黑曲霉浅盘生料发酵产单宁酶动力学研究

对黑曲霉浅盘生料发酵产单宁酶动力学进行研究。基于Logistic方程和Leudeking-Piret方程,提出了菌体生长动力学、单宁酶生成动力学、基质消耗动力学模型,同时对分批发酵实验数据应用软件Origin8.0进行了非线性拟合得出参数值。动力学分析结果表明:所建立的分批发酵动力学模型能较好地反映黑曲霉产单宁酶分批发酵的过程,相关性良好。     

葡萄籽原花青素提取动力学研究

通过分析葡萄籽原花青素提取过程的传质机理,确定以溶质浓度的宏观变化描述微观过程。在质量守恒原理的基础上建立动力学方程,并通过实验对方程进行检验。运用Arrhenius 方程求出提取过程中重要的动力学参数,其表观活化能为2.08 × 104J/mol。结果表明：所建立的方程能够较好的描述葡萄籽原花青素的提取过程,原花青素提取符合扩散传质的动力学规律。     

红曲色素醇提过程中传质动力学模型的构建

通过分析70%乙醇提取红曲色素过程中的色价-时间的变化关系,结合经典传质数学模型,建立了提取过程中红曲色素色价与提取时间的动力学方程.经验证,所推导出的动力学方程能较好地反映红曲色素提取过程中色价-时间之间的关系.     

L-乳酸生产菌分批发酵动力学模型

对L-乳酸生产菌的分批发酵动力学进行了研究.通过对Logistic方程、Luedeking-Piret方程和LuedekingPiret-Like方程进行最优参数估计和非线性拟舍,得到了菌体生长、产物生成和底物消耗的动力学模型和模型参数.对动力学模型的拟合曲线进行分析,发现发酵实验值与拟合值能较好地拟合.结果表明,所建立的分批发酵动力学模型能较好地反映L-乳酸分批发酵过程.     

不同贮藏温度条件下大白菜品质动力学方程分析研究

采用鲁春白1号大白菜为试验材料,研究不同贮藏温度下大白菜失重率、叶绿素和维生素C降解的动力学规律,并建立动力学模型。结果表明：不同贮藏温度下大白菜失重率符合零级反应动力学和Arrhenius方程,叶绿素和维生素C降解符合一级反应动力学和Arrhenius方程;经验证所建立的失重率、叶绿素和维生素C降解动力学模型有效,可用于预测不同温度条件下大白菜贮藏过程中品质的变化。这项研究可为大白菜贮藏保鲜提供理论参考。     

变质量条件下Tzénoff方程的新形式

航天器运行系统大都属于变质量力学系统,研究变质量系统的运动方程是研究航天系统力学性质的基础.本文构造了变质量力学系统的Tzénoff函数,建立了用普通偏导数表示的变质量完整系统和非完整系统的Tzénoff方程,所给出的运动方程具有新的结构形式,该微分方程的建立对变质量系统的动力学研究具有一定的理论价值.     

酿酒酵母工程菌分批发酵产UMP动力学模型

对酿酒酵母工程菌产UMP的分批发酵动力学进行了研究。通过对Logistic方程、Leudeking-Piret方程和类Luedeking-Piret方程进行参数估计和非线性数据拟合,分别得到发酵过程中菌体干重、UMP产量、残糖含量动力学模型及模型参数。对拟合曲线进行分析,结果表明模型值与实验值拟合性良好,线性拟合度大于98%,所建立模型能较好的反映UMP的分批发酵过程。     

α-蒎烯的发酵动力学模型

以α-蒎烯生产菌株YJM28为供试菌株,对其发酵动力学特征进行了研究。通过对Logistic等方程进行了最优参数估计和非线性拟合,得出了α-蒎烯的发酵动力学模型及相关参数。并且对动力学模型的拟合曲线分析可知,发酵实验值与模型预测值能够较好的吻合,说明所建立的发酵动力学模型能够较好的反应α-蒎烯的发酵过程。     

谷胱甘肽分批补料发酵动力学模型的建立

研究了酿酒酵母分批补料发酵生产谷胱甘肽的动力学特性,利用Logistic方程和Luedeking-Piret方程建立了菌体生长、产物生成、基质消耗动力学模型。对得到的模型和实验数据进行了验证,模型计算值和实验数据拟合较好,模型能够较好地反映谷胱甘肽分批发酵动力学特性。     

计算机仿真在机构动力学分析中的应用

介绍了计算机仿真技术在机构动力学分析中的应用。根据牛顿力学原理建立和推导了机构的运动方程。使用MATLAB／SIMAULINK对运动方程进行动力学仿真,求解机构运动副中的反力及机构中的平衡力矩。     

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.     

Differentiation in improvements of gel strength in chicken and beef sausages induced by transglutaminase

This research investigated the improvement in the texture of chicken and beef sausages induced by using microbial transglutaminase (MTG). The ε-(γ-glutamyl)lysine (G-L) content and the extractability of myofibrillar proteins from these sausages were also investigated. Treatment with MTG significantly affected the breaking strength score in both meat types, especially for beef cooked at 80°C (p<0.001). The protein concentration of both meat types treated with MTG and extracted in water-soluble protein solution (WSP) was slightly decreased; compared with a significant decrease (p<0.003) in samples extracted in Guba-Straub-ATP solution (GS-ATP). The variation in protein extractability of both meat types could lead to some considerations of the mechanisms and the high affinity reaction between MTG and myosin heavy chain (MHC). SDS-PAGE analysis revealed significant changes in the density of the bands after adding MTG, especially for the beef samples. The G-L content in the presence of MTG was double that in control samples of both meat types. The amount of crosslinking in chicken and beef meat was different and found to be reasonable. Collectively, this suggests that the binding ability of myofibrillar proteins with MTG is strong and dominated by MHC. There was a unique reaction among MHC proteins with MTG molecules considered as a very advantageous reaction. This leads us to suggest that the functional properties of MTG make it a beneficial protein-binding agent, positively helping the functionality of proteins to improve the texture and gelation of meat products that are treated mechanically, such as sausages. Some variation in gel improvement level between chicken and beef sausages was observed; this resulted from the variation in meat proteins in response to MTG, as well as to the original glutamyl and lysine contents.     

Dependence of microbial transglutaminase on meat type in myofibrillar proteins cross-linking

The objectives of this study were to determine the factors that cause differences in the improvements of gel strength and ε(γ-glutamyl)lysine (G-L) content in chicken and beef (Japanese black cattle) myofibrillar proteins after adding microbial transglutaminase (MTG). As the amount of MTG added increased, the breaking strength increased progressively (p < 0.01) in chicken and beef samples, with the exception of chicken samples treated at 40 °C. The values of elasticity in the chicken samples were lower than those of the beef samples (p < 0.01). Surprisingly, the elasticity level, ε(γ-glutamyl)lysine contents and myosin heavy chain (MHC) band sizes of chicken and beef at all levels of MTG were significantly different (p < 0.01). The results of this study suggest that MTG activity was affected by MTG inhibitors; that MTG develops the texture of myofibrils differently in different species. However, the activity is limited and inconstant among meat proteins, as suggested by the data collected from the chicken samples. As a result, when the transferable amino acid residues are depleted (cross-linked) by MTG activity, the function of MTG will be insignificant. The correlation between MTG and different sources of meat protein is quite unstable but it is strong, which was observed when chicken and beef responded differently to MTG because their chemical and physiological properties were different. The remarkable rate of formation of cross-linked proteins and the discrepancy between the expected and observed amount of dipeptide raises the possibility that there are enzymes capable of reversing the reaction induced by transglutaminase in chicken and beef myofibrils. In summary, our results suggest that access of MTG to chicken and beef myofibrils is different because it depends on physiological (muscles and their fibre types), biological (substrates) and biochemical (inhibitors and amino acids) variables.     

复合诱变法选育谷氨酰胺转胺酶高产菌株

为筛选谷氨酰胺转胺酶高产菌株,利用紫外-硫酸二乙酯复合诱变、一次筛选的方法诱变生产菌株茂源链霉菌（Streptoymyces mobaraensis）,结合高通量筛选技术筛选高产菌株。结果表明：复合诱变的方式较单独诱变的方式效率高。经过诱变的高产菌株由于酶的成熟加快或者蛋白表达量增加而提高了酶活力,最高可达7.02 U/mL,比野生菌株提高了54%。进一步研究高产菌株发现,高产菌株谷氨酰胺转胺酶的成熟加快,可提前24 h结束发酵;发酵液中酶原含量高,会降低发酵液中酶活性。     

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.     

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.     

Texturisation and modification of vegetable proteins for food applications using microbial transglutaminase

Microbial transglutaminase (MTG) isolated from Streptomyces mobaraensis has been available on a commercial scale for several years. MTG generates inter- and intramolecular cross-links between γ-carboxylamide groups of glutamine residues and ɛ-amino groups of lysine residues in proteins. Due to its great potential to improve various functional properties of proteins, MTG is mainly used to enhance texture, stability, and water binding. Application of MTG for the production of plant protein-based foodstuffs such as tofu, noodles, bread and bakery products, is still limited to raw materials from soybean and wheat. However, with the increasing demand for vegetarian foods, the utilisation of novel proteins as functional ingredients, e.g. from peas, lupins, sesame, and sunflower, seems promising. To open new horizons for MTG application, this review aims at demonstrating the actual potential of MTG in processing foodstuffs based on vegetable proteins. Particular focus was laid on novel plant protein sources suitable for cross-linking with MTG. Furthermore, strategies for improving texture and nutritive value of the proteins are discussed.     

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.     

Emulsion properties of pork myofibrillar protein in combination with microbial transglutaminase and calcium alginate under various pH conditions

In this study, the effects of microbial transglutaminase (MTG) and calcium alginate (CA) systems in combination with soybean oil on the emulsion properties of porcine myofibrillar protein (MP) were evaluated under various pH conditions. MTG was shown to improve emulsifying capacity and creaming stability, which increased with increasing pH values up to 6.5. The CA did not influence emulsifying capacity, but it improved the creaming stability of the MP-stabilized emulsions. Both MTG and CA enhanced the rheological properties, but their effects on the physical characteristics of the protein evidenced an opposite trend in relation to pH, i.e., the MTG system improved both the emulsion and gelling properties with increasing pH, whereas the CA system was effective when the pH was lowered. By combining the two MP gelling systems, a stable and pH-insensible emulsion could be produced.     

Effect of storage time on sensory and instrumental properties of skim‐milk yoghurt obtained with microbial transglutaminase

Not many studies have examined changes in microbial transglutaminase (MTG) yoghurts during storage. In this work, yoghurts manufactured with skimmed milk and treated with MTG were evaluated in refrigerated storage for 35 days. Instrumental measurements showed that firmness, consistency and pH values in MTG yoghurt experienced a significant increase with the storage time. However, sensory measurements showed that MTG yoghurts were not affected significantly by storage time. Acid taste scores only increased significantly with storage time in the control samples. Microbial transglutaminase treatment showed a positive effect on textural properties and allowed syneresis to be prevented completely during storage.