Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. In plant cells, pectin consists of a complex set of polysaccharides that are present in most primary cell walls and particularly abundant in the non-woody parts of terrestrial plants. Pectin is a natural part of human diet, but does not contribute significantly to nutrition. The daily intake of pectin from fruits and vegetables can be estimated to be around 5 g. Consumption of pectin has been shown to reduce blood cholesterol levels. The mechanism appears to be an increase of viscosity in the intestinal tract, leading to a reduced absorption of cholesterol from bile or food.
Another structural type of pectin is rhamnogalacturonan II. Amidated pectin as a food additives is a modified form of pectin. Here, some of the galacturonic acid is converted with ammonia to carboxylic acid amide. To prepare a pectin-gel, the ingredients are heated, dissolving the pectin. Upon cooling below gelling temperature, a gel starts to form.
The amount, structure and chemical composition of pectin differs among plants, within a plant over time and in various parts of a plant. During ripening, pectin is broken down by the enzymes pectinase and pectinesterase, in which process the fruit becomes softer as the middle lamellae break down and cells become separated from each other. High-ester pectins set at higher temperatures than low-ester pectins. However, gelling reactions with calcium increase as the degree of esterification falls.
Other food additives: Xanthan Gum Carboxy Methyl Cellulose Guar Gum
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