【作者】 姚丽娅；

【导师】 汪志君； 徐为民；

【作者基本信息】 扬州大学 ， 微生物学， 2008， 硕士

【摘要】 随着我国连锁超市的逐步普及,集众多优点的冷却肉在消费市场上所占比重越来越大,围绕冷却肉品质的研究已成为我国肉类研究的最新热点。本研究通过有益微生物的筛选和在冷却肉保鲜中的应用,目的在于更好地保证其品质、延长其货架期,为冷却肉的品质研究提供新的思路,并为冷却肉的生产实践提供理论依据。本文主要包括四个部分:第一部分为冷却羊肉菌相的分析;第二部分为具有抑菌作用乳酸菌的筛选及鉴定;第三部分为目的乳酸菌与腐败菌低温共培养,分析菌株之间的拮抗性;第四部分为目的乳酸菌培养液喷洒冷却羊肉对其品质影响的研究。第一部分:利用选择性培养基分析冷却羊肉的初始菌相,结果显示,假单胞菌(Pseudomonas)、乳酸菌(Lactobacillus)、微球菌(Micrococcus)、肠杆菌(Enterobacteriaceae)、索丝菌(Brochothrix)是构成该品种冷却羊肉初始菌相的主要微生物,其中假单胞菌所占比率最大,达到72.86%,是构成冷却羊肉初始菌相的主要菌群;在贮存期间,普通包装的冷却羊肉中,假单胞菌数量呈增加的趋势;真空包装冷却羊肉中,乳酸菌数量呈现上升趋势。第二部分:从我国传统发酵肉制品中分离筛选到50株乳酸菌(Lactic acid bacteria),通过琼脂扩散法从中筛选出9株对指示菌具有明显抑菌作用的菌株,进一步研究其代谢产物的抑菌特性,结果显示S1-1为产细菌素菌株;利用常规的生理生化实验手段鉴定这9株乳酸菌,结果为:TD3-1和TD3-7为戊糖片球菌(Pediococcus.pentosaceus),ZJ3-4,M-2为德氏乳杆菌(Lactobacillus.rhamnosus),ZJ3-8为米酒乳杆菌(Lactobacillus.sake),S1-1为戊糖乳杆菌(Lactobacillus.pentosus),S2-1为植物乳杆菌(Lactobacillus.plantarum),M-1、S1-2为乳杆菌属(Lactobacillus);利用特异的引物扩增乳酸菌S1-1、TD3-1的16SrRNA基因序列,并与NCBI基因库中的已有序列进行比对,结果分别与戊糖乳杆菌和戊糖片球菌的同源性达到99%。第三部分:分别人工接种目标乳酸菌TD3-1、S1-1和假单胞菌属(P)、肠杆菌科(E),索斯菌属(S)3株腐败菌于模拟肉汤中低温共培养,并测定共培养过程中各细菌数量的变化。结果表明,TD3-1对3株腐败菌有较好的抑制作用;S1-1能较好的抑制腐败菌P、E,但是对S的抑制作用不明显。第四部分:目的乳酸菌培养液喷洒处理真空包装的冷却羊肉,并设置乳酸、Nisin水溶液处理方式作对照,通过测定其贮存过程中的微生物指标、理化指标和感官品质评价乳酸菌培养液对冷却羊肉的保鲜效果。结果显示,真空包装的冷却羊肉经不同保鲜液处理后,以107CFU/mL浓度的乳酸菌处理组的保鲜效果最好,产细菌素菌株S1-1与不产细菌素菌株TD3-1之间差异不显著,两者都能使冷却羊肉的pH值始终维持在一个较低的水平,在贮存末期TVB-N值低于国家标准(15mg/100g),感官品质良好,保质期与对照组相比有效延长。更多还原

【Abstract】 Along with the development of chilled meat in the consumption market, it is significant to study in this field. One of the key point of chilled meat is its shelf-life. How to extend the shelf-life and protect the quality are very important. In this paper we selected several lactic acid bacterias and studied their functions in preservation of chilled mutton, to provide some new ideas about chilled meat preservative technologies .Meanwhile, wishing this idea can guide the productions of chilled meat, hoping it make a better development.The paper is consisted of four parts: In part one, the dominate spoilage bacteria in the chilled mutton were studied; In part two, inhibition lactic acid bacteria(LAB) was selected and identified ;In part three, we inoculated the LAB with the dominant spoilage bacteria in broth and co-cultured at 4℃to demonstrate the restraining interaction between these strains; In part four, two LAB fermented solutions were sprayed on chilled mutton, and we did several tests to demonstrate the usefulness of the LAB to prolong the storage time of chilled mutton.Part one: Main microorganisms of chilled mutton were incubated with different selective medium. The results indicated that Pseudomonas , Lactobacillus, Micrococcus, Enterobacteriaceae and Brochothrix were the main bacteria in the chilled mutton. Pseudomonas was the dominant bacteria , its ratio arrived at 72.86% and was raising slowly under the air packages. But in vacuum packaged chilled mutton, LAB was increasing in the storage time instead of Pseudomonas.Part two: Fifty LAB were selected from the traditional fermented meat products. 9 of these strains showed preferable inhibition effects to the Indicator bacteria by the Agar Diffuse Method. Studied the characteristic of inhibition substants more, it is resulted that S1-1 maybe a bacteriocin-production strain.These strains were indentified by analysis their physiological and biochemical characters. The results showed that: TD3-1 and TD3-7 were Pediococcus.pentosaceus; ZJ3-4 and M-2 were Lactobacillus.rhamnosus; ZJ3-8 was Lactobacillus.sake; S1-1 was Lactobacillus.pentosus; S2-1 was Lactobacillus.plantarum; M-1 and S1-2 were Lactobacillus. Using the special primers to PCR amplification of 16SrRNA sequences of LAB S1-1, TD3-1, and the whole sequences were identified by submission to the nucleotide database of NCBI. The results showed that the homologous of 16SrRNA sequences of S1-1 with Lactobacillus.pentosus were 99%, and so did TD3-1 with Pediococcus.pentosaceus.Part three: This part investigated the usefulness of two selected lactic acid bacteria to extend the shelf-life of chilled mutton meat products. The results showed that the lactic acid bacteria TD3-1 can inhibit the growth of three spoilage organisms which selected from chilled mutton. Co-culture with TD3-1 can inhibit the population density of spoilage organism at a lower value than mono-culture. Otherwise, strain S1-1 can inhibit bacteriaP, E, but S.Part four: The vacuum packaged chilled mutton was treated with LAB fermented solutions, at the same time, comparing with different preservation solutions(lactic acid,Nisin), monitoring the microflora counts, psychochemical value and taste panel scores to make sure the effect of the preservation solutions. It was concluded that, after treated with different preservation solutions, the 107CFU/mL LAB solutions showed the best protective effects. There was no evident difference between S1-1 and TD3-1 at the effect of prolong the sorage life of chilled mutton. Both of the two LAB can make the pH value keeping at a low level all the while; The TVB-N value was lower than 9mg/100g at the last time of the storage. The taste panel scores was high. The preservation time was longer than comparisons.更多还原