【作者】 梁艳；

【导师】 李晓东；

【作者基本信息】 东北农业大学 ， 食品科学， 2008， 硕士

【摘要】 近些年随着我国乳品行业的悄然兴起,各种各样的乳制品已经走进人们的生活。巴氏奶作为乳制品的主打产品,更加受到老百姓的喜爱。然而,由于夏天天气炎热、交通不便、冷却设备短缺,都会造成大量巴氏奶酸败,因此急需一种行之有效的保鲜方法。本论文以优质经75℃15秒巴氏杀菌的牛奶为试验材料,研究了0、4、20℃下将二氧化碳充入到巴氏奶中,研究二氧化碳对巴氏奶的最佳保鲜条件:以及0、4、20℃下,协同二氧化碳和乳酸链球菌素（Nisin）共同作用于巴氏奶中,研究其对巴氏奶的最佳保鲜条件。主要研究内容如下:1.研究了巴氏杀菌奶各种菌群的生长曲线,针对巴氏杀菌奶中在不同期间占优势的各种菌群,采用选择性培养基进行培养。在4℃培养的19天内,共出现了四个期间。①抑制期;②假单胞菌期;③乳链球菌期;④乳杆菌期。结果表明:与原料奶对比,经巴氏杀菌处理的牛奶同样出现四个时期。若结合4℃低温贮存,巴氏杀菌奶货架期可延长到7天（4.37Logcfu/ml）,未超出国家标准4.48Logcfu/ml。在货架期贮存期间,主要腐败菌群为假单胞菌群。2.复合保鲜配方1采用协同二氧化碳和温度共同作用,根据货架期间各微生物、感官、理化指标的变化情况,找出巴氏杀菌奶最佳保鲜条件。即在巴氏奶中充入2.03、11.43、28.6、42.87、57.16mmol/L二氧化碳并分别在0、4、20℃进行贮存。脱气前,每天检测巴氏奶中pH值、滴定酸度、微生物、酶活性、热稳定性和各物质含量的变化情况;脱气后,每天检测巴氏奶中感官品质变化情况;并对比比较稳定性、滴定酸度和pH。结果表明:脱气前,①二氧化碳溶解在巴氏奶中对假单胞菌（-）和总菌数均有较好的抑菌作用,并且随着二氧化碳浓度的提高,抑菌效果越明显。②对蛋白水解酶有明显抑制效果（P＜0.05）,对脂肪水解酶效果不明显（p＞0.05）。从对巴氏奶中各物质百分含量的影响效果看,这与蛋白水解和脂肪水解作用效果一致;③对巴氏杀菌奶的热稳定性影响显著（p＜0.05）,pH值下降（p＜0.05）;滴定酸度上升（p＜0.05）④二氧化碳浓度与酸度与pH值和滴定酸度呈非线性变化;而其脱气后,对巴氏杀菌奶的感官品质影响不显著（p＞0.05）,对乳热稳定性、pH值和滴定酸度效果均较好。巴氏奶的最佳保鲜条件为:0℃/42.87 mmol/L CO₂货架期为11天。3.复合保鲜配方2在通入最佳二氧化碳最佳浓度的基础上,采用协同添加0、40、150、400IU/g Nisin,Nisin与温度协同作用,根据货架期间各微生物、感官、理化指标的变化情况,找出巴氏杀菌奶最佳保鲜条件。即充入最佳浓度42.87 mmol/L CO₂于巴氏杀菌奶中,脱气前,每3天检测巴氏杀菌奶中pH值、滴定酸度、微生物、酶活性、热稳定性和常规指标的变化情况;脱气后,每三天检测巴氏杀菌奶中感官品质变化情况;并对比比较稳定性、滴定酸度和pH。结果表明:脱气前,①添加Nisin后的巴氏杀菌奶对总菌数有较好的抑菌作用,并且随着Nisin浓度的提高,抑菌效果越明显。虽然对假单胞菌数作用效果不明显,但并无毒副作用。②对蛋白水解酶有明显抑制效果（p＜0.05）,对脂肪水解酶效果不显著（p＞0.05）。从对巴氏奶中各物质百分含量的影响效果看,与蛋白水解和脂肪水解作用效果一致。③对巴氏杀菌奶的热稳定性影响不显著（p＞0.05）,滴定酸度上升（p＜0.05）,pH值下降（p＜0.05）;其脱气后,对巴氏杀菌奶的感官品质影响不显著（p＞0.05）,对乳热稳定性、pH值和滴定酸度效果更好。巴氏奶的最佳保鲜条件为:0℃/42.87mmol/LCO₂/400IU/g Nisin货架期为18天。更多还原

【Abstract】 There is a variety of dairy products have entered people’s lives in recent years as China’s dairy industry emerged.Pasteurized milk as the main dairy produc has become more and more popular in the near future.However,there is a large number pasteurized rancidity cause of hot summer weather,traffic inconvenience and cooling equipment shortage,and therefore there needs an effective preservation methods.In this paper,milk will be Pasteurized for the test material at 75℃to 15 s,and then filled in different concentrations of carbon dioxide to store under 0,4,20℃.The purpose of this study is to find the best concentrion of carbon dioxide to improve the storage time. Under the best concentration of carbon dioxide,pasteurized milk will be added to different concentrations of Nisin to store under 0,4,20℃,then find the best concentrion of Nisin to improve the storage time.Main contents are as follows:1.Studied Pasteurized Milk various flora growth curve.During storage of 4℃for 19 days, there are four periods,such as①inhibit period;②Pseudomonas period;③Streptococcus lactis period④Lactobacillus period.The results show that:raw milk contrast,the pasteurization of milk processing in the same period four.During storage of 4℃,Pasteurized Milk shelf life will be extended to 7 d（4.37 Logcfu/ml）,did not exceed the national standard 4.48 Logcfu / ml, respectively.During the shelf life storage,there shows Pseudomonas mainly for the bacteria corruption group.2.Preservation Formula 1:Study on the antibacteria and preservative effect of cooperating with carbon dioxide and temperature on the Pasteurized Milk.pasteurized milk will be filled in 2.03,11.43,28.6,42.87,57.16 mmol/L carbon dioxide and storage of 0,4,20℃.Before degassing, there will be detected pH,acidity titration,microorganisms,activity and thermal stability of the material and content changes of pasteurized milk each day;After degassing,there will be detected sensory quality changes of pasteurized milk each day,and comparatived with stability,acidity and pH titration.The results show that:before degassing①carbon dioxide dissolved in pasteurized milk produced positive inhibition against the total number of bacteria and Pseudomonas（-）;②proteolytic enzymes are inhibited（p＜0.05）,fat hydrolase effect was not significant（p＞0.05）. From the pasteurized milk in the percentage of the material effects,this is the same effect of fat and protein hydrolysis;③the Pasteurized Milk impact on the thermal stability significantly（p＜0.05）, pH decreased（p＜0.05）;titration acidity increased（p＜0.05）.④carbon dioxide concentration and pH & acidity titration was nonlinear changes.After degassing,the Pasteurized Milk sensory quality effect is not significant（p＞0.05）,milk thermal stability,pH and acidity titration are better. Pasteurized best fresh condition is 0℃/42.87 mmol/LCO₂ storage of 11 days.3.Preservation Formula 2:Study on the antibacteria and preservative effect of cooperating with Nisin and temperature on the Pasteurized Milk on the basic of the best concentration of carbon dioxide,pasteurized milk will be added to 0,40,150,400 IU/g Nisin and storage of 0,4,20℃. Before degassing,there will be detected pH,acidity titration,microorganisms,activity and thermal stability of the material and content changes of pasteurized milk each three days;After degassing, there will be detected sensory quality changes of pasteurized milk each three days,and comparatived with stability,acidity and pH titration.The results show that:before degassing①carbon dioxide dissolved in pasteurized milk produced positive inhibition against the total number of bacteria,but never for Pseudomonas（-）②proteolytic enzymes are inhibited（p＜0.05）,fat hydrolase effect was not significant（p＞0.05）. From the pasteurized milk in the percentage of the material effects,this is the same effect of fat and protein hydrolysis;③the Pasteurized Milk impact on the thermal stability significantly（p＜0.05）, acidity increased（p＜0.05）,pH decreased（p＜0.05）;titration acidity increased（p＜0.05）④carbon dioxide concentration and pH & acidity titration was nonlinear changes.After degassing, the Pasteurized Milk sensory quality effect is not significant（p＞0.05）,milk thermal stability,pH and acidity titration are better.Pasteurized best fresh condition is 0℃/42.87 mmol/LCO₂/400IU/g Nisin storage of 18 days.更多还原