Pectic purified isolated

The quality of extracted citrus juices depends on enzyme reactions that occur not only in the fruit during the development period, but also in the juice during processing. When juice is extracted from citrus fruit, enzymes are released from their normal restraint in the cell. Several of these enzymes catalyze reactions that adversely affect taste and appearance of the juice. Unless the reactions are controlled, the juice products will not meet the standards of quality set up by the USDA Food Safety and Quality Service. The two reactions of commercial importance are the hydrolysis of pectin to pectic acid, which clarifies juice, and the lactonization of limonoic acid A-ring lactone to the bitter compound, limonin. Research efforts to identify and characterize the reactions, to isolate and purify the enzymes, and to develop methods to control the reactions are described in this review. 

The only pentosans which have been studied to any great extent are the xylans. These can be obtained from all lignified cell membranes by extraction with 5% sodium hydroxide solution after lipids, pectic materials etc. have been removed. The conditions necessary to avoid degradation during isolation have been outlined.2 Early structural determinations indicated that arabinose was present as a non-reducing end-group in a branched molecule which had a chain-length of 18-20 D-xylo-furanose residues.27 It has been shown recently, however, that the xylan from esparto holocellulose can be purified free of arabinose after several re-precipitations of the copper-complex.28... 

A second group of endo pectin lyases is characterized by optimum activity at slightly basic pH and by the ability to degrade polygalac-turonic acid (even though pectin is still favored). Sherwood 129) isolated this type of pectin lyase from Rhizoctonia solani. The enzyme had an optimal activity at pH 7.2 and degraded pectin faster than pectic acid. Bateman 128) found two pectin lyases from this microorganism which, when purified, were stimulated by cations and inhibited by EDTA. Optimal activity was between pH 8.0 and 9.0. 

Continued efforts are still ongoing to find economical ways to isolate and purify these compounds [20], Furthermore, rme sees in olive pomace a source for squalene (16) [32], tocopherols (17) [33], D-marmitol (18) [34], triterpenes oleanolic (19) and maslinic (20) acids [35], pectic polysaccharides [13], hemicelluloses [36], and oligosaccharides [34]. 

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