Pectin pectins

Pectin. Pectin [9000-69-5] is a generic term for a group of polysaccharides, mainly partially methoxylated polygalacturonic acids, which are located in the cell walls of all plant tissues. The main commercial sources of pectin are citms peel and apple pomace, where it represents 20—40% and 10—20% of the dry weight respectively. The pectin is extracted, the extract purified, and the pectin precipitated (50) increased extraction times lead to the production of low methoxyl pectins. 

Pectin is a thickener in many products. If there is sufficient sugar in the mixture, pectin forms a firm gel. Jams and jellies are thickened with pectin. Pectin binds water, and thus keeps products from drying out. It stabilizes emulsions. 

Plant cell walls provide the obvious functions of stmctural support and integrity and can vary tremendously in size, shape, composition and stmcture depending on cell type, age and function within the plant body. Despite this diversity, plant cell walls are composed of only three major classes of polysaccharides cellulose, hemicellulose and pectins. Pectins, or polyuronides, are imbedded throughout the cell wall matrix and are particularly abundant in the middle lamella region. Pectins generally account for 10-30% of the cell wall dry weight and... 

Enzymes can be used to specifically modify the pectins. Pectin methyl esterase is already widely used to adjust the gelling properties of commercially available pectins. The acetyl esters also strongly affect the gelation [2,3] and removal is important for the upgrading of sugar beet pectin, extractable from a by-product of the sugar industry. 

Fig. 8 Preparation of amphiphilic polysaccharide. Chemical structures of deoxycholic acid-modified chitosan (a) and Phe-modified pectin (pectin-gra/t-Phe) (b). SEM image of nanoparticles prepared from pectin-gra/t-Phe (c)...

Pectin is used in foods in two forms, high methoxyl pectin and low methoxyl pectin. High methoxyl pectin is the form normally found in fruit while low methoxyl pectin is a chemically modified pectin. Pectins are acidic polysaccharides that occur in the cell walls of fruit. The commercial source of pectin is either citrus peel or apple pomace. The citrus peel is the residue from the production of citrus juices while apple pomace is the residue of cider production. Thus pectin is a by-product of either cider or fruit juice production. 

Galacturonic acid is the major constituent of all natural pectins. Pectins also contain varying quantities of neutral sugars, principally arabi-nose, galactose and rhamnose (5). The carboxyl function of the galactur-onosyl residues may be present as a methyl ester, acid or salt. 

Metabolism of pectin. Pectin has only recently come, to be considered a part of the dietary fiber complex. Previously it was excluded because 1) it is not fibrous (except at the molecular level), 2) it escapes detection in standard fiber tests owing to its solubility, and 3) it usually does not survive intestinal passage. In a reassessment of which dietary components should be considered fiber, Trowell (49) proposed that dietary fiber include those constituents of food resistant to hydrolysis by man s alimentary enzymes. Spiller (50, 51) suggested that confusion surrounding the term "fiber" be avoided by using the term "plantix" to denote those plant materials of polymeric nature not attacked by human digestive enzymes. 

Other commercial applications are found in the food industry, where lyases already have a long history of safe use. In these applications, isolated enzymes are preferred for safety reasons. Well-known examples include lyases that degrade polysaccharides, such as pectin (pectin lyases), alginate (alginate... 

Extraction with cold/ambient 0.05 M sodium carbonate f (+NaBH4) 1 Carbonate-soluble pectins — (pectins bound by ester linkages) 1 and hydrogen bonding)... 

Christensen, P.E. 1953. Methods of grading pectin in relation to the molecular weight (Intrinsic Viscosity) of pectin, Pectin Symposium of the New York Preservers Association, pp. 163-172. 

The reaction mechanism of lyases is characterized by a trans-elimination reaction resulting in 5 4,5-unsaturated galacturonic acid molecules. The lyases are calcium dependent and attack either pectin (pectin lyases) or pectic acid (polygalacturonate lyases) from the non-reducing end (Fig. 11.4-10c). 

The acidic form of the pectin (pectinic acids) were obtained by percolation through a strong H exchanger column (Amberlite IRN 77). Salts (pectinates) of these pectinic acids were obtained by exact neutralization with the desired Ccu bonate-free hydroxide. 

Pectin is extracted commercially from citrus peel (lemon, lime and grapefruit) and apple pomace.1,2 The food industry is the most important field of application of extracted pectin. Pectins from different sources are widely used to stabilize food emulsions and dispersions in products such as fruit drinks, and fruit and tomato pastes.3 Pectin can form gels under certain circumstances and it... 

Methylated pectin Pectin shreds Water Methanol ... 

FIGURE 2.12 Cryo-SEM micrograph of fresh cheese elaborated with pectin. Pectin network interacting with the protein shell surrounding fat globules (arrows). 

Pectins are used as gelling agents either through the use of calcium cross-linking in the case of LM-pectins or sugar-induced dehydration with HM-pectin. Pectins are used as thickeners and stabilizers in jams, jelly, and fruit products [82]. Pectin can act as a protein dispersion stabilizer in acidified dairy products like yogurt and milk-based fruit drinks. 

Palm (Elaeis guineensis) kernel oil Palm (Elaeis guineensis) oil Peanut glycerides Peanut (Arachis hypogaea) oil Pectin Pectin, amidated PEG-4 dilaurate PEG-6 dilaurate PEG-20 dilaurate PEG-32 dilaurate PEG-75 dilaurate PEG-150 dilaurate PEG-4 dioleate PEG-6 dioleate PEG-8 dioleate PEG-12 dioleate PEG-20 dioleate PEG-32 dioleate PEG-75 dioleate PEG-150 dioleate PEG-4 distearate PEG-12 distearate PEG-20 distearate PEG-32 distearate PEG-75 distearate... 

Pectin Pectin, amidated Potassium alginate Potassium carrageenan Potassium chloride... 

Oat gum Oleic acid Palm glyceride Pectin Pectin, amidated... 

Gum ghatti Hydrogenated tallow glyceride Hydrolyzed oat flour Hydroxypropylcellulose Hydroxypropyl distarch glycerol Hydroxypropyl distarch phosphate Hydroxypropyl methylcellulose Hydroxypropyl starch Karaya (Sterculia urens) gum Konjac flour Lauryl betaine Locust bean (Ceratonia siliqua) gum Malt extract D-Mannitol Methylcellulose Methyl ethyl cellulose Mono- and diglycerides, of fatty acids ,Oat gum Pectin Pectin, amidated... 

Pectin Pectin was crosslinked in the presence of pensnlfate ion by oxidation. 

Pectin in almond kernels can be determined by extracting ground samples with water (soluble pectins) and then 0.05 M HCL at 100 °C for 90 min (insoluble pectins). Pectins can be determined as uronic acid by the carbazole method, using galacturonic acid as standard (Bitter and Muir 1962). 

FT-IR spectra (9) of pectin/starch/glycerol (P/S/G) films were taken to provide information concerning the microstructure around ester and carboxylic acid side chains in the backbone of pectin. Pectin, unlike starch and glycerol, exhibits infrared absorption bands in the regions near 1610 and 1740 cm For pectin dissolved in D2O, absorption bands occur at about 1730, 1740, and 1607 cm. These arise from the carboxylic acid C=0 stretching band, the methyl ester C=0 stretching band, and iht antisynunetric COO stretching band, respectively. The carboxylic acid band overlaps the ester band sufficiently that these appear as one broad band (22). 

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