Аbоut a theoretical yield of glucose from starch

Abstract

Starch is the raw materials for production of crystal food glucose. With at enzyme conversion of the high purity starch, it is possible to receive glucosic syrups of a glucose equivalent (GE) 98%, where there is about 95% glucose and maltose and maltotriose – of about 5%. Starch hydrolysis is carried out with a gain of solids. Thus, 100 kg of amylum is possible to give up to 109.81 kg of glucose syrup on dry basis. Taking in account the losses at manufacture steps a yield can decrease to 105.61 kg. The purified glucose syrup is concentrated up to 73–75% of dry matters and goes to a crystallization step. Crystallization of glucose is carried out in a supersaturated solution within 56–70 hours at reduced temperature from 46–48 °C to 24–26 °C, resulting a mixture of glucose crystals and an intercrystal run-off syrup called a massecuite. The crystallization process is stopped when a 50% of crystals content in massecuite is reached. At the same time glucose yield will be 105.61/2 = 52.8%. Crystallization is carried out according to the single-stage scheme, with partial return of the end product – hydrol into the hydrolised syrup. Then the massecuite is sent to a centrifugation step for dividing glucose crystals and a run-off syrup, which is partially returned to the initial syrup to reduce in GE. The second part of the run-off syrup goes to realization. It must be kept in mind: the higher GE of the glucose syrup sent to a crystallization step, the more quantity of a hydrol is possible to be returned to hydrolysed syrup. Therefore, it is in a resulted a higher yield of glucose crystals. On the basis of the carried-out calculations the computer program was made with which it is possible to define a theoretical glucose and a hydrol yield, while changing values of a hydrolysed syrup. The higher GE values of a hydrolysed syrup are the higher yield of crystal glucose and the lower one of hydrol are. So, at 98% GE of a hydrolysed syrup it is possible to return about 64.66 kg of a hydrol to 105.61 kg of syrup the glucose yield will increase up to 85%, and at the same time a hydrol yield will be (105,61 – 85) i.e. 20.61%.