利用Maillard反应制备大豆蛋白-葡聚糖共价复合物

研究了大豆酸沉蛋白和葡聚糖共价键合制备反应及其产物乳化性能的变化.在干热条件下,两种大分子通过Maillard反应进行共价键合并通过聚丙烯酰胺凝胶电泳验证了大分子复合物的存在. 结果表明产物具有比大豆酸沉蛋白更高的对油/水乳状液的乳化能力,复合物在pH 3.0和pH 10.0时均能保持较好的乳化活性,并且在高温、高盐条件下乳化活性变化很小.     

蛋白质-多糖共价复合物

蛋白质和多糖在控制条件下通过Maillard反应可发生一定程度的复合,而且复合物具有良好的功能性。因此,该课题成为近年来国外食品科学界的一个研究焦点。简要介绍了近年来国外在该领域进行的部分研究工作,包括复合反应的基本形式和主要影响因素,复合产物对蛋白质溶解性、乳化性能、抗氧化性能以及抗菌性能等的影响,并指出作为性能良好的多功能食品添加剂,蛋白质与多糖的共价复合物的研制和应用必将有着良好的前景。     

液相体系制备大豆酸沉蛋白-葡聚糖共价复合物及其反应机制（Ⅲ）功能性质的改善

对SAPP与葡聚糖（DEX）复合物的乳化活性以及乳化稳定性等功能性质进行系统研究。结果表明,液相体系反应产物在酸性条件下和100℃处理3min时乳化活性指数（EAI）降低,中性和强碱性条件下表现为优越的乳化活性和乳化稳定性。无论是干热5d或者液相体系反应,SAPP-葡聚糖共价复合物在所有pH范围内都能达到很好的溶解性能,并对80％乙醇体系反应前后的Maillard反应产物进行差示扫描（DSC）分析,进一步证实蛋白已经与多糖结合反应生成新的化合物,该产物热稳定性很高。     

大豆蛋白-多糖干热制备复合物及其反应机理研究(Ⅰ)共价复合物的制备及生成机理探讨

通过干热反虑制备大豆蛋白-多糖共价复合物，并结合聚丙烯酰胺凝胶电泳验证了大分了复合物的共价结合。对于蛋白与多糖生成共价复合物的Maillard反应路线进行了分析，阐明对于蛋白与多糖在相对温和的反应条件下得到的主要是Maillard反应步骤中的第二步，属于Amadori产物中的一类，并采用红外光谱分析了产物分了结构特征。     

液相体系制备大豆酸沉蛋白-葡聚糖共价复合物及其反应机制(Ⅰ)共价复合物的制备

作为一项新的有效的制备方法,对液相体系中发生Maillard反应的的各种影响因素进行系统研究,结果表明,80%乙醇体系中,反应体浓度为60%、50℃时反应6h以及95%乙醇体系中,反应体浓度为60%、60℃时反应24h条件下得到的产物表现出了优越的乳化活性.并采用SDS-PAGE技术证实蛋白与多糖之间发生共价结合反应.     

大分子拥挤环境下大豆7S球蛋白糖基化研究

生命科学领域中的大分子拥挤环境作为反应介质进行Maillard反应制备大豆7S球蛋白-葡聚糖共价复合物。对液相体系中发生Maillard反应的各种影响因素进行系统研究,并采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）技术证实大豆7S球蛋白和葡聚糖发生了共价结合,得出共价复合物制备的最优条件。结果表明:5%的7S球蛋白与15%的葡聚糖在pH7.0条件下,95℃反应6h后,形成了良好的大分子共价复合物。产物色泽良好,褐变程度较低,反应时间大大缩短。      

大分子拥挤环境下多糖对蛋白肽的修饰研究

采用胃蛋白酶适度水解大豆分离蛋白得到蛋白肽,在大分子拥挤环境下通过Maillard反应制备蛋白肽-葡聚糖共价复合物(Hydrolated Soy Protein Isolated-Dextran Conjugates,HDC),采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)技术证实大豆7S球蛋白和葡聚糖发生了共价结合,并通过乳化剪切机、荧光分光光度计、差示扫描量热仪和粒度分布仪等对其接枝度、溶解性、热稳定性、抗氧化性和乳化性能进行系统分析。结果表明:大分子拥挤环境下大豆水解蛋白肽-葡聚糖60℃反应4 h就可以形成较高接枝度的共价复合物,溶解性较大豆分离蛋白(Soybean protein isolated,SPI)和大豆分离蛋白-葡聚糖(Soybean Protein Isolated-Dextran Conjugates,SDC)有所提高,热稳定性好,HDC的自由基清除率明显高于大豆水解蛋白和它与葡聚糖的混合物,达到66.39%,且羟自由基清除率高于维生素C,HDC的乳液粒径最小并具有优越的乳化稳定性。     

荞麦分离蛋白-葡聚糖共价复合物的制备

以荞麦蛋白为原料,在大分子拥挤条件下,采用湿法制备荞麦蛋白-葡聚糖共价复合物。选择60℃和70℃为反应温度,研究了不同反应条件对共价复合物溶解性、乳化性的影响,并通过游离氨基以及褐变程度来控制反应进程。结果表明,荞麦蛋白与葡聚糖在70℃反应6 h后,其乳化性得到明显改善。SDS-PAGE电泳(考马斯亮蓝染色和糖蛋白染色)验证了共价复合物的生成。DSC分析结果表明共价复合后荞麦蛋白的热稳定性得到提高。荧光光谱表明共价复合物的蛋白质极性降低,疏水性增强。     

蛋白-多糖共价复合作用研究进展

介绍了蛋白-多糖共价复合作用模式,复合物对蛋白质乳 化性能、热稳定性、抗氧化性能以及抗菌性能等的影响以 及近年来国外在该领域的最新研究动态。作为新型的高 分子食品配料,蛋白质与多糖复合物的研制和应用必将 有着良好的前景。      

大豆蛋白-多糖干热制备复合物及其反应机理研究(Ⅱ)功能性质的改善

对SAPP与葡聚糖(DEX)复合物的乳化活性以及乳化稳定性等功能性质进行系统研究。结果表明,干热反应产物在pH3.0以及pH10.0时保持好的乳化活性;并且在高温、高盐条件下乳化活性变化很小。对反应产物进行差示扫描(DSC)分析,进一步证实蛋白已经与多糖结合反应生成新的化合物,该产物热稳定性很高,比原有蛋白的变性温度提高了几乎两倍。     

Formation of soy protein isolate–dextran conjugates by moderate Maillard reaction in macromolecular crowding conditions

BACKGROUND: Several methods have been reported for the conjugation of proteins with polysaccharides. Protein–polysaccharide conjugates can be formed by traditional dry heating, but this process is not attractive from an industrial viewpoint, and no commercial conjugates have been manufactured in this way. In the present study, in order to develop a more practical reaction method, macromolecular crowding was used to attach polysaccharides to proteins. RESULTS: Soy protein isolate–dextran conjugates (SDCs) were prepared via the initial stage of the Maillard reaction in macromolecular crowding conditions. The impact of various processing conditions on the formation of SDCs was investigated. The optimal conditions chosen from the experiments were a soy protein isolate/dextran ratio of 1:1 (w/w), a pH of 6.5, a reaction temperature of 60 °C and a reaction time of 30 h. Circular dichroism spectroscopy showed that the secondary and tertiary structures of the conjugates were changed significantly. Structural flexibility increased, allowing better display of their functional characteristics. The conjugates had a composition with various sizes, especially macromolecules, according to gel permeation chromatography. Thermal analysis showed that the thermal stability of the conjugates was improved. CONCLUSION: The production of SDCs under macromolecular crowding conditions appears to be an effective and promising technique, representing an advance over classic protein glycosylation methods. Copyright © 2012 Society of Chemical Industry     

Formation of acid‐precipitated soy protein–dextran conjugates by Maillard reaction in liquid systems

The conjugation reaction between soybean acid‐precipitated protein (SAPP) and dextran in liquid systems via the initial stage of the Maillard reaction was studied. Functional SAPP–dextran conjugates were prepared in 80% ethanol‐reacting system at 50 °C for 6 h, along with 95% ethanol‐reacting system at 60 °C for 24 h. The covalent attachment of dextran to SAPP was confirmed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis and gel filtration chromatography.Compared to the classical dry‐heating, the reaction time of glycosylation in the two ethanol systems was largely shortened. Emulsifying activity of SAPP–dextran conjugates obtained by dry‐heating incubation and in ethanol was similar at pH 7.0 and10.0, significantly higher than that of SAPP–dextran mixture or SAPP alone. In addition, SAPP–dextran conjugates obtained in 80% ethanol‐reacting system for 6 h were completely soluble after heating at 90 °C for 20 min. The impact of various processing conditions on the formation of SAPP–dextran conjugates was investigated. This study provides important guidance to create protein–polysaccharide conjugates at mild temperatures in liquid systems.     

大分子葡聚糖-牛血清蛋白抗原偶联物的制备与表征

用还原胺化法制备大分子葡聚糖-牛血清蛋白(BSA)拟糖蛋白抗原,通过SDS-聚丙烯酰胺凝胶电泳结合考马斯亮蓝和过碘酸-品红两种染色方法验证偶联物的生成。考察不同反应条件(葡聚糖T40的氧化度,偶联pH,氧化葡聚糖和蛋白质的比值,偶联时间)对偶联反应的影响。确定拟糖蛋白抗原的最佳偶联条件为:葡聚糖T40/氧化剂NaIO4=1/120(物质的量比),偶联溶液pH8.0,葡聚糖T40/BSA=1/1(物质的量比),偶联时间24h。并将此反应条件用于T10和T100拟糖蛋白抗原的合成。     

Improvement of functional properties of acid-precipitated soy protein by the attachment of dextran through Maillard reaction

The functional acid-precipitated soy protein (SAPP)–dextran conjugate was prepared by dry-heated storage at 60 °C under 79% relative humidity (RH) for 5 days through Maillard reaction between the ε-amino of lysine in soy proteins and the reducing-end carbonyl residue in the dextran. The covalent attachment of dextran to SAPP was confirmed by SDS-polyacrylamide gel electrophoresis and gel filtration chromatography. Functional properties of soy protein depend on the structural and aggregation characteristics of their major components (storage globulins 7S and 11S). The conjugate seemed to be predominantly formed by 7S, and the acidic subunits of 11S in soy protein. The emulsifying properties of the SAPP–dextran conjugate were about four times higher than those of SAPP. The solubility of the protein was not enhanced as a result of preheating, but rather it was not decreased when the conjugated protein was heated at 90 °C for 20 min due to the presence of the polysaccharide. The excellent emulsifying properties of SAPP–dextran conjugate were maintained even at pH 3.0 and were further improved at pH 10.0. The object of Maillard reaction is to guarantee the suitable reaction degree, and the resulting soluble conjugate can have excellent emulsifying properties.     

葡聚糖-大豆分离蛋白耦联接枝工艺优化及接枝产物理化特性研究

为研究条件温和、高接枝度、低褐变程度的糖接枝技术,以葡聚糖、大豆分离蛋白为原料,研究大豆分离蛋白-葡聚糖接枝物的制备工艺。选取物料比、接枝温度及接枝时间进行单因素实验;采用物料比、接枝温度及接枝时间为变量,以接枝度(DG)为响应值,通过响应面实验设计,优化糖接枝蛋白制备工艺,并进行理化特性分析。结果表明,糖接枝反应的最佳工艺条件为:蛋白:糖(质量比)1:1.2,接枝温度83 ℃,接枝时间7.3 h,此工艺条件下,接枝度可达56.38%,褐变程度为0.041。分别以聚丙烯酰胺电泳、氨基酸分析鉴定糖接枝蛋白,表明葡聚糖以共价键接枝在蛋白上。糖接枝蛋白在pH为7.0处的溶解性与原蛋白相比提高40.48%;乳化活性和乳化稳定性明显提高,分别比原蛋白提高69.76%和62.11%。     

加热方式对大豆分离蛋白-糖接枝反应的影响

采用常压电加热与微波辐射加热两种方式对大豆分离蛋白(SPI)-糖接枝反应程度的影响进行了研究.实验结果及通过动力学模型计算表明,微波大大地促进了SPI-糖接枝反应,对于SPI-多糖接枝反应尤为显著,其反应速率较常压电加热反应提高了60倍;对于SPI-双糖接枝反应则提高了4倍.     

Structure and functional properties of rice protein–dextran conjugates prepared by the Maillard reaction

Dextran was grafted on to rice protein (RP) by the wet‐heating Maillard reaction, and the structure and functional properties of the rice protein–dextran conjugates (RPDCs) were investigated. The RPDCs obtained by the Maillard reaction exhibited superior functionality compared with original RP. The solubility, emulsifying activity index, emulsifying stability index, foaming activity index and foaming stability of the RPDCs increased by factors of 7.50, 1.79, 2.20, 1.69 and 2.01, respectively, compared to original RP. The molecular weight, particle size distribution, surface hydrophobicity, secondary structures, amino acid compositions and chemical bonds of RPDCs were also characterised. The structure–function relationship was preliminary discussed, and the relationship suggests that the improvements in the functional properties were closely related to structural changes.     

小麦胚芽蛋白糖基化反应改性的研究

以葡聚糖为糖基供体,采用糖基化反应对小麦胚芽蛋白进行改性。通过单因素实验摸索和正交实验优化确定了改性的最佳工艺条件:底物浓度2%,蛋白∶葡聚糖=1∶1,pH11,温度110℃,时间20min。在此条件下,接枝度达到11.27%,产物溶解性达到85.91%。反应产物在激发波长347nm,发射波长422nm处有最大荧光强度,且随着反应时间的延长,荧光强度增大,符合美拉德反应产物的荧光特征。傅立叶红外分析(FTIR)结果证实了葡聚糖以共价键的形式接入了小麦胚芽蛋白。      

Effects of casein- and whey protein–dextran conjugates on the stability of bog bilberry anthocyanin extract

Bog bilberry ( Vaccinium uliginosum ) contains a high concentration of anthocyanins. Anthocyanin stability depends on many factors, including pH, temperature and composition of food matrices in a product, such as protein and polysaccharide. The effect of casein–dextran and whey protein–dextran conjugates on the stability of bog bilberry anthocyanin extract (BBAE) was investigated in an accelerated model system. Cyanidin-3-glucoside was the main anthocyanin (79%) found in BBAE. The cyanidin-3-glucoside content, absorbance and ABTS [2, 2-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical scavenging activity of BBAE significantly ( P  < 0.05) decreased after heating at pH 8.0 and 80 °C for 60 min. The addition of casein–dextran and whey protein–dextran conjugates significantly ( P  < 0.05) prevented cyanidin-3-glucoside from degradation, and increased the absorbance and ABTS radical scavenging activity of heated BBAE. The protection of casein–dextran conjugate on BBAE was significantly higher ( P  < 0.05) than that of whey protein–dextran conjugate. The results suggest that protein–dextran conjugates have the ability to stabilise BBAE.