Anthocyanins extracting from grape pomace

Supercritical fluid extraction (SEE) is another modern separation technology usually employed to extract lipophilic compounds such as cranberry seed oil, lycopene, coumarins, and other seed oils. Anthocyanins generally and glycosylated anthocyanins in particular were considered unsuitable for SEE due to their hydrophilic properties, since SEE is applicable for non-polar analytes. However, a small amount of methanol was applied as co-solvent to increase CO2 polarity in anthocyanin extraction from grape pomace. New applications of SEE for anthocyanin purification have been reported for cosmetic applications from red fruits. ... 

To obtain anthocyanins closer to their natural state, a number of researchers have used neutral solvents for initial extraction such as 60% methanol, n-butanol, cold acetone, mixtures of acetone, methanol, and water, or simply water. Methanol is the most common solvent used for anthocyanin extraction. Metivier et al. (1980) compared the efficiency of extraction with three different solvents (methanol, ethanol, and water) and different acids, and found that methanol extraction was 20% more effective than ethanol and 73% more effective than water when used for anthocyanin recovery from grape pomace. 

Mantell, C., Martinez de la Ossa, E., and Rodriguez, M., Supercritical fluid extraction of anthocyanins from grape pomace, in Solvent Extraction for the 21st Century, Cox, M., Hidalgo, M., and Valiente, M., Eds., Barcelona, Spain, 1999. 

FIGURE 11.17 Extraction of anthocyanins from grape pomace at room temperature with ethanol containing 1% HC1. (From Metivier et al., 1980)... 

Kammerer, D. et al.. Recovery of anthocyanins from grape pomace extracts Vitis vinifera L. cv. Cabernet Mitos) using a polymeric adsorber resin, Eur. Food Res. Technol, 220, 431, 2005. 

Two classes of dimeric anthocyanins isolated from plants (section 10.2.6) have been identified in plants for the first time. One class includes pigments where an anthocyanin and a flavone or flavonol are linked to each end of a dicarboxylic acyl unit. The other class includes four different catechins linked covalently to pelargonidin 3-glucoside. During the last decade, seven new desoxyanthocyanidins and a novel type of anthocyanidin called P)Tanoanthocyanidins have been reported (Section 10.2.2). Toward the end of the 20th century, several color-stable 4-substituted anthocyanins, pyranoanthocyanins, were discovered in small amounts in red wine and grape pomace.Recently, similar compounds have been isolated from extracts of petals of Rosa hybrida cv. M me Violet, scales of red onion, and strawberries. About 94% of the new anthocyanins in the period of this review are based on only six anthocyanidins (Table 10.2). 

Phenolic compounds, anthocyanins and tannins, are considered among the most important substances extracted from the grape pomace. 

Mantell, C., Rodriguez, M., and de la Ossa, E. M. (2003). A screening analysis of the high-pressure extraction of anthocyanins from red grape pomace with carbon dioxide and cosolvent. Eng. Life Sci. 3, 38M2. 

Anthocyanins are extracted at the beginning of vatting, mainly in the aqueous phase, during maceration prior to fermentation and at the beginning of alcoholic fermentation. When the alcohol content reaches a certain level, a decrease is observed in the results of assays for these molecules. At this stage, extraction of anthocyanins from the grapes is almost completed and several mechanisms intervene to decrease concentrations. These include adsorption of anthocyanins on solids (yeast, pomace), modifications in their structure (formation of tannin-anthocyanin complexes) and, possibly, breakdown reactions (Volume 1, Section 12.5.2). 

Monrad JK, Howard LR, King JW, Srinivas K, Mauromoustakos A (2010) Subcritical solvent extraction of anthocyanins from dried red grape pomace. J Agric Food Oiem 58(5) 2862-2868... 

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