Study On The Extrusion Maize Without Germ With Acid Aid For Alcohol Production

In this paper, traditional cooking and liquefaction process of alcohol production was substituted by extrusion process of maize without germ. Process parameters of the extrusion with acid aid procedure were researched, the results as follows:First, with theα-degree as evaluation index, extrusion parameters were studied. Optimum parameters of extrusion system were obtained from the experiment, that are diameter of die nozzle 11mm, extrusion temperature170℃, moisture of material 24%, speed of screw200r/min.Second, on the basis of the first experiment, we fixuped the diameter of die nozzle 11mm, carried out the experiment with acid aid. Hydrochioric acid was improved the best acid additive. Meanwhile, the alcohol fermentation experiment showed us that, extrusion maize without germ with hydrochioric acid better than extrusion maize without germ unitary. With the experimental method of the central composite design of four factors and five levels, the optimum parameters of extrusion system with acid aid were as follows: moisture of material 23.40%, speed of screw 234r/min, extrusion temperature 143℃, the mass ratio of hydrochioric acid/starch of material 0.0257.Third, the method of orthogonal test design was used to qualify the ratio of stuff and water, the quantity of carbohydrase and saccharifying time. The optimum parameters of saccharification process were obtained: the ratio of stuff and water 1∶3, the quantity of carbohydrase 120u/g, saccharifying time 45min. Saccharifying solution with 9.75% of reducing sugar can be obtained at the levels of the parameters.Fourth, yeast was added to the saccharifying solution for alcohol fermentation. The optimum parameters of fermentation process were obtained by the experimental method of quadratic general rotary design: fermentation temperature was 34.4℃, additive quantity of phytase was 7.12u/g and urea 0.093%. Extrudate of the maize without germ fermented in this process, the out put rate of starch was 58.35% in 55hours. The production period of alcohol was shortened for 9 hours.Fifth, though the comparison of energy consume, we drew a conclusion as follows: extrusion with acid aid can save energy 49.24% than traditional cooking and liquefaction, so the application of extrusion with acid aid to alcohol production industry is very feasible and it will have far-reaching meaning to the manufacturer.