Grape skins anthocyanins

Segade, S. R., Vazquez, E. S., and Losada, E. D. (2008). Influence of ripeness grade on accumulation and extractability of grape skin anthocyanins in different cultivars. ]. Food Compos. Anal. 21,599-607. 

Table 12.2 recapitulates the principal modifications of wine constitution caused by destem-nung. Despite the increase in total phenolic compounds in the presence of stems, color intensity diminishes. This long-observed fact is interpreted as the adsorption of grape skin anthocyanins on the ligneous surface of the stems. This interpretation has been confirmed in a model solution containing anthocyanins and tannins either a stem extract or the stems themselves is added, fir the first case, the tannin concentration increases considerably, while the... 

Grape skin anthocyanins are soluble in water and water—alcohol mixtures to yield red to magenta solutions with an acidic pH (ca. 3). The color varies with the pH, from red to purple, and finally to almost blue as the pH is changed from 1 to 8. The pigments are most stable below pH 3 and are not stable at higher pH values they are also sensitive to heat, oxygen, and light. ... 

Typically, grape skin extract has a specific gravity of 1.13 g/mL at 20°C, a solids content of 28—32° Brix (=t3°), a pH of 3.0, and a color strength as anthocyanin of about 1.25% (as measured at 520 nm ia pH 3.0 citrate buffet). Grape skin extract is also available as spray-dried powders with color values three to four times those of the liquid. The properties and uses of grape skin extract ate similar to those of grape color extract. 

Revilla, 1. et al.. Identification of anthocyanin derivatives in grape skin extracts and red wines by liquid chromatography with diode array and mass spectrometric detection, J. Chromatogr. A, 847, 83, 1999. 

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. 

Anthocyanins, grape color extract, grape skin extract E 163 Yes... 

Anthocyanins are extracted commercially using either acidified water or alcohol. The extract is then vacuum evaporated to produce a commercial colour concentrate. The raw materials can be blackcurrants, hibiscus, elderberry, red cabbage or black grape skins. The most commonly used commercially are black grape skins, which can be obtained as a by-product. 

The optimum conditions for the MS detection of anthocyanin derivatives have also been intensively studied. Grape skin extract was prepared by macerating skins with methanol-formic acid (95 5) for three days changing the extracting agent each day. The combined extracts were evaporated and diluted with water. RP-HPLC measurements were carried out in an ODS column (150 X 4.6 mm i.d. particle size 5 /an) at 30°C. The solvents were water-formic acid (90 10, v/v, A) and methanol-water-formic acid (45 45 10, v/v, B). The gradient was from 35 to 95 per cent B in 20 min to 100 per cent B in 5 min final hold... 

Vidal, S. et al.. Mass spectrometric evidence for the existence of oligomeric anthocyanins in grape skins, J. Agric. Food Chem., 52, 7144, 2004. 

Anthocyanin Measurements. Quantitative analysis of concentration by direct colorimetry in the visible range is not practical with red wines because of substances (tannins in particular) which absorb at the maximum for anthocyanins (from 500 to 550 nm). Such a simple method may be used if need be for plant parts especially rich in anthocyanins, such as grape skins. 

Anthocyanins Grape skins, elderberry, Red-purple-blue, E163 Good Good... 

The discussion above has addressed the assessment of a product s colour or perceived colour in basic terms. In the next two sections, methods to determine which coloured compounds are present in a product will be addressed. For the purpose of this chapter, the section on synthetic dyes will cover the analysis of the water-soluble dyes, or so-called coal tar dyes, and the section on natural pigments will cover the anthocyanin pigments, such as grape skin extracts, and the carotenoid-based materials, even if they are of synthetic origin. 

The red wines have an abundance of anthocyanins such as delphini-din 3-0-/i-L)-glucosidc, petunidin 3-0-/ -D-glucoside, malvidin 3-0-/3-D-glucoside, and cyanidin 3-0-/J-o-glucosidc from grape skins [33,34], These anthocyanins also might have antioxidant activity against the oxidation of LDL [11]. 

Red Anthocyanins E163 Anthocyanins Grape skins, red cabbage... 

Polymeric color is a term that has been recognized in the wine industries for many years. Condensation of anthocyanins and proanthocyanidins may contribute to the formation of polymeric color, although the structural characterization of the compounds that contribute to polymeric color are poorly defined. Studies using electrospray mass spectrometric analysis demonstrated the presence of pigmented material from grape skins that was chiefiy composed of direct condensation products of anthocyanins extending up to trimers (Vidal et al., 2004). Recent studies have evaluated the effects of processing of blueberries. 

High-performance liquid chromatography equipped with diode array (HPEC-DAD) and electrospray ionization mass spectrometric detection (ESI-MS(n)) has been used to identify anthocyanins in muscadine grapes (Sandhu et ah, 2010). Six different anthocyanin 3,5-diglucosides were identified in muscadine grape skins (Sandhu et al., 2010). 

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