Tannins separation

Tannins occur in many plants and are separated by extraction. At present, only quebracho extract is used as a mud thinner in significant quantity in the United States. Quebracho is an acidic material and performs best at high pH. It is an excellent thinner for lime-treated and cement-contaminated muds. However, it is not effective at high salt concentrations. Sulfomethylated tannin products are functional over a wide range of pH and salinity and have either been treated with chromium for good thermal stabiUty (58) or are chrome free. Concentrations of tannin additives are ca 1.5—18 kg/m (0.5—6 lb/bbl). 

Treatment of the Wort. The hot wort produced in the brewhouse cannot be transferred directly to the fermenting room. If natural hops are used they must be separated by a hop strainer as shown in Figure 8. During boiling, protein—tannin complexes are precipitated in the form of warm sludge. 

Hplc techniques are used to routinely separate and quantify less volatile compounds. The hplc columns used to affect this separation are selected based on the constituents of interest. They are typically reverse phase or anion exchange in nature. The constituents routinely assayed in this type of analysis are those high in molecular weight or low in volatility. Specific compounds of interest include wood sugars, vanillin, and tannin complexes. The most common types of hplc detectors employed in the analysis of distilled spirits are the refractive index detector and the ultraviolet detector. Additionally, the recent introduction of the photodiode array detector is making a significant impact in the analysis of distilled spirits. 

NOTE Where MU requirements exceed 5 to 10% ofLTHW system volume per month, or 5% of the steam output ofLP steam boilers, a separate oxygen scavenger is required. This usually is tannin, diethylhydroxylamine (DEHA), or erythorbic acid (isoascorbic acid). 

Tannin-based multiblends cannot incorporate amines directly into their formulations (unlike sulfite-based multiblends). The neutralizing amine component must be added separately when using tannin multiblends. 

Amines can be blended into multifunctional product formulations containing alkali, polymer, and phosphate and where sulfite- or hydrazine-based oxygen scavengers are part of the formula, but not where tannins are employed. Amines must be fed separately from tannins. 

CZE is particularly useful for separating anthocyanin dimers or polymeric anthocyanins. Calvo et al. (2004)" separated 13 anthocyanins by CZE including acylated and non-acylated anthocyanins, pyranoanthocyanins, and flavonol derivatives in wine. Saenz-Lopez et al. (2004)" applied CZE to analyze wine aging (1 to 14 yr) as related to monomeric anthocyanins, anthocyanin derivatives, tannins, and fla-vonols. Bicard et al. (1999)" reported the improved detection sensitivity of anthocyanin chemical degradation analysis by CZE. 

Systems with different selectivity were nsed for the separation of 10-deacetyl-baccatin III (10 DAB 111) from yew extracts [69]. A silica column with stepwise gradient elution with aqneous methanolic mobile phases can be nsed for separation of the taxoid fraction from nonpolar materials, partial separation of the taxoid fraction into a polar one (containing 10-DAB 111), and for a medinm polarity taxoid fraction (containing paclitaxel and cephalomannine). Most polar material (tannins... 

Fig. 3.6 Tannin crude extract from grape seed separated by normal-phase HPLC with post-coiumn...

Crude GSE can be separated into distinct components from monomer-rich to oligomer- and polymer-rich fractions by solvent extraction followed by chromatography on Toyopearl resin. The pre-fractionation of the tannin crude extract by liquid-liquid extraction with ethyl acetate fractionates the monomers into the organic phase and improves the subsequent fractionation of oligomers and polymers on Toyopearl HW 40 resin. This fractionation technique is easy to operate and... 

Wall, M. E., H. Taylor, L. Ambrosio, and K. Davis. Plant Antitumor agents III a convenient separation of tannins from other plant constituents. J Pharm... 

Cheynier, V. et al.. Size separation of condensed tannins by normal-phase high-performance liquid chromatography. In Methods in Enzymology, Volume 299. Oxidants and Antioxidants. Part A. (ed. L. Packer), Academic Press, San Diego, 1999, p. 178. 

M.-E. Chevreul, near the beginning of his surprisingly long career, studied Hatchett s papers and prepared some of the tannin. Hatchett had found that pit coal which contained no resinous substance was dissolved completely by nitric acid and converted into the artificial tannin, whereas any resinous matter remained undissolved. When Chevreul treated pit coal with nitric acid, however, evaporated the solution, and poured it into water, a yellow matter separated, which was much more abundant than what remained in solution, and had no property that rendered it similar to resins. . . yet I do not allow myself, said Chevreul, the least reflection on the labours of that celebrated English chemist, as I am too fully aware that different modes of operating and the different varieties of the bodies examined. . . may produce a variation in the results.. . Chevreul found that the water-soluble substance which precipitated gelatine copiously was a compound of nitric acid and carbonaceous matter. . (22). These artificial tannins... 

By another method, Reid makes the decoction of galls as above directed, and exposes it freely to the air for ton days, agitating it two or tlirec times eaeh day. By this means much of the tannin is converted into gallic acid. To each quart of the decoction, add three and a half pints of water, nine ounces of sulphate of iron, and the same quantity of gum. The deposit which forms may, after three days, be separated, when tli iak is fit for use. 

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