响应面法优化双蛋白干酪加工工艺

根据Box-Behnken中心组合实验设计原理,采用4因素3水平响应曲面分析法,以凝乳效果为响应值建立二次多项回归模型,并验证模型的有效性。实验结果表明：双蛋白干酪最佳制作工艺为豆乳添加量为20％（V／V）,氯化钙添加量0．04％,凝乳酶添加量为0．02％,凝乳温度为32℃。在此条件下,理论凝乳效果得分为87．67,验证值为88．00。     

响应面法优化黑豆干酪工艺条件

采用Box-Behnken中心组合响应面试验,研究黑豆干酪的最佳工艺条件,建立氯化钙添加量、凝乳酶添加量以及凝乳温度对凝乳效果影响的二次多项回归模型,并验证模型的有效性.结果表明,黑豆干酪的最佳工艺条件:氯化钙添加量0.06％、凝乳酶添加量0.025％、凝乳温度32℃.此时模型预测凝乳效果评分为88.5,验证实验结果为88.0,与理论预测值基本吻合.     

花生乳生鲜干酪的研制

以花生乳部分代替牛乳制作混合干酪,不仅可以使动植物蛋白得到互补,还可以使干酪具有花生的保健功效和特有的香味。针对花生乳添加量、发酵剂添加量、氯化钙添加量、凝乳酶添加量四个因素对凝乳效果和成品质量的影响进行单因素实验及L9(34)正交试验,最终结果表明:花生乳添加量为10%,发酵剂添加量为3%,氯化钙添加量为0.04%,凝乳酶添加量为0.025%时,凝乳效果最好。     

响应面法分析牛乳成分对凝乳特性的影响

为研究乳中主要成分的含量以及体细胞数对牛乳在凝乳酶作用下凝固特性的影响,对不同组成成分的乳样于35℃条件下添加一定量的商品凝乳酶和氯化钙,测定乳样凝固的凝乳时间和凝乳黏度。单因素试验显示,乳中蛋白质含量、脂肪含量、氯化钙添加量和体细胞数等因素对凝乳特性有明显影响。对这4个因素采用响应面法分析其交互作用,确定最佳凝乳条件。结果表明:蛋白质含量与脂肪含量、氯化钙添加量或体细胞数之间,以及脂肪含量与氯化钙添加量之间交互作用对凝乳特性的影响显著;氯化钙添加量或脂肪含量与体细胞数之间的交互作用不显著。获得最佳凝乳效果的牛乳组成成分是:蛋白质含量4.97 g/100 m L、脂肪含量4.93 g/100m L,氯化钙添加量4 mmol/L,体细胞数≤20万个/m L。     

嗜酸乳杆菌发酵生产低脂干酪凝乳工艺的优化

以脱脂乳为原料,采用嗜酸乳杆菌发酵进行预酸化,对其生产的低脂干酪凝乳工艺条件进行了研究。实验选取凝乳pH、氯化钙添加量、凝乳酶添加量、凝乳温度4个影响因素,以干酪产率、乳清中非脂乳固体物质残留量、嗜酸乳杆菌活菌数为指标,采用L₉（3⁴）正交实验进行优化。结果表明,凝乳的最佳工艺参数为凝乳pH6.0,氯化钙添加量0.02%（w/w）,凝乳酶添加量0.01%（w/w,酶活20000u/g）,凝乳温度35℃,以此条件生产的低脂干酪脂肪含量小于5%,干酪产率29.41%,乳清中非脂乳固体物质残留量5.66%,嗜酸乳杆菌活菌数在10⁹cfu/mL以上。     

响应面法优化“曲拉”凝乳酶干酪素凝乳工艺

以"曲拉"为原料,采用筛选的微小毛霉凝乳酶为凝乳剂,在酶添加量、凝乳温度、凝乳pH值、CaCl2添加量4个单因素试验基础上,利用响应面试验设计法进行试验设计,取得曲拉凝乳酶干酪素出品率与各单因素的函数关系,并建立曲拉凝乳酶干酪素凝乳工艺模型。回归方程和响应曲面结果表明:4个因素对曲拉凝乳酶出品率影响大小依次为:凝乳pH值>凝乳酶添加量>CaCl2添加量>凝乳温度;最佳凝乳工艺为凝乳pH6.2、凝乳酶添加量0.05g/kg、CaCl2添加量2.5%、凝乳温度42℃。在此条件下,曲拉凝乳酶干酪素的理论出品率为75.23%,实验验证出品率为73.54%。     

花生混合乳干酪的研制

用花生乳代替部分牛乳生产干酪,既强化了干酪风味又增强了干酪的保健功能,并可降低生产成本.本试验对花生乳比例、发酵剂添加量、氯化钙的添加量、凝乳酶添加量4个因素对凝乳效果的影响进行单因素试验,确定适合比例后,再采用L9(34)正交试验设计,通过凝乳效果、出品率和感官评价等进行极差分析,确定最佳工艺参数为:花生乳添加量为10 %,发酵剂添加量为0.03 %,氯化钙添加量为0.08 %,凝乳酶添加量为0.0025 %.     

牦牛奶软质鲜奶酪生产技术研究

以牦牛鲜乳为原料,以凝乳时间、奶酪产率和感官评价为主要指标,采用单因素实验和正交实验,研究氯化钙和凝乳酶的添加量,凝乳温度对牦牛奶软质奶酪成品感官质量及出品率的影响,确定了牦牛奶软质鲜奶酪生产最佳生产工艺参数为:凝乳温度为35℃,凝乳酶添加量为0.003 g/100 mL,CaCl2的添加量为0.03 g/100 mL。     

花生乳牛乳新鲜干酪加工工艺优化

用花生乳代替部分牛乳生产新鲜干酪,对花生乳添加比例、氯化钙添加量、凝乳酶添加量3个因素对凝乳效果的影响分别进行单因素试验,确定各自合适比例后,再采用L9(33)正交试验,确定花生乳牛乳新鲜干酪最佳生产工艺。结果表明花生乳添加量20%、氯化钙添加量0.06%、凝乳酶添加量0.002%时制作出的新鲜花生乳牛乳干酪成品呈乳白色、柔软、有弹性、具有花生风味,产品出品率为16.33%。     

牦牛乳Halloumi奶酪工艺优化及理化特性研究

以牦牛乳与荷斯坦牛乳为原料，通过牦牛乳与荷斯坦牛乳比例、氯化钙添加量、凝乳酶添加量、凝乳温度、热烫温度做单因素试验，以产率为评价指标进行四因素三水平正交试验，即牦牛乳与荷斯坦牛乳比例、氯化钙添加量、凝乳酶添加量、热烫温度，得到Halloumi奶酪最佳生产工艺为牦牛乳与荷斯坦牛乳比例4∶1、氯化钙添加量0.04 g/100 m L、凝乳酶添加量0.003 g/100 m L、热烫温度65℃。选取圆柱探头TA3/100，夹具TA-RT-KIT,测试速度为0.5 mm/s,返回速度为0.5 mm/s,形变量为50%的参数下测得单因素试验与正交试验产品的质构。制得的Halloumi奶酪水分含量26.04%，脂肪含量38.81%,pH 7.40，蛋白质含量30.16%。     

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.     

凝乳工艺对功能性低脂干酪中活菌数的影响

活菌数是功能性低脂干酪的重要指标,本文就凝乳工艺过程对功能性低脂干酪活菌数的影响进行了研究,旨在通过控制凝乳工艺过程参数而使干酪最终活菌数达到功能性食品的标准。通过对单因素实验和正交实验研究与分析,结果表明:凝乳酶添加量0.01%,凝乳温度35℃,凝乳pH值为6.2,CaCl2添加量0.03%,干酪活菌数均能达到107mL-1,符合功能性低脂干酪的活菌数要求,能够获得较为理想的实验效果。     

The influence of milk pasteurization temperature and pH at curd milling on the composition, texture and maturation of reduced fat cheddar cheese

Reduced fat milks were pasteurized, for 15 s, at temperatures ranging from 72 to 88°C to give levels of whey protein denaturation varying from ˜ 3 to 35%. The milks were converted into reduced fat cheddar cheese (16–18% fat) in 500 litre cheese vats; the resultant cheese curds were milled at pH values of 5.75 and 5.35. Raising the milk pasteurization temperature resulted in impaired rennet coagulation properties, longer set-to-cut times during cheese manufacture, higher cheese moisture and moisture in the non-fat cheese substance, lower levels of protein and calcium and lower cheese firmness. Increasing the pH at curd milling from 5.35 to 5.75 affected cheese composition and firmness, during ripening, in a manner similar to that of increasing milk pasteurization temperature. Despite their effects on cheese composition and rheology, pasteurization temperature and pH at curd milling had little influence on proteolysis or on the grading scores awarded by commercial graders during ripening over 303 days .     

Improvement of low fat mozzarella cheese properties using denatured whey protein

Mozzarella cheese was made from buffalo milk (6% fat) or from partially skimmed buffalo milk (2 and 4% fat) with 0.5 and 1% denatured whey protein. Adding whey protein to buffalo milk decreased rennet coagulation time and curd tension whereas increased curd synaeresis. Addition of whey protein to cheese milk increased the acidity, total solids, ash, salt, salt in moisture, also some nitrogen fractions. The meltability and oiling‐off values increased but the calcium values of mozzarella cheese decreased. The sensory properties of low fat mozzarella cheese were improved by addition of whey protein to the cheese milk.     

Effect of cutting time, temperature, and calcium on curd moisture, whey fat losses, and curd yield by response surface methodology

Response surface methodology was used to study the effect of temperature, cutting time, and calcium chloride addition level on curd moisture content, whey fat losses, and curd yield. Coagulation and syneresis were continuously monitored using 2 optical sensors detecting light backscatter. The effect of the factors on the sensors’ response was also examined. Retention of fat during cheese making was found to be a function of cutting time and temperature, whereas curd yield was found to be a function of those 2 factors and the level of calcium chloride addition. The main effect of temperature on curd moisture was to increase the rate at which whey was expelled. Temperature and calcium chloride addition level were also found to affect the light backscatter profile during coagulation whereas the light backscatter profile during syneresis was a function of temperature and cutting time. The results of this study suggest that there is an optimum firmness at which the gel should be cut to achieve maximum retention of fat and an optimum curd moisture content to maximize product yield and quality. It was determined that to maximize curd yield and quality, it is necessary to maximize firmness while avoiding rapid coarsening of the gel network and microsyneresis. These results could contribute to the optimization of the cheese-making process.     

Effects of indirect indicators of udder health on nutrient recovery and cheese yield traits in goat milk

In dairy goats, very little is known about the effect of the 2 most important indirect indicators of udder health [somatic cell count (SCC) and total bacterial count (TBC)] on milk composition and cheese yield, and no information is available regarding the effects of lactose levels, pH, and NaCl content on the recovery of nutrients in the curd, cheese yield traits, and daily cheese yields. Because large differences exist among dairy species, conclusions from the most studied species (i.e., bovine) cannot be drawn for all types of dairy-producing animals. The aims of this study were to quantify, using milk samples from 560 dairy goats, the contemporary effects of a pool of udder health indirect indicators (lactose level, pH, SCC, TBC, and NaCl content) on the recovery of nutrients in the curd (%REC), cheese yield (%CY), and daily cheese yields (dCY). Cheese-making traits were analyzed using a mixed model, with parity, days in milk (DIM), lactose level, pH, SCC, TBC, and NaCl content as fixed effects, and farm, breed, glass tube, and animal as random effects. Results indicated that high levels of milk lactose were associated with reduced total solids recovery in the curd and lower cheese yields, because of the lower milk fat and protein contents in samples rich in lactose. Higher pH correlated with higher recovery of nutrients in the curd and higher cheese yield traits. These results may be explained by the positive correlation between pH and milk fat, protein, and casein in goat milk. High SCC were associated with higher recovery of solids and energy in the curd but lower recovery of protein. The higher cheese yield obtained from milk with high SCC was due to both increased recovery of lactose in the curd and water retention. Bacterial count proved to be the least important factor affecting cheese-making traits, but it decreased daily cheese yields, suggesting that, even if below the legal limits, TBC should be considered in order to monitor flock management and avoid economic losses. The effect of NaCl content on milk composition was linked with lower recovery of all nutrients in the curd during cheese-making. In addition, high milk NaCl content led to reductions in fresh cheese yield and cheese solids. The indirect indicators of the present study significantly affected the cheese-making process. Such information should be considered, to adjust the milk-to-cheese economic value and the milk payment system.