الفهرس 
IntroductiionOnly 14 pages are availabe for public view
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Abstract
A range of different pectinolytic enzymes occur in nature, produced by plant and microbial species. Pectic enzymes act on pectic substances which occur as structural polysaccharides in the middle lamella and the primary cell wall of higher plants. They are important for the texture of fruit and vegetables; texture changes during ripening and post-harvest storage are ascribed to pectic changes brought about by native pectic enzymes. These enzymes, together with microbial pectic enzymes, must also be considered in the technology of fruit and vegetable products
Pectic substances are complex acidic polysaccharides which occur in varying amounts in the middle lamella or intercellular spaces of all higher plants. They consist of α-l,4-D-polygalacturonide polymers, often complexed with two other polymers, a highly branched L-araban and a β-l,4-D-galactan. The carboxyl groups of the galacturonic acid units are partially esterified with methanol. The ethoxyl content varies with source and in the case of fruits varies with fruit development and ripening. The pectic enzymes are glycosidases and lyases which depolymerise the molecular chain without affecting the degree of esterification and esterases which de-esterify the molecule without changing the degree of polymerization.