天然Mozzarella干酪和再制Mozzarella干酪理化特性和功能特性的比较

对天然Mozzarella干酪和再制Mozzarella干酪的理化特性（蛋白质、脂肪和水分质量分数及pH值）和功能 特性（质构特性、拉伸性、熔化性、油脂析出性和流变特性）进行分析。结果表明：天然Mozzarella干酪的蛋白质 量分数显著高于再制Mozzarella干酪,水分质量分数和pH值显著低于再制Mozzarella干酪,脂肪质量分数随干酪品 牌的不同存在差异;天然Mozzarella干酪的硬度、拉伸性、熔化性和油脂析出性都显著高于再制Mozzarella干酪;动 态温度扫描显示天然Mozzarella干酪和再制Mozzarella干酪的损耗角正切都随着温度的升高呈现先增加后降低的趋 势,天然Mozzarella干酪的损耗角正切在50～60 ℃时达到1,再制Mozzarella干酪的损耗角正切始终低于1。研究发 现天然Mozzarella干酪更适宜作为制作比萨、焗饭等需要焙烤食品的原料,再制Mozzarella干酪可以应用于三明治等 不需要焙烤的食品中。     

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。     

低脂Mozzarella干酪品质的研究

通过设定不同脂肪含量,研究低脂Mozzarella干酪的蛋白水解、TPA质构、功能特性和微观结构.结果表明,低脂Mozzarella干酪的各个指标较全脂Mozzarella干酪均有所降低.其中,脱脂Mozzarella干酪的品质明显降低,接受性差;中脂Mozzarella干酪品质接近于全脂Mozzarella干酪,部分脱脂Mozzarella干酪介于脱脂和中脂Mozzarella干酪之间,具有可接受性.     

不同乳酸菌对低脂Mozzarella干酪品质的影响

研究不同乳酸菌对低脂Mozzarella干酪品质的影响。采用无盐渍新工艺制作低脂Mozzarella干酪,经测定干酪的脂肪含量为9.85%。通过测定可溶性氮的指标、未融化干酪的质构特性、融化干酪的融化性和感官评定等对其进行研究。结果表明：低脂组的质构、融化性和风味均低于全脂组,但唾液链球菌嗜热亚种（ST）＋德氏乳杆菌保加利亚亚种（LB）＋干酪乳杆菌（LC）3 种乳酸菌组合制作的低脂Mozzarella干酪质构、融化性和风味等指标最接近全脂组。与生产Mozzarella干酪所用的传统乳酸菌组合（ST＋LB）相比,ST＋LB＋LC 3 种乳酸菌的组合,能有效地改善低脂Mozzarella干酪硬度大、融化性小、风味差的缺陷。     

原料奶中脂肪与干物质比例对水牛奶Mozzarella鲜干酪质地的影响

研究了原料奶脂肪与干物质不同比例对水牛奶Mozzarella鲜干酪质地的影响.实验以原料奶脂肪与干物质比例、实验批次和干酪槽为试验因素,设计3×3拉丁方实验方案.结果表明,原料奶的脂肪与干物质比例对干酪的硬度有极显著影响,对干酪的黏着性、耐嚼性、油脂析出性和成品率有显著影响,对干酪的弹性和融化性无显著影响.原料奶的脂肪与干物质比例为0.5时,干酪的总体品质较差.     

低脂Mozzarella干酪的品质研究

通过设定不同脂肪质量分数,研究了低脂Mozzarella干酪的蛋白水解、TPA质构、功能特性和微观结构.结果表明,低脂Moz-zareUa干酪的各个指标较全脂Mozzarella干酪均有所降低.其中, 脱脂Mozzarella干酪的品质明显降低,接受性差;中脂Mozzarella干酪品质接近于全脂Mozzarella干酪,部分脱脂Mozzarella干酪介于脱脂和中脂Mozzarella干酪之间,也有一定的可接受性.     

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。     

模拟Mozzarella干酪工艺参数优化的研究

模拟Mozzarella干酪是一种类似天然干酪的产品。为使其品质更接近于天然Mozzarella干酪,研究了以干酪的质构、融化性、拉伸性和油脂析出性为指标,对生产工艺中的几个关键工艺参数进行优化。结果表明,融化温度、搅拌时间和搅拌速度对模拟Mozzarella干酪未融化时的物理特性和融化时的主要功能特性都有极显著性影响(P<0.01);融化温度为85℃,搅拌时间(加柠檬酸前)为5min,搅拌速度为250r/min时加工的模拟干酪的品质最接近于天然Mozzarella干酪。因此,在模拟Mozzarella干酪的加工工艺中选择融化温度85℃,搅拌时间5min,搅拌速度250r/min。     

Mozzarella再制干酪辅料及其工艺条件的选择

研究了利用Mozzarella天然干酪制备再制干酪的工艺。通过单因素试验和正交试验,确定了最佳辅料配方和工艺条件：成熟期为1个月和4个月的Mozzarella干酪以2：1混合,复配乳化盐（添加柠檬酸钠量0．80％、多聚磷酸钠为0．08％、焦磷酸钠为0．15％）,乳清浓缩蛋白用量6％,黄油用量15％,加水量20％,乳化水浴温度100℃,乳化时间7min,乳化转速1000r／min。利用GC—MS法对再制干酪中主要挥发性风味化合物进行分析共鉴定出23种风味物质其中烃类7．8％;醇类9．56％;醛类4．81％;酮类5．82％;酸类22．91％;酯类41．1％;酚类0．269％及二甲基砜7．73％。     

The effect of homogenization and milk fat fractions on the functionality of Mozzarella cheese

Mozzarella cheese was manufactured from milk containing either a low (olein) or a high (stearin) melting point fraction of milk fat or anhydrous milk fat. The fat was dispersed into skim milk by homogenization at 2.6 MPa before being manufactured into cheese. The melting point of the milk fat did not affect the size or shape of the fat globules, nor was there any effect of homogenization on the polymorphic state of the milk fat. There were no changes in milk fat globule size and shape concomitant with the amount of free oil formed. The polymorphic state of the milk fat did affect the amount of free oil formed and the apparent viscosity of the cheese. The lower melting point fraction yielded a larger amount of free oil. The higher melting point fraction yielded a higher viscosity of melted cheese at 60 degrees C. Mozzarella cheese was also manufactured from homogenized milk, nonhomogenized milk, and a 1:1 ratio of the two, without altering the milk fat composition. Increasing the proportion of homogenized milk yielded a lower free oil content and higher viscosity of the cheese.     

拉伸工艺对Mozzarella干酪品质的影响

选择不同的拉伸温度和拉伸时间,研究拉伸工艺对Mozzarella干酪组成、游离水分和功能特性的影响。结果表明,随着拉伸温度的升高和拉伸时间的延长,干酪的游离水分增加,脂肪和蛋白质质量分数下降,干酪产量下降。拉伸温度为60℃时,干酪的融化性最高,油脂析出性适中,拉伸性较好。延长拉伸时间,导致干酪产量下降,功能特性没有明显提升。本研究确定的最佳拉伸工艺:拉伸温度60℃,拉伸时间10min。     

不同工艺参数对Mozzarella干酪质构和功能特性的影响

采用三因素二次通用旋转组合设计,研究热缩温度、堆酿pH、拉伸温度等关键工艺参数对全脂Mozzarella干酪的质构特性(硬度、凝聚性、弹性)和功能特性(融化性和油脂析出性)的影响规律,结果表明提高热缩温度可增加干酪硬度及干酪的油脂析出性;提高拉伸温度也可增加干酪的油脂析出性;堆酿pH对干酪的弹性有较大影响,随着堆酿pH的降低,干酪的弹性增大,并与热烫拉伸温度之间有交互作用,即低的堆酿pH和高的拉伸温度时干酪的弹性大。     

常温贮藏燕麦干酪食品的研发

研究开发了常温贮藏燕麦干酪食品,利用SAS软件Box-Behnken对产品关键工艺参数进行了优化设计。常温贮藏燕麦干酪食品的最佳配方为：选择1个月快速成熟切达干酪和Mozzarella干酪（按照1∶2配比）共100g,加入11．46％燕麦,1．2％NaCl、2．27％乳化盐（柠檬酸钠）,大豆分离蛋白添加量为3．76％,45％纯净水,融化温度86℃,保温搅拌8 min。同时,燕麦干酪食品在90天的理化、微生物指标,测项目均符合国标要求。     

Effect of milk preacidification on low fat mozzarella cheese: II. Chemical and functional properties during storage.

The effect of milk preacidification on cheese manufacturing, chemical properties, and functional properties of low fat Mozzarella cheese was determined. Four vats of cheese were made in 1 d using no preacidification (control), preacidification to pH 6.0 and pH 5.8 with acetic acid, and preacidification to pH 5.8 with citric acid. This process was replicated four times. Modifications in the typical Mozzarella manufacturing procedures were necessary to accommodate milk preacidification. The chemical composition of the cheeses was similar among the treatments, except the calcium content and calcium as a percentage of protein were lower in the preacidified treatments. During refrigerated storage, the chemical and functional properties of low fat Mozzarella were affected the most by milk preacidification to pH 5.8 with citric acid. The amount of expressible serum, unmelted cheese whiteness, initial unmelted hardness, and initial apparent viscosity were lower with preacidification. The reduction in initial unmelted cheese hardness and initial apparent viscosity in the pH 5.8 citric treatments represents an improvement in the quality of low fat Mozzarella cheese that allows the cheese to have better pizza bake characteristics with shorter time of refrigerated storage.     

Effect of milk preacidification on low fat mozzarella cheese: III. Post-melt chewiness and whiteness.

The effect of calcium reduction (as a result of milk preacidification) on post-melt chewiness and whiteness of low fat Mozzarella cheese was determined. Four vats (230 kg of milk per vat) of cheese were made in 1 d using no preacidification (control), preacidification pH 6.0 and pH 5.8 with acetic acid, and preacidification to pH 5.8 with citric acid. Cheese manufacture was repeated on four different days using a randomized complete block design. The total calcium content and the water-insoluble calcium content of the cheese were lower in the cheeses made from preacidified milks. The amount of water-soluble and water-insoluble calcium changed during refrigerated storage, as did pH. The post-melt chewiness and whiteness of low fat Mozzarella cheese were affected by milk preacidification. The largest level of calcium reduction and modification in post-melt chewiness and whiteness occurred in the pH 5.8 citric treatment. Multiple regression analysis of post-melt chewiness and cheese whiteness at 38 degrees C after heating and cooling indicated that both water-insoluble calcium and proteolysis were strongly associated with changes in the post-melt chewiness and whiteness of low fat Mozzarella cheese. High levels of proteolysis and low levels of water-insoluble calcium were associated with decreased post-melt chewiness and whiteness of low fat Mozzarella cheese.     

Textural Properties of Mozzarella Cheese Analogs Manufactured from Soybeans

Mozzarella cheese analogs were produced from soybeans or soy protein products, gelatin, gum arabic and other ingredients. The method for production of the cheese analog consisted of the following: (1) mixing at controlled temperatures to obtain a homogeneous mass, and (2) tempering at a temperature of 4°C for 24 hr. Several analog formulations were evaluated and the factors such as pH, fat content, salt content, influencing textural characteristics were studied with an Instron Universal testing machine and a modified Weissenberg test. The physical and functional properties of the final product were found to be similar to those of natural mozzarella cheese (low moisture part-skim) tested and evaluated with the same experimental methods.     

EVALUATING RHEOLOGICAL PROPERTIES OF MOZZARELLA CHEESE BY THE SQUEEZING FLOW METHOD

We adapted the squeezing flow technique to make compression and relaxation tests on Mozzarella cheese at temperatures ranging from 30 to 60C during one month of refrigerated storage. The deformability modulus of the cheese decreased with aging and temperature but increased with deformation rate. The average decrease in the deformability modulus was 0.4 kPa/day and 0.5 kPa/C. Relaxation data also indicated a continuous increase in viscous character of Mozzarella with aging and temperature. Apparent relaxation time was less than 10 s. Relaxation parameters showed a strong temperature dependency in the range of 10-60C. Lubricated squeezing flow data showed that the resistance of Mozzarella to flow decreased with aging and temperature indicating an increased meltability.     

Whiteness change during heating and cooling of Mozzarella cheese

Whiteness (L-value) changes in low-fat and low-moisture, part-skim Mozzarella cheeses during heating (7 to 60 degrees C) and cooling (60 to 7 degrees C) were evaluated. In low-fat Mozzarella, a large increase in whiteness was observed during heating, and a decrease in whiteness was observed during cooling. In low-moisture, part-skim Mozzarella, the whiteness changes during heating and cooling were smaller. Serum phase was removed from low-fat and low-moisture, part-skim Mozzarella cheeses. White protein gels were formed when the isolated serum phase from either low-fat or low-moisture, part-skim Mozzarella was heated. The white gel that formed was composed predominantly of casein and casein proteolysis products. The gel might have been produced by heat-induced, hydrophobic protein-protein interactions, and it tended to dissociate when cooled. Formation of a gel during heating increased light scattering, which increased the L-value. The gel dissociated during cooling and no longer scattered light, which decreased the L-value. We hypothesized that a gel, which was reversible, formed in the serum phase of cheese during heating and might have been responsible for the observed changes in the L-value of low-fat Mozzarella cheese during heating and cooling. The additional fat in low-moisture, part-skim Mozzarella compared with low-fat Mozzarella masked some of the color changes in the serum phase of low-moisture, part-skim Mozzarella. A model was developed to describe the contributions of the casein matrix plus serum phase of Mozzarella cheese and the contribution of fat to the changes in whiteness of Mozzarella cheese during heating and cooling.