【作者】 孙森；

【导师】 宋俊梅；

【作者基本信息】 山东轻工业学院 ， 食品科学， 2008， 硕士

【摘要】 豆豉是以整粒大豆或(豆瓣)为原料,经浸泡、蒸煮、制曲、发酵等工序加工而成的,具有极高的营养价值和医疗价值的大豆发酵食品。豆豉天然发酵生产周期过长,受季节气温的限制不能常年生产,严重影响了企业的厂房利用,资金周转,市场供应和规模扩大,增加了厂家的生产成本。为了控制发酵,实现豆豉生产的工业化,必须实现纯种发酵。要想实现纯种发酵及工业化生产,其前提是了解自然发酵产品中微生物的分布﹑变化及其与基质之间的关系,掌握其发酵机理,确定各微生物菌群在发酵过程中所起的作用,然后才能筛选出合适的目的菌种进行纯种发酵,实现豆豉的规模化工业生产。同时也要了解后发酵过程中生成的主要营养成份和风味物质的含量及变化。豆豉后发酵过程中理化指标对产品成熟时间和产品风味有很大影响,只有各理化指标都达到国家标准,产品才能成熟。同时也测定了关键酶酶活在后发酵过程中的变化,确定了它们对后发酵过程的影响。本论文通过研究豆豉后发酵过程中微生物菌相的变化、理化指标和关键酶酶活的变化以及盐度对豆豉后发酵周期的影响,确定了豆豉后发酵过程中的优势菌群,由理化指标的变化趋势确定了后发酵周期,并降低了盐度。对豆豉后发酵过程中微生物菌相变化的研究表明,豆豉后发酵过程中主要起作用的微生物是细菌、霉菌和酵母菌。后发酵前六天,微生物数量变化较大。细菌总数由制曲末期的7.9×109cfu/g迅速降低,到后发酵的第六天降为0.085×106cfu/g,以后继续降低,但降低的趋势越来越缓慢,后发酵十五天后细菌总数基本趋于平稳。由对优势菌群的鉴定可知细菌主要是乳酸菌,乳酸菌可以产生乳酸和醋酸等有机酸。有机酸也是豆豉风味物质的重要成分。在豆豉后发酵初期,酵母菌大量繁殖,出现了一个高峰。随着后发酵的继续进行,由于酸性代谢产物和酒精的积累,酵母菌的活性受到抑制,所以在后发酵7天以后酵母菌数量急剧下降,18天以后酵母菌总数基本维持在一个较稳定的低数量水平上。经鉴定酵母菌优势菌群主要是鲁氏酵母菌Saccharomyces rouxii。后发酵初期,霉菌的生长已经基本停止并逐渐消亡,但霉菌所产生的酶类继续发挥作用。在计数平板培养基中的菌落数目基本保持不变,数量级在102~103之间。经鉴定优势菌群是米曲霉。对后发酵过程中理化指标变化的研究表明,豆豉后发酵过程中氨基酸态氮含量逐渐增加,前期变化较快,后期变化较慢,第21天时达到0.655%,符合国家标准,且在以后的几天里其含量变化不大。还原糖在豆豉后发酵过程中的变化不是很明显,变化很小,后发酵开始时略有上升,但整体呈下降趋势。总酸含量是逐渐增加的,初期上升明显,后期缓慢,最后达到1.5%。后发酵过程中蛋白酶的活力总体呈下降趋势。纤维素酶的活力总体是呈下降趋势的,中间略有波动。对添加不同食盐量的豆豉的后发酵过程进行研究,随着盐度的升高微生物含量下降,豆豉成熟时间延长,在保证质量和风味的前提下,食盐添加量为9%的豆豉产品成熟时间短,可以降低成本、缩短豆豉生产周期,并且食盐含量低可以降低高盐量对人体的危害。更多还原

【Abstract】 Dou-chi is fermented soybeans (or watercress), processed by soaking, cooking, making starter and fermentation processes, and has high nutritional and health value. The traditional fermentation time of Dou-chi is too long and cannot product perennial because of the season and temperature. Affect the workshop utilization capital turnover、market accommodativeness and the scope broaden, therefore increasing the production cost. For controlling the fermentation to realize the production of Dou-chi industrialization, we must realize pure seeds fermentation. To realizing these, we must know the distributing、change of microbial and the connection with the group.Predominating the fermentation mechanism, make sure the function of apiece microbe in the process of fermentation, and then screen out appropriate aim bacterium to pure seeds fermentation, realizing industry scope production of Dou-chi. At the same time we must know the content and change of nutrition shares and flavor which produced in the later fermentation process. It’s deeply affect the production mature time and flavor for its physics and chemistry index in the later fermentation process. None but the indexes achieve the country index, production are mature. At the same time, the key enzyme energy also is determined, making sure the affection to later fermentation process.In this paper, through research on the change of microbe、physics and chemistry index、the key enzyme energy and the affection of salinity to the periodic of Dou-chi later fermentation, confirm the ascendant bacterium, by the change trend of physics and chemistry index confirm the periodic of Dou-chi, and reduce the salinity. The studies on microbe change show that bacteria、mildew and microzyme are mostly acting microbe.The former six days of later fermentation, the number of microbe decreases quickly. The number of bacteria reduces speedily from 7.9×109cfu/g to 0.085×106cfu/g, and then continues reduced. But the trend is slowly, fifteen days later the bacteria number is essential fixedness. In virtue of the appraisal of preponderant microbe, bacteria are lactobacillus mostly. Lactobacillus can produce lactic acid and acetic acid and so on. Organic acid are the important ingredient of Dou-chi flavor.In the initial stages of later fermentation, microzyme reproduce rapidly. Along with the later fermentation go along, due to the accumulation of acidity metabolizable production and alcohol, after seven days, the number of microzyme reduced speedily, eighteen days later, the total steady nearly. By appraisal the preponderant microzyme are Saccharomyces rouxii. At the initial stage of later fermentation, mildew growth already stops and dies out gradually, but the enzyme which produced by mildew keep on exerting function. At the flats which take count of the number the microbe number is steady, number grade is about 102~103, by appraisal the preponderant mildew are Aspergillus oryzae.The studies on physics and chemistry index show that amino acid content increase gradually, prophase changed quickly, anaphase changed slowly, the twenty first day the amino acid content achieved 0.655%, accord with country standard, and changed slowly in anon days. Deoxidize sugar content changed not obviously, at the beginning, the deoxidize sugar increased appreciably, but the whole assume downtrend. The acid increased gradually, at the initial stages, the increasing is evidence. Anaphase is slowly, finally achieved 1.5%.In the later fermentation process, albumen enzyme energy collectivity assumes downtrend. Cellulose enzyme energy collectivity also assumes downtrend, but fluctuate appreciably.The studies on the Dou-chi which with different salinity show that the number of microbe reduce with the salinity hoist, and the mature time extend. On the premise of ensure the quality and flavor, when the salinity is 9%, the mature time is short and depress the cost、shorten the periods and depress the harm to people.更多还原