微生物谷氨酰胺转胺酶对乳清蛋白的改性

介绍了该酶的来源、性质及催化反应机理。由于乳清蛋白应用于食品加工中时，其理化功能尚不突出，所以通过谷氨酰胺转胺酶对乳清蛋白的改性，可以加强乳清蛋白的功能性质，从而合理利用资源，开发新产品，扩大其在食品中的应用。     

谷氨酰胺转移酶对食品中蛋白质改性研究进展

谷氨酰胺转移酶是一类可以催化酰基转移反应的酶,能够促进蛋白质分子间发生交联反应,催化蛋白质之间异肽键的形成,并广泛应用于食品加工过程中蛋白质的改性。本文通过查阅近年来国内外研究进展,对谷氨酰胺转移酶的酶来源、酶学性质、酶的催化机理及其对食品蛋白质的改性、在食品中的应用进行了综述。      

Application of microbial transglutaminase in meat foods: A review

Microbial transglutaminase (MTG) is an enzyme isolated from a variant of Streptomyces mobaraensis that forms covalent cross-links between protein molecules. Studies are being conducted since last two decades on utilization of MTG in meat foods to improve their characteristics, such as gelation, water-binding, emulsion stability, purge loss, cooking loss, etc. MTG is one of the important topics of interest in meat processing industry due to its advantages in practical utilization and commercial exploitation. This review will discuss about the overall applications of MTG in manipulating the functional properties of meat and meat products by means of various processes such as restructuring, value addition, etc.     

Mechanical and functional properties of beef products obtained using microbial transglutaminase with treatments of pre-heating followed by cold binding

Beef proteins are considered non-setting proteins and usually gels obtained by adding of microbial transglutaminase are obtained by cooking directly the solubilized paste. The aim of this work was to determine the effect of pre-heating treatments on the mechanical properties of restructured beef gels treated with microbial transglutaminase (MTG). The effect of cooling (cold binding) the solubilized pastes after the pre-heating treatments was also studied. The restructured beef gels were obtained by adding 0.3% MTG or 0% MTG (control). Three pre-heating temperatures (40, 50 or 60 °C) for 30 or 60 min were studied, followed by heating at 90 °C for 15 min. Control samples without pre-heating were also prepared. Cold binding was studied by holding pre-heated gels at 4 °C for 12 h before heating at 90 °C for 15 min. Changes in mechanical properties (texture profile analysis and puncture test), color attributes, expressible water and cooking loss were determined. Results indicated that the better mechanical properties can be obtained by pre-heating beef pastes at 50 °C for 30 min with minimal effect on color, expressible water and cooking loss when 0.3% of MTG is added. It was concluded that there were no practical advantages by pre-heating the gels for 60 min. Cold binding did not improve the mechanical properties of beef gels.     

Impact of microbial transglutaminase on gelling properties of Indian mackerel fish protein isolates

Impacts of microbial transglutaminase (MTGase) (0–0.6 units/g sample) on gel properties of Indian mackerel unwashed mince, surimi and protein isolates with and without prewashing were studied. Generally, lower myoglobin and lipid contents were found in protein isolate with and without prewashing, compared to those of unwashed mince and surimi (P < 0.05). Protein isolate had the decreased Ca²⁺-ATPase and protein solubility, indicating protein denaturation. When MTGase was incorporated, breaking force and deformation of all gels markedly increased, especially as MTGase levels increased (P < 0.05). At the same MTGase level, gel from protein isolate with prewashing exhibited the highest breaking force and deformation (P < 0.05). The addition of MTGase could lower the expressible moisture content of most gels. No change in whiteness of gel was observed with the addition of MTGase (P > 0.05), but gel from protein isolate gels had decreased whiteness as MTGase at high level was added. The microstructure of protein isolate gels without prewashing showed a similar network to unwashed mince gels, whilst a similar network was observed between surimi gel and gel from protein isolate with prewashing. Nevertheless, a larger void was noticeable in gels from protein isolates. All gels incorporated with MTGase (0.6 units/g) showed a slightly denser network than those without MTGase. Thus, gel with improved properties could be obtained from protein isolate from Indian mackerel with added MTGase.     

谷氨酰胺转胺酶的特性及其在食品工业中的应用

谷氨酰胺转胺酶可以催化蛋白质分子内或分子间的酰基转移反应，通过形成的交联键改善蛋白质的功能性质。本文介绍了谷氨酰胺转胺酶的作用机理及谷氨酰胺转胺酶在食品工业中的应用。     

Effect of formaldehyde on protein cross-linking and gel forming ability of surimi from lizardfish induced by microbial transglutaminase

Impact of formaldehyde (FA) at various levels (0–9 μmol/g surimi) on gel properties of surimi from lizardfish added with microbial transglutaminase (MTGase) was studied. During iced storage of 10 days, total and free FA in lizardfish flesh increased continuously (P < 0.05). In the presence of FA, breaking force of gels slightly increased, whilst the deformation decreased (P < 0.05). The addition of MTGase (0.4 units/g surimi) was able to increase gel strength and water holding capacity of resulting gel. Nevertheless, gel strengthening effect of MTGase was lowered when FA at higher level was present. Myosin heavy chain (MHC) dominantly underwent polymerisation to a higher extent when either MTGase or FA was added. The higher reduction in ε-amino group content was observed in natural actomyosin (NAM) when FA at higher levels (0–30 μmol/g protein) was incorporated. Acyl transfer reaction mediated by MTGase was impeded in NAM containing FA, especially at higher levels. Generally, FA had an adverse effect on cross-linking ability towards surimi proteins induced by MTGase. Therefore, cross-linking and gel-forming ability of lizardfish surimi could be maximised by MTGase when surimi contained no FA.     

酶法交联对食物蛋白的改性作用研究进展

食物蛋白通过分子间或分子内的交联作用,可有效地改善功能特性,有利于在食品加工中的应用。可用于蛋白交联的酶主要有转谷氨酰胺酶、多酚氧化酶、过氧化物酶等。主要阐述了转谷氨酰胺酶、多酚氧化酶、过氧化物酶交联蛋白的作用机理及最新研究进展。      

Rheological and baking characteristics of batter and bread prepared from pregelatinised cassava starch and sorghum and modified using microbial transglutaminase

The effect of different concentrations (0, 0.5, 1 and 1.5 U/g) of microbial transglutaminase (MTG) on the creep-recovery properties of gluten-free batter prepared from pregelatinised cassava starch, sorghum and egg white was investigated. The test conducted in the rheometer had an instant loading of 80 Pa for 60 s and recovery of 0 Pa for 140 s. Increasing MTG concentration decreased the batters’ resistance to deformation and compliances but increased zero shear viscosity and elastic recovery. Changes in batter rheological properties were insignificant (P > 0.05) at MTG concentrations beyond 0.5 U/g. Crumb properties of gluten-free bread baked from the batter revealed that increasing MTG concentration increased (P < 0.05) crumb firmness and chewiness, whereas increasing incubation time decreased (P < 0.05) crumb cohesiveness, chewiness and resilience. There were no significant interaction effects (P > 0.05) between enzyme concentration and incubation time.     

Enzymatic properties of transglutaminase produced by a new strain of Bacillus circulans BL32 and its action over food proteins

The aim of this study was to physicochemically characterize transglutaminase (TGase) from Bacillus circulans BL32, a strain recently isolated from the Amazon basin region, for its application in food systems. The effects of pH and temperature on the enzyme activity were determined by Central Composite Rotatable Design (CCRD), with maximal TGase activities obtained for pH between 5.7 and 8.7 and temperatures of 25-45 °C. This microbial TGase showed to be remarkably stable: over 90% of its activity was retained after 120 min of incubation at 50 °C. The Ca²⁺ and Mg²⁺ cations enhanced enzyme activity and its thermal stability when in concentrations of up to 2 and 1 mol L⁻¹, respectively. Casein, isolated soy protein, and hydrolysed animal protein were treated with this TGase. The decrease in the amount of free amino groups, especially for casein, showed the cross-linking of protein catalysed by this enzyme, while the emulsifying properties of these proteins were improved with treatment. These results suggest that this microbial TGase has a good potential to be used in food and other industrial applications.     

Quality characteristics of low-salt restructured poultry with microbial transglutaminase and seaweed

Characteristics of restructured poultry steaks as affected by addition of Sea Spaghetti seaweed (3% dry matter) combined with NaCl reduction and a microbial transgutaminase/caseinate (MTGase/caseinate) system as a cold binding agent were studied during chill storage. The incorporation of Sea Spaghetti caused a slight (P<0.05) increase in purge loss but reduced cooking loss in the products. Addition of MTGase/caseinate did not affect water binding properties. The added seaweed and the MTGase/caseinate system both increased (P<0.05), the Kramer shear force (KSF) of raw products, making them easier to handle. No such effect was observed in cooked products. Products with Sea Spaghetti had higher levels (P<0.05) of total viable counts and lactic acid bacteria, and also higher levels of tyramine and spermidine. All products were judged acceptable by a sensory panel. During chill storage no important changes were found in the target properties due to composition.     

转谷氨酰胺酶及非肉蛋白在重组碎羊肉卷加工中的应用

在原料肉中添加0.04%转谷氨酰胺酶,分别与0、0.2%、0.4%、0.6%、0.8%、1.0%酪蛋白、淀粉、大豆分离蛋白组成3个试验组,在6℃条件下催化反应138min,经过成型、解冻,以保形性作为指标,并用扫描电子显微镜(SEM)观察其微观结构。结果表明:大豆分离蛋白(0.8%)和酪蛋白(0.2%)都可以提高原料肉的保形性。SEM分析结果表明,转谷氨酰胺酶的加入可使碎肉形成致密的凝胶网络结构,在3个实验组中转谷氨酰胺酶与酪蛋白结合效果更好。     

转谷氨酰胺酶的性质、制备及在食品加工中的应用

转谷氨酰胺酶是催化蛋白质分子之间交联的一种酶，对蛋白质的成胶能力、热稳定性、持水能力等功能特性有独特的改善作用。目前从微生物Streptoverticillium spp．中分离转谷氨酰胺酶和在食品工业中的实际应用都已经实现，因为从微生物制备可以实现大规模的工业化生产，成本低廉，为转谷氨酰胺酶在工业上的应用奠定了基础。现在转谷氨酰胺酶广泛地应用于海洋食品、面条／面团、奶制品、烘焙食品等食品加工领域，通过温和的酶反应可以明显地改善食品的硬度、弹性、热稳定性和持水能力。主要讨论了转谷氨酰胺酶的性质、分离和在食品加工中的应用。     

Immobilization of alkaline phosphatase on magnetic particles by site-specific and covalent cross-linking catalyzed by microbial transglutaminase

Bacterial alkaline phosphatase (BAP) was site-specifically and covalently immobilized on magnetic particles (MPs) using the enzymatic reaction of microbial transglutaminase (MTG). Immobilization efficiency was affected by the chemical surface treatment of MPs and immobilized BAP exhibited more than 90% of the initial activity after 10 rounds of recycling.     

Effect of microbial transglutaminase on the protein fractions of rice,pea and their blends

BACKGROUND: Transglutaminase (TG) is a transferase that has been used for crosslinking proteins. In general, those interactions are promoted within proteins of the same nature, and very few studies have been conducted for creating new bonds between proteins from different sources catalysed by TG. The effect of TG on the protein fractions of rice flour, pea protein isolate and their blends was studied by using different electrophoretic analyses (simple sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) and multistaking SDS‐PAGE under reducing and non‐reducing conditions). RESULTS: TG induced the disappearance of numerous protein bands as a consequence of the formation of large protein polymers, linked by isopeptidic and disulfide bonds, with reduced solubility. The main protein fractions involved in those interactions were the albumins and globulins, from the pea protein isolate, and the rice flour; and the glutelins were also crosslinked. CONCLUSION: Composite flours containing the rice flour and the pea protein isolate are proposed for obtaining a protein‐enriched dough with better amino acid balance. Also a protein network formed of protein aggregates of high molecular weight can be created in the presence of transglutaminase. Copyright © 2007 Society of Chemical Industry     

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.     

微生物谷氨酰胺转氨酶的来源与生物工程技术研究进展

微生物谷氨酰胺转氨酶（MTGase）是一种通过异肽键来催化蛋白质或多肽链之间的酰基发生转移反应的重要酶制剂,在食品、生物医药、化妆品、纺织等领域有着广泛的应用前景。该文综述了MTGase的国内外研究现状,MTGase基因、MTGase工程菌株的构建和表达,以及MTGase的分子改造技术研究进展,并对生物工程技术应用于MTGase的产品生产进行了展望,为高效和低成本MTGase的产品开发及应用提供新的思路和方法。     

Formation and rheological properties of ‘cold-set’ tofu induced by microbial transglutaminase

Microbial transglutaminase (MTGase) has been shown to effectively induce soymilk with a certain level of solid content to form filled tofu. The gel formation of this kind of tofu and the influence of reaction parameters on the properties of formed tofu were investigated by dynamic oscillatory and/or large-strain rheological measurements. The gelation process and the development of the mechanical moduli (especially the storage modulus, G′) of this kind of tofu were highly dependent upon the incubation temperature. Textural property analysis (TPA) results showed that many TPA parameters of this kind of tofu, including gel hardness, gumminess, springiness and cohesiveness, were also affected by the applied enzyme amount, the pH of soymilk and the presence of NaCl, especially for gel hardness. In addition, the additional heating and cooling treatment could significantly improve the gel strength of tofu, induced by MTGase at lower temperatures (e.g. 25 and 37 °C). These results suggested that a new kind of tofu with good quality could be produced using the enzymatic cross-linking technique, by the combination with the thermal treatment.     

Effect of microbial transglutaminase treatment on thermal stability and pH-solubility of heat-shocked whey protein isolate

Whey protein isolate (WPI) dispersions (5% protein, pH 7.0) were subjected to heat-shock at 70 °C for 1, 5 and 10 min. The heat-shocked WPI dispersions were treated with microbial transglutaminase (MTGase) enzyme, and thermal properties and pH-solubility of the treated proteins were investigated. Heat-shocking of WPI for 10 min at 70 °C increased the thermal denaturation temperature (T_d) of β-lactoglobulin in WPI by about 1.5 °C. MTGase treatment (30 h, 37 °C) of the heat-shocked WPI significantly increased the T_d of β-lactoglobulin by about 6.3–7.3 °C when compared with heat-shocked only WPI at pH 7.0. The T_d increased by about 13–15 °C following pH adjustment to 2.5; however, the T_d of heat-shocked WPI was not substantially different from heat-shocked and MTGase-treated WPI at pH 2.5. Both the heat-shocked and the heat-shocked-MTGase-treated WPI exhibited U-shaped pH-solubility profiles with minimum solubility at pH 4.0–5.0. However, the extent of precipitation of MTGase-treated WPI samples at pH 4.0–5.0 was much greater than all heat-shocked and native WPI samples. The study revealed that while MTGase cross-linking significantly enhanced the thermal stability of β-lactoglobulin in heat-shocked WPI, it caused pronounced precipitation at pH 4.0–5.0 via decreasing the hydrophilic/hydrophobic ratio of the water-accessible protein surface.     

转谷氨酰胺酶对大豆分离蛋白凝胶性的影响

以微生物来源的转谷氨酰胺酶(MTGase)对大豆分离蛋白(SPI)进行改性,主要考察了凝胶性的变化.结果显示,MTGase对SPI的凝胶性有明显的改善作用,且加酶量、pH、反应温度、底物蛋白浓度及反应时间均对凝胶性影响显著.改性SPI在加酶量为5 U/g、pH 8.0、反应温度为37℃、蛋白浓度为12%时凝胶性改善明显,随着MTGase作用时间的延长,SPI凝胶性也呈增加趋势.MTGase的作用使SPI凝胶的蛋白质分子间形成了空间的网络交错结构.