The reduction of Cu(II)/neocuproine complexes by some polyphenols: Total polyphenols determination in wine samples

Modified CUPRAC spectrophotometric quantification of total polyphenol content in beer samples using Cu(II)/neocuproine complexes

“…The average value of b obtained from each curve was used as the average value of the apparent molar absorptivity (e) of each polyphenol in both methods (Table 5). It can be seen that, for the 5 compounds analyzed, the proposed method is about twice as sensitive as the reference method as already observed in our previous work evaluating samples of wine (Moya et al, 2008;Lee et al, 2011).…”

“…As reported in previous works (Moya et al, 2008;Marino et al, 2009;Lee et al, 2011), these differences indicate that the analytical response of a spectrophotometric method for one complex sample containing various polyphenols depends on the antioxidant activity of each phenolic compound, which may explain the different results obtained with some wine samples. Indeed, the antioxidant capacity of any phenolic compounds is related to the number and position of the hydroxyl groups and the degree of conjugation of the molecule; the measurement of the polyphenol content itself provides no information about the chemical characteristics of the compounds with phenolic structure.…”

“…The absorbance value at 454 nm, characteristic of the Cu(I)/NC complexes, was related to the total polyphenol concentration in wines (Lee et al, 2011). Since spectrophotometric methods are more attractive because of low cost, simplicity and versatility, we used this reaction in that study to quantify polyphenol content in beer samples.…”

Characterization of taste-active compounds of various cherry wines and their correlation with sensory attributes

“…It has been selected as standard solution for tannins quantification in wines by the official AOAC method [35]. The concentration of tannic acid in cherry wines ranged from 0.0566 to 0.1327 g L −1 .…”

A new method for quantification of total polyphenol content in medicinal plants based on the reduction of Fe(III)/1,10-phenanthroline complexes

“…At this pH the phenolic compounds are present as phenolates which are easier to oxidize. This may be the cause of obtaining results generally higher than those obtained with other methods [23][24][25]. Although the pH ranges in which these two reactants (…”