Extraction pectin

The dynamic Weiflenberg number of pectin gels is influenced by the raw material used for pectin extraction and by the degree of esterification of the applied pectin. With a decreasing degree of esterification the dynamic WeiBenberg number also decreases. 

Characteristics of the pectins extracted from citrus fibres... 

The gel/sol transitions cannot be distinguished for pectins extracted by after acid treatment and water-soluble pectins after extrusion. A minimal pectin concentration of 0.2% is required for gelation and no gels can be obtained below a sucrose concentration of 45 %. Commercial pectin (Hercules) with a dm 73 % has a lower phase transition line with a minimal pectin concentration of 0.1 % and sucrose concentration of 40 %. 

Figure 4 Phase diagrams of pectins extracted by water from extruded citrus fibre and by acid from the fibres (upper curve), and of commercial citrus pectins (dm 73%) (lower curve)...

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. 

Influence of microwave pretreatment of fresh orange peels on pectin extraction... 

Sam- ple Nr Kind of initial material for pectin extraction Extraction time min Yield of pectin, g per 200 g fresh material AUAC, % DE, % Molecul mass Mv Huggins constant Kh Intrinsic viscosity [ft] dl.g- Gel. strengtl TB... 

Figure 3. Titration of pectin fractions extracted from young cell walls. A, B, C, pectins extracted with boiling water D, extracted with hot EDTA. A, B, intact PFi C, demethylated PFj. Titrations were performed...

The polysaccharide compositions of potato cell walls have been genetically manipulated for two main reasons first to attempt to understand the functions of the different cell-wall polysaccharides, and second to improve the value of potato pulp waste. The yield of pectin extracted from the pulp would be improved by decreasing the proportion of cellulose in the walls. The gelling quality of this pectin would also probably be improved by reducing the proportion of RG-1 side chains (Sorensen et al., 2000). 

Renard, C.M.G.C. and Thibault, J.-F. 1993. Structure and properties of apple and sugar-beet pectins extracted by chelating agents. Carbohydr. Res. 244 99-114. 

Viscosity poses a similar problem in the production of pulp wash concentrate. Pulp wash consists of juice solids obtained by countercurrent washing of pulp after its separation from juice. On a °Brix basis, pulp wash liquids are higher in pectin than juice from which the pulp has been screened (19). Concentration of pulp wash above 40°Brix is at times hampered by excessive pectin levels (20). To control viscosity processors may be forced to reduce finisher pressure to minimize pectin extraction, thereby curtailing yield. A more effective solution is to treat pulp wash with pectinases to reduce pectin levels (21). If pectinases are incorporated into the wash water, this method has the advantage of increasing total solids yield by reducing juice retention in the pulp. 

Finally, the alteration of the pectin extractability and the corresponding tissue hardening is the result of the liberation and insufficient inactivation of enzymes especially of the Pectinmethylesterase (PME) during a HP-application, which could be shown by our investigations and was also confirmed by Japanese researches [7]. 

Concn of starch effiuents concn of pectin extracts Concn/purification of iignosuiphonates Concn of PVA/CMC desize wastes... 

Dirt, soils, and clays Retention of particulates and colloids in turbid water supplies concn of fines in kaolin processing Polysaccharides and oligosaccharides Concn of starch effluents concn of pectin extracts... 

Some nonconventional approaches have also been applied to pectin extraction. These include use of various enzymes (Sakai, 1992 Shkodina et al., 1998 Matthew et al., 1990 Williamson et al., 1990), extrusion (Thibault et al., 1996), heat and pressure treatments (Fishman, 2000) and ultrasonic treatment (Panchev et al., 1988). These studies indicate that among many factors that affect the yields and properties of pectin extracts, pH, temperature and, in the case of low-DE pectin, the presence of chelating agents are the most important. (Renard and Thibault, 1993 Eriksson, 1997). In general, severe conditions increase the yield but also accelerate degradation, resulting in lower MW and lower DE pectins. 

Most commercial pectins are produced from apple pomace and citrus peels, although other raw materials are also used, including sugar beet pulp (in Sweden, Germany and England), sunflower seed head (in Bulgaria), and potato pulp. The industrial process for pectin extraction was described in detail by May (1990) and Voragen... 

Wang, S., Chen, F., Wu, J., Wang, Z., Liao, X., and Hu, X. (2007). Optimization of pectin extraction assisted by microwave from apple pomace using response surface methodology.. Food Eng. 78, 693-700. 

In addition to the harsh extraction conditions, not all citrus waste is amenable to conventional pectin extraction. Mandarin orange peel becomes jelly-like on heating and separation of pectin from the residue is difficult (27). Milder extraction conditions and more effective extraction has been reported if mandarin citrus peel was suspended in water with Trichosporon pencillatum for 15 to... 

Some of naturally occurring polysaccharides contain a ferulic ester group in the side chain and they are subjected to enzymatic crosslinking [82, 83]. Pectin extracts containing feruloylated rhamnogalacturonan and feruloylated arabinan groups were crosslinked by HRP to form hydrogels. 

Cellulose and pectin extracts from soybean hulls and endosperm were characterized in terms of their rate of degradation in the presence of sheep rumen fluid.13313C CPMAS NMR was used to study the ultrastructural aspects of ultra-thin cellulose microfibrils extracted from sugar beet pulp during the purification procedure. It was found that crystallinity increases as the purification proceeds. A crystallite size of 4 nm was derived from the NMR results, in good agreement with the transmission electron microscopy (TEM) observations.134... 

Figure 3. Neutral sugar distribution curves of pectins extracted from ripe and unripe apple AIS. The total area represents 100% of the AUA present in the four extracts.

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