在玉米液化液中添加膨润土絮凝蛋白质的应用

以玉米粉为原料 ,采用酶法生产DE值低于 2 0的麦芽糊精过程中 ,玉米粉中含有水溶蛋白质和灰分 ,会进入液化液中 ,增加过滤的难度。经研究得到在液化液中加入膨润土絮凝蛋白质 ,应用在麦芽糊精的生产中 ,达到过滤容易。

玉米液化清液发酵生产柠檬酸工艺研究

以玉米液化清液为原料,黑曲霉为发酵菌株,通过单因素筛选以及正交试验对玉米清液发酵培养基进行优化研究。通过测定产酸量及菌丝球形态的观察,最终确定最优的培养基配方为:玉米浆0.7%,(NH_4)_2SO_41.0 g/L,MgSO_40.1 g/L,CuSO_40.8 mg/L,ZnSO_40.02 g/L,CaCl22.0 g/L,KCl 0.1 g/L,FeSO_40.34 mg/L,肌醇0.07 g/L。通过30 L发酵罐放大试验确定发酵液初糖浓度为18%、种龄27 h,分段通风转速控制,发酵60 h,柠檬酸产量达到18.33 g/100 m L,糖酸转化率达到100.3%,与带渣发酵方式相比,产酸量和转化率有较大幅度提高。

A mutation of Aspergillus niger for hyper-production of citric acid from corn meal hydrolysate in a bioreactor

The properties of the screened mutants for hyper-production of citric acid induced by carbon （12C6＋） ion beams and X-ray irradiation were investigated in our current study. Among these mutants, mutant H4002 screened from 12C6＋ ion irradiation had a higher yield of citric acid production than the parental strain in a 250-ml shaking flash. These expanded submerged experiments in a bioreactor were also carried out for mutant H4002. The results showed that （177.7-196.0） g/L citric acid was accumulated by H4002 through exploiting corn meal hydrolysate （containing initial 200.0-235.7 g/L sugar） with the productivity of （2.96-3.27） g/（L.h）. This was especially true when the initial sugar concentration was 210 g/L, and the best economical citric acid production reached （187.5±0.7） g/L with a productivity of 3.13 g/（L.h）. It was observed that mutant H4002 can utilize low-cost corn meal as a feedstock to efficiently produce citric acid. These results imply that the H4002 strain has the industrial production potentiality for citric acid and offers strong competition for the citric acid industry.