Combination Effects of Microbial Transglutaminase, Reducing Agent, and Protease Inhibitor on the Quality of Hairtail Surimi

A combination of microbial transglutaminase (MTGase), reducing agent and protease inhibitor was employed to improve the quality of underutilized fish surimi. SDS-PAGE indicated that cross-linking of myosin heavy chain (MHC) occurred in MTGase-contained samples, while MHC of samples without MTGase disappeared after 120 min incubation at 45°C. Although the gel-forming ability increased with MTGase added up to 0.6 unit/g, it was still too low to be commercially acceptable. However, the combined use of 0.1% NaHSO₃, 0.01 mM transepoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64) and 0.35 units MTGase/g substantially improved the quality of hairtail surimi. Based on this result, the combined use of E-64, MTGase and NaHSO₃ seemed to be a better way to improve gel-forming ability of hairtail surimi.     

蛋白酶的生产和应用(下)

为充分了解蛋白酶,介绍了我国在中性蛋白酶、碱性蛋白酶、酸性蛋白酶、低温蛋白酶和耐高温蛋白酶研究概况.     

牡蛎复合酶解提高蚝油风味的工艺探讨

采用多种酶复配的方法对牡蛎进行酶解处理,以获得风味良好、且蛋白质回收率和水解程度都比较高的产品.研究结果表明采用含0.05%中性蛋白酶+0.1%碱性蛋白酶+0.1%风味蛋白酶+0.1%复合蛋白酶的复合酶,可以使蛋白质回收率达到85%、水解度达到43.5%,酶解后的游离氨基酸含量比酶解前提高122.2%,酶解液无腥味,且...     

酱油发酵中制曲条件对制曲效果的影响

通过对米曲霉和黑曲霉在不同作用条件下混合制曲的曲料蛋白酶活力和曲酶孢子数的变化分析,探讨了制曲温度、制曲时间和曲霉的不同配比对米、黑曲霉混合制曲效果的影响。结果表明,制曲温度为30℃,制曲时间为35h,米曲霉和黑曲霉配比为3∶1时作用效果最佳,此时,曲料的曲酶孢子数为8.66×109个/g,蛋白酶活力可达2588μ/g。     

双酶水解脱脂麦胚制备抗氧化肽工艺的研究

以脱脂麦胚为原料,利用中性蛋白酶和木瓜蛋白酶双酶水解制备具有抗氧化活性的麦胚肽。以水解度为考察指标,采用响应面法,对酶解工艺进行优化。实验结果表明双酶水解最佳条件是：[E]/[S]为0.03,温度在52℃,酶解2.2 h时,麦胚蛋白水解度达到最大值为17.26%。     

Studies on the remedial effect of transglutaminase on protease anti‐felting treated wool

Oxidative protease treatment can improve anti‐felting of wool and also result in its loss of strength. In this study, one kind of microbial transglutaminase (MTG) was applied in the wet process of wool fabrics. The results indicated that transglutaminase could remediate wool damage following hydrogen peroxide and protease anti‐felting finishing, resulting in an increase in wool fabric strength and a decrease in alkali solubility. In addition, the evidence was provided that some cross‐linking through transglutaminase had occurred in the wool protein. The SEM showed that the scale structure became smoother after MTG treating. Analyzing of the thermal behavior revealed that the thermal stability of the MTG‐treated wool was enhanced. UV‐spectrum analysis suggested a decrease in protein extracted from the intercellular cements of the treated wool with MTG.     

酸性蛋白酶对黄酒常规质量指标的影响

随着酿酒工业的发展,酶制剂在黄酒酿造中的应用也越来越广泛。主要对酸性蛋白酶在黄酒生产中对常规质量指标的影响进行了研究。研究表明,添加不同量的酸性蛋白酶对黄酒2d内的酒精度影响较大;可以使总糖含量略微增加;易引起黄酒的酸败,并且与添加量成正比;当酸性蛋白酶添加量为50U/g时黄酒中的氨基态氮含量能达到一级黄酒的级别。旨在为进一步研究酸性蛋白酶在黄酒生产的应用提供依据。     

酿酒酵母表面展示技术表达酸性蛋白酶

为解决白葡萄酒蛋白不稳定性问题,实现酸性蛋白酶的利用与酒精发酵的同步进行,本研究以酿酒酵母单倍体菌株BY4741和二倍体菌株82-9-35为宿主菌,通过酵母表面展示系统中的启动子和锚定蛋白的作用在酵母细胞表面表达酸性蛋白酶.将来源于宇佐美曲霉酸性蛋白酶基因(pepA)克隆,构建表达酸性蛋白酶的细胞展示盒,利用同源重组定...     

Evolutionary Diversity and Function of Metacaspases in Plants: Similar to but Not Caspases

Caspase is a well-studied metazoan protease involved in programmed cell death and immunity in animals. Obviously, homologues of caspases with evolutionarily similar sequences and functions should exist in plants, and yet, they do not exist in plants. Plants contain structural homologues of caspases called metacaspases, which differ from animal caspases in a rather distinct way. Metacaspases, a family of cysteine proteases, play critical roles in programmed cell death during plant development and defense responses. Plant metacaspases are further subdivided into types I, II, and III. In the type I Arabidopsis MCs, AtMC1 and AtMC2 have similar structures, but antagonistically regulate hypersensitive response cell death upon immune receptor activation. This regulatory action is similar to caspase-1 inhibition by caspase-12 in animals. However, so far very little is known about the biological function of the other plant metacaspases. From the increased availability of genomic data, the number of metacaspases in the genomes of various plant species varies from 1 in green algae to 15 in Glycine max. It is implied that the functions of plant metacaspases will vary due to these diverse evolutions. This review is presented to comparatively analyze the evolution and function of plant metacaspases compared to caspases.     

Gelation Characteristics of Paddlefish (Polyodon spathula) Surimi Under Different Heating Conditions

Gelation properties of paddlefish surimi were investigated with different heating procedures. Without pre-incubation, gel strength of paddlefish surimi increased as temperature increased from 40 to 60 °C. Pre-incubation at 40 °C caused myosin degradation and reduced gel strength by 55% compared to the control. Pre-incubation at 70 °C followed by cooking at 90 °C produced gels with maximum strength. Isothermal heating between 40 and 50 °C produced rheological transitions between 0 and 15 min. Beef plasma powder reduced myosin degradation and enhanced gelation of surimi incubated around 40 °C. These results indicated that the gel-weakening phenomenon in paddlefish surimi was due to the degradation of myosin by some endogenous protease(s).