Fruits are rich in polyphenols, compounds associated with human health benefits, and with the sensory characteristics of bitterness and astringency. Although polyphenols are structurally diverse, they are often quantified as a group of compounds, as “total polyphenols” by the Folin-Ciocalteu (FC) and the Prussian Blue (PB) methods, and as “total procyanidins (PC)” by the 4-dimethylaminocinnamalehyde (DMAC) and bovine serum albumin (BSA) precipitation methods. The results of these methods are often compared across fruit types; however, the impact of the diversity in polyphenol structures among fruits on the quantitative results of these methods has not been systematically evaluated. The objective of this research is to quantify the contribution of specific polyphenol compounds commonly found in fruit to the results of four above methods.<br/> Aqueous solutions of the most prevalent polyphenol compounds found in fruit juices and fruit beverages (catechin, epicatechin, PC B2, PC pentamer, chlorogenic acid, phloretin, quercetin) were made at known concentrations of 0, 1, 5, 10, 20, 50, and 100 mg/L. The contribution of each of these individual polyphenol compounds to the overall response of each method was determined.<br/>                       <br/>Different polyphenol compounds responded to the same method differently. Epicatechin and catechin generally had the highest responses in all the methods except for the PB method, in which PC B2 and quercetin had the highest responses. Phloretin and chlorogenic acid consistently gave the lowest responses for all four methods. The relative contributions of different polyphenol compounds to the results of four common analytical methods used to quantify total polyphenols or total procyanidins in fruit varies. This finding indicates that polyphenol composition, which is largely determined by fruit genotype, could influence the results of these methods. This finding, along with the polyphenol composition of a given fruit sample should be taken into consideration when making comparisons of total polyphenol concentration among fruits.<br/>

Polyphenol quantification in fruits: Determination of the contribution of individual polyphenols to quantitative results of four common analytical methods

2019 Spring National Meeting

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