Pectins purification

The following are some of the typical industrial applications for liquid-phase carbon adsorption. Generally liquid-phase carbon adsorbents are used to decolorize or purify liquids, solutions, and liquefiable materials such as waxes. Specific industrial applications include the decolorization of sugar syrups the removal of sulfurous, phenolic, and hydrocarbon contaminants from wastewater the purification of various aqueous solutions of acids, alkalies, amines, glycols, salts, gelatin, vinegar, fruit juices, pectin, glycerol, and alcoholic spirits dechlorination the removal of... 

In a more recent study it was shown that the roots from G. uralensis, after isolation, fractionation and purification, contain two bioactive polysaccharides of the pectin family termed GU-3IIa-2 and 3IIb-l. 

This paper concerns the main properties of water soluble pectins in sol and gel states. First of all, the methods of purification and characterization are discussed. The method of steric exclusion chromatography equipped with different detectors is demonstrated as the most useful to determine the macromolecular characteristics of these polymers the role of aggregation is pointed out. 

Pitkanen, K., Heikinheimo, R. and Pakkanen, R. (1992) Purification and characterization of Erwinia chrysanthemi B374 pectin methylesterase produced by Bacillus subtilis. Enzyme Microb TechnoHA, 832-836. 

Acetyl esterase (AE) has been purified to homogeneity from orange peels. The purification steps included cation exchange chromatography and gel filtration. The enzyme has affinity for triacetin and sugar beet pectin with K, of 39 mM and of 26 mg/ml, respectively. AE has a MW of 42 kD and is a monomer. The isoelectric point is at pH > 9. 

Pectin lyase from Fusarium oxysporum f. sp. radicis lycopersici purification and characterization... 

The objective of this work has been the purification of the pectin lyase with pi 9.20, which is the most abundant. 

Preparation of enzyme. Culture fluids of three days on glucose 0.5% (w/v) and then four days on pectin 0.5% (w/v), cleared by passing through glass fibre filter, were used for the purification of PNL. A small quantity was remainder, dialyzed, and assayed for enzyme actitity and the remained was precipitated. 

Experimental low-methoxyl pectin was obtained from dry heads (without seeds) of sunflower Helianthus annus L.). The extraction of pectin was carried out according to the method of Lin et al. (1975) with slight modifications. Only oxalate-soluble fraction which was submitted to consecutive treatments of purification as described previously was considered (Leitao et al., 1995). 

Synthetic examples include the poly(meth)acrylates used as flocculating agents for water purification. Biological examples are the proteins, nucleic acids, and pectins. Chemically modified biopolymers of this class are carboxymethyl cellulose and the lignin sulfonates. Polyelectrolytes with cationic and anionic substituents in the same macromolecule are called polyampholytes. 

Adsorption on calcium pectate and calcium phosphate, and chromatography on DEAE-cellulose, were used for the purification of pectin lyase from Aspergillus fonsecaeus.253 Two forms of pectin lyase (having pH optima at 7.3 and 8.3) were isolated266 from the culture filtrate of Sclerotinia fructigena by chromatography on Seph-adex G-75 and CM-Sephadex C-50. 

Sometimes natural fine chemicals are by-products in bulk products refining. Examples are (a) lecithin and steroids in vegetable oil refining (b) betaine, pectin and raffinose in sugar manufacture (c) quinic acid in quinine extraction of the bark of Cinchona trees (d) chitin and the red pigment asthaxanthin in lobster and shrimp processing and (e) lanolin, lanosterol and cholesterol in sheep wool purification. 

In one recent study (15), isolation and purification of tobacco pectin yielded a series of related rhamnogalacturonans. All of these polysaccharides were found to have a backbone consisting of 4-linked a-D-galactopyranosyluronic acid residues interspersed with 2-linked L-rhamno-pyranosyl residues in a ratio of 16 1 (see Fig. 1). The presence of rhamnose in the backbone of pectin is believed to create kinks which probably disrupt helical stretches of the 4-linked a-D-galactopyranosyluronic acid... 

Citrus peel, apple pomace from juice manufacture, and beet pulp left over from the manufacture of sucrose are common commercial sources of pectins. After some preliminary purification of the raw material, the extraction is usually performed with hot dilute acid (pH —1.0-3.5 in a temperalure range of 70-90°Ci. The pectin is then precipitated from the extract with ethanol or isopropanol, or with metal salts (copper or aluminum). The metal ions have to be subsequently removed by washing... 

The solubility of NHDC in hot water, alcohol, aqueous alkali, acetonitrile, dimethyl sulfoxide, and alcohol/water mixture facilitates its selective extraction from food samples (20,91,94). It is extracted from jams, fruit juices, and dairy products with methanol (66,93) or acetone (95) and filtered or centrifuged. Chewing gum samples are dissolved in chloroform and extracted with water. The extract is centrifuged, and the clear supernatant is injected into the HPLC (95). If necessary, sample cleanup and concentration may be achieved by selective adsorption or desorption (20) on Sep-Pak Cl8 (96). Tomas-Barberan et al. (93) used Amberlite XAD-2 resin for purification of jam extract. Sugars, pectin, and other polar compounds were eluted with water, and NHDC was eluted with methanol. After concentration, the extract was further purified on a Sephadex LH-20 column prior to HPLC analysis. 

Pfeffer et al. (82) have found that bile salt binding activity of commercial citrus pectins was lost if these products were dissolved, filtered, centrifuged, and reprecipitated before testing. Binding activity was concentrated in the residue pellet from centrifugation, which was found to be fine diatomaceous earth. This contaminant was probably introduced during filtration steps in processing and purification of pectin. The authors concluded that any hypocholesterolemic effect of commercial pectin was due solely to its diatomaceous earth contamination. 

Anthocyanins are generally more stable at an acidic pH. Therefore, anthocyanins are commonly extracted under cold conditions using either acidic methanol or ethanol to avoid degradation1 5169 (Table 3.4). In comparison, acetone allows more reproducible extraction and avoids problems with pectins. However, it is limited by the coextraction of proanthocyanins.39 In general, ethanol is preferable as an extraction solvent, although it can require an additional step for the removal of lipid-soluble substances. SPE using Ci8, polyamide, HLB (hydrophilic lipophilic balanced stationary phases), or Amberlite has been employed for the purification of anthocyanidins prior to HPLC analysis.39-51 66 69... 

De Vries, J. A., Voragen, A. G. J., Rombouts, F. M., and Pilnik, W. (1981). Extraction and purification of pectins from alcohol-insoluble solids from ripe and unripe apples. Carbohydr. Polym. 1 117-127. 

Albersheim, P., and U. Kilias. 1962. Studies relating to the purification and properties of pectin transelimi-nase. Arch. Biochem. Biophys. 97 107-115. 

Concentration.—The next stage in the process is the purification and concentration of the juice and the crystallization of the sugar. The raw juice contains, as impurities, pectins, proteins and mineral salts. These are usually removed by the addition of lime at S °-go°, which causes the precipitation of the impurities. Care must be exercised however, or some sugar will also be precipitated in the form of calcium... 

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