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.     

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.     

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。     

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.     

Test for measuring the stretchability of melted cheese

A test for measuring the stretchability of cheese was developed by adapting a texture-profile analyzer to pull strands of cheese upwards from a reservoir of melted cheese. Seven different cheeses were analyzed using the Utah State University stretch test. The cheeses were also analyzed for apparent viscosity with a helical viscometer, for meltability using a tube melt test, and for stretch using the pizza-fork test. Cheese was placed into a stainless steel cup and tempered in a water bath at 60, 70, 80, or 90 degrees C for 30 min before analysis. The cup was then placed in a water-jacketed holder mounted on the base of the instrument. A three-pronged hook-shaped probe was lowered into the melted cheese and then pulled vertically until all cheese strands broke or 30 cm was reached. This produced a stretch profile as the probe was lifted through the reservoir of melted cheese and then pulled strands of cheese upwards. Three parameters were defined to characterize the stretchability of the cheese. The maximum load, obtained as the probe was lifted through the cheese, was defined as melt strength (F(M)). The distance to which cheese strands were lifted was defined as stretch length (SL). The load exerted on the probe as the strands of cheese were being stretched was defined as stretch quality (SQ). There was a correlation between F(M) and apparent viscosity. There was also some correlation between SL measured by the fork test and SL when the cheese was tested at 90 degrees C, but no correlation occurred at lower temperatures.     

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。     

Use of ozone in production chain of high moisture Mozzarella cheese

This work aimed to evaluate ozone effectiveness in reducing viable spoilage bacteria load throughout high moisture (HM) Mozzarella cheese-making process. At first, Mozzarella cheese samples were packaged with ozonated water (2 mg/L), stored at low temperature and monitored during shelf life. In a following phase cheese samples were put, before packaging, in direct contact with ozonated water at ozone concentrations of 2, 5 and 10 mg/L for 60 min. Then, gaseous ozone at concentrations of 10, 20 and 30 mg/m³ for different times was tested. In these experiments ozone was not effective in surface microbiological decontamination of cheeses. In all cases, there was no increase in the formation of primary and secondary lipid oxidation products.