山羊乳软质干酪加工技术研究

探讨了山羊乳软质干酪最佳工艺条件。采用正交试验的方法,研究发酵剂用量、凝乳酶用量、凝乳温度对山羊乳软质干酪凝乳时间和感官评鉴的影响,最终确定该产品最佳工艺条件:发酵剂用量2.5%(m/v)、凝乳酶用量0.2%(m/V)、凝乳温度28℃。     

蒙古干酪生产工艺研究

以鲜牛乳为原料,根据蒙古干酪的生产工艺,采用L9(34)正交实验的方法,研究了不同灭菌条件、发酵剂添加量、捶捣切割pH值和热烫温度对蒙古干酪蛋白利用率、干酪品质的影响,确定了生产蒙古干酪的最佳工艺条件为63℃/1800 s的灭菌条件,发酵剂添加量为2.5%(体积分数),捶捣切割pH值为4.8,热烫温度为47℃.     

夸克干酪工艺条件优化研究

为了获得适合中国人口味夸克干酪的最佳加工工艺和条件,以鲜乳为原料,经杀菌、冷却、接种、添加凝乳酶、凝块切割、排乳清、包装等工艺制作夸克干酪,主要通过L9(34)正交试验,发酵剂添加量、凝乳酶添加量、切割p H值和排乳清条件等4个关键工艺进行了优化,试图优选出适合中国人口味的夸克干酪制品最佳工艺条件。结果表明:当发酵剂添加量为3.5%、凝乳酶添加量为0.15%、切割p H为4.7和排乳清条件为2 400 r/min、20 min条件下制作夸克干酪时,可获得最佳感官品质的夸克干酪。当发酵剂添加量为4.0%、凝乳酶添加量为0.18%、分离p H为4.7和排乳清条件为3 600 r/min 20 min时,制作的夸克干酪出品率最高。     

半硬质干酪加工工艺条件的研究

通过单因素试验和正交优化试验,研究发酵剂添加量、CaCl2添加量、凝乳酶添加量、凝乳温度和盐水浓度对半硬质干酪感官品质的影响,从而得出加工半硬质干酪的最佳工艺条件。结果表明,其最佳工艺参数为发酵剂添加量5%、CaCl2添加量0.02%、凝乳酶添加量3.0 g/100 L、凝乳温度36 ℃、盐水质量分数18%。此最佳工艺条件下得到干酪的感官评分最高为93.25分,干酪产率为10.37%,含盐量为0.74%,含水量为43.58%。香味浓郁、组织细腻、软硬适度、呈现乳白色且有光泽。     

混合乳干酪生产工艺研究(2)混合乳干酪生产最佳工艺参数优化

本试验在已筛选出的发酵剂菌种、最佳凝乳酶和钙化合物的基础上,又综合考虑了影响混合乳(豆乳和牛乳)干酪的几大因素,即豆乳添加量,发酵剂添加量,乳酸钙添加量和凝乳酶添加量,由此优化出混合乳干酪生产的最佳工艺参数.结果表明最佳发酵剂为干酪乳杆菌99108+嗜热链球菌(11),最佳凝乳酶为皱胃酶,最佳钙化合物为乳酸钙,而70%大豆豆乳与30%牛乳混合,添加4%发酵剂,0.2%乳酸钙和0.015%皱胃酶则为最佳的工艺参数.     

发酵剂的添加量对半硬质干酪品质影响研究

研究发酵剂的添加量对半硬质干酪品质的影响,以确定其最佳添加量。采用单因素试验设计,发酵剂的添加量(体积比)分别为1%、2%、3%、4%、5%。在其他工艺条件相同的情况下,分别加工一批干酪,然后测定成熟干酪的性能指标。结果表明,随着发酵剂添加量的增加,干酪的感官评定值先升高后降低;干酪的硬度和pH 值逐渐降低;总酸度、pH4.6 可溶性氮含量、游离氨基酸总量和水分含量逐渐增加。以感官评定值为主要指标,结合其他性能指标,确定发酵剂的最佳添加量为2%～3%。     

乳糖替代凝乳酶制作大豆干酪技术初探

对加酶发酵制作干酪的传统方法进行了改进,用添加乳糖的方法来代替添加酶进行发酵.试验综合考察了影响混合豆乳(豆乳和牛乳)干酪凝乳的几个因素,即豆乳添加量、发酵剂添加量、乳糖添加量和乳酸钙添加量,并确定混合豆乳干酪的最佳凝乳工艺参数.试验结果表明,最佳工艺参数为:80%豆乳 3%发酵剂 3%乳糖 0.1%乳酸钙.     

响应面法结合模糊数学优化牦牛乳酸凝干酪生产工艺

为了优化牦牛乳酸凝干酪生产工艺,以牦牛乳为原料,在单因素试验的基础上,以模糊数学处理牦牛乳酸凝干酪感官评价结果为响应值,采用响应面试验进行分析,确定干酪的最佳工艺参数。对干酪感官品质的影响因素依次为:发酵剂添加量切割pH值凝乳温度氯化钙添加量。最佳工艺参数为:发酵剂添加量0.10%,凝乳温度55℃,氯化钙添加量0.03%,切割pH值4.4,在此条件下,得到的干酪,组织状态细腻,色泽均匀有光泽,滋气味浓郁,牦牛乳酸凝干酪感官评分为95.632,验证试验干酪感官评分为95.517。试验结果可为牦牛乳酸凝干酪的生产加工提供理论基础和参考依据。     

新鲜软质干酪加工工艺的研究

以鲜牛乳为原料,研究了新鲜软质干酪的制作工艺,采用L9(34)正交试验的方法,研究了不同发酵剂菌种添加比例、发酵温度、切割pH值对成品干酪滋味口感、色泽和涂抹性的影响,最终确定了该产品生产的最佳配方和工艺条件:菌种比为1:1(质量比),发酵剂添加量为3%(质量分数),发酵温度为37℃,切割pH值为4.6。     

Edam干酪加工工艺研究

对Edam加工关键因素进行了研究。通过实验得出Edam干酪的最佳工艺条件为发酵剂添加量为0.01%,CaCl2添加量为0.015%(均为质量分数),热缩温度为38℃,可得到较高的干酪得率及较好的产品品质。     

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.     

解淀粉芽孢杆菌GSBa-1凝乳酶对羊奶干酪成熟特性的影响

为探究解淀粉芽孢杆菌GSBa-1凝乳酶制备的羊奶干酪(干酪B)成熟特性的变化,以采用商业凝乳酶和同批次羊奶制作的干酪(干酪A)为对照组,比较两组干酪在60d成熟期主要组分、质构特性、微生物指标及风味物质的变化。结果表明,两组干酪得率相差不大。成熟期间干酪的水分、蛋白质及脂肪含量呈先上升后下降趋势,干酪B始终高于干酪A;干酪游离氨基酸总量在成熟期间呈先下降后上升趋势,且干酪B中苯丙氨酸、天冬氨酸、异亮氨酸、甲硫氨酸、丝氨酸含量高于干酪A。成熟前期干酪B质构特性优于干酪A。干酪A成熟后乳酸乳球菌数量增加了(5.22±0.02)%,干酪B无显著变化(P>0.05)。成熟期内,两组干酪中挥发性风味物质种类和含量均增加,但干酪B中的壬酸、辛醇、2-庚酮、2-壬酮、二甲基砜使羊奶干酪风味独特、浓郁。因此,GSBa-1凝乳酶具备替代商业凝乳酶用于羊奶干酪生产的潜力,可对干酪风味的形成和品质的提升起到一定促进作用。     

Effect of calcium and water injection on structure-function relationships of cheese

Our objectives were to determine the effect of calcium and water injection on cheese structure and to relate changes in structure to changes in functional properties of cheese. Cheese with fat and moisture content similar to that of low-moisture part-skim Mozzarella was made according to a direct-acid, stirred/pressed-curd procedure. The cheese was then cut into blocks that were high-pressure-injected from one to five times, with either water or a 40% calcium chloride solution. Successive injections were performed 24 h apart. After 42 d of refrigerated storage, cheese microstructure and functionality were analyzed. When injected three or more times, water tended to increase cheese weight. The control, uninjected cheese, had the typical structure of a stirred/pressed-curd cheese: protein matrix interspersed with areas that originally contained fat and/or serum. Injecting water increased the area of cheese matrix occupied by protein, but it did not affect textural properties or melting of cheese. In contrast, when calcium was injected, a decrease in cheese weight was observed that was manifested through syneresis. The moisture content and pH of the cheese decreased as well. Calcium injection also decreased the area of cheese matrix occupied by protein. Cheese hardness increased, and cohesiveness and melting of cheese decreased upon calcium injection. We concluded that adding calcium to cheese alters how the proteins interact, which is manifested as changes in cheese microstructure. Such changes in cheese structure provide an understanding of changes in functional attributes of the cheese.     

Effect of lecithin addition on the yield and quality of soft cheeses

The effect of lecithin added at levels of 0.025 %, 0.050 % and 0.075 % to cheese milk used in manufacture of Domiati and Kareish cheese on yield, weight losses and quality of cheese was studied. Addition of lecithin increased cheese yield and decreased weight losses during pickling. The bacterial content of all cheeses treated with lecithin was higher than that of control cheese when fresh and during pickling. Cheese made with added lecithin showed higher moisture, salt, fat, and acidity than control cheese. The total nitrogen percentage was almost the same in all treatments. The levels of both soluble nitrogen and total volatile fatty acids in cheese containing lecithin were higher than in the control cheese. No marked differences were evaluated for flavour, body and texture of fresh cheese made from milk with or without lecithin, while during pickling the organoleptic properties of cheese containing lecithin were improved.     

强化维生素C的涂抹型再制干酪的研制

使用2个月和7个月的天然契达干酪为原料制作涂抹型再制干酪,对其进行VC强化,测定VC含量及其在产品中的稳定性。同时研究水分、乳化盐添加量对再制干酪质构的影响。使用木糖醇、白砂糖、葡萄糖调整产品口味。结果表明:2个月成熟干酪与7个月成熟干酪以2:1的配比,50%水,2%的乳化盐焦磷酸钠与三聚磷酸钠(1:1),80℃,1 500 r/min搅拌10min,加入VC,2%木糖醇、3%白砂糖与2%葡萄糖搅拌3min,得到易于保存,风味良好的产品。VC含量在储存期间无较大改变。     

添加酿酒酵母的类Cheddar干酪生产工艺

开发具有特色风味的干酪产品是提高我国消费者对干酪接受度的重要手段。以新鲜牛乳为原料,选取蔗糖添加量、干酪发酵剂添加量、凝乳酶添加量为因素,以干酪产率、感官评定为主要检测指标,通过单因素实验和正交实验对添加酿酒酵母的类Cheddar干酪的加工工艺进行优化,并以感官评定为主要检测指标,对最佳工艺进行验证。结果表明,添加酿酒酵母的类Cheddar干酪的最佳工艺条件为:蔗糖质量浓度50 g/L,干酪发酵剂质量浓度0.02 g/L,凝乳酶活力223.5 IMCU/L。在此优化条件下,成品新鲜干酪的感官评分为76.29,色泽明亮,组织状态结实,奶香味与酒香味浓郁且适宜。     

Use of low concentration factor ultrafiltration retentates in reduced-fat Minas Frescal cheese manufacture: effect on yield and sensory properties

The yield and sensory properties of reduced-fat Minas Frescal cheese made from low concentration factor (CF) retentates were studied. Three different CFs were tested (1.2, 1.5 and 1.8). The chemical compositions of the milk, retentate, whey and cheese were determined, as well as the cheese yield. The cheese moisture content decreased with increasing CF. The cheese yield was significantly dependent on the CF in the same direction as the moisture content. Despite compositional differences among the samples, only the cheese made with a CF of 1.8 presented low sensorial acceptance. CF 1.2 was found to be the optimum value for reduced-fat Minas Frescal cheese manufacture in the CF range studied.     

Effect of pH on the chemical composition and structure-function relationships of cheddar cheese

The objectives of this study were to determine the effect of pH on chemical, structural, and functional properties of Cheddar cheese, and to relate changes in structure to changes in cheese functionality. Cheddar cheese was obtained from a cheese-production facility and stored at 4 degrees C. Ten days after manufacture, the cheese was cut into blocks that were vacuum-packaged and stored for 4 d at 4 degrees C. Cheese blocks were then high-pressure injected one, three, or five times with a 20% (wt/wt) glucono-delta-lactone solution. Successive injections were performed 24 h apart. Cheese blocks were then analyzed after 40 d of storage at 4 degrees C. Acidulant injection decreased cheese pH from 5.3 in the uninjected cheese to 4.7 after five injections. Decreased pH increased the content of soluble calcium and slightly decreased the total calcium content of cheese. At the highest level, injection of acidulant promoted syneresis. Thus, after five injections, the moisture content of cheese decreased from 34 to 31%, which resulted in decreased cheese weight. Lowered cheese pH, 4.7 compared with 5.3, also resulted in contraction of the protein matrix. Acidulant injection decreased cheese hardness and cohesiveness, and the cheese became more crumbly. The initial rate of cheese flow increased when pH decreased from 5.3 to 5.0, but it decreased when cheese pH was further lowered to 4.7. The final extent of cheese flow also decreased at pH 4.7. In conclusion, lowering the pH of Cheddar cheese alters protein interactions, which then affects cheese functionality. At pH greater than 5.0, calcium solubilization decreases protein-to-protein interactions. In contrast, at pH lower than 5.0, the acid precipitation of proteins overcomes the opposing effect caused by increased calcium solubilization and decreased calcium content of cheese, and protein-to-protein interactions increase.     

Assessing the yield,microstructure, and texture properties of miniature Chihuahua-type cheese manufactured with a phospholipase A1 and exopolysaccharide-producing bacteria

Chihuahua cheese or Mennonite cheese is one of the most popular and consumed cheeses in Mexico and by the Hispanic community in the United States. According to local producers the yield of Chihuahua cheese ranges from 9 to 9.5 kg of cheese from 100 kg of milk. Cheese yield is a crucial determinant of profitability in cheese-manufacturing plants; therefore, different methods have been developed to increase it. In this work, a miniature Chihuahua-type cheese model was used to assess the effect of a phospholipase A₁ (PL-A₁) and exopolysaccharide (EPS)-producing bacteria (separately and in combination) on the yield, microstructure, and texture of cheese. Four different cheeses were manufactured: cheese made with PL-A₁, cheese made with EPS-producing bacteria, cheese with both PL-A₁ and EPS-producing bacteria, and a cheese control without PL-A₁ or EPS-producing bacteria. The compositional analysis of cheese was carried out using methods of AOAC International (Washington, DC). The actual yield and moisture-adjusted yield were calculated for all cheese treatments. Texture profile analyses of cheeses were performed using a texture analyzer. Micrographs were obtained by electron scanning microscopy. Fifty panelists carried out sensorial analysis using ranking tests. Incorporation of EPS-producing bacteria in the manufacture of cheese increased the moisture content and water activity. In contrast, the addition of PL-A₁ did not increase fat retention or cheese yield. The use of EPS alone improved the cheese yield by increasing water and fat retention, but also caused a negative effect on the texture and flavor of Chihuahua cheese. The use of EPS-producing bacteria in combination with PL-A₁ improved the cheese yield and increased the moisture and fat content. The cheeses with the best flavor and texture were those manufactured with PL-A₁ and the cheeses manufactured with the combination of PL-A1 and EPS-producing culture.     

Reduced fat process cheese made from young reduced fat Cheddar cheese manufactured with exopolysaccharide-producing cultures

In a previous study, exopolysaccharide (EPS)-producing cultures improved textural and functional properties of reduced fat Cheddar cheese. Because base cheese has an impact on the characteristics of process cheese, we hypothesized that the use of EPS-producing cultures in making base reduced fat Cheddar cheese (BRFCC) would allow utilization of more young cheeses in making reduced fat process cheese. The objective of this study was to evaluate characteristics of reduced fat process cheese made from young BRFCC containing EPS as compared with those in cheese made from a 50/50 blend of young and aged EPS-negative cheeses. Reduced fat process cheeses were manufactured using young (2 d) or 1-mo-old EPS-positive or negative BRFCC. Moisture and fat of reduced fat process cheese were standardized to 49 and 21%, respectively. Enzyme modified cheese was incorporated to provide flavor of aged cheese. Exopolysaccharide-positive reduced fat process cheese was softer, less chewy and gummy, and exhibited lower viscoelastic moduli than the EPS-negative cheeses. The hardness, chewiness, and viscoelastic moduli were lower in reduced fat process cheeses made from 1-mo-old BRFCC than in the corresponding cheeses made from 2-d-old BRFCC. This could be because of more extensive proteolysis and lower pH in the former cheeses. Sensory scores for texture of EPS-positive reduced fat process cheeses were higher than those of the EPS-negative cheeses. Panelists did not detect differences in flavor between cheeses made with enzyme modified cheese and aged cheese. No correlations were found between the physical and melting properties of base cheese and process cheese.