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 Starch is characterized by instability in thermal action and easily changes its physical and chemical properties during intense heat treatment. Heating above 50 ° C and in the presence of moisture leads to irreversible swelling of starch grains and their possible partial gelatinization, and at temperatures above 80 ° C - even cracking of the grains, as a result of which they lose their characteristic luster (chandeliers) and become dull.
Such starch gives a paste of low viscosity and high acidity caused by the partial destruction of starch molecules and its oxidation.
Natural potato starch is characterized by a higher heat resistance compared to extrusion. The heat resistance of extrusion starch types is determined by the extrusion temperature and the type of raw material. Loss of starch mass, both in the area of dextrusion and in direct dextrusion, affect the activation energy of thermodextrusion.
During drying, a certain amount of grit is formed from the glued grains, which is isolated by sifting the starch.
A method for producing starch from potatoes has been developed, which provides for the simultaneous grinding, separation of the slurry and dehydration of the pulp in an inertial filter centrifuge, the rotor of which has a cone angle equal to or greater than the friction coefficient of the pulp, and is equipped with a means of grinding potatoes. The starch suspension removed from the centrifuge is concentrated on a hydrocyclone, refined and washed. Then the starch is dehydrated and dried.
A method for determining the ratio of amylose and amylopectin in potato starch has been developed.
To determine the ratio of polymer components in starch, a spectrophotometric method is used. Measurements are carried out on Photocolorimeters of the KFK-2 brand and an SF-26 spectrophotometer. The measurements are based on the ability of starch to form colored molecular complexes with iodine. Iodine complexes of amylose and amylopectin have a bright blue-violet color, differ significantly in their intensity. The absorption of light by the iodine amylopectin complex is only 3% of the intensity of the amylose complex. For the quantitative determination of amylose in natural starch, the method of constructing calibration lines is used - the dependence of the intensity of light absorption of a solution on the ratio of amylose and amylopectin in it.
German firms consider tapioca starch to be an alternative to potato starch, the prices of which have risen sharply. The new starch contains 10% more active substance than potato starch and therefore has a higher viscosity. It does not affect the taste of dishes, allows you to reduce the cost of seasoning, improves the transparency of the filling without the formation of lumps. This starch is obtained from fresh, ripe cassava roots by extraction. It is used in sausage production, for making sauces, soups, sweet dishes, yoghurts, processed cheeses, bakery, confectionery, low fat foods and snacks to build or improve texture.
Denisov D.
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