Pectinic acids, commercial production

There are important developments to be expected in the commercial production of PM. As noted above, this enzyme proved to be a useful demethylating agent in the production of low-ester pectins. The use of enzymes has certain advantages over acid or alkali, and this fact might eventually create considerable market for PM preparations that are free or essentially free of PG. 

Most plants contain pectin in the intercellular layer between the primary cell walls of adjoining cells. Six to seven million kg of purified pectin are produced annually, more than half of which is extracted from citrus peel C. ) Of this amount, 80 to 90% is used in the manufacture of jellies, jams, and similar products ( ). In this chapter, jelly will be used to denote the product formed from pectin, sugar, and acid under specific conditions. Gel will mean a similar physical state but not the commercial product O). 

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 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. 

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. 

Yapo, B. M. Lemon juice improves the extractability and quality characteristics of pectin from yellow passion fruit by-product as compared with commercial citric acid extractant. Bioresource Technology, v. 100, p. 3147-3151, 2009b. 

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