【作者】 刘明春；

【导师】 李正国；

【作者基本信息】 重庆大学 ， 植物学， 2009， 硕士

【摘要】 榨菜是茎用芥菜经整理、脱水、加盐腌制后熟而成的一种特色蔬菜腌制品。涪陵榨菜以其鲜、香、嫩、脆的独特品质,享誉世界,与德国甜酸甘蓝、欧洲酸黄瓜并称世界三大名腌菜。作为香气、口感、风味俱优的传统腌制品,榨菜的独特挥发性风味是评价其品质的重要指标,但目前对榨菜腌制加工过程中挥发性风味的形成及其变化机理仍缺乏深入研究,对脱盐脱水加工工艺对榨菜挥发性风味成分的损失等问题尚不明确,为了提高榨菜的风味品质,开展榨菜加工过程中挥发性风味成分形成变化的研究具有十分重要的意义。本研究以传统方法腌制加工的涪陵榨菜为原料,测定了榨菜腌制加工过程中风味前体物质芥子苷的含量变化;提取、纯化了榨菜中的内源芥子苷酶并对其在腌制加工过程中的活性变化进行了研究;提取、分离鉴定了榨菜腌制加工过程中各个腌制阶段的挥发性风味成分;初步探讨了榨菜腌制加工过程中挥发性风味成分形成及其变化机理;研究了脱盐脱水工艺对榨菜挥发性风味成分的影响,以期为榨菜品质改良提供理论依据。主要研究结果如下:①采用改良氯化钯法测定榨菜中的芥子苷的含量,结果表明,榨菜腌制加工过程中,挥发性风味前体芥子苷的含量呈不断下降的趋势。②采用己糖激酶法测定内源芥子苷酶的活性,结果表明,榨菜腌制加工过程中,内源芥子苷酶活性逐渐下降。同时内源芥子苷酶的活性受多种因素的影响,其中,温度、pH、NaCl含量等因素对其活性的影响最为显著。③采用同时蒸馏萃取法(SDE)提取榨菜的挥发性风味成分,气相色谱-质谱联用(GC-MS)对挥发性风味成分进行分离鉴定,结果表明,榨菜腌制加工过程中酸类、硫化物、醛类、醇类、酚类、酯类、腈类和杂环类化合物的含量呈不断升高的趋势,其中酸类、硫化物、醛类、酯类等化合物增加最为显著。而异硫氰酸酯类化合物的含量呈现先增加后减少的趋势,在第一次加盐腌制和第二次加盐腌制时期其含量不断升高,第三次腌制时期其含量开始下降。④芥子苷在内源芥子苷酶作用下的水解和乳酸菌等微生物的发酵作用是榨菜腌制加工过程中挥发性风味的成分形成的主要原因。同时,榨菜细胞内合成代谢及各种产物之间的反应也是其风味形成及变化的重要途径。⑤榨菜经脱盐脱水加工工艺处理后,其挥发性风味成分减少22种,酸类、硫化物、醛类、醇类、酚类、酯类、异硫氰酸酯类、腈类等化合物均有不同程度的损失,其中醇类、酚类、醛类、酸类等小分子量的挥发性成分减少最为明显。更多还原

【Abstract】 The pickled mustard tuber, which is produced by pickling the stem mustard (Brassica juncea coss var tnmida Tsen et Lee) in salt solution, is an indigenous Chinese fermented vegetable product. With its fresh, fragrant, crisp and tender quality, Fuling Pickled mustard tuber has become famous all over the world. Its unique volatile flavor is an important factor which is used to evaluate the quality of the pickled mustard tuber. However, the research on the formation and changes of volatile compounds of pickled mustard tuber during the pickling process is limited. There is also little known about the effect of desalting and dewatering process on volatile flavor of pickled mustard tuber. It’s necessary to research the formation and changes in volatile compounds of pickled mustard tuber during the pickling process in order to improve the flavor quality of pickled mustard tuber.In this work, stem mustards which pickled with traditional method were used as experiment material. The changes of sinigrin content during the pickling process were studied. Myrosinase was isolated and purified from the extraction by DEAE-52 and Sephadex G-100 chromatography, and the changes of myrosinase activity in pickled mustard tuber during the pickling process were detected in this paper. The formation and changes in volatile compounds of pickled mustard tuber during the pickling process were investigated, and the effect of desalting and dewatering process on volatile flavor was also studied in this paper. The results were as follows:①The content of sinigrin gradually decreased during the pickling process, as tested by improved palladium chloride method.②The activity of myrosinase in pickled mustard tuber was tested by hexokinase (HK) method, the results showed that the activity of myrosinase gradually decreased during the pickling process, and the activity of myrosinase was significantly influenced by temperature, pH and salt content.③The volatile oil was obtained from the pickled mustard tuber by simultaneous distillation extraction method (SDE), and the volatile compositions were analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 45 volatile compounds were isolated and identified from fresh stem mustard and the pickles. They were grouped into 9 major chemical classes. The relative abundance of acids, sulfides, aldehydes, alcohols, phenols, esters, nitriles and heterocyclic compounds showed gradually increased during the pickling process, especially for sulfides, sulfides, aldehydes and esters. The relative abundance of isothiocyanate compounds increased at the first and second pickling stages, then started to decrease in the last pickling stage.④The hydrolysis of myrosinase and fermentation of lactic acid bacteria were the main formation ways of volatile flavor in pickled mustard tuber during the pickling process, and the anabolic and catabolic metabolism in the cell of pickled mustard tuber and the reaction of the degradation products were also important ways to form the volatile flavor in pickled mustard tuber during the pickling process.⑤After desalting and dewatering process, there were 22 volatile components lost in pickled mustard tuber. Acids, sulfides, aldehydes, alcohols, phenols, esters, nitriles, isothiocyanates and heterocyclic compounds all decreased in the process, especially for alcohols, aldehydes, phenols and acids.更多还原