Makanjuola Oyenike, Greetham Darren, Zou Xiaoyan, Du Chenyu
School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK.
Key Laboratory of Functional Inorganic Material Chemistry, Heilongjiang University, Harbin 150080, China.
Foods. 2019 Jul 24;8(8):279. doi: 10.3390/foods8080279.
Sorghum bran, a starch rich food processing waste, was investigated for the production of glucoamylase in submerged fungal fermentation using . The fermentation parameters, such as cultivation time, substrate concentration, pH, temperature, nitrogen source, mineral source and the medium loading ratio were investigated. The glucoamylase activity was improved from 1.90 U/mL in an initial test, to 19.3 U/mL at 10% (w/v) substrate concentration, pH 6.0, medium loading ratio of 200 mL in 500 mL shaking flask, with the addition of 2.5 g/L yeast extract and essential minerals. Fermentation using 2 L bioreactors under the optimum conditions resulted in a glucoamylase activity of 23.5 U/mL at 72 h, while further increase in sorghum bran concentration to 12.5% (w/v) gave an improved gluco-amylase activity of 37.6 U/mL at 115 h. The crude glucoamylase solution was used for the enzymatic hydrolysis of the sorghum bran. A sorghum bran hydrolysis carried out at 200 rpm, 55 °C for 48 h at a substrate loading ratio of 80 g/L resulted in 11.7 g/L glucose, similar to the results obtained using commercial glucoamylase. Large-scale sorghum bran hydrolysis in 2 L bioreactors using crude glucoamylase solution resulted in a glucose concentration of 38.7 g/L from 200 g/L sorghum bran, corresponding to 94.1% of the theoretical hydrolysis yield.
高粱麸皮是一种富含淀粉的食品加工废料，本文研究了利用其通过深层真菌发酵生产糖化酶的过程。研究了发酵参数，如培养时间、底物浓度、pH值、温度、氮源、矿物质源和培养基装液量比。在初始试验中糖化酶活性为1.90 U/mL，在底物浓度为10%（w/v）、pH值为6.0、500 mL摇瓶中装液量为200 mL、添加2.5 g/L酵母提取物和必需矿物质的条件下，糖化酶活性提高到了19.3 U/mL。在最佳条件下使用2 L生物反应器进行发酵，72 h时糖化酶活性为23.5 U/mL，而将高粱麸皮浓度进一步提高到12.5%（w/v）时，在115 h时糖化酶活性提高到了37.6 U/mL。粗糖化酶溶液用于高粱麸皮的酶解。在200 rpm、55℃下以80 g/L的底物装料比进行48 h的高粱麸皮水解，得到了11.7 g/L的葡萄糖，与使用商业糖化酶得到的结果相似。使用粗糖化酶溶液在2 L生物反应器中进行大规模高粱麸皮水解，从200 g/L高粱麸皮中得到了38.7 g/L的葡萄糖浓度，相当于理论水解产率的94.1%。
