Patent ID: 7150794
Filing Date: 2006-12-19
Classification: C13B,C13K

Abstract:
1. A process for the production of a crystalline fructose of high purity, utilizing as raw material the sucrose, comprising: (a) subjecting an aqueous solution of sucrose having a minimal degree of purity of 99.5% (dsb), and with a dry solids concentration of 60% by weight, to hydrolysis catalyzed by hydrochloric acid, thereby producing a solution of fructose and glucose having a dry solids concentration of 60% by weight, which is then neutralized and deionized; (b) chromatographing the neutralized and deionized aqueous solution of fructose and glucose having a dry solids concentration of between 58% and 59% by weight at a temperature of between 58° C. and 62° C., to partially separate fructose from the glucose, thereby yielding a solution of fructose and glucose having a dry solids concentration of between 22% and 26% by weight and a fructose content of between 84% and 90% (dsb), which is then evaporated under vacuum, at a temperature of between 59° C. and 61° C., until a dry solids concentration of between 79% and 81% by weight is reached, and concentrating by vacuum evaporation at the same temperature of between 59° C. and 61° C. to obtain an aqueous feed syrup at a temperature of between 59° C. and 61° C., and having a dry solids concentration of at least 92% by weight, a fructose content of between 84% and 90% (dsb) and a glucose content of between 9% and 15% (dsb); and (c) rapidly cooling the aqueous syrup obtained from a temperature of between 59° C. and 61° C. to a temperature of between 52° C. and 58° C., maintaining the temperature constant, and seeding the syrup with crystallization seeds consisting of pure fructose crystals having sizes of between about 40 microns and about 80 microns, for a period of between two hours and four hours, and in the proportion of between 5% and 9% by weight of the mass of pure fructose seed in relation to the mass of fructose in the syrup, to produce a massecuite comprised of a mass of slightly grown fructose crystals and an aqueous syrup of fructose and glucose, (d) subjecting the massecuite to a controlled slow cooling at a constant cooling rate of between 0.7° C./h and 0.9° C./h, until the temperature of the massecuite is stabilized at a value of between about 54° C. and about 48° C., thereby yielding an aqueous massecuite containing moderately grown and morphologically well defined fructose crystals, (e) slowly and regularly adding absolute ethanol at the same temperature as the temperature of the massecuite over a period of between 6 hours and 10 hours, until a weight ratio alcohol to water in the massecuite of between 1.0 and 2.0 grams of ethanol per gram of water is reached, thereby producing an aqueous alcoholic massecuite containing substantially grown crystals, (f) cooling the massecuite slowly from the stabilized temperature of between about 54° C. and about 48° C., to a temperature of between about 30° C. and about 25° C., at a constant cooling rate of between 0.4° C./h and 0.8° C./h, which cooling is followed by an additional period of 1 hour to stabilize the temperature, to obtain fully grown fructose crystals, (g) separating the fully grown fructose crystals from the aqueous alcoholic mother liquor by centrifugation, washing the fructose crystals with cold ethanol at a temperature of 4° C., and drying the fructose crystals by direct contact with dry air at a temperature of at most 80° C., to obtain crystalline fructose of high purity.