小麦及其麦芽的木聚糖和木聚糖酶的研究

Research of Arabinoxylan and Xylanase in Wheats and Wheat Malts

作者: 专业:细胞生物学 导师:杜金华 年度:2010 学位:硕士  院校: 山东农业大学

Keywords

Wheat, Wheat malt, Arabinoxylans, Xylanase

        小麦麦芽是良好的啤酒酿造原料,酿出的啤酒风味独特,符合啤酒的发展潮流,应用前景广阔。研究筛选适宜酿造的小麦品种,作为延长小麦产业链条,提高小麦附加值的一种方式可以扩大小麦出路,刺激小麦种植业以加工为导向发展;拉动小麦内需,增加农民收入;推动我国小麦产业、麦芽工业、啤酒工业健康发展,其经济意义、社会意义巨大。然而小麦芽中富含的阿拉伯木聚糖对小麦芽在酿酒中的应用又很大的影响,因此研究阿拉伯木聚糖含量与木聚糖降解酶系的酶活成为重要项目之一。本研究对11个小麦品种的阿拉伯木聚糖含量及木聚糖酶酶活进行测定,并对木聚糖酶的酶学性质进行了研究,为适于酿酒小麦品种的筛选提供基础,主要结果如下:1间苯三酚-冰醋酸法的最适条件是反应液用量10 mL、反应20min,冷却后30min内基本稳定(P>0.05)。2 8、9、10号小麦中碱溶性阿拉伯木聚糖含量最低(P>0.05),分别为0.5811±0.0127%、0.6605±0.0620%和0.6603±0.0301%;9、10号麦芽中碱溶性阿拉伯木聚糖最低(P>0.05),含量分别为0.9746±0.0085%和0.7797±0.0508%。3 4、8、10号小麦中水溶性阿拉伯木聚糖含量最低(P>0.05),分别为0.5423±0.0645%、0.4681±0.0127%和0.3828±0.0403%;而在麦芽中,7、8号品种最低(P>0.05),含量为0.3362±0.0518%和0.2429±0.0467%。4小麦发芽后,大部分品种碱溶性阿拉伯木聚糖含量升高,增大最多的是4、7、8号品种(P>0.05),只有3号品种略微减少;水溶性阿拉伯木聚糖含量都降低。5 DNS反应最适条件为反应液用量3 mL、反应15min,反应完成后35min内基本稳定(P>0.05)。6小麦发芽后木聚糖酶酶活均增大,小麦的酶活都在65.00~85.00 IU/g之间,而在麦芽中各个品种间的差异不显著(P>0.05),都在100.00~115.00 IU/mL之间。7原小麦中水溶性阿拉伯木聚糖含量与碱溶性阿拉伯木聚糖含量呈极显著正相关(P<0.01),而木聚糖酶酶活与阿拉伯木聚糖含量呈负相关(P<0.05)。而在小麦芽中水溶性阿拉伯木聚糖含量与碱溶性阿拉伯木聚糖含量呈负相关(P<0.05),而木聚糖酶酶活与水溶性阿拉伯木聚糖含量呈负相关(P<0.05),而与碱溶性阿拉伯木聚糖呈极显著正相关(P<0.01)。8小麦木聚糖酶酶促反应的最适温度是50℃,最适pH值是5.5~6.0,最适底物浓度是1.0000%,最适底物与酶液用量比例为9/1,最适反应时间为5~9min。9降低浸麦度能够促进碱溶性阿拉伯木聚糖的形成和水溶性阿拉伯木聚糖的降解,提高了木聚糖酶酶活。在制麦过程中,20℃和50℃时测得的木聚糖酶酶活最高。因此在小麦制麦工艺的改进中可适当延长木聚糖酶活性较高时温度的时间,以增强木聚糖酶的作用,降低阿拉伯木聚糖的含量。
    Wheat malt is a good raw material for brewing, and the beer is a popular drink in current in the world. Selecting the suitable wheat variety for malting is an effective measure to develop advanced processing of wheat, to enhance the income of peasant, and is helpful to the development of wheat, malting and beer industry. But the arabinoxylans which is rich in wheat malts affect the application of wheat malts in beer brewing, so the research of the content of arabinoxylans and the activities of xylanolytic system is important. In this research the content of arabinoxylans and the activities of xylanase of 11 wheat cultivars were determined and the characteristics of xylanases were researched. The main conclusions were as follows:1 The optimal determination condition of arabinoxylans was 10 mL phloroglucin-glacier acetic acid reagent, react time 20min, and within 30min after cooled the reaction product was stable (P>0.05).2 The No.8, No.9 and No.10 of wheat had the lowest contents of AEAX, which were 0.5811±0.0127%, 0.6605±0.0620% and 0.6603±0.0301%, respectively (P>0.05); the No.9 and No.10 of wheat malts had the lowest content of AEAX, which were 0.9746±0.0085% and 0.7797±0.0508% respectively (P>0.05).3 For content of WEAX, the No.4, No.8 and No.10 of wheats (P>0.05) and the No.7 and No.8 of wheat malts (P>0.05) had the lowest, which were 0.5423±0.0645%, 0.4681±0.0127%, 0.3828±0.0403%, 0.3362±0.0518% and 0.2429±0.0467% severally. No.7 and No.8 was maximum (P>0.05).4 WEAX contents of all the wheat cultivars were declined and xylanases activities of all the wheat cultivars were raised.5 The optimal determination conditions of xylanase activities were as follows: 3 mL DNS, react time 15min, and within 35min the reaction product was stable (P>0.05).6 In the wheats researched, the xylanase activities were between 65.00~85.00 IU/mL, and 100.00~115.00 IU/mL after malting (P>0.05).7 In wheats, the contents of water extractable arabinoxylans and alkaline extractable arabinoxylan showed significant positive correlation (P<0.01), and xylanase activities and the content of arabinoxylans was negative correlation (P<0.05). However, in wheat malts, the contents of water extractable arabinoxylans and alkaline extractable arabinoxylan showed negative correlation(P<0.05), so did xylanase activities and the content of water extractable arabinoxylans(P<0.05), and xylanase activities and the content of alkaline extractable arabinoxylans showed significant positive correlation(P<0.01).8 The optimal temperature of action catalyzed by xylanase was 50oC, optimal pH was 5.5~6.0, optimal concentration of xylan was 1.0000%, optimal ratio of substrate and enzyme was 9/1, and optimal reaction time was 5~9min.9 Lower steep-out moistures can advance the synthesis of alkaline extractable arabinoxylans and the degradation of water extractable arabinoxylans, and enhance the xylanase activities. During malting, the xylanase activities in 20oC and 50oC were highest. So we can properly extension the time of higher activities temperature to enhance the xylanase activities and decrease the content of arabinoxylans.
        

小麦及其麦芽的木聚糖和木聚糖酶的研究

摘要7-9
Abstract9-10
1 引言11-33
    1.1 啤酒11-14
    1.2 我国小麦生产与加工现状14-15
    1.3 小麦啤酒15-17
    1.4 小麦芽17-18
    1.5 阿拉伯木聚糖18-25
        1.5.1 结构18-20
        1.5.2 理化性质20-21
        1.5.3 含量21-24
        1.5.4 阿拉伯木聚糖对酿酒的影响24
        1.5.5 阿拉伯木聚糖的提取、纯化与测定24-25
    1.6 木聚糖酶25-32
        1.6.1 来源25-26
        1.6.2 结构26
        1.6.3 作用机理26-27
        1.6.4 酶学性质27-30
        1.6.5 纯化30-31
        1.6.6 测定31-32
    1.7 立题背景及研究的目的意义32
    1.8 主要研究内容与目标32-33
2 材料与方法33-40
    2.1 试验材料33
    2.2 主要药品33-34
    2.3 主要仪器34
    2.4 试剂34-35
    2.5 试验方法35-40
        2.5.1 制麦芽35
        2.5.2 间苯三酚标准工作曲线的制作35-37
        2.5.3 木聚糖的提取37
        2.5.4 木聚糖样品测定37
        2.5.5 木糖与DNS 反应标准工作曲线37-38
        2.5.6 木聚糖降解酶系粗酶液的提取38
        2.5.7 木聚糖酶酶活测定38
        2.5.8 酶活计算38-39
        2.5.9 酶学性质39-40
        2.5.10 浸麦度对木聚糖含量和木聚糖酶活的影响40
        2.5.11 制麦过程中木聚糖酶酶活变化40
    2.6 数据处理与统计分析40
3 结果与分析40-56
    3.1 间苯三酚木糖反应扫描图谱标准工作曲线40
    3.2 间苯三酚反应条件40-43
    3.3 阿拉伯木聚糖含量43-45
        3.3.1 碱溶性木聚糖含量43-44
        3.3.2 水溶性木聚糖含量44-45
        3.3.3 小结45
    3.4 DNS 标准曲线45
    3.5 DNS 反应条件45-48
    3.6 小麦与麦芽木聚糖酶48-49
    3.7 阿拉伯木聚糖含量和木聚糖酶酶活的相关性分析49-50
    3.8 木聚糖酶酶学性质50-53
        3.8.1 最适温度50
        3.8.2 最适pH50
        3.8.3 最适反应时间50-51
        3.8.4 最适E/S51-52
        3.8.5 最适底物浓度52-53
        3.8.6 小结53
    3.9 浸麦度的影响53-54
    3.10 制麦过程中木聚糖酶酶活的变化情况54-56
4 讨论56-58
    4.1 阿拉伯木聚糖的提取56
    4.2 间苯三酚-冰醋酸双波长比色法56-57
    4.3 木聚糖酶的提取测定57
    4.4 影响比色法测定结果的因素57
    4.5 制麦工艺的影响57-58
5 结论58-59
6 进一步研究方向59-60
7 参考文献60-69
8 致谢69-70
9 攻读学位期间发表论文情况70
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