Evaluation of red bean protein [Vigna angularis] isolate on rheological properties of pork myofibrillar protein gels induced by microbial transglutaminase

The effects of 1% red bean protein isolate (RBPI) on the gel properties of myofibrillar protein (MP) in various levels of microbial transglutaminase (MTG: 0%, 0.1%, 0.5%, & 1%) were evaluated. The cooking yield (CY) of the MP gels decreased with increasing MTG level, while the addition of RBPI improved the CY of the MP gels. Gel strength (GS) was also improved when RBPI was incorporated into the MP gels containing higher than 0.5% of MTG. The addition of MTG and RBPI was slightly changed the endothermic peak temperatures. Scanning electron microscopy (SEM) showed that the three‐dimensional structure of MP with RBPI alone or in combined with MTG was compacted as compared to the control. Based on the results, RBPI could be functioned as a substrate for MTG (0.5–1.0%) and a water binder of meat protein gel mediated by MTG.     

Effect of non-meat proteins on hydration and textural properties of pork meat gels enhanced with microbial transglutaminase

The combined effect of incorporation of four non-muscle proteins, NMP (blood plasma, BP; sodium caseinate, SC; soy protein isolate, SPI; gelatin, G) at 2 g/100 g levels on hydration and textural characteristics of pork gels processed without or with 0.6 g/100 g microbial transglutaminase preparation (MTG) was investigated. Addition of SC and BP most favourably affected hydration properties and thermal stability, yielding lower cooking loss and expressible moisture for pork gels. Interactions between NMP and MTG were observed. Improvement of gel strength by addition of transglutaminase was observed for treatments containing SC and BP but not G nor soy isolate. Of the four proteins tested SC was found to be a superior substrate for MTG in enhancing textural properties of a gelled meat system. None of the tested ingredients was able to yield gel cohesiveness equivalent to the control containing 8% muscle proteins. Results of this study indicate a potential for using MTG to improve or modify the functional and textural properties of investigated food proteins (SC and BP in particular) in comminuted meat products.     

预处理在羊毛MTG酶处理工艺中的应用

为解决单独用蛋白酶处理羊毛织物时防缩效果不明显的问题,文章在谷氨酰胺转胺酶(MTG酶)处理前对比了H2O2、等离子体、超声波预处理对羊毛织物防缩等性能的作用效果,选择最佳的预处理方法.讨论了在最佳预处理条件下,MTG酶浓度、处理温度和时间的改变对羊毛织物防缩性能的影响,并借助电镜扫描照片观察处理前后羊毛纤维的微观结构.结果表明:采用等离子预处理效果比较好,最佳工艺条件为,MTG酶浓度3%,30℃,处理50 min.     

重组大肠杆菌产谷氨酰胺转氨酶的发酵条件优化

以谷氨酰胺转氨酶生产菌株重组大肠杆菌BL21（DE3）/mtg为研究对象,对工程菌的发酵产酶条件进行了优化。首先通过单因素实验法,对培养基碳、氮源种类及浓度、培养温度、初始p H、装液量、接种量、诱导时机、诱导浓度、诱导温度及诱导时间进行了优化;随后采用Plackett-Burman设计从中筛选出3个关键影响因子:初始p H、培养温度及诱导温度;最后通过Box-Benhnken设计建立上述3个因子对谷氨酰胺转氨酶比酶活的响应面模型。结果表明,最佳发酵条件为:葡萄糖5 g/L,酵母粉28 g/L,蛋白胨14 g/L,培养温度34℃,初始p H7.0,装液量50 m L（250 m L三角瓶）,接种量5%,诱导时机4 h,IPTG浓度0.6 mmol/L,诱导温度25℃,诱导时间14 h。在该条件下,优化后的谷氨酰胺转氨酶比酶活达1.507 U/mg,为未优化前的1.56倍。      

微生物谷氨酰胺转胺酶改善羊毛织物性能

以微生物发酵生产的谷氨酰胺转胺酶(MTG)作为羊毛织物的酶整理剂,探讨了MTG在羊毛织物防毡缩和强力损伤恢复中的作用。对所用的羊毛纤维进行了氨基酸分析,从理论上为MTG的作用提供了依据。经过高锰酸钾和蛋白酶预处理后再利用MTG处理,与对照样相比,织物强力提高了30%,毡缩率从处理前的9.35%下降至2.30%。与树脂整理方法比较,结果表明强力不及树脂整理方法,毡缩率达到了与之相当的效果,并且处理液的COD值只有树脂整理的1/3。     

燕麦麸皮球蛋白的糖基化结构修饰及功能性变化

在氨基葡萄糖存在的条件下,利用转谷氨酰胺酶(transglutaminase,TG)对燕麦麸皮球蛋白糖基化结构修饰,进而探讨糖基化蛋白功能性质与结构之间的关系。结果表明,糖基化交联球蛋白的溶解性、乳化稳定性、起泡性及泡沫稳定性相比于未修饰的球蛋白都有明显的改善,但表面疏水性明显下降;另外,酶促糖基化球蛋白的变性温度和焓变值都有所下降,其二级结构变化为:α-螺旋结构相对含量呈增加趋势,β-折叠和β-转角结构相对含量呈下降趋势,无规卷曲结构相对含量几乎没变。经糖基化处理的球蛋白酪氨酸分子主要呈现"暴露态",色氨酸相对拉曼强度更趋近于"包埋态"。酶促糖基化球蛋白二硫键振动模式为t-g-t。通过对球蛋白、修饰球蛋白的功能特性与空间构象的比较分析,明确TG催化葡萄糖结合在燕麦麸球蛋白上,进一步明晰修饰蛋白功能特性与空间构象之间的构效关系。结果可为延长杂粮产业链提供良好的理论依据,同时可以为今后制备燕麦蛋白特定产品进行分子设计和重组提供基础数据。     

加工参数对转谷氨酰胺酶促大豆分离蛋白凝胶的影响

本文采用动态粘弹性测量技术研究了处理温度,底物蛋白与酶的浓度,热处理及添加盐类等处理参数对微生物转谷氨酰胺酶(MTGase)诱导形成的大豆分离蛋白(SPI)凝胶的影响。通过测量凝胶的起始时间(tgel)和机械模量(储存模量G′和损耗模量G″)等一些特性,发现tgel随着热处理温度的增加(15～60℃)而逐渐减少,而G′/G″在37℃达到最高。在最适温度下,增加蛋白质的浓度(4.0%～8.0%,m/V)或酶的浓度(0.2～0.8 U/mL),能使凝胶的起始时间逐渐减少,而G′或G″则会增加。适度的热预处理能够显著地减少tgel,及改善凝胶的机械模量。然而,盐类(如NaCl和CaCl2)的存在能够显著地弱化形成凝胶的机械强度。     

谷氨酰胺转移酶处理对大豆分离蛋白、酪蛋白酸钠和明胶可食膜特性的影响

研究了谷氨酰胺转移酶(TGase)对大豆分离蛋白(SPI1和SPI2)、酪蛋白酸钠(NaCN1和NaCN2)及明胶(G1和G2)3类蛋白质成膜特性的影响。研究表明在成膜溶液中加入TGase(8U/g蛋白),可以使SPI、NaCN和明胶等3类蛋白质膜的抗拉强度和表面疏水性有不同程度的改善,其中抗拉强度增加的辐度为13.1%(P≤0.05),而表面疏水性增加的辐度为2%～216%(P≤0.05);明显降低了膜的水分含量、总可溶性物量及透光率。对于断裂伸长率,TGase的处理使G1膜、NaCN2膜、G2膜、NaCN1膜和SPI2膜分别增加16.3%、16.8%、43.0%、72.6%和440.5%,而使SPI1膜降低7.5%。SDS-PAGE电泳分析表明TGase使这3类蛋白质均产生了共价交联。