Pectinase, enzyme from commercial

Enzymes most frequently proposed to fruit juices producers are pectinases coming from Aspergillus. Pectinases are exocellular enzymes and are the main activities produced among numerous side activities type hemicellulases, glycosidases. The Table 1 gives the spectrum of enzymatic activities contained in three commercial preparations A, B and C. 

Wild apricot (Prunus armenica L.) grows naturally in hilly areas of northern India. It is highly acidic, fibrous, and low in TSS, and, thus, not utilized commercially. Preparation and evaluation of a vermouth from its fruit was undertaken (Abrol, 2009). Vermouths at different sugar (8,10, and 12 °Brix), alcohol (15%, 17%, and 19%), and spices levels (2.5% and 5%) were prepared. Those used in extract preparation are shown in Plate 8.1. The base wine was prepared from crushed fruit, adjusted to 24 °Brix, and diluted in a 1 2 ratio with water. To this mixture was added 200 ppm sulfur dioxide, 0.1% diammonium hydrogen phosphate (DAHP), and 0.5% pectinase enzyme. A 24-h active yeast culture initiated fermentation. The procedure is illustrated in Fig. 8.4. A maturation period of 6 months improved the quality of the vermouth. 

Apricot was used as a model for studies of fruit puree clarification. Various puree concentrations were treated for 30 min at 50° C with 0.4 cc/L, each, of commercial cellulase and pectinase enzyme and clarified by filtration through a 0.45(im pore size ceramic microfilter. Sparkling clear apricot juice was produced at flux rates from 90-190 L/m2h. Above 13° starting Brix. juice flux showed little increase with increasing starting Brix. Dissolved solids flux increased substantially with increasing starting Brix. Permeate remained clear and retained most of its flavor and aroma when concentrated by vacuum evaporation to 58° Brix. There appears to be some retention of enzymes by the filter. Retained enzymes were successfully utilized in a 4 h trial in which untreated puree was continuously added to retentate. in amounts equal to permeate removed, after startup on enzyme-treated puree. 

Neukom and coworkers isolated, from commercial pectinase, an enzyme that catalyzes the /8-eliminative degradation of pectin and that was called pectin trans-eliminase. 

For enzymes for commercial use, the purification process may be rather rough and proteins and enzymes with similar properties to the objective enzyme may be included in the preparation. Therefore, there is the possibility that the some chitosanolytic enzymes may be present in the crude lipase. According to the previous literature mentioned above and results of this present work, among the commercial enzymes which exhibit both their labeled activity and chitosanolytic activity, we speculate that carbohydrases such as pectinases and cellulases are more likely to be bifunctional enzymes than lipases and proteases, because the structures of the substrates of these carbohydrases are similar to each othe, which is confirmed from the experiments. 

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. 

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. 

As this enzyme proved specific for the release of acetyl groups from MHR, to a maximum of 70 %, and is essential for the degradation of MHR by RG ( Figure 3), it was concluded to be comparable to that isolated previously from A. aculeatus[8,9]. The importance of this enzyme in the application of tailormade commercial pectinases is discussed elsewhere in these proceedings as well (H.P. Heldt-Hansen et al.). 

A commercial pectinase, immobilised on appropriately functionalised y-alumina spheres, was loaded in a packed bed reactor and employed to depolymerise the pectin contained in a model solution and in the apple juice. The activity of the immobilized enzyme was tested in several batch reactions and compared with the one of the free enzyme. A successful apple juice depectinisation was obtained using the pectinase immobilised system. In addition, an endopolygalacturonase from Kluyveromyces marxianus, previously purified in a single-step process with coreshell microspheres specifically prepared, was immobilised on the same active support and the efficiency of the resulting catalyst was tested. 

Cloud loss may also be prevented by enzymic destruction of low ester pectins prior to their precipitation as pectates. Commercial fungal PG preparations (AO, Al) or PG derived from yeast (A2) have been used successfully to stabilize cloud of unpasteurized PE active juice. As only the low ester pectins need be destroyed to prevent cloud loss, considerably less PG is required than PL (30). Cloud stabilization with pectinases permits production of cloud stable juices with lower pasteurization temperatures (AO). 

Enzyme Activity. Seven commercial pectinases were obtained from Miles Laboratories, Elkhart, IN 46514, Novo Laboratories, Wilton,... 

Figure 9. Gel filtration chromatography of the HCl-soluble apricot pectin fraction, degraded by various enzyme systems on a Sephacryl S—300 column (68 x 1.05 cm), eluent 0.05 M phosphate buffer pH 7. AGA is anhydrogalacturonic acid Pectinex is a wide-spectrum commercial pectinase. (Reproduced with permission from ref. 54. Copyright 1985.)...

Similarly, an a-L-arabinosidase has been affinity purified from a commercial pectinase preparation on columns of immobilized arabinan (Waibel et al., 1980). The techniques of affinity chromatography therefore offer a rapid and relatively simple method for obtaining highly purified, specific enzymes. 

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