裂褶菌产内切β-1,3-葡聚糖酶的分离纯化

采用不同饱和度的硫酸铵溶液对内切β-1,3-葡聚糖酶粗酶液进行分段盐析,以确定最佳盐析条件,将盐析处理后的酶液经透析浓缩、DEAE-Sephadex A-50离子交换层析、Sephadex G-75凝胶过滤层析等进一步分离纯化,浓缩纯化后的含酶组分,经过SDS-PAGE电泳分析其纯度并初步确定其分子量。结果显示:经过纯化后的内切β-1,3-葡聚糖酶的比活力由20.90U/mg提高到933.37U/mg,纯化倍数为44.7倍,酶活回收率为11.6%,电泳分析呈单一条带,分子量近似为45ku。     

苹果渣对高级醇的降解作用

将用冷冻丙酮处理过的苹果渣制粉装柱(简称酶柱),用于处理不同高级醇的混合体系。以正己醇降解率表示酶活,在正己醇水溶液体系中研究酶粉对高级醇的降解机制。研究表明,酶粉能有效降低混合体系中的正己醇、异丁醇和异戊醇含量,同时形成新物质正己醛,并提高了体系中乙酸丙酯和反-2己烯醛的含量。处理过的高级醇体系的香气变得柔和。初始酶柱对正己醇(浓度为3 g/L)的降低率可达90%以上,处理液体系增大至理液达到4BV时,酶柱对体系中正己醇降解率降至12%。以灭活后酶柱为对照,酶柱对正己醇的降解作用60%来自酶的催化作用,40%来自吸附作用。     

利用(NH_4)_2SO_4分步盐析法从麦芽中初步分离极限糊精酶

文中对极限糊精酶的(NH4)2SO4盐析法进了研究。从大麦芽中萃取得到的粗酶液,采用(NH4)2SO4盐析法进行粗分级提取,绘制盐析曲线,确定盐析法纯化极限糊精酶的方案,并研究了各方案对极限糊精酶纯化纯度和得率的影响。研究结果表明:盐析曲线中饱和度分别为35%和80%时出现两个酶活峰,但80%饱和度时可以将绝大部分酶蛋白沉淀;分别采用一步法盐析(80%),二步法盐析(25%,80%),三步法盐析(25%,35%,80%)沉淀酶蛋白,其中三步法盐析可使极限糊精酶的纯度(A510/A280)达到1.635,纯化倍数和得率分别为8.8倍和49.5%,均优于其他两种方法。极限糊精酶盐析方案的优化可为其进一步分离纯化奠定基础。     

利用(NH_4)_2SO_4分步盐析法从麦芽中初步分离极限糊精酶

文中对极限糊精酶的(NH4)2SO4盐析法进了研究。从大麦芽中萃取得到的粗酶液,采用(NH4)2SO4盐析法进行粗分级提取,绘制盐析曲线,确定盐析法纯化极限糊精酶的方案,并研究了各方案对极限糊精酶纯化纯度和得率的影响。研究结果表明:盐析曲线中饱和度分别为35%和80%时出现两个酶活峰,但80%饱和度时可以将绝大部分酶蛋白沉淀;分别采用一步法盐析(80%),二步法盐析(25%,80%),三步法盐析(25%,35%,80%)沉淀酶蛋白,其中三步法盐析可使极限糊精酶的纯度(A510/A280)达到1.635,纯化倍数和得率分别为8.8倍和49.5%,均优于其他两种方法。极限糊精酶盐析方案的优化可为其进一步分离纯化奠定基础。     

一种枯草芽孢杆菌亮氨酸氨肽酶的提取及部分酶学性质研究

采用(NH4)2SO4盐析法、有机溶剂沉淀法以及超滤浓缩等操作提取亮氨酸氨肽酶,初步建立了一种易于规模化提取枯草芽孢杆菌亮氨酸氨肽酶的工艺。发酵液采用质量分数为15%的(NH4)2SO4澄清,再经30kDa的超滤膜浓缩2.5倍时,纯化倍数为6.1,酶的回收率为87.7%。超滤后的保留液再经质量分数为25%的(NH4)2SO4盐析,可沉淀出保留液中90%的酶。按此工艺超滤浓缩后的液态酶稳定性较好,85d仍能保留80%以上的酶活。Co2+对此亮氨酸氨肽酶有较强的激活作用,Zn2+、Fe2+、Mn2+和Ca2+等几种金属离子对酶有不同程度的抑制作用。     

两步盐析联合双水相萃取提取纯化蓝藻中藻蓝蛋白

以巢湖新鲜蓝藻为处理对象,采取冻融破壁的方式获取藻蓝蛋白的粗提液,采取两步盐析联合双水相萃取的方法提取纯化藻蓝蛋白。运用0.618法选点实验研究了两步盐析中(NH4)2SO4饱和度对提取纯化影响,构建了聚乙二醇（polyethylene glycol,PEG）-(NH4)2SO4的双水相体系,综合考虑PEG相对分子质量、PEG质量分数、(NH4)2SO4质量分数、pH值和藻蓝蛋白质量浓度对提取纯化藻蓝蛋白的影响。结果表明：室温25 ℃条件下,一步盐析时(NH4)2SO4的最佳饱和度为21%,二步盐析时(NH4)2SO4的最佳饱和度为30%。两步盐析后得到的藻蓝蛋白构建成PEG-(NH4)2SO4的双水相体系后,当PEG相对分子质量1 000、PEG 1 000质量分数10%、(NH4)2SO4质量分数25%时,藻蓝蛋白的纯度可达3.45。     

植物源抗烟草花叶病毒活性物质的初步筛选

利用半叶枯斑法,测定了13科18种植物蛋白粗提液对烟草花叶病(TMV)的抑制效果。结果表明,不同植物蛋白粗提液对TMV侵染心叶烟的抑制效果存在差异,6种植物蛋白粗提液对TMV的抑制效果达到50%以上,其中菠菜和合欢最高,分别达到了97.44%和96.92%。进一步通过(NH4)2SO4盐析,对菠菜和合欢蛋白粗提液抗病毒活性成分进行了初步分离,并测试(NH4)2SO4盐析的不同蛋白组分对TMV的抑制效果。结果显示,菠菜蛋白粗提液盐析后的两个蛋白组分都表现出很高的抗病毒活性,而合欢蛋白粗提液只在40%~80%饱和度盐析的蛋白组分具有较强的抗病毒活性。     

用于烟梗木质素降解的漆酶的分离纯化研究

通过云芝菌发酵得到的漆酶粗酶液经超滤浓缩后,以硫酸铵为盐析剂进行分级盐析沉淀,利用DEAE-Sepharose-F.F.柱层析对漆酶的发酵液进行分离纯化.SDS-PAGE电泳分析证明获得了电泳纯漆酶,其分子量约为64.4 k D.分离纯化过程中酶被纯化了22.80倍,酶活的回收率为36.32%,表明云芝菌产漆酶得到了很好的分离纯化.将漆酶液用于烟梗木质素的降解,实验结果表明,经此降解处理过的烟梗其内在品质得到了一定的提高:杂气和刺激性明显降低,木质气明显减弱,香气和余味均有改善.     

法尔凯干酵母乙醛脱氢酶的提取和纯化研究

应用硫酸铵分级盐析、热沉淀及双水相萃取方法提取并纯化了法尔凯干酵母胞浆内的乙醛脱氢酶(ALDH).结果表明,粗酶液经过硫酸铵分级盐析、热沉淀和2次双水相萃取后得到的ALDH酶液,比活性为0.14,纯化倍数为3.5,回收率为58 %;酶的最适pH为7.5,最适反应温度为35～40 ℃,以乙醛为底物的Km值为6.9×10-3 mol/L, K+离子为激活剂,Zn2+离子为抑制剂.     

黑曲霉TC-01产柚苷酶分离纯化及其降解内毒素研究初探

[目的]对黑曲霉TC-01产柚苷酶进行分离纯化及酶学性质研究,并对柚苷酶降解内毒素进行初步研究。[方法]黑曲霉TC-01发酵优化后的酶液经硫酸铵分级盐析、透析浓缩、DEAE Bio-Sep FF离子交换层析等分离纯化,考察酶学性质,初步研究柚苷酶对内毒素的降解作用。[结果]柚苷酶纯化后,比活力6429.3u/mg,纯化倍数31.1倍。酶学性质研究结果表明TC-01产柚苷酶最适pH4,最适温度60℃,考察金属离子对酶活影响,1~10mM Ca~(2+)、Mg~(2+)对柚苷酶酶活有促进作用,Zn~(2+)、Fe~(2+)、Fe~(3+)、Cu~(2+)对柚苷酶的酶活有抑制作用,Fe~(2+)抑制作用最为强烈。柚苷酶对内毒素具有降解作用,柚苷酶与内毒素反应1h,内毒素降解率达到79.9%。[结论]研究为柚苷酶的工业化生产提供理论依据,同时拓宽了柚苷酶的应用范围,为进一步研究柚苷酶降解内毒素提供了基础数据,具有重要的科学意义和应用价值。     

CAB/正庚烷/正己醇反胶束体系前萃大豆蛋白的研究

探讨了CAB／正庚烷／正己醇反胶束溶液萃取大豆蛋白的前萃机理和工艺，系统地研究了盐的种类、pH、KCl的浓度、表面活性剂CAB的浓度、加料量、萃取温度、萃取时间和w。对蛋白前萃率的影响，得到了以cAB／正庚烷／正己醇反胶束体系萃取全脂大豆粉中蛋白质的最佳前萃工艺条件。     

蒲公英多糖脱色脱蛋白方法及其降血糖活性研究

以蒲公英为原料,采用超声波辅助法提取蒲公英粗多糖,对其脱色和脱蛋白工艺进行研究,并评价纯化前后多糖的体外降血糖能力。以脱色率和多糖损失率为考察指标,对大孔树脂、活性碳、过氧化氢、壳聚糖的脱色效果进行对比,筛选出最佳的脱色方法;以脱蛋白率和多糖损失率为考察指标,对Sevag法、盐析法、酶-三氯乙酸(trichloroacetic acid,TCA)法、酶-Sevag法的脱蛋白效果进行比较,筛选出最优的脱蛋白方法;利用抑制α-葡萄糖苷酶能力评价多糖的体外降血糖活性。结果表明:大孔树脂S-8脱色效果最优,色素脱除率为86.45%,多糖损失率为18.9%;盐析法脱蛋白效果最优,蛋白质脱除率为85.64%,多糖损失率为20.51%。所得精制多糖对α-葡萄糖苷酶有一定的抑制能力,随着多糖质量浓度的增加,抑制率逐渐增大,当质量浓度为1.0 mg/mL时,抑制率达到76.28%。     

复合酶法提取红雪茶粗多糖工艺优化研究

为了获得复合酶法提取红雪茶粗多糖的最佳工艺,采用单因素实验和正交实验,研究了不同料液比、pH、酶解温度、提取时间和不同复合酶配比对红雪茶粗多糖提取率的影响;在此基础上采用L9(34)正交实验研究了各影响因素对红雪茶粗多糖提取率的影响,结果表明复合酶最佳配比为纤维素酶2.0%,果胶酶2.0%,木瓜蛋白酶0.5%;影响红雪茶粗多糖提取率的四个因素的主次顺序为:料液比>酶解温度>pH>酶解时间;最佳提取工艺条件是料液比1:40,pH4.5,酶解温度40℃,酶解时间80min,在此条件下红雪茶多糖提取率达8.91%。本研究确定了复合酶法提取红雪茶多糖的最佳工艺。     

盐析法制备寒富苹果渣果胶及其抗氧化性研究

为使苹果渣变废为宝,利用其生产果胶等高附加值产品,本文以酸法提取寒富苹果果渣中的果胶提取液为原料,采用盐析法得到果胶盐沉淀物,并对该沉淀进行脱盐处理获得果胶物质,期间对相关工艺进行优化,最后进行了果胶的抗氧化性研究。结果表明:硫酸铝为盐析法沉淀果胶的最佳用盐,沉淀果胶的最佳工艺参数为沉淀温度74 ℃、保温时间69 min、pH5.0、料液比1:17 (g:mL),此工艺下果胶得率达15.59%;脱盐最佳工艺为脱盐液中盐酸含量3%、脱盐液用量50 mL每克果胶盐、脱盐时间40 min、脱盐温度40 ℃,所得果胶质量为0.89 g。寒富苹果渣果胶具有清除自由基和抑制脂质过氧化的能力,可作为一种天然的抗氧化剂进行开发。     

Effects of salting processes and time on the chemical composition, textural properties, and microstructure of cooked duck egg

Chemical composition, textural properties, and microstructure of cooked duck egg salted by 2 methods (coating and immersing) were determined during 4 wk of salting. As the salting time increased, moisture content increased and salt content decreased for both cooked salted egg white and yolk. Oil exudation of cooked yolk and expressible water content of cooked egg white obtained from both salting methods increased as salting proceeded (P < 0.05). After cooking, oil exudation accompanied by the solubilized pigments, especially at the outer layer of yolk, was obtained. At week 3 of salting, egg yolk from coating method had the higher egg exudation than that from immersing method. As the salting times increased, the lower hardness, springiness, gumminess, chewiness, and resilience with higher adhesiveness and cohesiveness were generally found in cooked salted egg white (P < 0.05), irrespective of salting methods. Conversely, the hardness of cooked yolk increased continuously and reached the maximum at week 2 and 2 to 3 for immersing and coating method (P < 0.05), respectively. Confocal laser scanning micrographs revealed the smaller yolk granules with more release of free lipid in salted egg after heating, compared with the fresh counterpart. As visualized by scanning electron microscope, gel of cooked salted egg white was coagulum type with larger voids. Salting methods determined oil exudation in egg yolk and texture profile of egg white gel after cooking; however, those attributes were also governed by the salting time. PRACTICAL APPLICATION: Salted duck egg can be made by 2 methods (coating and immersing) affecting the characteristic of salted egg white and yolk after cooking. Desirable cooked salted egg having the red yolk with hardness and high oil exudation could be obtained when salting was carried out for 3 and 4 wk for immersing and coating method, respectively.     

Influence of brine salting prior to pickle salting in the manufacturing of various salted-dried fish species

In Portugal, the production of salted-dried cod and similar species is a relevant fish industry. Pickle salting is the most common salting method in this industry. The objective of this work was to study the influence of brine salting before pickle salting in the characteristics of the final salted-dried product of different fish species. Three salting methods were studied: only pickle salting, brine salting at 16°Baumé followed by pickle salting and brine salting at 25°Baumé followed by pickle salting. Fish species studied were Gadus morhua, Gadus macrocephalus, Theragra chalcogramma. The results showed from 4.7% to 9.2% significant higher yields of salted-dried fish when using the lower salt content brine, but drying time increased from 32 to 45 h (35–65%), depending on size of the fish, and texture became significantly softer, what may imply that salted-dried fish using lower salt content brines may be perceived by consumers as a different product. No significant differences of color were obtained.     

苦荞水溶性蛋白体外吸附胆酸盐能力的研究

通过采用硫酸铵盐析法、DEAE-Sepharose Fast Flow离子交换层析法提取分离制备苦荞水溶性蛋白,并通过磷酸盐缓冲液pH值、动态层析流速的最佳选择改善分离提纯效果。同时通过体外吸附胆酸盐能力的测定证实所提取分离得到的苦荞水溶性蛋白具有一定的降血脂功能。结果发现：当磷酸盐缓冲溶液pH值为6.5、流速1.0mL/min于室温下洗脱的效果最好,得到的3个主要分离组分中峰3的体外吸附胆酸盐能力最佳。     

纤维素酶法提取葡萄籽中原花青素的研究

研究了葡萄籽中原花青素的酶法提取工艺。以葡萄籽中原花青素的提取率为指标,采用单因素法和正交设计法对纤维素酶解法提取工艺条件进行优选。实验结果表明,影响酶法提取原花青素的因素次序为:酶解温度>酶解浓度>pH值>乙醇浓度,其最佳工艺条件为:酶解浓度为0.10%,酶解温度为50℃,pH值为5.5,乙醇浓度为60%,所得葡萄籽中原花青素的提取率为4.16%。     

Effect of ultrafiltration,fat reduction and salting on textural properties of white brined cheese

The influence of ultrafiltration of whole and skim milk on rennetability in the course of white pickled cheese manufacturing was investigated. Concentrating factors of the milk were selected as 3x, 4x, 5x and 5.5x. The renneting properties of the unconcentrated milk and the retentates (skim and whole milk ultrafiltration retentates) were explained. The white cheese produced from unconcentrated whole milk via a traditional industrial method was compared with the white cheese produced by whole milk retentate (5.5-fold). The cheeses manufactured from retentate were salted using different methods, i.e. dry salting, brine salting and salt addition before renneting. The effect of salting method on the texture of UF-cheese was determined after three months storage. It was suggested that producing of white pickled cheese from whole milk retentate (full-concentrated) was more suitable than manufacturing from skim milk retentate and was than better the conventional method which uses unconcentrated milk, actually.