【作者】 刘俊梅；

【导师】 孙宝忠； 贾英民；

【作者基本信息】 河北农业大学 ， 农产品加工及贮藏工程， 2008， 硕士

【摘要】 鸡蛋是人们喜爱的质优价廉的产品,但鸡蛋在产出及销售过程中经常会受到微生物的污染,甚至存在沙门氏菌等致病菌污染隐患,直接影响着鸡蛋的消费安全。本文用臭氧对鸡蛋进行杀菌处理,旨在延长鸡蛋的保质期,提高鸡蛋的质量安全。研究结果如下:本文对市场上鸡蛋的污染类型进行了分类并测定了不同污染类型蛋壳表面的细菌总数。结果显示:鸡蛋的主要污染类型为粪便污染、粉尘污染、血渍污染、羽毛污染及这几种污染类型构成的混合污染。其中粪便污染率最高,达到了13.6%。受污染鸡蛋蛋壳表面的细菌数为3.29×10~3cfu/个蛋壳～1.11×10~4cfu/个蛋壳。其中受粉尘污染的鸡蛋蛋壳表面细菌数最多,达到了1.11×10~4cfu/个蛋壳。对北京市场德青源,留民营等4种品牌包装鲜鸡蛋以及散装鸡蛋在贮存过程中蛋壳、蛋清及蛋黄中细菌总数,大肠菌群数及沙门氏菌检出情况进行了测定。研究发现,不同品牌的鸡蛋蛋壳表面在贮存初期细菌总数介于9.315×10~2cfu/个蛋壳～1.367×10~4cfu/个蛋壳之间,且随着贮存时间的延长存在上升趋势;品牌鸡蛋贮存初期蛋内容均未检出污染细菌,而在贮存6天后检出污染细菌,细菌总数与大肠菌群存在随着贮存时间的延长而增加的变化。除A品牌鸡蛋外,市售鲜蛋均存在沙门氏菌污染,蛋壳表面污染率为1.67%～8.3%,内容物中污染率为1.67%～5%。其中散装鸡蛋的细菌总数,大肠菌群数及沙门氏菌检出率均高于其它几种品牌的鸡蛋。本文对臭氧的溶解特性及臭氧在水中的稳定性进行了试验。结果显示,臭氧在水中的溶解性受温度、水质、时间等因素的影响。当温度为0℃时臭氧在水中的溶解度为3.42mg/L,温度为40℃时溶解度为1.18mg/L。室温下,将臭氧气体通入蒸馏水及自来水中10min后分别测定其浓度,在蒸馏水中臭氧的浓度为4.43mg/L,在自来水中的浓度为3.91mg/L。这说明低温、减少杂质有利于臭氧在水中的溶解。随着放置时间的延长,臭氧浓度逐渐减小。浓度为2.12mg/L的臭氧水放置50min后浓度为1.19mg/L。臭氧具有极强的氧化性,本研究中分别用浓度为2,3,4,5,6 mg/L的臭氧水对李斯特菌、金黄色葡萄球菌和沙门氏菌进行灭菌性实验,结果显示,不同浓度的臭氧水对李斯特菌、金黄色葡萄球菌和沙门氏菌均具有杀灭作用,且随着臭氧浓度的增加,杀菌率提高。当臭氧浓度达到6mg/L时,对李斯特菌,金黄色葡萄球菌和沙门氏菌的杀菌率分别为99.56%,97.20%,98.76%。用浓度为2,3,4,5,6mg/L的臭氧水处理鸡蛋,经处理的鸡蛋与对照组鸡蛋在温度为(20±2)℃,相对湿度为70%的条件下贮存,每隔两天对其理化及微生物指标进行测定。结果显示,经臭氧处理组的鸡蛋蛋壳,蛋清及蛋黄中的细菌数明显低于对照组;且处理组的鸡蛋新鲜度指标优于对照组。从本研究我们可以看出,臭氧对提高鸡蛋的安全性延长其保质期具有一定的作用,臭氧在鸡蛋方面有着广阔的应用前景。更多还原

【Abstract】 Egg is the high quality at low price product which people like, with the transportation and sale the eggs would probably contaminated by bacteria, and even pathogenic bacteria such as salmonella would probably exist, all of these directly influenced the egg safety.we treat the eggs with ozone sterilization in order to lengthening the shelflife and safe quality of eggs and provides the scientific basis for the fluid egg’s promoted production.The results were following:By analysising the types of pollution of eggs and the total bacteria of different contamination on the eggshell we found that the main infectant of fresh eggs were faeces, dust, bloodstain, feather and mixture contamination, the fecal pollution rate is highest, has achieved 13.6 percent.The total bacteria of eggshell of polluted eggs was from 3.29×10~3cfu/one eggshell to 1.11×10~4cfu/ one eggshell.The dust pollution has the greatest number of bacteria, achieved to 1.11×10~4ctu/ one eggshell.The changes of the total bacteria count, the number of coli group, and the salmonella population of the eggshell, egg white and egg yolk of the fresh egg products in bulk and in package branded DeQingyuan, LiuMinying and other two branded fresh egg during storage had been studied. It had found that the bacteria amount of eggshell of different brand was 9.315×10~2cfu/one eggshell to 1.367×10~4cfu/one eggshell and increased with the extension of storage time; the content of branded eggs were not found bacteria contamination at early storage time, but the bacteria contamination was found after 6 days, the total bacteria count and coli group showed increasing with the extension of storage time. Besides the A branded eggs, the other market eggs all have salmonella contamination, the rate of eggshell was 1.67 percent to 8.3 percent, and the rate of the content was 1.67 percent to 5 percent. The total bacteria count, the coli group and the salmonella population of bulk eggs were higher than the branded eggs.In this paper, the dissolution and stability of the ozone was tested. The results showed that, the ozone concentration was influenced by temperature, water quality, time and so on. When the temperature was 0℃, the solubility of the ozone was 3.42mg/L, when the temperature achieved 40 V, the concentration of the ozone was 1.18 mg/L. With the room temperature, we blowed ozone to the tap water and the distilled water, 10 minute later, the concentration of the ozone was tested, the ozone concentration in the distilled water was 4.43 mg/L, while in the tap water was 3.91 mg/L.So lower temperature and reduced impurity were all advantageous to the ozone dissolution.With the extension of time, the ozone concentration reduces gradually.The ozone water which concentration was 2.12 mg/L became 1.19mg/L after 50 minutes.The oxidability of ozone was extremely large, in this research the concentration of ozone water we used was 2,3,4,5 and 6 mg/L.The result demonstrated that different concentrations of ozone water all has the bactericidal power to Listeria monocytogenes, Staphylococcus aureus and Salmonella; and along with the ozone concentration increase, the sterilization rate increased. When the ozone concentration achieves 6 mg/L, the sterilization rate of Listeria monocytogenes, Staphylococcus aureus and Salmonella was separately 99.56 percent, 97.20 percent and 98.76 percent.The treated and comparison eggs were all storaged at the temperature of (20±2)℃, the relative humidity of 70%. The microorganism and physical target were tested every other two days.The result indicated that the bacteria amount of eggshell, white and yolk which were treated by ozone was significantly lower than the comparison group,and the freshness target was better than the comparison group.From this study we found that, by using ozone the safety and shelf life of eggs all have a certain exchange, the use of ozone in eggs has a broad application prospect.更多还原