共查询到20条相似文献,搜索用时 101 毫秒
1.
2.
干酪生产中影响凝乳酶活力因素的研究 总被引:11,自引:1,他引:10
干酪生产中凝乳酶活力是决定其添加量的重要指标,本试验就影响活力的多种因素进行探讨。其中原料乳中非脂乳固体含量,凝乳温度、酸度、CaCl2加入量,稀释液中盐含量和凝乳酶浓度是重要的凝乳条件。 相似文献
3.
《食品与发酵工业》2015,(5):227-234
牛凝乳酶具有高凝乳活性和低非特异蛋白水解活性而广泛用于干酪制备。随着干酪市场的逐年增长,牛凝乳酶出现供不应求,其替代品应运而生,包括其他动物凝乳酶、植物凝乳酶、微生物凝乳酶、重组凝乳酶。在这些替代品中,重组牛凝乳酶显示出与天然牛凝乳酶相似的酶学特性,并且纯度更高,制作的干酪品质更好。目前已经有重组牛凝乳酶上市出售,成功替代了天然牛凝乳酶,但关于提高重组牛凝乳酶表达量与催化活性的研究远未止步。文中主要综述了凝乳酶结构、牛凝乳酶的替代品和重组凝乳酶的研究进展,详细综述了一些提高重组牛凝乳酶的表达方法,为外源蛋白在宿主中的高水平表达提供了有效参考。 相似文献
4.
5.
传统干酪加工中使用的凝乳酶是从犊牛皱胃中提取出的一种天冬氨酸蛋白酶。世界干酪产量的增加和幼犊不能大量宰杀,刺激人们寻找新的来源。重组凝乳酶是重组DNA技术在食品工业中的首次成功应用。克隆凝乳酶的一般策略是经过mRNA反转录合成cDNA,将内涵子拼接掉后把cDNA克隆在表达宿主中进行表达。使用控制的启动子有lac、trp、trp—beta、tac、T7、phoA、λPR、gly A、pgk、gall、tpi、glaA和丝氨酸羟甲基转移酶启动子等,在原核和真核细胞中都已经得到了表达。目前世界上许多公司已经商业生产,许多国家已经正式批准使用。重组凝乳酶的加工特性与天然凝乳酶没有差别。 相似文献
6.
7.
为了探究甲醇芽孢杆菌(Bacillus methanolicus)凝乳酶在马苏里拉干酪加工中的应用,分别以使用甲醇芽孢杆菌凝乳酶、混合酶制剂(含质量分数10%甲醇芽孢杆菌凝乳酶和90%商品凝乳酶)制作的马苏里拉干酪作为实验组,以商品凝乳酶干酪作为对照组,测定不同组别干酪成熟期间的蛋白水解特性、质构、风味和微观结构变化,研究甲醇芽孢杆菌凝乳酶对马苏里拉干酪加工特性的影响。结果表明,实验组干酪在成熟过程中pH值(4.6~5.3)、微生物数量(8.80~9.68(lg(CFU/g)))与对照组无显著差异(P>0.05);实验组干酪水分质量分数(混合酶干酪为(43.21±1.17)%、甲醇芽孢杆菌凝乳酶干酪为(46.15±0.94)%)均显著高于对照组((41.08±1.04)%),得率(混合酶干酪为(9.27±0.17)%、甲醇芽孢杆菌凝乳酶干酪为(9.46±0.16)%)也显著高于对照组((8.98±0.13)%)(P<0.05);且实验组干酪的蛋白水解特性(pH 4.6时可溶性蛋白、酪蛋白水解程度和游离氨基酸质量分数)以及风味物质种类和相对含量等指标也优于对照组干酪。但是实验组中甲醇芽孢杆菌凝乳酶干酪保形性相对欠佳,感官评定得分偏低,混合酶干酪与对照组质构及感官基本得分一致,因此甲醇芽孢杆菌凝乳酶可以作为商品酶的部分代替品应用于干酪的生产中。 相似文献
8.
利用地衣芽孢杆菌凝乳酶制作切达干酪和切达干酪类似物,分析干酪成熟过程中各蛋白水解指标的变化规律,以揭示地衣芽孢杆菌凝乳酶对切达干酪成熟过程中蛋白水解的影响。结果表明,CDF组(添加地衣芽孢杆菌D3.11凝乳酶所制切达干酪)、CD3组(添加地衣芽孢杆菌D3.11凝乳酶但未添加发酵剂制成的干酪类似物)和CCF组(添加商品凝乳酶所制切达干酪)干酪蛋白含量、pH 4.6-可溶性氮、12%三氯乙酸-可溶性氮、5%磷钨酸-可溶性氮、总游离氨基酸含量均随着成熟时间延长呈显著增加趋势,并且成熟期间CDF组干酪均显著高于CCF组干酪(P<0.05);十二烷基硫酸钠-聚丙烯酰氨凝胶电泳分析表明,CDF组干酪α-酪蛋白水解程度较大;pH 4.6-可溶性肽段分析表明,随着干酪的成熟,总肽含量呈先增加后下降趋势,但疏水性肽与亲水性肽的比值呈持续下降趋势,在成熟第6个月时,CDF组、CD3组和CCF组干酪疏水性肽与亲水性肽比值分别为2.668、2.822、3.788。主成分分析表明,3 组干酪的蛋白水解程度与成熟度呈正相关,与疏水性肽和亲水性肽的比值呈负相关。以上结果表明,利用地衣芽孢杆菌凝乳酶制作的干酪蛋白水解度更高,但其疏水性肽比例较小,研究结果可为地衣芽孢杆菌凝乳酶在干酪生产中的应用提供理论依据。 相似文献
9.
小牛凝乳酶的分离及部分特性研究 总被引:4,自引:0,他引:4
用NaCl和乙醇的水溶液从小牛皱胃中提取小牛凝乳酶,此粗酶经DEAE-纤维素离子交换柱层析,pH值,离子强度线性梯度洗得6个蛋白峰,其中峰I,ⅡⅢ与酶活性重叠。并将峰I经SephadexG-75菌聚糖凝胶层析柱又得3个蛋白峰,峰Ⅲ与酶活性峰重叠。合并经DEAE-纤维素离子交换柱洗脱的峰I,ⅡⅢ酶液,其最适作用温度是50℃,55℃范围内酶活性仍稳定,最适pH为6左右,在pH值为3~6范围内稳定性较好 相似文献
10.
凝乳酶在干酪生产中的应用 总被引:9,自引:3,他引:9
酪蛋白凝聚是干酪生产中的基本工序,通常情况下,这一过程由凝乳酶来完成。文章分别对凝乳酶液状、粉朱状及锭状制剂的制作过程.凝乳酶凝结牛乳的机理及实际生产过程中直接影响凝乳酶活力测定以厦凝乳酶活性的因素等问题进行了详细地探讨。 相似文献
11.
12.
Concentrations of seven milk-clotting enzyme preparations were standardized to equal clot times. Portions of bovine αs-, β- and κ-casein were treated with enzymes. Proteolytic activity of the coagulants on each casein fraction was determined using the TNBS (2,4,6-trinitrobenzene-sulfonic acid) procedure. Recombinant chymosin showed the lowest degree of proteolysis on αs- and β-caseins. Excessive proteolysis of calf rennet appeared to be due to the pepsin fraction. M. miehei and M. pusillus var Lindt proteases showed similar degradation of caseins, but M. pusillus var Lindt was more proteolytic when β-casein was the substrate. C. parasitica protease showed the highest degree of proteolysis on αs- and β-caseins but was the least proteolytic on κ-casein. 相似文献
13.
14.
15.
16.
Briggiler-Marcó M Capra ML Quiberoni A Vinderola G Reinheimer JA Hynes E 《Journal of dairy science》2007,90(10):4532-4542
Nonstarter lactic acid bacteria are the main uncontrolled factor in today's industrial cheese making and may be the cause of quality inconsistencies and defects in cheeses. In this context, adjunct cultures of selected lactobacilli from nonstarter lactic acid bacteria origin appear as the best alternative to indirectly control cheese biota. The objective of the present work was to study the technological properties of Lactobacillus strains isolated from cheese by in vitro and in situ assays. Milk acidification kinetics and proteolytic and acidifying activities were assessed, and peptide mapping of trichloroacetic acid 8% soluble fraction of milk cultures was performed by liquid chromatography. In addition, the tolerance to salts (NaCl and KCl) and the phage-resistance were investigated. Four strains were selected for testing as adjunct cultures in cheese making experiments at pilot plant scale. In in vitro assays, most strains acidified milk slowly and showed weak to moderate proteolytic activity. Fast strains decreased milk pH to 4.5 in 8 h, and continued acidification to 3.5 in 12 h or more. This group consisted mostly of Lactobacillus plantarum and Lactobacillus rhamnosus strains. Approximately one-third of the slow strains, which comprised mainly Lactobacillus casei, Lactobacillus fermentum, and Lactobacillus curvatus, were capable to grow when milk was supplemented with glucose and casein hydrolysate. Peptide maps were similar to those of lactic acid bacteria considered to have a moderate proteolytic activity. Most strains showed salt tolerance and resistance to specific phages. The Lactobacillus strains selected as adjunct cultures for cheese making experiments reached 108 cfu/g in soft cheeses at 7 d of ripening, whereas they reached 109 cfu/g in semihard cheeses after 15 d of ripening. In both cheese varieties, the adjunct culture population remained at high counts during all ripening, in some cases overcoming or equaling primary starter. Overall, proximate composition of cheeses with and without added lactobacilli did not differ; however, some of the tested strains continued acidifying during ripening, which was mainly noticed in soft cheeses and affected overall quality of the products. The lactobacilli strains with low acidifying activity showed appropriate technological characteristics for their use as adjunct cultures in soft and semihard cheeses. 相似文献
17.
研究高达干酪在4℃条件下成熟16周过程中瑞士乳杆菌对蛋白水解的影响。制作4个高达干酪样品,2个为对照样品,不添加瑞士乳杆菌;另2个为试验样品,添加瑞士乳杆菌KLDS 1.0432。在干酪成熟过程中每隔一段时间测定pH4.6水溶性氮(SN-pH4.6)、12%三氯乙酸氮(SN-TCA)、5%磷钨酸氮(SN-PTA),并进行SDS凝胶电泳。结果显示:对照样品和试验样品的SN-pH4.6和SDS凝胶电泳没有显著差别,但是试验样品中的SN-TCA和SN-PTA比对照样品高。 相似文献
18.
为发掘性能优良的产凝乳酶细菌菌株,开发新型细菌凝乳酶。本文采用酪蛋白培养基从采自青海牧区土壤样品分离筛选产凝乳酶细菌,利用菌株16S rDNA基因序列对菌株进行鉴定并分析其多样性。结果表明,36个样品中分离得到21株产凝乳酶细菌,沉淀圈与菌落直径比值为1.41~5.5;分离菌株在不同培养基上凝乳酶和蛋白水解活性有明显差异,麸皮汁培养基中凝乳酶活性为11.3~1215.6 SU/mL,蛋白水解活力为14.6~59.5U/mL;21株菌中有14株菌属芽孢杆菌属(Bacillus),是产凝乳酶细菌的优势属;多样性指数分析表明,该地区产凝乳酶细菌具有丰富多样性。 相似文献
19.
20.