Retention of anthocyanins and

The retention of anthocyanins and pyruvic anthocyanin derivatives by the cell walls of yeasts used in the fermentation of red wines. 

Kopjar, M., Influence of trehalose addition on anthocyanin retention of evaporated and freeze-dried strawberry pastes, in Proceedings of 4th International Congress on Pigments in Food, Hohenheim, Germany, Carle, R. etal., Eds., Shaker Verlag, Aachen, 2006, 223. 

The data prove that the retention order of anthocyanins deviates from each other in HPLC and TLC suggesting the involvement of a different retention mechanism. It was stated that the preseparation of anthocyanins by size-exclusion chromatography is a prerequisite of the successful preparative separation by RP-HPLC [244],... 

Fig. 4.2 HPLC-DAD chromatograms of anthocyanins from soluble and insoluble extracts of black, red-brown, and brown soybean seed coats at 520 nm. (a, d) Black (Clark), (b, e) red-brown (Mil), and (c, f) brown (MlOO) seed coats, (a and b) Pulverized fresh seed coats extracted with 80% methanol in water, (d-f) Insoluble pulverized seed coat fraction extracted with 1-butanol/HCl (19 1) 1% SDS. Compound identifications were based on comparison of retention times and absorption spectra to authentic standards. Peak 1, unknown peak 2, delphinidin-3-O-galactoside peak 3, delphinidin-3-O-glucoside peak 4, cyanidin-3-O-galactoside peak 5, cyanidin-3-O-glucoside peak 6, petunidin-3-O-glucoside peak 7, pelargonidin-3-O-glucoside peak 8, peonidin-3-O-glucoside and peak 9, malvidin-3-O-glucoside...

The trends in wine pigment development seen above for the SO2 study have been consistently reported in MOX trials. These include a greater formation of sulfite-resistant pigments, a more rapid loss of monomeric anthocyanins, and a greater retention of wine color. Higher color intensity was one of the findings reported in early research work on the MOX... 

The exact gradient will have to be determined by the analyst, as variations in column brands causes significant differences in the retention times of the peaks of interest. A good material to use as a reference sample is commercial cranberry juice cocktail. It has a simple profile of four major peaks and two minor ones that cover the retention times of most peaks of interest, and will give the experimenter some assurance that the analytical system is behaving satisfactorily. See Figure FI.3.2 for a sample chromatogram with the peaks identified. Another alternative is purified anthocyanins. 

The identification and peak assignment of anthocyanins can often be based on a comparison of their retention time and MS data with standards and published data. There are some general guidelines that... 

Amic, D., Davidovic-Amic, D. and Trinajstic, N. (1995b). Calculation of Retention Times of Anthocyanins with Orthogonalized Topological Indices. J.Chem.lnf.Comput.Sci, 35,136-139. 

It has been known for decades that heat is one of the most destructive factors of anthocyanins in berry fruit juices (Jackman et al., 1987a). With strawberry preserves, it was shown as early as 1953 that the half-life time was 1 h at 100°C, 240 h at 38°C and 1300 h at 20°C. In a storage experiment with concentrates and dry powder of elderberry extracts, the stability increased 6-9 times when the temperature was reduced from 20°C to 4°C (Zajac et al., 1992). Anthocyanin degradation in anthocyanin solutions increased from 30% to 60% after 60 days when storage temperatures were increased from 10°C to 23°C (Cabrita et al., 2000). High-temperature short-time processing is recommended for maximum anthocyanin retention of foods containing anthocyanins (Jackman and Smith, 1996). 

Table 3.9 Retention times and molecular masses of anthocyanins (by off-line ESI-MS) separated in the chromatogram Figure 3.15 (Favretto and Flamini, 2000).

TABLE 6.11. Retention Times (RT) and Molecular Weights (MW) of Anthocyanins Identified in the Chromatogram2... 

Given the importance of colour to red wines, and the quantity of pigments lost when the lees is removed, was important to investigate the adsorption of anthocyanins by yeast cell walls during wine-making 1) to determine whether there are any differences between yeasts strains, and 2) to determine the degree of retention of different anthocyanins. 

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