Key Technology Of Glucoamylase Concentration By Carbon Dioxide Hydrate

With the boom in enzyme preparation industry,glucoamylase as a necessary biocatalyst of production process in the light industry gets more and more attention.Glucoamylase is widely used in food, pharmaceutical, chemical and other industries.Concentrate plays an important role in glucoamylase production. The concentration technology affects the quality and price of enzyme, and can also affect transport costs.Concentrate treatments by evaporation or by membrane are most commonly used in modern factory, but both of them have disadvantages such as poor economy. Freeze concentration can maintain the quality of the enzyme, but it is only applicable to small quantities of enzyme concentration. It still suffers from low cost and industrial-scale technological barriers.Concentrated solution by hydrates gets more and more attention because of its low temperature and low power consumption. The glucoamylase solution was concentrated by forming carbon dioxide hydrates in this paper. The effects of the initial glucoamylase concentration such as temperature and gas pressure on the phase equilibrium of carbon dioxide hydrates were systematically investigated. Compared with phase equilibrium curve in pure water, the carbon dioxide hydrates phase equilibrium curve in glucoamylase solution shifted to the left, which exhibited that lower temperature and higher gas pressure can form hydrates in glucoamylase solution than pure water. The gas pressure increased with the increase of enzyme content at the same temperature. The complex internal structure of the reactor could provide more condensation nuclei for hydrates forming, which can shorten the induction time required in the reaction.The factors that effected dehydration rates were discussed at different stirring speeds of 300 、 600 and 900 rpm. The results showed that stirring enhanced the hydrate formation, and then increased the reaction speed and the rates of dehydration.The influences of temperature to dehydration rates were discussed in different concentrations of 5 times and 10 times diluted glucoamylase solution. Above freezingtemperature, lower reacting temperatures were more conducive to rapidly produce large quantities of hydrates. The dehydration rates were measuered in different initial pressure of seven points chosen from 2.6 MPa to 4.2 MPa intermediately. In the selective pressure range, dehydration rates increased with the increasing initial pressure. The rates of hydrate formation should be controlled to reduce glucoamylase entrained in the hydrate crystal.