【作者】 胡晓溪；

【导师】 吴晖； 叶盛权；

【作者基本信息】 华南理工大学 ， 食品工程， 2011， 硕士

【摘要】 玉米酒精糟是玉米酒精工业的主要副产物。玉米酒精糟中含有丰富的蛋白质、膳食纤维及色素资源。我国玉米酒精糟产量巨大,但目前玉米酒精糟的应用范围仅局限于动物饲料方面,有的工厂甚至将其当废物排放。这样不仅造成资源的极大浪费,也对生态环境产生相当大的污染。因此,寻找新的途径,开发高附加值产品,更加高效地利用玉米酒精糟,具有重要的经济效益与环境意义。本文根据玉米酒精糟的组成特性,探索玉米酒精糟的高值化利用技术路线,即先以超声辅助法从玉米酒精糟中提取玉米黄色素;然后利用Alcalase蛋白酶对玉米酒精糟蛋白进行水解,制备具有醒酒活性的玉米活性肽并加以分离纯化;最后剩余的水解残渣经碱水解、分离、洗涤、烘干等工艺制得玉米膳食纤维。通过这一系列的深加工操作,力图实现玉米酒精糟资源的高值化利用。本论文主要研究内容如下:(1)对超声法提取玉米酒精糟中的玉米黄色素进行了研究,以吸光度值为指标,采用响应面法优化玉米黄色素的提取工艺条件。研究表明,在液料比为10.3:1、提取温度为51.7℃、超声时间为41min和100W超声功率的条件下玉米黄色素的提取效果最佳,得率为106.8μg/g。(2)应用碱性蛋白酶(Alcalase)对提取玉米黄色素后的酒精糟进行水解,考察了底物浓度、酶与底物比、温度、pH值和水解时间等因素对水解度的影响,并在此基础上进行正交试验,得到玉米酒精糟蛋白水解的最佳条件为:底物浓度6%,加酶量2400U/g原料、温度55℃,pH值为9,水解160min,水解度达到最大值33.37%,肽提取率可达52.46%,玉米肽得率为18.25%。同时利用大孔吸附树脂AB-8对玉米肽液进行脱色处理,脱色率为61.43%、氮回收率82.73%。(3)以乙醇脱氢酶(ADH)的激活率跟踪测试玉米酒精糟水解产物玉米肽的醒酒活性,试验结果表明,水解得到的玉米肽具有较强的醒酒活性。在33.37%DH范围内玉米肽醒酒活性随水解度的增大而增大,最佳醒酒活性与最大水解度条件一致。将玉米粗肽通过Sephedax G-25、Sephedax G-15凝胶层析进行分离纯化,获取了醒酒活性最强的组分C-3,其对ADH的激活率达34.26%。而后通过凝胶过滤层析法测得了该组分的分子量大小为528D。并测试了玉米粗肽及C-3组分的氨基酸组成,结果显示丙氨酸、亮氨酸含量相对较高,推测它们可能与醒酒活性相关性最大。(4)以玉米酒精糟水解残渣为原料,采用碱法对总膳食纤维进行了提取,在氢氧化钠浓度为0.2mol/L,用量为10:1(V/M),反应时间为80min,反应温度为70℃的碱水解条件下,水解最彻底,所得到的膳食纤维蛋白含量最低,膳食纤维得率和纯度分别为27.64%和85.42%。所得膳食纤维用10%的H2 O2脱色处理1h,产品可达到较理想的浅黄色。膳食纤维的膨胀性为4.96mL/g,持水性为5.31 g/g,持油性为2.83g/g。更多还原

【Abstract】 Corn distillers dried grains with solubles is the main by-product of the corn-based alcohol industry. It is rich in protein, dietary fiber and pigment resources. Though the output of corn distillers dried grains with solubles is very high in China, currently, its scope of application is just limited to animal feed. Some factories even pull it as waste. In this case, it not only causes tremendous waste of resources, but also generates considerable ecological environmental pollution. Therefore, finding a new way to make corn distillers dried grains with solubles used more efficiently and to develop high value-added products is of great economic and environmental significance.According to its composition characteristic, a technology route of higher value application of corn distillers dried grains with solubles was studied in this paper. Firstly, ultrasound-assisted method was used to extract maize yellow pigment from corn distillers dried grains with solubles. Secongdly, alcalase was used to make protein from corn distillers dried grains with solubles hydrolyzed so as to produce corn activity peptides. Then the peptides were separated and purified. Finally corn dietary fiber is prepared by alkali hydrolysis from hydrolysis residue through alkaline hydrolysis, separating, washing, drying and other operations. After these operations, corn distillers dried grains with solubles would be highly efficiently utilized. Generally speaking, the main contents of this paper are as follows:(1) Ultrasound extraction of maize yellow pigment from corn distillers dried grains with solubles was studied. The extracting conditions were optimized by response surface method. Results indicated that the optimum conditions were liquid-solid ratio of 10.3:1, extraction time of 41 minutes, extraction temperature of 51.7℃and ultrasonic power of 100W. And the greatest extraction ratio achieved 106.8μg/g。(2) After extracting maize yellow pigment, protein of corn distillers dried grains with solubles was hydrolyzed by alkaline protease. Effect of the substrate concentration, enzyme dosage, reaction time, temperature and pH on the degree of hydrolysis was studied. Then the enzymatic hydrolysis conditions were optimized by an orthogonal test. Results indicated that substrate concentration of 6%, enzyme dosage 2400U/g, temperature of 55°C, pH9 and hydrolysis for 160 minutes were the optimum conditions. Under such conditions, degree of hydrolysis was 33.37%, extraction rate of peptide was 52.46% and the yield of corn peptide was 18.25%. Then corn peptide was decolorized by AB-8 macroporous adsorption resin. The decolorization rate was 61.43% and the nitrogen recovery rate was 82.73%.(3) The antialcoholism activity of hydrolyzate was tested by the activity ratio of alcohol dehydrogenase. Tests showed that the hydrolyzate had a fairly strong antialcoholism capacity. Within the 33.37% DH,antialcoholism activity increased with the degree of hydrolysis, and the maximum antialcoholism activity was consistent with the maximum degree of hydrolysis. Then crude corn peptide was separated and purified by gel chromatography. The component C-3 was got, which had the greatest antialcoholism activity. Its ADH activation ratio was 34.26%. Molecular weight of the C-3 was measured by gel filtration chromatography and it was 528Da. Meanwhile the aminso acid composition of crude corn peptide and C-3 was tested. Results showed that contents of alanine and leucine contents were very high. They should be associated with the antialcoholism activity.(4) Alkaline process was used to extract total dietary fiber from the residue of corn distillers dried grains with solubles after enzymatic hydrolysis. When NaOH concentration was 0.2mol/L, liquid-solid ratio was 10:1(V/M), reaction time was 80 minutes and reaction temperature was 70℃, protein content of the dietary fiber was the lowest. The yield of dietary fiber was 27.64% and its purity was 85.42%. Then the dietary fiber was decolorized by 10% H2 O2. It was available to achieve an ideal light yellow colour within 1h. The expanding ratio of dietary fiber was 4.96mL/g,water holding capability was 5.31g/g,oil absorption was 2.83g/g.更多还原