原料乳中蛋白质与脂肪比例对 Mozzarella干酪品质的影响

采用3×3拉丁方试验设计,3个奶酪槽中原料乳的蛋白质与脂肪质量比分别为1∶1,1.2∶1,1.3∶1(通过添加脱脂干奶粉调整蛋白质含量)。研究蛋白质与脂肪比例对Mozzarella干酪的品质的影响。结果表明,随着原料乳中蛋白质脂肪比例的增加,干酪的含水量、油脂析出性显著降低(P<0.05),干酪的弹性显著升高(P<0.05),蛋白质与脂肪比例对Mozzarella干酪的蛋白质水解没有显著的影响。     

组合赋权法结合响应面分析法优化娟姗牛奶Mozzarella干酪制作工艺

以娟姗牛奶为原料乳,制作Mozzarella干酪,采用组合赋权法综合评价娟姗牛奶Mozzarella干酪的质量品质,并通过响应面分析法优化娟姗牛奶Mozzarella干酪的制作工艺。结果表明,Mozzarella干酪的色泽、风味、质构、特征结构的组合权重分别为0.052、0.427、0.351、0.170,质构指标中的硬度、弹性、凝聚性的组合权重分别为0.742、0.095、0.163,特征结构指标中的拉伸性、融化性、油脂析出性的组合权重分别为0.372、0.334、0.294。响应面分析法优化发现娟姗牛奶Mozzarella干酪的最佳工艺参数为:发酵剂添加量0.020%,拉伸温度76℃,拉伸时间3min,在此条件下娟姗牛奶Mozzarella干酪的理论综合值为15.97,实验验证综合值为15.99,模型拟合程度较高。      

Effect of whey pH at drainage on physicochemical, biochemical, microbiological, and sensory properties of Mozzarella cheese made from buffalo milk during refrigerated storage

The objective of this research was to determine the effect of drainage pH on physicochemical, biochemical, microbiological and sensory properties of Mozzarella cheese made from buffalo milk during refrigerated storage. Four vats of cheese were made at 4 different whey drainage pH (6.2, 5.9, 5.6, and 5.2). Lower drainage pH caused higher pH 4.4-soluble N and pH 4.4-soluble N:total N. Interaction of drainage pH at d 1 and 30 of storage on all soluble nitrogen fractions was significant. Degradation of caseins in samples made at a drainage pH of 6.2 was lower than that of other cheese samples. The decreasing whey drainage pH significantly increased counts of thermophilic and mesophilic lactobacilli of the samples during refrigerated storage. No coliforms or Escherichia coli were detected in the cheeses. The average sensory property scores of all cheese samples were very close, and, as expected, storage time had a negative effect on all sensory scores.     

Mozzarella干酪的研制

以新鲜牛乳为主要原料,通过干酪制造条件的优化研究,确定了制造Mozzarella干酪的工艺流程及主要参数,实验表明,新鲜牛乳经标准化使得酪蛋白与脂肪之比为0．84,然后加入发酵剂和凝乳酶,凝乳形成后,经切割,排乳清,并在热水中拉伸,盐渍即到成品,产品的平均脂肪和水分的含量分别为22．82％和50．74％,达到了Mozzarella干酪的质量要求。     

原料乳热处理条件对Mozzarella干酪品质的影响

采用3×3拉丁方试验设计,3个奶酪槽中原料乳热处理条件分别设为未杀菌,63℃(30min)杀菌,72℃(15s)杀菌。研究干酪加工中原料乳热处理条件对Mozzarella干酪的品质的影响。结果表明,未杀菌乳制干酪的蛋白水解、硬度及弹性与杀菌乳制干酪的蛋白水解、硬度及弹性值具显著差异(p<0.05),未杀菌乳制干酪的蛋白水解显著增加,弹性及硬度显著降低;63℃(30min)及72℃(15s)不同杀菌温度处理的乳制得的干酪之间蛋白水解、硬度及弹性无显著差异;不同热处理乳制干酪之间的融化性和油脂析出性在统计学上无显著差异。     

Improving the yield of Mozzarella cheese by phospholipase treatment of milk

Part-skim Mozzarella cheese was manufactured from milk hydrolyzed with fungal phospholipase A₁ prior to renneting. The phospholipase treatment reduced fat losses in whey and cooking water and increased cheese yield as a result of improved fat and moisture retention in the cheese curd. The amount of phospholipids in the whey was reduced because of improved retention of lysophospholipids in the cheese curd. Water binding in the fresh curds and young cheeses up to 3 wk of storage was investigated by a ¹H nuclear magnetic resonance spin-spin relaxation technique. In the fresh curds, 2 dominant water fractions were present, characterized by average spin-spin relaxation times (T₂) of 14 and 86 to 89 ms, respectively. These 2 fractions of low- and high-molecular-mobility water were similar in all cheeses and presumed to represent water associated with the casein matrix and water present in the pores. A few hours after manufacture, cheeses made with phospholipase showed decreased T₂ of the high-mobility fraction, indicating improved water-holding capacity. It is suggested that lysophospholipids released from the fat globule membranes act as surface-active agents in the cheese curd, helping emulsification of water and fat during processing and reducing syneresis. During 3 wk of storage after manufacture, the mobility of both water fractions increased in all cheeses, but was highest in the cheeses made with phospholipase. The increase in mobility during the first weeks of storage has earlier been ascribed to structural changes in the protein matrix, which in principle could be accelerated because of the higher moisture content. However, the microstructure of phospholipase-treated cheese was investigated by confocal laser scanning microscopy and found to be very similar to the control cheese during processing and up to 28 d of storage. In addition, flowability, stretchability, and browning were acceptable and similar in all the manufactured cheeses. Thus, phospholipase hydrolysis of cheese milk improved the cheese yield without changing the cheese microstructure, and resulted in cheese with functional properties that were identical to traditional Mozzarella cheese.     

Use of milk protein concentrate to standardize milk composition in Italian citric Mozzarella cheese making

To better exploit manufacturing facilities and standardize cheese quality, milk composition could be standardized by fortifying its protein content with a milk protein concentrate (MPC) addition so avoiding partially skimming the milk. With this aim Mozzarella cheese was obtained adding citric acid into milk standardized at 4% protein and a fat to protein ratio of 1.0. Protein fortification was obtained adding MPC produced by ultrafiltration. Milk, whey, curd, cheese and stretching water were weighed and analysed for total solid, fat and protein content, to measure component recovery and yield. Yield increase (from 13.8% to 16.7%) was due to the higher recovery of the milk total solids and proteins in MPC cheese (48.2 and 78.3%, respectively) and to the slightly higher cheese moisture, obtained with a little modification of the cheese technology when adding MPC. Milk fat in cheese was lower than that reported in literature. Hot water stretching of the curd resulted in very low losses (1%) of protein and considerable losses (14%) of fat for both control and MPC cheeses. The likely reasons of this low recovery are discussed and it can be supposed that a further cheese yield increase is possible by changing the curd stretching procedures.     

不同杂交代水牛奶对Mozzarella鲜奶酪品质的影响

本文分析了尼里-拉菲及其不同杂交代水牛奶的理化特性,并研究了以尼里-拉菲及其不同杂交代水牛奶制备的Mozzarella鲜奶酪的理化指标、感官、盐水贮存中的含水率及在2⁶℃冷柜内保存期间p H变化。结果表明,不同杂交代水牛奶的蛋白质、脂肪、总乳固体含量均高于尼里-拉菲,不同杂交代水牛奶制备的Mozzarella鲜奶酪蛋白质含量13%、脂肪含量23%、水分含量59%、出品率20%左右,采用尼杂二代、三代及以上的水牛奶制备的Mozzarella鲜奶酪质量较好,鲜奶酪在2⁶℃的冷柜内保存宜控制在10d内。      

Improvement in melting and baking properties of low-fat Mozzarella cheese

Low-fat cheeses dehydrate too quickly when baked in a forced air convection oven, preventing proper melting on a pizza. To overcome this problem, low-fat Mozzarella cheese was developed in which fat is released onto the cheese surface during baking to prevent excessive dehydration. Low-fat Mozzarella cheese curd was made with target fat contents of 15, 30, 45, and 60 g/kg using direct acidification of the milk to pH 5.9 before renneting. The 4 portions of cheese curd were comminuted and then mixed with sufficient glucono-δ-lactone and melted butter (45, 30, 15, or 0 g/kg, respectively), then pressed into blocks to produce low-fat Mozzarella cheese with about 6% fat and pH 5.2. The cheeses were analyzed after 15, 30, 60, and 120 d of storage at 5°C for melting characteristics, texture, free oil content, dehydration performance, and stretch when baked on a pizza at 250°C for 6 min in a convection oven. Cheeses made with added butter had higher stretchability compared with the control cheese. Melting characteristics also improved in contrast to the control cheese, which remained in the form of shreds during baking and lacked proper melting. The cheeses made with added butter had higher free oil content, which correlated (R² ≥ 0.92) to the amount of butterfat added, and less hardness and gumminess compared with the control low fat cheese.     

水牛奶Mozzarella干酪生产中凝乳酸度对钙转移率的影响

凝乳酸度影响酪蛋白胶束中的钙含量,导致影响从原料奶到干酪的转移率.为了研究适合于水牛奶Mozzarella干酪生产的凝乳酸度,最大限度减少原料奶钙的损失,以凝乳酸度为试验考察因素、试验批次和不同干酪槽为辅助试验因素,设计3×3拉丁方试验方案,凝乳酸度设置pH值为6.40,6.20和6.00三个水平,研究其对原料奶中的钙转移到干酪的比率的影响.结果表明,采用pH值≥6.20的酸度凝乳,可以使干酪获得更高的钙转移率,而不影响其他主要化学成分的转移率及成品率.     

Physicochemical characterization of Mozzarella cheese wheys and stretchwaters in comparison with several other sweet wheys

To better understand the origins of the problems occurring during Mozzarella cheese whey concentration, lactose crystallization, and spray-drying steps, a physicochemical characterization was achieved. For this purpose, Mozzarella cheese wheys were sampled and their content in different compounds such as total nitrogen, noncasein nitrogen, nonprotein nitrogen, lactate, citrate, chloride, sulfate, phosphate anions, calcium, magnesium, potassium, sodium cations, and the sugars glucose and galactose were measured. In a second step, the results were compared with the corresponding content in Cheddar cheese wheys, Raclette cheese wheys, soft cheese wheys, and Swiss-type cheese wheys. At the end of this survey, it was shown that Mozzarella cheese wheys were more concentrated in lactate and in minerals—especially phosphate, calcium, and magnesium—than the other cheese wheys and that they contained galactose. These constituents are known to be hygroscopic. Complementary surveys are now necessary to compare the hygroscopicity of galactose and lactate and discover whether the amounts of these compounds found in Mozzarella cheese wheys are a factor in the problems encountered during the concentration, lactose crystallization, and spray-drying steps.     

提高成熟温度加快Mozzarella干酪成熟的研究

制作2批Mozzarella干酪A和B，分别在4℃(A)和7℃(B)下成熟，观察其在成熟期间的变化及测定可溶性N的含量等指标，可知在7℃下成熟的干酪在制作后30d的蛋白水解性、功能特性等和4℃下成熟50d的干酪无显著差异，而和7℃下成熟50d的干酪有显著差异。说明成熟温度显著影响干酪的蛋白水解性。在7℃下贮藏的Mozzarella干酪成熟30d可达到4℃下贮存50d的成熟度，即将成熟温度从4℃提高到7℃，可将成熟期缩短20d左右。     

不同发酵剂对Mozzarella干酪品质的影响

采用嗜热链球菌和嗜热乳杆菌作为Mozzarella干酪的发酵剂，研究单一嗜热链球菌发酵剂与嗜热链球菌和嗜热乳杆菌组成的混合发酵剂对Mozzarella干酪品质的影响。结果表明，混合菌作发酵剂制得的干酪品质优于用单一嗜热链球菌作发酵剂的干酪。     

Mozzarella cheese: 40 years of scientific advancement

An overview is presented of selected advances in the science of mozzarella cheese during the past 40 years. This is not intended to be a comprehensive review but rather to focus on several key milestones in the ongoing quest to understand the physicochemical basis for cheese structure and function. In keeping with the theme of this symposium, this paper highlights the pivotal role that Professor P. F. Fox had in shaping my understanding of mozzarella structure–function and the direction of my research during the past decade. The unfolding of mozzarella science has ebbed and flowed, with significant advances being made early on that were not fully recognized until much later.     

Mozzarella干酪生产工艺的优化

选择了影响Mozzarella干酪生产的3个关键因素：热缩温度、堆酿pH值和热烫拉伸温度；采用三因素二次通用旋转组合设计，以干酪的实际产率、pH值为4．6可溶性N，质量分数为12％的TCA可溶性N和感官评定值为指标，进行综合评定。优选出Mozzarella干酪的最优工艺参数为：热缩温度38℃，堆酿pH值为5．25，热烫拉伸温度58℃。在这一条件下，生产的干酪产率及综合质量最好。同时探讨了3个因子对以上4个指标的影响，为生产不同用途的Mozzarella干酪提供了一定的理论依据。     

Microbiological safety and quality of Mozzarella cheese assessed by the microbiological survey method

Dairy products are characterized by reduced shelf life because they are an excellent growth medium for a wide range of microorganisms. For this reason, it is important to monitor the microbiological quality of dairy products and, in particular, the total viable count and concentration of Escherichia coli, as they are indicators of the hygienic state of these products. In addition, in dairy products such as Mozzarella cheese, it is important to monitor the concentration of lactic acid bacteria (LAB), as they are the major components of starter cultures used in cheese production, contributing to the taste and texture of fermented products and inhibiting food spoilage bacteria by producing growth-inhibiting substances. For these reasons, to ensure the quality and safety of their products, cheese makers should monitor frequently, during fresh cheese production, the concentration of LAB and spoilage bacteria. However, usually, small- to medium-size dairy factories do not have an internal microbiological laboratory and external laboratories of analysis are often too expensive and require several days for the results. Compared with traditional methods, the microbiological survey (MBS) method developed by Roma Tre University (Rome, Italy) allows faster and less-expensive microbiological analyses to be conducted wherever they are necessary, without the need for a microbiological laboratory or any instrumentation other than MBS vials and a thermostat. In this paper, we report the primary validation of the MBS method to monitor LAB concentration in Mozzarella cheese and the analysis, using the MBS method, of total viable count, E. coli, and LAB concentrations in the production line of Mozzarella cheese as well as during the shelf life of the product stored at 20°C. The results obtained indicate that the MBS method may be successfully used by small- to medium-size dairy factories that do not have an internal microbiological laboratory. Using the MBS method, these dairy factories can monitor autonomously the microbiological safety and quality of their products, saving both time and money.     

模拟胃肠液环境下Mozzarella干酪提取液抗氧化活性

为评价干酪成熟过程中形成的活性肽及存活的发酵剂菌种对人体的抗氧化作用,对不同菌种组合Mozzarella干酪的蒸馏水、pH4.6醋酸缓冲液和12%三氯乙酸（TCA）提取液在模拟胃肠液环境下对DPPH自由基的清除率以及还原力进行测定。结果表明,所有不同菌种组合Mozzarella干酪的不同溶剂提取液在模拟胃肠液的环境下具有一定的抗氧化活性,并且模拟肠液的抗氧化活性大大低于模拟胃液环境,活性下降最高达88.35%。添加干酪乳杆菌（Lactobacillus casei）LPC-37的3号Mozzarella干酪提取液在模拟胃肠液环境下的抗氧化活性高于其他Mozzarella干酪,其水、pH4.6醋酸缓冲液、12%TCA提取液在模拟肠液环境下对DPPH清除率分别为73.96%、30.28%、70.27%,还原力分别为0.37、0.18、0.18。     

Understanding the role of calcium in functionality of part skim Mozzarella cheese

The impact of calcium on softening, melting, and flow characteristics of part skim Mozzarella cheese was evaluated. Four cheeses containing different calcium levels (viz. 0.65, 0.48, 0.42, and 0.35%) were manufactured by direct acidification using glucono-delta-lactone on four different occasions. Preacidification of milk was done to alter the calcium content of the cheeses. Cheeses were made with uniform composition. Lowering of calcium to 25, 35, and 45% levels increased the melt by 1.4, 2.1, and 2.6 times, respectively, 1 d after manufacture. Low calcium cheeses softened and melted at lower time and temperatures. These cheeses flowed faster and to a greater extent. Higher proteolysis at a faster rate was observed in low calcium cheeses. Refrigerated storage up to 30 d also increased melt area, flow rate, extent of flow, and soluble protein and lowered softening and melting times in all the cheeses. The effect of calcium reduction was more noticeable as compared to the effect of storage on functionality of Mozzarella cheese. Improved softening, melting, and flow properties of low calcium part skim Mozzarella cheese is a clear advantage to cheese manufacturers and end users as they may not have to wait 15 to 20 d for proteolysis of cheese to obtain desired melt properties.     

成熟温度对Mozzarella干酪蛋白水解和质构的影响

研究了温度为4,7,10℃时对干酪成熟过程中蛋白水解和质地的影响。结果表明,随着干酪成熟温度的升高,成熟期间干酪中可溶性氮与总氮的比值增加较快,干酪的硬度下降速度也较快。说明在较高的成熟温度下,干酪在较短的时间内能够达到成熟的状态。