市售酵母发酵菌粉中酵母菌特性研究
关键词：酵母粉；酵母菌；发酵；碳源；氮源
The Characteristic Research of Yeast on Market
Abstract: Usable saccharomycetes were purified from actively dry baking powder in markets which brand is “Anqi”. The tester strain were observed the morphological characteristics of both its bacterial colony and cell as well,and noting the saccharomycetes is accorded with the characteristics of saccharomycetes cerevisiae. After conducting a series of single factor fermentation experiments, the results showed saccharomycetes experienced the fastest growing period at the temperature 35℃ and pH6. The low concentration of NaCl exerted no influence on its growing, however, the influence become severe with increasing concentration, and alcohol severely restraining that. It is accessible to gain the most suitable cane sager and glucose by carbon source assimilation experiment and nitrogen source assimilation experiment, and the usage of ammonium sulfate and lysine as its nitrogen source.
Key words: Baking powder;Fermentation;Saccharomycetes;Characteristics;Carbon source;Nitrogen source
目 录
摘 要 1
Abstract 1
引言 2
1. 材料和方法 2
1.1实验材料和培养基 2
1.2实验方法 3
2．结果与分析 5
2.1形态学观察 5
2.2生长曲线的测定 5
2.3发酵条件对酵母菌生长活性的影响 6
2.3.1温度对酵母菌生长活性的影响 6
2.3.2 pH对酵母菌生长活性的影响 7
2.3.3 NaCl对酵母菌生长活性的影响 7
2.3.4酒精对酵母菌生长活性的影响 8
2.4碳源同化实验 8
2.5氮源同化实验 9
3. 小结与讨论 9
参考文献 10
致谢 12 ,228
市售酵母发酵菌粉中酵母菌特性研究
引言
酵母菌是人类最早利用的微生物，被用于早期的面团发酵、酿酒、酿造食醋、腌制酱类等。酵母菌是单细胞微生物，属于真菌类，从酵母菌系统分类来讲属于真酵母属。酵母菌在自然界分布甚广，空气中、土壤中、水中都存在酵母,而且容易生长，有氧或者无氧条件下都能生存[1]。酵母菌大多数生活在偏酸性和含糖量较高的环境中[2]。其依靠出芽生殖，能够在短时间内大量增殖。
市售发酵粉中的酵母是由工厂纯种培养菌培育而成的活酵母。用于发酵馒头或面包的酵母是酿酒酵母(S.cerevisiae)，属于酵母菌属(Saccharomyces)[3]，其特征是：细胞呈圆形、椭圆形或腊肠形；发酵力强，主要产物是乙醇和CO2。目前市售的均为快速活性干酵母[4]。这是一种新型的具有快速高效发酵力的细小颗粒状（直径小于1mm）产品。水分含量为4～6％。它是在活性干酵母的基础上，采用遗传工程技术获得高度耐干燥的酿酒酵母菌株，与活性干酵母相比，颗粒较小，发酵力高，使用时不需先水化而可直接与面粉混合加水制成面团发酵，在短时间内发酵完毕即可焙烤成食品[5]。该产品在本世纪70年代才在市场上出现，深受消费者的欢迎。研究发现，安琪酵母的活力是最高的。本实验即采用市售的安琪高活性干酵母粉作为酵母菌菌源，从中分离纯化得到酿酒酵母，以进行其形态学观察及特性研究。