerstone in quantifying TPC, it serves as a starting point requiring deeper exploration to decode the precise health impacts of individual phenolic compounds within complex dietary patterns like the Mediterranean diet (1).

This article was written with the help of artificial intelligence and has been edited to ensure accuracy and clarity. You can read more about our policy for usingAIhere.


(1) Perez, M.; Dominguez-Lopez, I.; Lamuela-Raventos, R. M. The Chemistry Behind the Folin–Ciocalteu Method for the Estimation of (Poly)phenol Content in Food: Total Phenolic Intake in a Mediterranean Dietary Pattern. J. Agric. Food Chem. 2023, 71 (46), 17543–17553. DOI: 10.1021/acs.jafc.3c04022

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