干酪成熟过程发酵剂的作用及快速成熟的研究进展

干酪的成熟过程,是在添加酶及各种微生物的协同作用下完成的.干酪中的微生物作用也包括人为添加发酵剂的作用.本文综述了干酪生产过程中发酵剂的使用和成熟过程所起的作用,主要有酸化、改善质构、形成风味物质.此外,本文也讨论了干酪的成熟机制,综述了目前用于促进干酪成熟所使用的一些方法和技术以及对它们的最新研究进展.     

干酪生产用菌种的筛选

发酵剂菌种对干酪的品质有重要影响.采用从新疆民族乳制品(奶疙瘩、酸奶)中分离的菌株,研究了3种单一菌株(乳酸乳球菌、瑞士乳杆菌、干酪乳杆菌)和4种混合菌株(乳酸乳球菌:瑞士乳杆菌(1:1)、乳酸乳球菌:干酪乳杆菌(1:1)、瑞士乳杆菌:干酪乳杆菌(1:1)、嗜热链球菌:保加利亚乳杆菌(1:1))的发酵性能和生化特性,确定了适于干酪加工的菌种为乳酸乳球菌、乳酸乳球菌:干酪乳杆菌(1:1)、瑞士乳杆菌:干酪乳杆菌(1:1).     

中国干酪产业发展对策

通过对中国干酪产业的发展趋势分析,研究了我国干酪产业发展的现状和亟待解决的问题.旨在对我国干酪产业商品化提供参考.     

豆奶软质干酪的研制

通过不同豆奶比例、发酵剂添加量、氯化钙添加量对凝乳特性的影响进行研究，确定了豆奶软质干酪的制作工艺为：原料奶-杀菌-冷却（32℃）-混合（加入豆奶比例为20％）-加发酵剂（0．20％）-加氯化钙（0．06％）-加凝乳酶-切割-排乳清-压榨-盐渍-喷霉-熟化（后发酵）-包装，可得口感风味良好的白霉成熟干酪。     

比萨干酪的加工工艺

描述了以鲜牛乳为主要原料加工制作比萨干酪的加工工艺,主要包括原料乳杀菌、添加菌种、凝乳、切割、排乳清、热烫拉伸、盐渍等7步,也是比萨干酪加工的主要控制点。     

干酪促熟方法的研究进展

干酪成熟时间较长，费用较高，导致生产成本增加。因此干酪的促熟受到人们普遍关注。干酪促熟常用的方法有酶法、修饰发酵剂细胞、悬浮液系统、提高成熟温度、高压处理等。其中提高成熟温度和高压处理法不需要额外的干酪添加剂，是应用于生产中成本较低且易实现的方法。本文主要就以上两种方法促熟干酪作以详述。     

硬质干酪加工工艺的研究

以鲜牛乳为原料,研究了硬质干酪的制造工艺,确定了发酵剂;凝乳酶;氯化钙的添加量和成熟条件等主要工艺参数,并探讨了影响凝乳酶活力的主要因素.     

搅拌凝块干酪的加工工艺

搅拌凝块法是一种半硬质干酪的制造方法,通过研究实践介绍搅拌凝块干酪的加工工艺及其操作要点。     

马苏里拉干酪(Mozzarella Cheese)的生产工艺探讨

介绍生产马苏里拉Mozzarella干酪的制作工艺,研究和探讨了最佳工艺参数,可为国内准备实现马苏里拉干酪工业化的生产单位提供参考。     

Mozzarella干酪拉伸机的设计

描述一种用于生产Mozzarella干酪的单螺杆拉伸机的设计,包括理论分析、机械设计以及试验论证.该拉伸机可以实现对凝乳颗粒的可控加热与拉伸,同时,为了直接获得直径20 mm～30mm的干酪块,在拉伸机出口处安装了小孔均匀分布的挤出板,使小尺寸的干酪块冷却时间缩短.该机试制的样品符合美国农业部关于Mozzarella干酪产品的标准.     

干酪质地及流变学特性的研究进展

介绍了有关干酪的成分及工艺过程对质地和流变学特性影响的研究。在干酪成分中，蛋白质是影响产品流变学特性的主要因素，酪蛋白空间形成的网状结构构成了干酪流变学的基础。在加工过程中，pH、温度、钙浓度、蛋白水解等所有对干酪成分分子产生变化的因素都可能使干酪的流变学特性和质地发生变化。因此，干酪流变学特性的研究对更好地控制质地，生产出质优价廉的干酪，具有重要的意义。最后，研究状况进行了展望。     

干酪中微生物研究方法的比较

干酪中微生物的研究是现在一热点问题,其方法随着生物的各个学科的发展得以发展.本论文将现有的干酪微生物研究方法进行了简单的阐述和比较,各种方法各有利弊同时在这一领域依然需要进一步的完善方法,以更好地确定干酪微生物和干酪口味的关系.     

豆奶干酪制备的影响因素研究

通过对豆奶干酪生产因素的研究,发现豆乳添加量、混合乳杀菌温度、发酵剂添加量、混合酶比例和CaCl2添加量等因素对豆奶干酪的产率都有影响,从而确定最佳工艺参数.实验结果表明,为了提高豆奶干酪的产率,同时保证豆奶干酪的品质,豆乳添加量为10%;杀菌条件为80℃、15 s;发酵剂添加量为2.00%;调酸pH为5.8;谷氨酰胺转胺酶与凝乳酶比例为4∶1;CaCl2添加量为0.06%;热缩温度为40℃;干酪切割时间为120min,切割大小为10mm.     

修饰发酵剂细胞促熟干酪的研究进展

修饰发酵剂细胞是采用各种物理、化学或基因修饰等方法使发酵剂(主要是乳酸菌)不能生长而不致产生过量的乳酸。同时在干酪中添加时细胞会完整存在，并能在成熟期间释放出活性胞内酶。修饰发酵剂的方法主要有热休克、冷休克、冷冻或喷雾干燥、溶菌酶处理、溶剂处理和基因修饰等。这些方法修饰乳酸菌(包括乳球菌，乳杆菌)与原发酵剂一并加入乳中，可加速干酪中的蛋白质降解和脂肪分解，缩短其成熟期，且增强风味(减少苦味)，在促熟干酪方面取得了较好的实验效果。综述了现有的修饰发酵剂细胞促熟干酪的方法，详述了热休克、冷休克这两种常用的方法，最后对修饰发酵剂细胞促熟干酪的应用前景作以展望。     

混合型大豆干酪成熟中蛋白质降解特性的研究

对混合型大豆干酪成熟过程中蛋白质的降解及感官特性变化进行了研究。检测了混合型大豆干酪成熟过程中pH4．6水溶性氮、12％三氯乙酸氮、5％磷钨酸氮和游离氨基酸含量的变化；在不同成熟时间下对混合型大豆干酪进行了感官评定。结果表明，随着成熟时间的延长，混合型大豆干酪的pH4．6水溶性氮、12％三氯乙酸氮、5％磷钨酸氮的含量增大；游离氨基酸含量变化较为显著；8℃下成熟30d时，混合型大豆干酪的感官特性最好。     

EFFECT OF FERMENTED WHEY PROTEIN CONCENTRATE ON TEXTURE OF IRANIAN WHITE CHEESE

The influence of fermented whey protein concentrate (FWPC) added before and after formation of cheese curd on the textural characteristics of Iranian white cheese was studied. The FWPC, prepared from whey obtained during cheese making, was added at different levels 5, 10, 15 and 20% (v/v) after (A) or before (B) cheese curdling. The changes in rheological parameters of cheeses were determined before and after 1 month of ripening. It was found that both incorporation level and stage of addition of FWPC (A and B) caused significant effects on texture profile analysis of cheeses. Increasing the level of FWPC in B group, except samples containing 10% FWPC, in contrast with A cheeses led to considerable increase in moisture and decrease in hardness and chewiness. Samples containing more than 15% FWPC had undesirable texture and were too soft. All experimental cheeses exhibited a decline in values for each rheological parameter after 1 month of ripening.

PRACTICAL APPLICATIONS

Perhaps the biggest story in the dairy industry in the past couple of decades has been the rise of new applications for whey and whey proteins. Once considered a waste product in the cheese manufacturing process, whey and whey protein products today are used for a wide range of functional and nutritional properties. In the cheese industry, particularly in soft cheese varieties, whey proteins have shown good applications to replace caseins as they act as fat replacer and bind more water than caseins, which results in softer cheeses. Therefore, this study was attempted to investigate the impact of fermented whey protein concentrate on textural attributes of Iranian white cheese.     

RHEOLOGICAL PROPERTIES OF MOZZARELLA CHEESE DETERMINED BY CREEP/RECOVERY TESTS: EFFECT OF SAMPLING DIRECTION, TEST TEMPERATURE AND RIPENING TIME

The viscoelastic properties of mozzarella cheese using a creep/recovery test considering different sampling directions (parallel and perpendicular to protein fiber orientation), test temperatures (20, 30 and 40C) and ripening times (1, 8, 15, 29 and 36 days) were studied. Creep data were interpreted by a Burger model of four parameters. A semiempirical approach was proposed to obtain the contribution of each main compliance to the total deformation of the system. Creep tests at different temperatures allowed gaining a better understanding of changes that occur in the cheese matrix during heating and ripening. Sampling direction did not affect any of the parameters studied. Finally, it was clearly observed that cheese matrix behaves as a quite different physicochemical system depending on temperature. Therefore, it is recommended to carry out the rheological tests at different temperatures to evaluate appropriately the viscoelastic properties of mozzarella cheese.

PRACTICAL APPLICATIONS

Mozzarella cheese must have certain characteristics to be used on pizzas and on other prepared foods that use the cheese in melted state. The protein chains in the mozzarella curds coalesce into large strands that are oriented in the direction of stretching. For this reason, mozzarella cheese has an anisotropic structure. Therefore, it is relevant to determine the effect of protein fiber orientation on the rheological properties. Valuable information may be obtained through the creep/recovery test of mozzarella cheese samples to study its rheological properties and to explain molecular mechanisms that occur during ripening or melting processes considering sampling direction.