GB437683A - Improvement in pectin and its manufacture - Google Patents

Abstract

Dried pectin is obtained by incorporating with liquid pectin obtained in any suitable manner an adherence retarding agent and then applying the mixture to a drying surface in the form of a relatively thin layer whereby a dry coherent film is formed which can readily be removed. Suitable substances which act as adherence retarding agents include certain polyhydric alcohols, such as glycerine, and some derivatives; oils such as olive oil, lemon oil or animal oils such as cod liver oil; refined mineral oil or petroleum; waxes, paraffins and sugars. The natural product from which the pectin is extracted may contain a sufficient amount of one or more of these bodies. Substances which are insoluble in or immiscible with the liquid pectin may be readily dispersed therein. The pectin may be dried on a heated drum, disc, travelling metallic belt or other suitable smooth surface. Preferably the liquid is applied to the surface of a drum and is fed into a trough extending across the face of the drum and formed by a portion of the cylindrical drying surface and a plate arranged at an angle. A short distance in advance of the pool in the trough an adjustable bar is mounted across the surface of the drum to free the film from air bubbles. The applied coating is preferably about 0,05 to 0,06 inches in thickness and is dried until the coherent film is about 10 per cent of the thickness of the applied coating. It is then removed, e.g. by a flexible blade of stainless steel maintaining contact across the entire face of the drum. For example, liquid pectin mixed with glycerine is dried in approximately 20 seconds at 214 DEG F. and in 7,5 seconds at 225 DEG F. The temperature and duration of heating should be arranged to avoid deterioration of the pectin. If desired, the adherence retarding agent together with other impurities may be removed by passing the pectin film through a solvent which will not affect the pectin itself, e.g. using glycerine, a solution of 95 per cent alcohol may be used for its removal. Any solvent retained in the film can be removed by careful drying, e.g. in an air drier. Furthermore, the film may be treated to control its hydrogen ion concentration by passage through a bath of weak alkali or acid. The alkali or acid may be incorporated in the solvent bath employed to remove the adherence retarding agent, or in a subsequent bath. For domestic jelly manufacture, the hydrogen ion concentration is adjusted to a pH of 3,55 to 2,0, and for commercial purposes, preferably above pH 3,55. Excessive ash content of the pectin, due to alkali and alkaline earth salts of the pectin acids, may be removed by treatment in an acid bath, and the hydrogen ion concentration is also increased.