Microencapsulation of Lactobacillus rhamnosus GG by Transglutaminase Cross‐Linked Soy Protein Isolate to Improve Survival in Simulated Gastrointestinal Conditions and Yoghurt

Microencapsulation is an effective way to improve the survival of probiotics in simulated gastrointestinal (GI) conditions and yoghurt. In this study, microencapsulation of Lactobacillus rhamnosus GG (LGG) was prepared by first cross‐linking of soy protein isolate (SPI) using transglutaminase (TGase), followed by embedding the bacteria in cross‐linked SPI, and then freeze‐drying. The survival of microencapsulated LGG was evaluated in simulated GI conditions and yoghurt. The results showed that a high microencapsulation yield of 67.4% was obtained. The diameter of the microencapsulated LGG was in the range of 52.83 to 275.16 μm. Water activity did not differ between free and microencapsulated LGG after freeze‐drying. The survival of microencapsulated LGG under simulated gastric juice (pH 2.5 and 3.6), intestinal juice (0.3% and 2% bile salt) and storage at 4 °C were significantly higher than that of free cells. The survival of LGG in TGase cross‐linked SPI microcapsules was also improved to 14.5 ± 0.5% during storage in yoghurt. The microencapsulation of probiotics by TGase‐treated SPI can be a suitable alternative to polysaccharide gelation technologies.     

响应面优化转谷氨酰胺酶改性花生分离蛋白工艺的研究

为了改善花生分离蛋白的凝胶特性,研究了利用转谷氨酰胺酶交联改性花生分离蛋白的工艺。在进行了酶添加量、花生分离蛋白浓度和酶作用时间单因素试验基础上,利用响应面试验设计优化了酶交联改性的最佳条件。并分别测定了酶改性前后花生分离蛋白的功能性,包括:溶解性、吸油性、持水性、乳化性和乳化稳定性、起泡性和起泡稳定性。通过响应面分析得到酶改性的最佳条件:酶添加量、花生分离蛋白质量浓度和酶作用时间分别为17.75 U/g、29.60 g/mL和376 min,在此条件下,凝胶的硬度可达到333.49 g。经转谷氨酰胺酶改性后,花生分离蛋白的吸油性和持水性均有不同程度的提高,分别提高了27.41%和61.24%。     

谷氨酰胺转氨酶对碱溶酸沉法提取南极磷虾(Euphausia superba)蛋白质得率的影响

通过碱溶酸沉法提取了南极磷虾蛋白质,研究了谷氨酰胺转氨酶的应用对蛋白质得率的影响。结果表明:碱溶酸沉法能够较好地回收南极磷虾蛋白质;在酸沉过程中,合理添加谷氨酰胺转氨酶能够提高蛋白质得率约5%。     

超高压与转谷氨酰胺酶协同对碎猪肉凝胶成型的研究

研究了超高压与TGase协同对碎猪肉凝胶成型的影响,采用Box-Behnken实验设计获得的碎猪肉凝胶成型最佳工艺条件为:TGase添加量4.5g/kg,压力水平240MPa,保压时间10min。最佳工艺条件下的碎猪肉凝胶成型制品与鲜猪肉的硬度、粘着性、内聚性、胶凝性差异不显著。超高压与TGase结合的技术,实现了碎猪肉的凝胶成型,为碎猪肉边角料的利用提供了新方法。     

Microbial transglutaminase-mediated modification of ovalbumin

In the present paper we have investigated the impact of microbial transglutaminase on thermally treated ovalbumin. In fact, ovalbumin was modified by microbial transglutaminase following heat treatment for 1 h at 80 °C. The protein was both intra- and inter-molecularly crosslinked as shown by the formation of high molecular weight polymers and a monomer having similar molecular weight but higher electrophoretic mobility when compared to unmodified ovalbumin. Analysis of simulated digestion under physiological conditions has demonstrated that the biopolymers obtained after transglutaminase treatment were more resistant to both gastric and duodenal digestion. Whilst they started gradually being digested after 5 min of incubation with pepsin, some of them were still present even after 60 min incubation with the duodenal enzymes, trypsin and chymotrypsin. Furthermore, incubation of 1.5% (w/v) ovalbumin gel in the presence of transglutaminase led to the formation of a well-developed viscoelastic gel network with higher modulus and lower phase angle values. These results suggest a possible use of transglutaminase-modified ovalbumin in the food industry as a potential ingredient to enhance both the functional properties of many food-based products, such as digestibility, and mechanical properties, such as viscoelasticity and gel strength.     

大豆蛋白凝胶显微结构研究

使用盐卤、葡萄糖酸内酯和转谷氨酰胺酶制备大豆蛋白凝胶,为了真实反映大豆蛋白凝胶的结构,分别采用戊二醛和乙醇2种固定剂固定形成的凝胶结构.通过扫描电子显微镜(SEM)观察不同的凝固剂和固定剂处理的大豆蛋白凝胶的显微结构,结果表明戊二醛和乙醇都能起到固定凝胶网络结构的效果,由0.7％(质量体积比)盐卤、0.06 mol/L葡萄糖酸内酯、40 kat/g转谷氨酰胺酶制备的凝胶的网孔较多.此外通过物性分析仪分析凝胶硬度,结果表明100％乙醇固定的凝胶硬度比戊二醛固定凝胶的硬度大.     

转谷氨酰胺酶(mTG)改性明胶可食性薄膜的制备

以转谷氨酰胺酶（mTG）改性明胶为基料、丙三醇为增塑剂制备可食性食品包装薄膜。研究了mTG、丙三醇的添加量以及膜的成型方法对产品的抗张强度、最大伸长率、韧性、水溶性、吸水性等物理机械性能的影响；筛选出了最佳工艺条件。     

Effect of microbial transglutaminase on autolysis and gelation of lizardfish surimi

In the absence of microbial transglutaminase (MTGase), the textural properties of lizardfish surimi (Saurida spp) improved when pre‐incubated at 4 and 25 °C for 24 and 4 h, respectively. MTGase optimally catalyzed incorporation of monodansylcadaverine (MDC) into surimi at 40 °C. Addition of MTGase appeared to reduce autolytic activity at 25 and 40 °C, but had no effect on autolytic activity at 65 °C. Breaking force and deformation of lizardfish surimi significantly improved when 0.1 unit MTGase g^?1 surimi (1.8 g kg^?1) was added and pre‐incubated at either 25 or 40 °C. Textural properties improved concomitant with cross‐linked polymers of myosin heavy chain and tropomyosin, but not actin. Addition of MTGase also improved the storage modulus (G′). The gel network of surimi mixed with MTGase and pre‐incubated at 40 °C readily formed during the pre‐incubation period, while formation of the gel network began at 48.1 °C in the absence of MTGase. Copyright © 2005 Society of Chemical Industry     

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。