【作者】 潘运国；

【导师】 陈义伦；

【作者基本信息】 山东农业大学 ， 农产品加工及贮藏工程， 2006， 硕士

【摘要】 短碳链羧酸酯是重要的自然风味香气成分,是酿酒、食品、饮料、医药工业、香精香料行业等常用的添加剂或原料,采用生物催化（酶或细胞） ,特别是通过酯化酶催化合成的风味酯是安全有效的,被称为“绿色产品”。根霉酯化酶具有多向合成功能,既能同时合成浓香型酒己酸乙酯为主体香的四大酯,也可单一合成纯己酸乙酯,还可合成稀有酯类。本文研究了根霉酯化酶液态培养技术条件、酶学特性及在酸性饮料中的应用。主要结果和结论如下:1、培养基中氮源的种类、碳氮比、发酵培养基组分浓度以及发酵的初始pH值影响根霉酯化酶酶活。有机氮源较无机氮源好,黄豆粉和蛋白胨作为复合氮源,碳氮比为5,培养基浓度5%,有利于酯化酶的合成,添加4%的橄榄油可提高根霉酯化酶酶活。采用黄豆粉5%、麸皮6%、磷酸氢二钾0.2%培养36h,可获得高酶活酯化酶。2、在液态培养条件下,接种量、装液量、初始pH值、温度、摇床转速等因素影响根霉酯化酶的酶活。影响产酶的主要因素是温度、转速。在培养基为黄豆粉5%,麸皮6%,磷酸氢二钾0.2%,初始pH值7.0,接种量为12%,最适的培养条件为:温度30℃,装液量为35mL（250mL三角瓶）,摇床转速150r/min。3、根霉酯化酶最适酶活温度40℃,在30⁵0℃范围内酶活较高,在40℃稳定性较好,在pH值6⁸之间时,有较大的稳定性。添加0.2% TritonX-100有利于酶活提高。Ca²⁺对提高酶活有促进作用, Zn²⁺、Cu²⁺对酶活有相对较强的抑制作用。在反应时间1³h范围内,反应时间与转化率有良好的线性关系,此时反应速度为酶促反应初速度。4、饮料酸度、酶添加量及时间影响酯化酶在酸性苹果饮料中的增香效果。在0.51%的酸度苹果饮料中,添加1%的酯化酶,35℃下酯化3d总挥发酯达到0.594g/L,有良好增香效果。更多还原

【Abstract】 Esters of short chain fatty acids and alcohols are known as flavour and fragrance compounds, and they are widely used in the food, beverage, cosmetic and pharmaceutical industries. The flavour and fragrance esters prepared by enzymatic synthesis may be labeled as“natural food”. A new method to produce natural esters is opened by enzyme catalysis. Esterifying enzyme of Rhizopus sp. not only has the ability to synthesize ethyl hexanoate but also synthesize other esters.The medium components, cultivation conditions and enzyme properties of Rhizopus sp. were studied in this research. Esterifying enzyme was used in sour apple beverage. Primarily study results as follows:1、This thesis has used Rhizopus sp. as the experiment bacterial and carried research on the effects of the ratio of carbon and nitrogen source,nitrogen source,carbon source,density of component of fermented culture,and the results indicated that: The best nitrogen source was the mixture of soybean powder and albumen peptone, the best ratio of carbon and nitrogen source was 5.The enzyme activity would be higher if 4% olive oil was added. Optimal liquid medium components were as follows: soybean powder 0.5%, bran 6%,K₂HPO₄ 0.2%, the enzyme activity could be reached the highest after 36h.2、Esterifying enzyme activity of Rhizopus sp. was affected by the inoculating volume,culture density,flask of fermentation volume,initial pH value, temperature and agitation frequency. The optimal fermentation conditions were pH 7.0, inoculating amount12%, fermentation temperature 30℃,the agitation frequency 150r/m and 35mL/250ml flask of fermentation volume.3、The optimum temperature of esterifying enzyme was 40℃.It also had activity at a range from 30℃to 50℃.The optimum pH was 7.0.The activity was maintained by heating at 40℃and pH 6⁸. The enzyme activity was promoted by Ca²⁺ ,but was inhibited by Zn²⁺、Cu²⁺. In reaction time within 1³更多还原