Grapes red, anthocyanins

ReviUa, E. et al.. Comparison of several procedures used for the extraction of anthocyanins from red grapes, J. Agric. Food Chem., 46, 4592, 1998. 

Hong, V. and Wrolstad, R.E., Use of HPLC separation/photodiode array detection for characterization of anthocyanins, J. Agric. Food Chem., 38, 708, 1990. Osmianski, J. and Lee, C.Y., Isolation and HPLC determination of phenolic compounds in red grapes. Am. J. Enol. Vitic., 41, 204, 1990. 

Ju and Howard (2003) studied pressurized hquid extraction of anthocyanins from dried red grape skins with six solvents at temperatures ranging from 20 to 140°C using 10.1 MPa. They found that the type of solvent and the temperature used affected the types and levels of anthocyanins in the PLE extracts. 

Ju, Z.Y. and Howard, L.R., Effects of solvent and temperature on pressurized liquid extraction of anthocyanins and total phenolics from dried red grape skin, J. Agric. Food Chem., 51, 5207, 2003. 

A similar RP-HPLC method was developed and employed for the separation and quantitative determination of nine anthocyanins in red grape cultivars and red wines. Analysis... 

F.J. Heredia, E.M. Francia-Aricha, J.C. Rivas-Gonzalo, I.M. Vicario and C. Santos-Buelga, Chromatic characterization of anthocyanins from red grapes. 1. pH effect. Food Chem. 63 (1998) 491-198. 

E. Revilla, E. Garcia-Beneytez, F. Cabello, G. Martin-Ortega and J.-M. Ryan, Value of high-performance liquid chromatographic analysis of anthocyanins in the differentiation of red grape cultivars and red wines made from them. J. Chromatogr.A 915 (2001) 53-60. 

Spectrophotometric studies were conducted from pH 0.1 to 5.7. The thermodynamic constants calculated, assuming that the absorbance of AH+-AH+ was twice that of AH -AOH and that the second hydration constant (pAhi) was equal to the proton transfer constant (pA, were 1.8 (pAhi) for the first hydration reaction and 4.6 (pAThi pA) for the second, whereas the hydration and proton transfer constants calculated for malvidin 3-glucoside are 2.6 and 4.25, respectively. Based on these hydration constants, the only significant form of the methylmethine dimer at wine pH is AH+-AOH, in which one of the anthocyanin moieties is under the red flavylium form and the other one is hydrated, as predicted from mass spectrometry data. Thus, conversion of grape anthocyanins (75 to 80% colorless AOH, 20 to 25% red AH+ in wine pH range) to the methylmethine bis-anthocyanin (50% AOH, 50% AH ) may be responsible not only for a shift toward a more purple tint but also for a twofold increase in color intensity. 

Figure 3. Device for separating red wine anthocyanins on paper to detect wines from hybrid grapes...

This method is used for anthocyanin samples of lesser complexity that do not contain acylated pigments. It is the most common method used for anthocyanin analysis and is effective for most commodities the major exceptions being red grape and cabbage containing products. This protocol describes the dilution, filtration, and reversed-phase HPLC analysis of these samples. 

A method for fractionation of polyphenoiics into non-anthocyanin and anthocyanin fractions from red grapes by solid-phase extraction using disposable C18 cartridges. 

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