Effect of camel chymosin on the texture,functionality, and sensory properties of low-moisture,part-skim Mozzarella cheese

The objective of this study was to compare the effect of coagulant (bovine calf chymosin, BCC, or camel chymosin, CC), on the functional and sensory properties and performance shelf-life of low-moisture, part-skim (LMPS) Mozzarella. Both chymosins were used at 2 levels [0.05 and 0.037 international milk clotting units (IMCU)/mL], and clotting temperature was varied to achieve similar gelation times for each treatment (as this also affects cheese properties). Functionality was assessed at various cheese ages using dynamic low-amplitude oscillatory rheology and performance of baked cheese on pizza. Cheese composition was not significantly different between treatments. The level of total calcium or insoluble (INSOL) calcium did not differ significantly among the cheeses initially or during ripening. Proteolysis in cheese made with BCC was higher than in cheeses made with CC. At 84 d of ripening, maximum loss tangent values were not significantly different in the cheeses, suggesting that these cheeses had similar melt characteristics. After 14 d of cheese ripening, the crossover temperature (loss tangent = 1 or melting temperature) was higher when CC was used as coagulant. This was due to lower proteolysis in the CC cheeses compared with those made with BCC because the pH and INSOL calcium levels were similar in all cheeses. Cheeses made with CC maintained higher hardness values over 84 d of ripening compared with BCC and maintained higher sensory firmness values and adhesiveness of mass scores during ripening. When melted on pizzas, cheese made with CC had lower blister quantity and the cheeses were firmer and chewier. Because the 2 types of cheeses had similar moisture contents, pH values, and INSOL Ca levels, differences in proteolysis were responsible for the firmer and chewier texture of CC cheeses. When cheese performance on baked pizza was analyzed, properties such as blister quantity, strand thickness, hardness, and chewiness were maintained for a longer ripening time than cheeses made with BCC, indicating that use of CC could help to extend the performance shelf-life of LMPS Mozzarella.     

国内外拉伸型干酪的种类及研究进展

概述了拉伸型干酪的种类、工艺,以及国外拉伸型干酪的研究进展.同时研讨了我国少数民族传统拉伸型干酪-乳扇的生产历史、工艺、研究情况,以及与国外传统拉伸型干酪的比较;并介绍了国内对Mozzarella干酪的研究进展.     

Proteolysis of low-moisture Mozzarella cheese as affected by substitution of NaCl with KCl

The proteolytic and ACE inhibitory activities of low-moisture Mozzarella cheese (LMMC) as affected by partial substitution of NaCl with KCl were investigated. Experimental LMMC were made and salted with 4 salt mixtures: NaCl only (control), 3NaCl:1KCl, 1NaCl:1KCl, and 1NaCl:3KCl, and then proteolytic activity and angiotensin-converting enzyme inhibitory activity were determined. Salt treatment significantly affected angiotensin-converting enzyme inhibitory activity and phosphotungstic acid-soluble N of LMMC during storage. Water-soluble N, trichloroacetic acid-soluble N, lactic acid bacteria population, and total free amino acids were unaffected during storage. Nonetheless, water-soluble N and trichloroacetic acid-soluble N increased significantly during storage within a salt treatment. Peptide profiles and urea-PAGE gels did not differ between experimental cheeses at the same storage time.     

Effect of different curd-washing methods on the insoluble Ca content and rheological properties of Colby cheese during ripening

A curd-washing step is used in the manufacture of Colby cheese to decrease the residual lactose content and, thereby, decrease the potential formation of excessive levels of lactic acid. The objective of this study was to investigate the effect of different washing methods on the Ca equilibrium and rheological properties of Colby cheese. Four different methods of curd-washing were performed. One method was batch washing (BW), where cold water (10°C) was added to the vat, with and without stirring, where curds were in contact with cold water for 5 min. The other method used was continuous washing (CW), with or without stirring, where curds were rinsed with continuously running cold water for approximately 7 min and water was allowed to drain immediately. Both methods used a similar volume of water. The manufacturing pH values were similar in all 4 treatments. The insoluble (INSOL) Ca content of cheese was measured by juice and acid-base titration methods and the rheological properties were measured by small amplitude oscillatory rheology. The levels of lactose in cheese at 1 d were significantly higher in CW cheese (0.06-0.11%) than in BW cheeses (∼0.02%). The levels of lactic acid at 2 and 12 wk were significantly higher in CW cheese than in BW cheeses. No differences in the total Ca content of cheeses were found. Cheese pH increased during ripening from approximately 5.1 to approximately 5.4. A decrease in INSOL Ca content of all cheeses during ripening occurred, although a steady increase in pH took place. The initial INSOL Ca content as a percent of total Ca in cheese ranged from 75 to 78% in all cheeses. The INSOL Ca content of cheese was significantly affected by washing method. Stirring during manufacturing did not have a significant effect on the INSOL Ca content of cheese during ripening. Batch-washed cheeses had significantly higher INSOL Ca contents than did CW cheeses during the first 4 wk of ripening. The maximum loss tangent values (meltability index) of CW cheese at 1 d and 1 wk were significantly higher compared with those of BW cheeses. In conclusion, different curd washing methods have a significant effect on the levels of lactose, lactic acid, meltability, and INSOL Ca content of Colby cheese during ripening.     

Technical note: At-line prediction of mineral composition of fresh cheeses using near-infrared technologies

Milk and dairy products are important sources of macro- and trace elements for human health. However, fresh cheeses usually have a lower mineral content than other cheeses, and this makes mineral prediction more difficult. Although mineral prediction in several food matrices using infrared spectroscopy has been reported in the literature, very little information is available for cheeses. The present study was aimed at developing near-infrared reflectance (NIR, 866–2,530 nm) and transmittance (NIT, 850–1,050 nm) spectroscopy models to predict the major mineral content of fresh cheeses. We analyzed samples of mozzarella (n = 130) and Stracchino (n = 118) using reference methods and NIR and NIT spectroscopy. We developed prediction models using partial least squares regression analysis, and subjected them to cross- and external validation. Average Na content was 0.15 and 0.22 g/100 g for mozzarella and Stracchino, respectively. The NIR and NIT spectroscopy performed similarly, with few exceptions. Nevertheless, none of the prediction models was accurate enough to replace the current reference analysis. The most accurate prediction model was for the Na content of mozzarella cheese using NIT spectroscopy (coefficient of determination of external validation = 0.75). We obtained the same accuracy of prediction for P in Stracchino cheese with both NIR and NIT spectroscopy. Our results confirmed that mineral content is difficult to predict using NIT and NIR spectroscopy.     

利用双螺杆干酪拉伸机生产水牛奶Mozzarella干酪操作条件试验研究

在以水牛奶为原料,商业发酵剂TCC-3为发酵剂,使用双螺杆干酪拉伸机拉伸Mozzarella干酪的试验中,研究了影响干酪的产率和感官质量的操作条件。通过试验初步确定了拉伸最佳操作条件:进料凝块pH值5.05,螺杆转速25r/min,机筒温度80℃。对最佳试验下产品的理化性质等做了测定和分析。     

莫扎雷拉干酪的工艺介绍

探讨制作莫扎雷拉干酪的制作工艺及拉伸工艺中的影响因素。经过试验,发现要获得优良的拉延特性,干酪凝块的最佳pH应控制在5.2~5.4,产品的钙/非脂乳固体比例约为3.1%±0.1%,水分含量为55%±2%,无脂干酪的水分含量为70%±3%,残糖含量按半乳糖计为7 g/kg,无乳糖残留。     

Mozzarella干酪提取液的抗菌活性

Mozzarella干酪中酪蛋白抗菌肽对人体有非常重要的作用。为了研究酪蛋白提取液的抑菌作用,对成熟期为40 d、50 d和60 d的Mozzarella干酪,分别用无菌蒸馏水、醋酸-醋酸钠缓冲溶液和TCA提取法制备干酪提取液,探讨了干酪提取液对大肠杆菌、枯草芽孢杆菌、酵母菌和黑曲霉的抑制作用。结果显示,不同成熟期Mozzarella干酪的提取液对大肠杆菌、枯草芽孢杆菌和酵母菌均有一定的抑制作用。成熟期为40 d的Mozzarella干酪,用无菌蒸馏水提取出的提取液对大肠杆菌的抑菌性最强;成熟期为60 d的Mozzarella干酪,用TCA提取法提取出的提取液对枯草芽孢杆菌、酵母菌和黑曲霉的抑菌性最强。     

脂肪替代物对Mozzarella干酪流变学特性影响研究

目的研究脂肪替代物对部分脱脂Mozzarella干酪的流变学特性及微观结构的影响。方法通过测定不同脂肪替代物(菊粉、麦芽糖醇、WPC-80、大豆卵磷脂)制成的部分脱脂干酪的基本组分、流变学特性、粘弹性模量变化、微观结构,研究不同脂肪替代物对干酪的影响。结果菊粉、WPC-80、大豆卵磷脂均能提高部分脱脂干酪的水分含量,加入脂肪替代物的干酪的pH明显低于对照组部分脱脂干酪的pH。WPC-80 G\"菊粉G\"大豆卵磷脂G\"麦芽糖醇G\"对照G\",说明加入脂肪替代物能显著改善部分脱脂干酪的黏弹流变学特性。结论麦芽糖醇作为脂肪替代物替代脂肪的效果较好,能提高蛋白分子间疏水作用,加入麦芽糖醇的部分脱脂干酪的黏弹性与对照组最为接近。     

高达干酪的生产工艺及控制要点

介绍了高达干酪的生产加工工艺以及在生产中的关键控制点。同时对高达干酪的生产工艺在理论上进行了探讨。高达干酪生产主要控制点包括发酵时间、凝乳时间、凝块的软硬程度以及酸度的控制。并且整个工艺过程都要控制好温度和搅拌速度。干酪在后期成熟时的成熟时间、温度、湿度及环境卫生的控制也非常重要。     

Proteolysis in Mozzarella cheeses manufactured by different industrial processes

The objective of the present study was to investigate the influence of stretching temperature, fat content, and time of brining on proteolysis during ripening of Mozzarella cheeses. Seventeen cheese-making experiments (batches) were carried out on an industrial scale on successive days, following the standard procedure with some modifications. Fat content of cheese milk, temperature at the stretching step, and time of brining varied from one batch to another as required by the experimental design, outlined by a surface response model. Proteolysis was assessed during ripening of samples, which was prolonged for at least 3 mo, by means of electrophoresis, nitrogen fractions, and soluble peptide mapping. The amount of soluble nitrogen at pH 4.6 was not significantly different in cheeses obtained by diverse procedures, but it increased during ripening of all samples. This result was coincident with the breakdown of α_s1- and β-caseins evidenced by electrophoresis, which reached similar extents at late stages of ripening, regardless of the cheese-making process. Multivariate analysis on soluble peptide profiles obtained by liquid chromatography also detected sample grouping according to ripening time, but did not evidence any separation caused by the cheese-making technology. We concluded that the changes in the cheese-making process assayed in this work were insufficient to produce significant differences in proteolysis of the cheeses. Ripening time had more influence on proteolysis of Mozzarella cheeses than any other assayed variable.     

Comprehensive analysis of proteolysis during 8 months of ripening of high-cooked Old Saare cheese

We applied capillary electrophoresis, liquid chromatography coupled with tandem mass-spectrometry (MS/MS), and ultra-performance liquid chromatography to determine the composition of water-insoluble and water-soluble proteinaceous fractions of the cheese and to study in detail the degradation of caseins during 8 mo of ripening of Estonian high-temperature cooked hard cheese Old Saare. The application of high-resolution and high-accuracy MS/MS enabled identification of more than 3,000 small peptides, representing a fairly full casein peptidome containing peptides of 4 to 25 AA in length: 1,049 from β-casein (CN), 944 from α_S1-CN, 813 from α_S2-CN, and 234 from κ-CN. The majority of β-CN- and α_S1-CN-derived peptides originated from the N-terminal parts of the molecule, f6-93 and f1-124, respectively; peptides from α_S2-CN arose predominantly from the C-terminal end f100-162. At the beginning of ripening, we found a relatively high amount of peptides originating from the glycomacropeptide part of κ-CN, whereas peptides from para-κ-CN prevailed during the later stages of ripening of the cheese. The cleavage patterns of β-CN, α_S2-CN, as well as α_S1-CN, showed that primary proteolysis was started mainly by plasmin, although a low proteolytic activity of chymosin was also evident. Based on the analysis of cleavage sites, we observed a significant participation of proteolytic enzymes, including amino- and carboxypeptidases, of both mesophilic and thermophilic starter bacteria in further hydrolysis of oligopeptides during the ripening. Several new phosphopeptides were detected in the result of MS/MS data analysis. The profiles of the estimated concentrations of phosphopeptides revealed that those originating from β-CN and α_S1-CN accumulated during cheese maturation. In contrast, we did not notice any generation of phosphopeptides from the highly phosphorylated part of α_S2-CN, f25-80, presumably due to the inaccessibility of this region to the action of plasmin and chymosin. The analysis of cleavage sites and the combination of principal component and clustering analyses provided a characterization of the complex dynamics of formation and degradation of peptides during cheese maturation. We made an attempt to obtain a comprehensive picture of proteolysis during Old Saare cheese ripening on the basis of the detailed peptidomic data, including also the less abundant peptides determined by MS/MS, and complemented by the data on intact caseins and free AA and reported the results in the paper.     

二次通用旋转组合设计优化Mozzarella干酪的制作工艺参数

通过采用三因子二次通用旋转组合试验设计,研究了酪蛋白和脂肪比例（C：F）、均质压力和均质温度对Mozzarella干酪品质的影响,结果表明：酪蛋白与脂肪比例和均质压力对Mozzarella干酪品质的影响极显著（p〈0．01）;单因子效益为酪蛋白与脂肪比例〉均质压力〉均质温度;酪蛋白与脂肪比例和均质温度之间以及均质压力和均质温度之间有明显的交互作用。Mozzarella干酪的优化工艺参数为酪蛋白与脂肪比例（C：F）0．9,均质压力6MPa,均质温度65℃。在此工艺条件下,感官评分达到13．05,为最佳。     

Conjugated Linoleic Acid Concentrations in Dairy Products as Affected by Processing and Storage

Total conjugated linoleic acid (CLA) concentrations increased 1.32 fold in salted and 1.27 in unsalted butter but did not alter the ratio of 9-cis 11-trans to total CLA. Nonfat yogurt showed an increase in CLA content with processing (5.25 mg total CLA/g fat) compared to unprocessed raw material (4.40 mg CLA/g fat). No changes in CLA content was observed in processed dairy products such as lowfat yogurt, regular yogurt, lowfat and regular ice cream, sour cream or cheeses such as Mozzarella, Gouda and Cheddar. Storage did not affect CLA concentration in any products suggesting that CLA is a stable component.     

Application of an antimicrobial packaging material from chicken bone gelatine and cinnamon bark oil to mozzarella cheese

Chicken bones are mostly discarded even though they contain a considerable amount of proteins, which would allow them to be applicable as a protein film source. In this study, chicken bone gelatine (CBG) films were prepared and characterised after the addition of cinnamon bark oil (CBO) to confer antimicrobial activity. The incorporation of 1% CBO increased the tensile strength of the CBG film from 18.2 to 23.9 MPa, whereas elongation at break was decreased from 15.6% to 5.91% and water solubility from 88.9% to 62.2%. Antimicrobial activity of the CBG films against foodborne pathogens as well as their antioxidant activity increased with the increase in CBO concentration. When CBG film containing 1% CBO was used for wrapping mozzarella cheese inoculated with Listeria monocytogenes, the population of the bacterium decreased after 20 days in storage, indicating that CBG films can be applied for improving the microbiological safety of mozzarella cheese.