【作者】 郑皓；

【导师】 鲁周民； 白卫东；

【作者基本信息】 西北农林科技大学 ， 野生动植物保护与利用， 2008， 硕士

【摘要】 随着柿子栽培面积的增加,柿子的加工也呈多元化趋势,柿子的加工是柿子产业增效的一条重要途经,柿子果醋具有良好的市场前景。本研究立足于自然界自身存在的大量天然菌种和传统的柿子果醋加工技术,围绕提高柿子果醋风味质量这一核心,应用微生物基本分离方法筛选适合柿子果醋酿造的酵母菌及醋酸菌,并进行鉴定,为柿子果醋生产奠定菌种基础;研究柿子果醋陈酿过程中发生的理化变化,为研究柿子果醋的陈酿工艺奠定理论基础;揭示柿子果醋香气的主要特征组成成分,为我国柿子果醋品质评价体系的建立以及柿子产业发展提供参考。以陕西杨凌产水柿为原料,自然发酵条件下,分离、鉴定其中的优势酵母菌及醋酸菌。待发酵终止后,在不同条件下陈酿,在陈酿过程中测定柿柿子果醋的可溶性固形物、总酸含量;并扫描吸光值得到其理化变化情况。陈酿180d后,采用固相微萃取法提取、富集自然发酵的柿子原浆果醋中的香气成分,经GC- MS分离与分析,鉴定其主要的香气成分;并对比不同条件陈酿的柿子果醋醋香气成分差异。得到以下结论:1.以自然发酵的柿子原浆果醋的发酵醪为试验材料,对其中的酵母菌进行分离筛选,分离出优势酵母菌(JM2)。根据对酵母菌形态学、有性生殖方式的观察,发酵糖、同化碳源、同化氮源、50%葡萄糖酵母膏中生长、37℃生长等试验结果,并对照《The Yeasts: a taxonomic study》(第三版)对酵母菌的描述,可确定JM2号菌株为克鲁维酵母属的马克思克鲁维酵母(Kluyveromyces marxianus)。2.以自然发酵的柿子原浆果醋的醋醅为试验材料,对其中的醋酸菌以变色圈法进行分离,再经过初筛,复筛,依据产酸量高低得到了1株优势醋酸菌(Af6)。通过对这株优势菌株的个体形态、培养特性进行观察,结合生理生化特性研究,鉴定醋酸细菌Af6为醋酸杆菌属( Acetobacter) ,巴氏醋杆菌( A . rancens)。3.以发酵完成的柿子果醋为试验材料,采用不同处理方法陈酿180d,研究陈酿过程中柿子果醋发生的理化变化:所有陈酿柿子果醋的可溶性固形物含量均呈下降趋势;只有G1(自然发酵、不离心、不灭菌、3-6℃)、G2(自然发酵、不离心、不灭菌、30-35℃)这两个样品的含酸量在陈酿过程中呈上升趋势,其余均有不同程度的下降。陈酿温度低(3-6℃)的柿子果醋醋样品含酸量在180d后均不同程度的高于陈酿温度高(30-35℃)的含酸量。离心后陈酿的柿子果醋样品在较高温度(30-35℃)条件下,最大吸收波长的有比较明显的增大,而在较低温度(3-6℃)条件下陈酿的样品最大吸收波长有小幅下降。样品Y1、Y2、Y3和Y4(添加酵母)的吸收波长范围在陈酿第3个月达到最大,而样品Y5、Y6、Y7和Y8(煮沸→酵母→醋酸菌)的吸收波长范围在陈酿第4个月达到最大。4.将自然发酵完成的柿子果醋分别置于3-6℃和30-35℃陈酿180d后,采用固相微萃取法提取、富集其中的香气成分,经GC- MS分离与分析,比较在不同温度陈酿的柿子果醋香气成分及其之间的差异。结果从3-6℃陈酿的柿子果醋香气成分中分离鉴定出63种挥发性化合物,从30-35℃陈酿的柿子果醋香气成分中鉴定出65种挥发性化合物,均包括羧酸类、醇类、醛酮类、酯类、酚类、烃类以及少量其他化合物。其中在30-35℃陈酿的柿子果醋香气成分中的醇类、酯类和烃类化合物含量高于在3-6℃陈酿柿醋中的含量,而羧酸类、醛酮类和酚类化合物含量低于在3-6℃陈酿柿醋中的含量。更多还原

【Abstract】 The crux of maintaining the persimmon industry developing steadily and healthily is to enhance its benefit keeping pace with the increasing of persimmon quantity and the development of persimmon industry. Now that the products of acetic acid fermentation have good market vista. The research stand on the natural strain and traditional technology of processing vinegar of persimmon. Rounding the core of improving the quality of flavor of the vinegar of persimmon. Applied basic method of microbial separation and identification to screening yeast and acetobacter acetic which suitable for brewing vinegar of persimmon, the work lays a strain foundation for producing vinegar of persimmon. Study on Physico-chemical changes in aging process, the work lays a theory foundation for researching aging technology. Revealed mainly characteristics composing component of fragrance of vinegar of persimmon, providing reference for establishing quality evaluated system of vinegar of persimmon.Mizukaki which yielded in Yang Ling taked to be raw material, fermented with no added microbial strain, separation and identification superior yeast and acetobacter acetic. Aging vinegar of persimmon after fermented accomplish under different temperature conditions during 180d, determination content of soluble solids and total acid and scanning absorption wavelength and its value. The flavoring compositions in Vinegar of Persimmon were extracted by solid phase micro-extraction (SPME) and was separated and analyzed by GC-MS, and contrasted fragrance of vinegar of persimmon aging in different conditions. Obtains the following conclusion:1. The solid-fermenter of Vinegar of Persimmon virgin pulp with no added microbial strain is tested in this experiment. Isolation, Screening of Yeasts, on base of satisfying requirements of brewing persimmon vinegar, but more emphasizes the performance of producing fragrant. Obtained one strain (JM2), this yeast is good at the performance of producing fragrant and typicality. According to observation of the morphology, the way of sexual reproduction, fermented sugar, assimilating carbon source, assimilating nitrogen source, growth in the 50% yeast extract, growth in 37℃etc. Compare to the decription of The Yeasts: a taxonomic study (3rd edition). In the end, this superior strain belongs to Kluyveromyces. JM2 was characterized as Kluyveromyces marxianus.2. The solid-fermenter of Vinegar of Persimmon virgin pulp with no added microbial strain is tested in this experiment. As to its inside acetobacter acetic, adopting the changing colour circle method to separate acetobacter acetic, then through early screening and second screening, finally according to the quantity of producing acid the author got one superior acetobacter acetic (Af6). The morphology, cultivation, physiology, biochemistry were tested for identification. In the end, this superior strain belongs to Acetobacter. Af6 was characterized as A. rancens.3. Aging Vinegar of Persimmon after fermented accomplish under different temperature conditions during 180d, study on Physico-chemical changes in aging process: All the soluble solids content of samples showed decending trend. Acid content of sample G1 and G2 showed rising trend and the rest decreased. After aged 180d, acid content of samples aged at 3-6℃is more than aged at 30-35℃. Centrifuged samples aged in 30-35℃, maximum absorption wavelength increased, centrifuged samples aged in 3-6℃, maximum absorption wavelength decreased. The range of absorption wavelength of sample Y1, Y2, Y3 and Y4 reached most widely when aged the third month, sample Y5, Y6, Y7 and Y8 reached most widely when aged the fourth month.4. Aging Vinegar of Persimmon after fermented accomplish under different temperature conditions during 180d. The flavor components in Vinegar of Persimmon were extracted by solid phase micro-extraction (SPME) and was separated and analyzed by GC-MS. About 63 different compounds were identified in the flavor components in Vinegar of Persimmon aged at 3-6℃; About 65 different compounds were identified in the flavor components in Vinegar of Persimmon aged at 30-35℃.All including acids, alcohols, aldehydes, ketones, esters, phenols,hydrocarbon and other a few compounds. Alcohols, esters and hydrocarbon in the flavor components in Vinegar of Persimmon aged at 30-35℃is more than in Vinegar of Persimmon aged at 3-6℃; Acids aldehydes, ketones and phenols in the flavor components in Vinegar of Persimmon aged at 30-35℃is less than in Vinegar of Persimmon aged at 3-6℃.更多还原