超声技术在皱胃酶提取中的应用

简要介绍了超声技术提取的基本原理,论述了超声技术在皱胃酶提取中的应用.讨论了超声提取中超声强度、超声处理时间、提取液浓度及温度的选择问题,为超声提取研究提供参考.     

皱胃酶提取工艺的研究

研究了小牛皱胃酶的提取工艺，分析了不同提取液、提取温度、时间、提取液量及换液频率对提取效果的影响。结果表明，4－10℃下，采用10％CaCl2和1％乙醇为提取取液，首次用800mL，每两天换液1次，后两次用量减半。     

从羔羊皱胃中提取凝乳酶

本文叙述凝乳酶提取方法的革新,利用羔羊皱胃提取的优点,并介绍羔羊皱胃的选择与处理、凝乳酶的纯化和结晶技术。     

硫酸铵盐析羔羊皱胃酶条件的研究

以羔羊皱胃为原料,研究了硫酸铵盐析法盐析羔羊皱胃酶的工艺条件,系统分析了硫酸铵饱和度、pH、盐析温度以及盐析时间对羔羊皱胃酶盐析效果的影响.结果表明,当硫酸铵饱和度为95%,盐析pH为4.60,盐析温度为4℃,盐析时问为14h时,羔羊皱胃酶盐析效果最好,酶活性回收率为92.86%.     

硫酸铵盐析羔羊皱胃酶条件的研究

以羔羊皱胃为原料,研究了硫酸铵盐析法盐析羔羊皱胃酶的工艺条件,系统分析了硫酸铵饱和度、pH、盐析温度以及盐析时间对羔羊皱胃酶盐析效果的影响。结果表明,当硫酸铵饱和度为95%,盐析pH为4.60,盐析温度为4℃,盐析时间为14h时,羔羊皱胃酶盐析效果最好,酶活性回收率为92.86%。      

皱胃酶酶学性质的研究

研究了皱胃酶的酶学性质。皱胃酶的最适作用温度和最适pH值分别为42℃和6.0。在45℃以下和pH4.5～7.0范围内,酶活保持稳定。Ca2+、Na+、Fe3+对皱胃酶的凝乳有明显的促进作用,Mg2+、Cu2+、Ba2+对凝乳有抑制作用。并研究了底物浓度对酶反应的影响。     

干酪制备中的皱胃酶性质

研究了制备干酪过程中皱胃酶的主要性质，主要是ＣａＣｌ２浓度、温度、ｐＨ值对皱胃酶的活性有显著影响。     

用于干酪生产的凝乳酶与小牛皱胃酶的制备

目前在世界各国干酪生产中使用的天门冬氨酸酶(EC3.4.23),无论何种来源,因其均能凝结牛奶,故称为凝乳酶(milk-clotting enzymes)。从哺乳动物器官中提取的含有天门冬氨酸酶的制品为粗制凝乳酶(rennet)。在国际市场上,用于干酪生产的商品化凝乳酶的来源可分为;动物80%、微生物20%,植物不到1%。小牛皱胃酶(calf rennet)多年来在各国的干酪生产中广为使用,它存在于小牛第四胃中,凝乳酶含量为70～90%。另外还含有胃蛋白酶,一般适合于制造各     

毛霉MJ229固态发酵凝乳酶提取工艺研究

凝乳酶是干酪生产中的关键性酶.它对干酪的质构形成及特有风味的形成有非常重要的作用.随着干酪工业的不断发展,传统来源的凝乳酶已远不能满足生产需要,各国研究者不断地寻找新的来源.霉菌MJ229是从我国传统食品江米酒酒醪中筛选得到的一株凝乳酶高产菌株.本论文对霉菌MJ229固态发酵物中凝乳酶的提取工艺进行了研究,分别研究了提取时间、食盐浓度、提取温度、次数对固态发酵液中凝乳酶提取效果的影响.结果表明,霉菌MJ229固态发酵中凝乳酶在温度40℃条件下,用0.3mol/L的NaCl溶液提取20min,提取3次的效果为最好.     

酶技术对红枣汁提取效果的影响

以红枣为原料,采用酶解浸提的方法制备红枣汁.主要研究酶解条件对红枣汁提取效果的影响,通过试验比较采用果胶酶、果胶酶与纤维素酶的复合酶、果胶酶与酸性蛋白酶的复合酶分别进行酶解浸提对红枣汁黏度和提取率的影响.试验表明:采用果胶酶与纤维素酶的复合酶时提取效果较好,在加酶量为果胶酶0.20%、纤维素酶0.15%;酶解温度T=50℃;浸提时间为t=3 h;料水比为1:5(g/mL)的条件下,提取率为60.2%,黏度为1.50mPa·s,所得汁液枣香浓郁、无苦味、颜色为枣红色,具有较好的稳定性.     

曲拉凝乳酶干酪素生产工艺研究

优化了曲拉凝乳酶干酪素的生产工艺,并通过中试实验验证。设计正交实验对影响曲拉溶解速率的4个因素、改善曲拉凝乳酶干酪素色泽的4种护色剂配比和曲拉溶解液离心脱脂效果的3个因素工艺参数进行了优化,实验结果确定了曲拉溶解的最佳工艺参数:pH10.5,温度55℃,搅拌转速300r/min,物料浓度10%;4种护色剂最佳配比:低亚硫酸钠0.2%、亚硫酸氢钠0.2%、乙二胺四乙酸二钠0.05%、焦亚硫酸钠0.23%;曲拉溶解液离心脱脂的最佳工艺:重力环内径为108mm、进料流量为2.5t/h、排渣间隔时间为5min。对15批次产品进行感官评价和理化检测,感官评价结果:呈淡黄色粉末,无嗅无味;各项目理化检测平均结果为:蛋白质91.0%,脂肪0.6%,乳糖0.19%,水分10.3%,灰分5.0%,pH7.07。工艺优化后,原料曲拉的溶解速率提高20.7%;曲拉凝乳酶干酪素感官指标得到很好改善;脂肪质量分数下降了50%,同时其他理化指标均优于优化前指标,大大提高了产品品质。      

Optimization of processing parameters for the ultrasonic extraction of goat kid rennet

Using abomasums of 2- to 3-week-old goat kids as material, the effects of some factors such as ultrasound intensity, extraction time, NaCl concentration in extraction solution and ratio of abomasums mucosa to extraction solution on the extraction yield of goat kid rennet were investigated. On the basis of single factor experiments, the processing parameters for ultrasound extraction were optimized using a four-factor orthogonal and rotatory combinatorial design. The results showed that the optimum processing parameters for the extraction of goat kid rennet were: ultrasound intensity, 44 W/cm²; extraction time, 25 min; NaCl concentration in extraction solution, 16%; and the ratio of abomasumal mucosa to extraction solution, 1 : 30. In addition, the ultrasonic extraction, as compared with traditional extraction, proved to be more effective.     

贯筋藤鲜茎中凝乳酶的提取工艺研究

以云南西北部地区的野生植物贯筋藤的鲜茎为原料,在单因素的试验基础上,采用L9（33）正交试验方法,以贯筋藤鲜茎中凝乳酶活力为评价指标,研究了不同的预处理方式、料液比、浸泡时间、浸泡温度对其提取工艺的影响,确定了贯筋藤鲜茎中凝乳酶的最佳提取条件和提取率。结果表明,贯筋藤鲜茎中凝乳酶的提取最佳条件为料液比1∶20（g∶mL）,提取时间40 min,提取温度65 ℃,在此条件下得到的凝乳酶活力为260.984 SU/mL,提取率为31.35%。     

酶凝干酪素生产过程中酶凝工艺的优化

研究了凝乳酶添加量、凝乳温度和凝乳时间对酶凝干酪素酶凝工艺的影响,通过对凝乳过程的感官评价,最终确定了酶凝干酪素的最佳酶凝工艺参数。结果表明:凝乳温度和凝乳时间对酶凝干酪素酶凝状态有显著影响,确定最优工艺条件为:凝乳酶添加量的体积分数为0.078%,凝乳温度为32℃,凝乳时间28 min。此条件下生产的酶凝干酪素与市售酶凝干酪素理化指标接近。     

Influence of lamb rennet paste containing probiotic on proteolysis and rheological properties of pecorino cheese

Pecorino cheeses made from heat-treated ewes’ milk using traditional lamb rennet paste (RP), lamb rennet paste containing Lactobacillus acidophilus (LA-5; RPL), and lamb rennet paste containing a mix of Bifidobacterium lactis (BB-12) and Bifidobacterium longum (BB-46; RPB) were characterized for proteolytic and rheological features during ripening. Consumer acceptance of cheeses at 60 d of ripening was evaluated. Lactobacillus acidophilus and Bifidobacterium mix displayed counts of 8 log₁₀ cfu/g and 9 log₁₀ cfu/g, respectively, in cheese during ripening. The RPB cheese displayed a greater degradation of casein (CN) matrix carried out by the enzymes associated to both Bifidobacterium mix and endogenous lactic acid microflora, resulting in the highest values of non-CN N and water-soluble N and the highest amount of α_s-CN degradation products in cheese at 60 d of ripening. The RPL cheese displayed intermediate levels of lactic acid bacteria and of N fractions. The percentage of γ-CN in RP and RPL cheeses at 60 d was 2-fold higher than in the cheese curd of the same groups, whereas the mentioned parameter was 3-fold higher in RPB cheese than in the corresponding fresh curd according to its highest plasmin content. The lower hardness in RPB at the end of ripening could be ascribed to the greater proteolysis observed in cheese harboring the Bifidobacterium mix. Although differences in proteolytic patterns were found among treatments, there were no differences in smell and taste scores.     

夸克生产中凝乳酶筛选的研究

本文以凝乳酶活力、夸克出品率和感官指标为依据,对凝乳酶在夸克生产中的应用进行了研究。结果表明,各种酶的综合性能顺序为:小牛皱胃酶>羔羊皱胃酶>木瓜蛋白酶>乳猪皱胃酶>毛霉凝乳酶>无花果蛋白酶>胃蛋白酶。利用正交试验对性能较好的前三种酶进行优化设计,确定夸克生产中酶的最佳复配添加量为:100L牛乳中加入小牛皱胃酶0.3g、羔羊皱胃酶0.2g以及木瓜蛋白酶0.15g。     

喷淋滴滤法咖啡提取工艺的研究

咖啡提取是生产咖啡饮料的关键工序,采用较先进的喷淋滴滤法工艺进行咖啡提取实验,找出影响该工艺咖啡提取率的关键因素:水温、咖啡粉与水的比例、咖啡焙烤程度(L值),最佳的工艺参数为:水温95～98℃、咖啡粉与水的比例1∶13～1∶14、咖啡焙烤度L值31.8～40.5。     

Probiotic in lamb rennet paste enhances rennet lipolytic activity, and conjugated linoleic acid and linoleic acid content in Pecorino cheese

Cheeses manufactured using traditional lamb rennet paste, lamb rennet paste containing Lactobacillus acidophilus, and lamb rennet paste containing a mix of Bifidobacterium lactis and Bifidobacterium longum were characterized for the lipolytic pattern during ripening. Lipase activity of lamb rennet paste, lamb rennet containing Lb. acidophilus, and lamb rennet containing a mix of bifidobacteria was measured in sheep milk cream substrate. Rennet paste containing probiotics showed a lipase activity 2-fold greater than that displayed by traditional rennet. Total free fatty acid (FFA) in sheep milk cream was lower in lamb rennet paste (981 μg/g of milk cream) than in lamb rennet containing Lb. acidophilus (1,382.4 μg/g of milk cream) and in lamb rennet containing a mix of bifidobacteria (1,227.5 μg/g of milk cream) according to lipase activity of lamb rennet paste. The major increase of FFA in all cheeses occurred during the first 30 d of ripening with the greatest values being observed for C16:0, C18:0 C18:1. At 60 d of ripening all cheeses showed a reduction in the amount of free fatty acids; in particular, total free fatty acids underwent a decrease of more than 30% from 30 to 60 d in cheeses manufactured using traditional lamb rennet paste, whereas the same parameter decreased 10% in cheeses manufactured using lamb rennet paste containing Lb. acidophilus and cheeses manufactured using lamb rennet paste containing a mix of B. lactis and B. longum. Cheese containing Lb. acidophilus was characterized by the greatest levels of total conjugated linoleic acids (CLA) 9-cis, 11-trans CLA and 9-trans, 11-trans CLA, whereas cheese containing bifidobacteria displayed the greatest levels of free linoleic acid. Rennet pastes containing viable cells of Lb. acidophilus and a mix of B. lactis and B. longum were able to influence the amount of FFA and CLA in Pecorino cheese during ripening.