谷氨酰胺转胺酶对大豆分离蛋白改性机理的研究

利用微生物谷氨酰胺转胺酶 (MTG)对大豆分离蛋白 (SPI)进行改性 ,结果表明 :SPI浓度、MTG浓度、反应温度、反应时间和pH值对SPI改性具有显著影响。改性SPI的凝胶性为11 6kcp ,比对照提高了 1833%。十二烷基硫酸钠 -聚丙稀酰胺凝胶电泳结果表明 ,经MTG改性 ,SPI可在分子间生成共价键 ,形成相对分子量较大的聚合物 ,从而增加了SPI的凝胶性。     

谷氨酰胺转胺酶对大豆分离蛋白改性机理的研究

利用微生物谷氨酰胺转胺酶(MTG)对大豆分离蛋白(SPI)进行改性，结果表明：SPI浓度、MTG浓度、反应温度、反应时间和pH值对SPI改性具有显著影响。改性SPI的凝胶性为11．6kcp，比对照提高了1833％。十二烷基硫酸钠-聚丙稀酰胺凝胶电泳结果表明，经MTG改性，SPI可在分子间生成共价键，形成相对分子量较大的聚合物，从而增加了SPI的凝胶性。     

不同改性大豆分离蛋白乳化性比较研究

利用氯气水浴加热、微生物谷氨酰转氨酶(MTG)以及二者复合改性大豆分离蛋白(SPI),3种处理结果比较发现,氮气水浴加热改性SPI的乳化性有所增加,比对照提高了7.2％,氮气水浴加热改性SPI和MTG改性的乳化性稳定性显著增加,分别比对照提高了91％、42％,并经电镜观察改性S PI微观结构,探讨了SPI改性机理.     

酶复合改性大豆分离蛋白相关功能性研究

利用微生物中性蛋白酶、微生物谷氨酰转氨酶(MTG)二者复合改性大豆分离蛋白(SPI),结果发现,双酶复合改性SPI的溶解性、吸水性、保水性和吸油性相关功能性显著增加,分别比对照提高了26.5%、48%、173%、35%,并经电镜观察改性SPI微观结构,探讨了SPI改性机理。     

大豆分离蛋白的复合改性及其对某些功能性的影响

利用中性蛋白酶和微生物谷氨酰胺转胺酶(MTG)对大豆分离蛋白进行复合改性,通过单因素实验和正交实验研究,获得改性SPI最佳凝胶性的反应条件为:添加中性蛋白酶0.003%,水解20min;添加MTG0.5%,作用2.0h。获得最佳溶解性的反应条件为:添加中性蛋白酶0.005%,水解30min;添加MTG0.3%,作用1.0h。正交实验结果表明,双酶复合改性的最佳处理组合为添加中性蛋白酶0.005%,水解30min;添加MTG0.5%,作用1.0h,得到产品凝胶性为4226cp,比对照提高了36.3%,溶解性为70.1%,比对照降低了5.8%。     

谷氨酰胺转胺酶改性大豆分离蛋白在低能量肉制品中应用的研究

利用谷氨酰胺转胺酶(MTG)对大豆分离蛋白(SPI)进行改性,并将改性SPI应用于低能量肉制品中。实验表明:除常温黏度外,改性SPI的其他功能性明显优于市售肉用SPI;改性SPI在低能量肉制品中适宜的添加量为5%,改性SPI使产品的固体脂肪乳化稳定性、得率分别比肉用SPI提高了14%和7%,产品的感官指标也明显好于肉用SPI。     

固定化酶改性酸法大豆浓缩蛋白在猪肉肠中应用的研究

利用固定化谷氨酰胺转氨酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并将改性SPC应用于猪肉肠.试验表明:改性后SPC的持水性和吸油性分别比未改性SPC提高了24.8%和64.5%;与大豆分离蛋白(SPI)相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则降低8.0%.改性后的SPC用于猪肉肠中,当添加量为6%时,猪肉肠的咀嚼性比未改性SPC和SPI分别提高了418.6%和187.1%;得率比未改性SPC和SPI分别提高了18.9%和4.8%,感官评分结果也与其相一致.     

利用固定化酶改善酸法大豆浓缩蛋白持水性和吸油性的研究

利用固定化谷氨酰胺转胺酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并对改性SPC进行红外光谱分析。通过单因素和正交实验研究了MTG改性对SPC持水性和吸油性的影响。结果表明,当固定化MTG添加量1U/g,pH6.0,50℃下反应2h时,改性后大豆浓缩蛋白的持水性和吸油性分别比对照提高了24.8%和64.5%;与大豆分离蛋白相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则低8.0%。     

谷氨酰胺转胺酶改性谷朊粉的研究

本文利用谷氨酰胺转胺酶(MTG)对谷朊粉(WG)进行改性,并将改性后的WG添加到低筋小麦面粉中,对面粉的流变学特性进行了系统的研究。结果表明:改性WG的凝胶性、乳化性、乳化稳定性、发泡性、泡沫稳定性分别比对照提高了96.7%、43.5%、39.1%、32.0%和75.9%。将改性谷朊粉添加到低筋面粉中,面粉的吸水率、稳定时间、形成时间、评价值、抗延伸性阻力50mm和Max处,分别比对照提高了7.2%、369.6%、121.7%、19.6%、184.3%和150.6%;软化度、延伸性分别比对照降低了63.6%和57.2%。MTG对WG中的球蛋白、醇溶蛋白、麦谷蛋白有交联作用,其中对麦谷蛋白的交联作用最明显。     

改性对大豆分离蛋白可降解材料力学性能的影响

利用环氧氯丙烷对大豆分离蛋白(SPI)进行改性制备可生物降解材料,探讨了改性制备因素对大豆分离蛋白可降解材料力学性能的影响.结果表明,改性制备因素对材料的力学性能有显著影响;材料形成过程中的抗拉强度与分子表面巯基含量的变化没有必然的联系;经改性后可在SPI分子间形成交联大分子,同时维持蛋白分子空间构象的作用力也会对材料的力学性能产生影响.     

Lipid and protein structure analysis of frankfurters formulated with olive oil-in-water emulsion as animal fat replacer

Lipid and protein structural characteristics of frankfurter formulated with olive oil-in-water emulsion stabilized with soy protein isolate (SPI) as pork backfat replacer were investigated using Fourier transform infrared spectroscopy (FT-IR). Proximate composition and textural properties were also evaluated. Different frankfurters were reformulated: F/PF with pork backfat, F/SPI with oil-in-water emulsion stabilized with SPI and F/SPI + SC + MTG with emulsion stabilized with a combination of SPI, sodium caseinate (SC) and microbial transglutaminase (MTG). Replacement of pork backfat with these emulsions produced an increase (P < 0.05) of hardness, springiness, cohesiveness and chewiness but a reduction (P < 0.05) of adhesiveness. F/SPI and F/SPI + SC + MTG frankfurters showed the lowest (P < 0.05) half-bandwidth in the 2922 cm⁻¹ band, which could be related to lipid chains were more ordered than in F/PF. Modifications in the amide I band profile revealed a higher concentration of aggregated intermolecular β-sheets in F/SPI + SC + MTG samples. Lipid and protein structural characteristics could be associated with specific textural properties of healthier frankfurters.     

Assessment of Cross-Linking in Combined Cross-Linked Soy Protein Isolate Gels by Microbial Transglutaminase and Maillard Reaction

ABSTRACT:  Soy protein isolate (SPI) gels were produced using single cross-linking agents (SCLA) of microbial transglutaminase (MTG) via incubation for 5 or 24 h (SCLA-MTG). When powdered SCLA-MTG gels were heated for 2 h with ribose (R2) (2 g/100 mL), dark brown gels were formed, and these were designated as combined cross-linking agent (CCLA) gels: MTG5(R2) and MTG24(R2). The results showed that the levels of Maillard-derived browning and cross-links of MTG5(R2) and MTG24(R2) gels were significantly ( P  < 0.05) lower than a control gel produced without MTG (SCLA-R2) even though the percentage of ribose remaining after heating of these gels was similar, indicating that a similar amount of ribose was consumed during heating. ɛ-(γ-glutamyl)lysine bonds formed during incubation of SPI with MTG may have reduced the free amino group of SPI to take part in the Maillard reaction; nevertheless, ribose took part in the Maillard reaction and initiated the Maillard cross-linkings within the CCLA gels.     

Gelling of microbial transglutaminase cross-linked soy protein in the presence of ribose and sucrose

Soy protein isolate (SPI) was incubated with microbial transglutaminase (MTGase) enzyme for 5 (SPI/MTG(5)) or 24 (SPI/MTG(24)) h at 40 °C and the cross-linked SPI obtained was freeze-dried, and heated with 2% (w/v) ribose (R) for 2 h at 95 °C to produce combined-treated gels. Longer incubation period resulted in more compact and less swollen SPI particle shape when reconstituted with sugar solution. Thus, this MTGase treatment affected samples in terms of flow behaviour and gelling capacity. Rheological study showed different gelling profiles with the cross-linking treatments and combined cross-linked SPI gave a higher G′ value compared to single treated samples. These are due to the formation of additional ε-(γ-glutamyl)lysine bonds and “Maillard cross-links” within the SPI protein network during the MTGase incubation and heating in the presence of ribose (i.e. reducing sugar). Network/non-network protein analysis found that network protein increased with cross-linking treatment, which also resulted in different SDS–PAGE profiles. As in non-network protein fraction, A₄ subunit was suggested to become part of the network protein as a result of combined cross-linking.     

Effect of microbial transglutaminase on spaghetti quality

ABSTRACT:  To examine the potential application of microbial transglutaminase (MTG) on semolina dough properties and quality of raw and cooked spaghetti, the effects of various MTG addition levels on the solubility of proteins, SDS-PAGE pattern of semolina dough proteins, and textural and structural properties of raw and cooked spaghetti were investigated using semolina from a high-protein good variety (MACS 1967) and a low-protein poor variety (PDW 274) durum wheat. To increase the concentration of lysyl residues and possibly enhance the extent of cross-linking of protein matrix by MTG, a commercial soy protein isolate (SPI) was added at a level of 3% (w/w) in combination with MTG, and its effect on semolina dough properties and spaghetti quality was investigated. The addition of MTG significantly decreased the solubility of semolina dough proteins. SDS-PAGE results showed that with increasing levels of MTG, a progressive decrease in the intensity of the bands corresponding to molecular weight of around 66 kDa was observed. Protein cross-linking reaction catalyzed by MTG resulted in changes in dough properties, dry spaghetti quality, cooking quality characteristics, and microstructure of cooked spaghetti. However, the quality improvements were more evident in spaghetti from the poor variety PDW 274 than from the good variety MACS 1967. The results also showed the ability of MTG in the formation of heterologous polymers between SPI and durum wheat proteins to improve the quality of spaghetti samples.     

The use of microbial transglutaminase and soy protein isolate to enhance retention of capsaicin in capsaicin-enriched layered noodles

Specialty layered noodles (LN) were prepared by sandwiching a capsaicin-enriched dough (CED) between two gastro-resistant dough layers made up of wheat flour, soy protein isolate (SPI) and microbial transglutaminase (MTG) at 0.5 (0.5MTG LN), 1.0 (1.0MTG LN) and 1.5 (1.5MYG LN) g/100 g of wheat-SPI flour. The textural, tensile and structural breakdown properties, capsaicin retention, microstructures and the sensory characteristics of cooked LN were evaluated. Compared to other LN, 1.5MTG LN exhibited the highest textural and tensile parameters, highest capsaicin retention, densest structure and was the most difficult to breakdown. The sensory quality of all LN was acceptable, even though it was the Control LN (prepared without SPI and MTG) that scored the highest acceptability. In general, increasing the level of MTG in the sandwiching dough layers of MTG LN reduced the release of capsaicin in simulated mouth, gastric and intestinal conditions, and these results could be due to increased protein cross-linking.     

金针菇多糖对大豆分离蛋白凝胶的增强作用及其结构表征

通过将金针菇多糖（Flammulina velutipes polysaccharide，FVP）添加到大豆分离蛋白（soy protein isolate，SPI）水凝胶中并进行热处理以提高SPI水凝胶强度、持水性和热稳定性。通过对二三级结构及分子间作用力的检测，进一步分析FVP-SPI水凝胶的稳定性。结果显示：热处理及添加FVP显著提高SPI水凝胶的持水能力，热变性焓ΔH提高了25.46%，水凝胶稳定性显著提高。疏水相互作用、二硫键和静电相互作用是形成热处理FVP-SPI水凝胶的主要作用力。FVP的加入提高了静电相互作用，使水凝胶中α-螺旋向β-折叠转变，SPI中色氨酸暴露于表面，疏水性增强。FVP对SPI水凝胶的增强作用为SPI水凝胶的开发应用提供一定参考。     

水力空化对大豆分离蛋白谷氨酰胺转氨酶促凝胶行为的影响

利用基于涡流的水力空化处理大豆分离蛋白,通过比较处理前后大豆分离蛋白在谷氨酰胺转氨酶的催化作用下形成凝胶的质构特性、持水性、流变学性质、分子间作用力、微观结构和二级结构的变化,来研究大豆分离蛋白经水力空化处理后其酶促凝胶行为的变化规律及机制。结果表明,与未经水力空化处理的大豆分离蛋白相比,大豆分离蛋白经水力空化处理30 min后形成的酶促凝胶强度（P＜0.05）、持水性（P＜0.05）和储能模量增加;凝胶形成的分子间作用力发生变化,离子键、氢键及疏水相互作用相对含量显著降低（P＜0.05）,而二硫键和非二硫共价键相对含量显著增加（P＜0.05）;扫描电子显微镜观察到经水力空化处理后的大豆分离蛋白形成的酶促凝胶孔洞较小,微观结构更加致密和均匀;红外光谱分析结果表明凝胶的二级结构也发生了改变,β-折叠、β-转角相对含量显著增加（P＜0.05）,而α-螺旋、无规卷曲相对含量显著降低（P＜0.05）。可见,水力空化处理在一定条件下可以改善大豆分离蛋白谷氨酰胺转氨酶促凝胶的性能,可作为一种有效的方法应用于食品工业。     

Gelation properties of salt-extracted pea protein isolate catalyzed by microbial transglutaminase cross-linking

Gelation is a fundamental functional characteristic of plant proteins. In this paper, a salt-extracted pea protein isolate (PPI) was mixed with microbial transglutaminase (MTG) to produce gels and the gelation properties were studied. When the MTG level increased, the magnitude of both the G′ and G″ moduli also increased, which means the gel strength increased. A second order polynomial equation was used to describe the relationships between the G′, G″ modulus and TG level. It was found that with increased heating and cooling rate at the same MTG level, G′ and G″ tended to decrease, resulting in a weaker gel. This was attributed to the rearrangement time of pea protein molecules; slower heating and cooling rates enabled protein molecules to have more time to rearrange and therefore form a stronger gel. At the same MTG level, higher pea protein concentration resulted in higher G′ and G″ values and a power law relationship was found between G′ and pea protein concentration or G″ and pea protein concentration. Frequency sweep data of PPI show that the MTG treatment resulted in higher G′ values and lower tan delta values, indicative of a stronger more elastic gel. The minimum gelation concentration was found to be 3% (w/v) with 10 U MTG treatment, lower than 5.5% required when no MTG was present. When compared to PPI and soy protein isolate (SPI) with and without 10 U MTG treatment, the gel strength of PPI with MTG was stronger than that of SPI with MTG treatment, whereas the opposite was true without the MTG treatment. SDS-PAGE showed that at the same pea protein concentration, higher MTG level induced more cross-linking as fainter bands were seen on the gel and there was a shift in the relative intensities of the bands in the molecular weight range of 35–100 kDa.