Pectin, commercial

However, if theoritically, the combination of pectinases to cellobiohydrolases plus endo-glucanases should release more than 80% of all polysaccharides from the cell walls (according to Voragen and al. [4]), in industrial conditions, we arrive almost at this level of degradation but only for the pectin. Commercial enzymes preparations contain pectinases, hemicellulases and cellulases. 

Free apple pectin Commercial apple 0.2 N NaCl 2.8 0.85 6.9 201,000... 

Pectin. Commercial extraction of pectin from citrus involves treatment of citrus waste at pH extremes with concentrated acids. 

Pectin, which occurs in most plants as the glue which binds the cells together, is extracted commercially from citms peel and has been extracted from apple pomace. It is suggested for many no-fat products including sauces, desserts, and dressings. 

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. 

Arabinogalactans (AGs) are widely spread throughout the plant kingdom. Many edible and inedible plants are rich sources of these polysaccharides. AGs occur in two structurally different forms described as type I and type II, associated with the pectin cell-wall component by physical bonds and some of them are covalently linked to the complex pectin molecule as neutral side chains. Commercial pectins always contain AG 10-15%). AG of type I has a linear (1 4)-y0-o-Galp backbone, bearing 20-40% of of-L-Ara/ residues (1 5)-linked in short chains, in general at position 3. It is commonly found in pectins from citrus, apple and potato [6]. Recently, this AG type has been isolated from the skin of Opuntia ficus indica pear fruits [372]. 

The commercial samples of pectins mainly used as food additives represent modified forms of the natural polymers due to the conditions of extraction. Nevertheless, it is usually recognized two categories of pectins the high methoxyl pectins (HM) with a degree of methylation DM>50% forming gels at low pH in presence of saccharose to reduce the water activity and the low methoxyl pectins (LM with DM<50%) forming gel in presence of calcium [4]. 

The source materials were commercial pectins apple A30 and citrus pectin C73 kindly supplied by Unipectine (France) and Copenhagen Pectin Factory (Denmark) respectively. Polygalacturonic acid samples (named SR) were obtained by acid hydrolysis of a fully de-esterified citrus pectin as previously described [24]. Citrus pectins with different degree of esterification (DE) were obtained by controlled acid de-esterification [8]. 

The Fourier Trairsform Infrared (FTIR) spectrum obtained from non-adapted tomato cell walls is very similar to that from the onion parenchyma cell wall (both contain cellulose, xyloglucan and pectin) although there is more protein in the tomato walls (amide stretches at 1550 and 1650 cm-i) (Fig 4). In DCB-adapted tomato cell walls, the spectrum more closely resembles that of either purified pectins or of a commercial polygalacturonic acid sample from Sigma with peaks in common at 1140, 1095, 1070, 1015 and 950 cm-t in the carbohydrate region of the spectrum as well as the free acid stretches at 1600 and 1414 cm-i and an ester peak at 1725 cm-k An ester band at 1740 cm-i is evident in both onion parenchyma and non-adapted tomato cell wall samples. It is possible that this shift in the ester peak simply reflects the different local molecular environment of this bond, but it is also possible that a different ester is made in the DCB-adapted cell walls, as phenolic esters absorb around 1720 cm-i whilst carboxylic esters absorb at 1740 cm-k The... 

The substrate for HGA synthesis is UDP-D-galacturonic acid (UDP-GalA) (81). UDP-GalA has been isolated from plants (59) and several pathways for its synthesis in planta have been reported (31). In vitro studies on pectin biosynthesis have been hampered since radiolabeled UDP-galacturonic acid is not commercially available. Previous researchers have used several... 

The Ridgelimeter is the most commonly used device to standardize high methoxyl pectins for commercial use (Cox and Higby, 1944). This empirical Sag-test is a one-point, nondestructive measurement. 

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)...

Whatever the concentration, commercial pectins formed the strongest gels followed by the acid-extracted pectins and the pectins from the extruded fibres. More differences have be seen when the storage moduli were measured as a function of the sucrose concentration (Figure 7). 

For commercial pectins, G increased rapidly up to 45 % of sucrose and remained constant. In contrast, the value of G for the other pectins increased more slowly and reached only a plateau for a concentration about 55 %. 

It is therefore possible to obtain gels with the pectins in the same conditions as other HM pectins. When these pectins are compared to the commercial pectins, it can be observed that higher pectin concentrations were needed and that the gelation was more dependent on the sucrose concentration this fact can be ascribed to a higher purity of the commercial pectins (17,18). 

However, the difference was more marked between the commercial pectins and the other pectins. The reasons for this discrepancy can be found either in differences in the values of the dm or in the origin of the raw materials. Indeed, a lower dm value can lead to firmer gels (19,20). However, the main reason is probably the fact that the citrus fibre used in this study was a commercial citrus (dietary) fibres of which the pectin quality may be lower than the citrus peels used by pectin industry. 

Some compression tests for gel made with extruded fibres have also be carried out in various conditions (Table 2). The Young moduli were in the range of the values obtained for commercial pectins. There was no marked influence of the severity of the treatment. The large difference between the Young moduli and the G value confirmed that these gels are far from ideal networks. 

Pectin degradation in UF-membrane reactors with commercial pectinases... 

Aim of this work was to optimise enzymatic depolymerization of pectins to valuable oligomers using commercial mixtures of pectolytic enzymes. Results of experiments in continuous and batch reactor configurations are presented which give some preliminary indications helpful to process optimisation. The use of continuous reactors equipped with ultrafiltration membranes, which assure removal of the reaction products, allows to identify possible operation policy for the improvement of the reaction yield. 

Thermostable pectinesterases (TSPE), operationally defined as activity that survives 5 min at 70°C, contribute most to cloud loss in juices at low temperatures and juice pH (26). The percentage of total activity that is thermostable is highly variable and differs in kinetic properties, (22, 26), ease of solubilization (28, 29), stability to low pH (25) and stability to freeze-thaw cycles (23). Some of the variability in reported total PE and TSPE may be related to limitations of current methods to quantify activity. Any processing treatment or assay condition that increases cell wall breakdown or release PE from a pectin complex would enhance detection of total and TS-PE activity. Commercially, PE is inactivated by pasteurization in a plate heat exchanger or during concentration in the TASTE evaporator. 

Rouse, A.H. Atkins, C.D. 1955. Pectinesterase and pectin in commercial orange juice as determined by methods used at the Citrus Experiment Station. Florida Agric. Exper. Station Bull. 570 1-19. 

Pectin degradation requires fee combined action of various enzymatic activities. However, evaluation of fee contribution of individual pectinases in Suit juice extraction and clarification is rather complicated. Most commercial pectinolytic enzyme preparations are produced by fermentation wife filamentous fungi, mostly strains belonging to fee genus Aspergillus,. plication studies with mixtures of isolat enzymes obtained by fermentation or by means of fractionation of commercial enzyme preparations can be used to assess the importance of fee various individual enzymes. Subsequently, molecular biology and fermentation technology can be used to enhance specific desirable enzymatic activities. 

Commercial Rapid Set citrus pectin (864 mg galacturonic acid per g, degree of methylation 73) was from SBI (Beaupte, France). 

Pectins were extracted from isolated cell walls of 5-week-old wheat plants using different methods. Enzymic digestions of the cell walls involved pectinases such as a commercial pectolayse or recombinant endopolygalacturonase [Maness Mort, 1989]. Chemical extractions involved the chelating agent imidazole [Mort et al., 1991] or solvolysis with anhydrous HF at 0 °C in a closed teflon line [Mort et al., 1989] followed by imidazole extraction. 

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. 

The endo-action of the K. marxianus PG was demonstrated by a extremely rapid attack on plant tissue. This activity appears to be at least equivalent to that of several commercial preparations used for separating plant cells for protoplast preparation (RMC, unpublished data). Most of the endo-PGs produced by plant pathogens and saprophytes have so far been reported to possess macerating activity. PG secreted by K. marxianus CCT 3172 also had a strong activity in reducing the viscosity of cocoa pulp. Cocoa pulp generally contains 1 - 1.5% (w/w) of pectin consisting of 68% esterification and 11.6% methoxyl content [18]. 

Following previous works on physico-chemical characterisation of sunflower low-methoxyl pectins (Alarc o-Silva, 1990, Leitao at al., 1995) and technological utilisation in the manufacture of low calorie gels (Alarc o-Silva et al., 1992), this investigation was carried out to test the suitability of that pectin to the confection of grape juice reduced calorie jellies in comparison with two types of commercial pectin. Aiming at the optimisation of low-calorie jelly formula, based on consumers preferences, the jellies were submitted to a sensory panel test judgement and instrumental texture-analysis. 

The standard low-methoxyl commercial pectins used were Violettband D-075 (amidated pectin) and Violettband Rein (non-amidated pectin) provided by OBIPEKTIN AG (Switzerland). 

From the results of this study it appears that commercial amidated and experimental sunflower pectins have similar behaviours and from a consumer s point of view there are only small differences mainly related with a visual evaluation of the jellies, and greasy" and clammy tastes. 

The good results obtained in the production of jellies with experimental sunflower pectin are all the more interesting as this pectin has not suffered any standardisation process like the commercial ones. Such a process could eventually overcome the undesirable characteristics mentioned above. 

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