On the Limits of Anthocyanins Co-Pigmentation Models and Respective Equations

Abstract

Anthocyanins co-pigmentation models with application on 1:1 complexes were revisited, and their limitations were critically commented. The flavylium multistate of species is dramatically simplified to a single acid–base equilibrium between flavylium cation and its conjugated base CB, equal to the sum of quinoidal base, hemiketal, and cis and trans-chalcones. Bearing this, a new equation that simultaneously allows calculation of the co-pigmentation constant with flavylium cation (K AH+CP) and with its conjugated base CB (K CBCP) was deduced. This equation can be used at a fixed co-pigment concentration with pH as a variable or at fixed pH and co-pigment concentration variable. A global fitting of all data allows us to calculate both association constants with good accuracy. The model was applied to the co-pigmentation of malvidin-3-glucoside with caffeine and pentagalloyl glucose (PGG). Caffeine gives rise to complexes not only with flavylium cation K AH+CP = 125 ± 7 M–1 but also with CB with K CBCP = 23 ± 3 M–1. PGG complexes exclusively with flavylium cation, K AH+CP = 914 ± 10 M–1, and the possible interaction with quinoidal base is lower than the detection limits that the inherent experimental error permits.

Anthocyanins: Factors Affecting Their Stability and Degradation

“…As such, the co-pigment anthocyanin complex will have a longer absorption wavelength [ 49 , 50 ]. The nature of these compounds can be extremely varied, therefore, pigments can be alkaloids, amino acids, nucleotides, organic acids, flavonoids, metals or even other anthocyanins [ 39 , 51 ]. The efficiency of the co-pigmentation effect depends on the steric arrangement of the substance (the best co-pigmentation effect occurs in the case of a planar structure) and its size, in order to achieve the stabilization of the flavylium ion [ 46 ].…”

Anthocyanin Color Stabilization by Host-Guest Complexation with p-Sulfonatocalix[n]arenes

“…The H4 and H6 signals seem to be the more affected than the protons around the B ring. The fast/medium exchange dynamics between the free and complexed guest produce a broadening of some proton signals in the 1 H NMR spectra, as frequently observed for the association of guest molecules with sulfonated calixarenes [43,44].…”

Evaluation Study on Extraction of Anthocyanins from Red Cabbage Using High Pressure CO2 + H2O: A Fuzzy Logic Model and Metabolomic Analysis

“…The increase in their content is mainly due to full contact with the extractant; (2) substances sensitive to solvent polarity, such as sinapic acid glucose, and the increase in content is mainly due to the change of solvent polarity. The content of strongly polar or nonpolar substances such as phloretin and phlorizin remains basically unchanged because high-pressure CO 2 + H 2 O treatment has little influence on solvent polarity; [52] and (3) substances sensitive to solvent temperature, such as 3-caffeoylquinic acid, which is greatly affected by temperature [53] and has high solubility in hot water and low solubility in cold water, decreased in content by high-pressure CO 2 + H 2 O treatment, which may have an opposite or ineffective influence on the two main factors (solvent polarity and temperature), and the comprehensive effect is not obvious. Specifically, CO 2 promotes the entry of the extractant into cells and fully extracts the substance, due to the evaporation and the endothermic heat of liquid CO 2 during high-pressure CO 2 + H 2 O decompression, the solution temperature suddenly decreases [54,55], and the solubility decreases sharply.…”