【作者】 郭娜；

【导师】 姜绍通；

【作者基本信息】 合肥工业大学 ， 农产品加工与贮藏工程， 2013， 博士

【摘要】 小麦麸皮是小麦制粉过程中的副产物,占小麦颗粒的14-17%左右,目前主要用于饲料和发酵工业,综合利用率低。小麦麸皮纤维难以降解是小麦麸皮利用率低的主要原因,因此促进小麦麸皮纤维降解糖化和提高其糖化液的利用研究有重要的现实意义。本研究以提高小麦麸皮综合利用价值为目的,实现小麦麸皮分层利用。以小麦麸皮为原料,采用酶解去除淀粉和碱浸提法去除蛋白质制备小麦麸皮纤维；利用小麦麸皮纤维发酵制备纤维素酶,并联合木聚糖酶酶解小麦麸皮纤维制糖；结合蒸汽爆破和酶解技术以及微波酸水解技术,降解糖化小麦麸皮纤维；使用小麦麸皮纤维糖化液发酵制备苹果酸,优化发酵条件；通过发酵法利用小麦麸皮纤维糖化液,富集制备阿拉伯糖；以5000t/a小麦麸皮综合利用厂为例分析小麦麸皮综合利用经济效益。主要研究内容及结果如下：1.小麦麸皮成分分析结果表明小麦麸皮含有12.80%的淀粉、18.51%的蛋白质和45.40%的小麦麸皮纤维等；优化确定了蛋白质提取的最佳工艺条件为体系pHH12,料液比1：15,温度50℃和时间3h,提取量达到15.85%。通过小麦麸皮蛋白质成分和营养评价结果表明：清蛋白含量占麸皮质量的4.42%,球蛋白含量占2.92%,醇溶蛋白占3.29%,谷蛋白占4.79%和不溶蛋白占2.97%;小麦麸皮蛋白质具有一定的营养价值,必需氨基酸含量占蛋白质质量的20.75%,E/T为37.04%。经过淀粉酶和蛋白质浸提后,小麦麸皮纤维含70.27%粗纤维。2.以钴-60诱变筛选出的高产纤维素酶的绿色木霉发酵并优化确定了纤维素酶发酵的最佳条件：固液比1：7.5,发酵液初始pH6.0,发酵时间96h,接种量4%。在此条件下,发酵产物中纤维素酶酶活可达到1.90u/mL。通过盐析、DEAE-52和Sephadex G-75层析分离纯化获得了β-葡萄糖苷酶,其分子量为59.8kDa,且酶比活力提高了128.93倍。在pH5.0和50-时,β-葡萄糖苷酶酶活能够保持高活力和稳定性；Mg+和表面活性剂吐温80能够明显促进β-葡萄糖苷酶酶活力,而Fe3+、Cu2+和SDS对β-葡萄糖苷酶的酶活力有较大抑制作用。通过对纤维素酶和木聚糖酶酶解条件的优化,获得最佳酶解条件：底物浓度为2g/40mL,温度50-,pH5.0,处理时间8h,此时,酶解小麦麸皮纤维后得到的糖溶液浓度为9.70mg/mL。3.蒸汽爆破破坏小麦麸皮纤维结构,纤维素和半纤维素有明显降解,汽爆后的纤维pH值随蒸汽压力增大而降低,并且颜色逐步加深；汽爆后小麦麸皮表面结构降解,纤维素晶体暴露：酶解汽爆后的小麦麸皮纤维时,还原糖和葡萄糖含量明显增大,但随着汽爆压力增大而降低；酶解后木糖含量降低且与汽爆压力关系不大。4.微波功率、水解时间以及酸浓度对小麦麸皮纤维糖化影响显著。根据单因素条件及响应面分析法优化分析结果,在小麦麸皮纤维1g/40mL,硫酸浓度1.86%、水解时间36min和微波功率350W的条件下,能得到浓度分别为4.86mg/mL的木糖和12.91mg/mL的还原糖。小麦麸皮纤维经微波酸水解处理后,麸皮中半纤维素溶解,纤维素暴露,结晶度提高,当微波功率增大到600W时,部分纤维素溶解,木质素变化不明显。5.以小麦麸皮糖化液为碳源,考察硫酸铵、硫酸镁、温度和碳酸钙添加量等单因素对曲霉发酵制备苹果酸产量的影响,并使用响应面分析法进行优化,获得最佳产酸条件,硫酸镁0.17g/L、硫酸铵2.34g/L、碳酸钙70g/L和温度31℃,该条件下,苹果酸产量达到最大值15.73g/L通过筛选出的管囊酵母发酵小麦麸皮纤维糖,发酵时间72h后,阿拉伯糖含量5.93g/L,占总糖比例上升至62.10%。经脱色、脱盐和浓缩处理后,阿拉伯糖母液在4-下重结晶,可制备纯度为90.80%的阿拉伯糖。6.以年加工量5000t小麦麸皮综合利用工厂为例,设计了小麦麸皮生产蛋白质、糖以及苹果酸等产品的工艺技术路线,并通过物料衡算分析经济效益,结果表明小麦麸皮深加工后,可获得一定的收益。更多还原

【Abstract】 Wheat bran is the main by-product of wheat flour, which is about14-17%of wheat grain.The comprehensive utilization rate of wheat bran is low for which is mainly used for feed and fermentation industry and fiber is hard degradation now. Therefore stduies for promoting the utilization of wheat bran have important practical meaning.In this study, wheat bran is a raw material for the purpose of enhancing utilization value. Wheat bran protein was extracted by alkali solution, and nutritive compositions were measured; wheat bran fiber was enzymatic saccharification by a combined treatment of xylase and cellulase prepared with fermentation; saccharification of wheat bran fiber using steam explosion combined enzymatic hydrolysis, and microwave acid hydrolysis; malic acid was prepared by fermentation of wheat bran sugar, and the fermentation conditions was optimized; arabinose was enriched preparation by fermentation using wheat bran fiber sugar; and finally the benefits of wheat bran was analyzed using a comprehensive utilization factory.The main results and conclusions obtained are as follows.1. Wheat bran component was analysised and showed that there were12.80%starch,18.51%protein and45.40%wheat bran fiber. enzymatic hydrolysis condition of starch and protein extraction condition were optimized, which showed the protein extraction reached the maximum of15.85%at pH12, solid-liquid ratio1:15,50℃and time of3h and precipitation pH3.8. There were4.42%of albumin,2.92%of bran globulin and3.29%of gliadin,4.79%of glutenin and2.97%of insoluble protein, and a high nutritional value with20.75%of essential amino acid content compared the protein quality,37.04%of E/T value. Wheat bran fiber reached70.27%after removing starch and protein.2. An efficient cellulolytic strain M9was selected from mutation Trichoderma viride with Co-60irradiated, and the culture condition was optimized which were composed of wheat bran fiber of3g, solid-liquid ratio of1:7.5, initial pH6.0, fermentation time96h, inoculation of4%. Cellulase activity of the strain M9produced reached1.90u/mL. β-glucosidase was separated and perificated with salting out, DEAE-52and Sephadex G-75chromatography, its molecular weight of59.8kDa and128.93times of activity than the initial. The β-glucosidase maintained a high activity and stability at pH5.0and50℃, and the activity was enhanced the activity with Mg2+, Tween80surfactant and inhibited with Fe3+, Cu2+and SDS. Enzymatic saccharification conditions of wheat bran fiber were optimized by a combined treatment of xylase and cellulase:the substrate concentration2g/40mL, temperature50c, pH5.0, time of8h, and concentration of the sugar solution reached9.70mg/mL at this condition.3. Wheat bran fiber structure was destroyed obviously with steam explosion pretreatment, especially significant degradation of cellulose and hemicellulose; pH of WBFSE reduced and its color deepened with the steam pressure increased; degrees of crystallization was enhanced with fiber structure degradation of WBFSE; reducing sugar and glucose concentrations increased significantly with eneymatic hydrolysised, but decreased with steam pressure increased, xylose concentrations decreased and little relationship with the pressure of the steam explosion.4. Microwave power, hydrolysis time and acid concentration played remarkable impacts on the saccharification of wheat bran fiber. Saccharification conditions were optimize by response surface methodology:sulfuric acid concentration of1.86%, hydrolysis time36min and microwave power350W. In this condition, the xylose got maximum of4.86mg/mL and total sugar12.91mg/mL. Hemicellulose of WBF was dissolved, and degrees of crystallization was enhanced with the cellulose exposed, even partially dissolved when the microwave power increased to600W; lignin did not change obviously.5. The fermentation culture mediums of malic acid were optimized with response surface methodology, which was composed of magnesium sulfate0.17g/L, ammonium sulfate2.34g/L, calcium carbonate70g/L and temperature of31℃with the wheat bran sugar. In this condition, the malic acid production reached a maximum concentration of15.73g/L. A Pachysolen tannophilus was screened for fementation of wheat bran fibers sugar, and arabinose content reached5.93g/L,62.10%of the sugar after72h cultivated. The purity of arabinose reached90.80%with recrystallized under the temperature of4℃after decolorization, desalting and concentration prtreatment.6. Wheat bran utilization was analyzed with a factory of5000t processing capacity as example, as well as technology route of protein、sugar and malic acid were designed. Economic benefit was analyzed through material calculation, and the statistical result showed that deep processing of wheat bran could bring a certain profit.更多还原