Immunochemical Properties of Proteins Glycosylated Through Maillard Reaction: β-Lactoglobulin-Lactose and Ovalbumin-Glucose Systems

β-Lactoglobulin and ovalbumin were glycosylated through Maillard reaction with glucose and lactose, respectively. The immunoreactivity between β-lactoglobulin-lactose and its specific antibody was inhibited strongly by free galactose and lactose, whereas free glucose did not at all inhibit the reaction between ovalbumin-glucose and its specific antibody. Furthermore, the antibody directed against β-lactoglobulin-lactose reacted also with other lactosylated proteins but the antibody to ovalbumin-glucose had no reactivity with the other proteins glycosylated with glucose, indicating that lactose attached to carrier proteins through Maillard reaction could be a hapten-like antigen but glucose could not.     

温度对碱作用下卵白蛋白-葡萄糖体系色泽、理化特性及抗氧化活性的影响

探讨温度（4、25、37 ℃）对碱作用下卵白蛋白-葡萄糖体系色泽、理化特性及其抗氧化活性的影响。结果表明,随着孵育时间延长和温度升高,卵白蛋白-葡萄糖体系色泽不断加深,棕色产物以及荧光化合物含量不断增加,其美拉德反应中间产物含量在4 ℃和25 ℃时不断上升,而在37 ℃时先上升后下降,其pH值在整个孵育期间呈现出先上升后下降的趋势。傅里叶变换红外光谱分析表明,卵白蛋白和葡萄糖发生了缀合反应。氨基酸分析表明在碱诱导下卵白蛋白中的丝氨酸、组氨酸和半胱氨酸具有较高的反应性,其中反应性最高的是半胱氨酸。孵育后卵白蛋白-葡萄糖体系的抗氧化活性与卵白蛋白葡萄糖混合物相比有了显著提升,但随孵育时间的延长有轻微下降。     

Reaction Characteristics of Polysaccharide-Iodine Complexes: A Mini-review

The potential reactions between natural polysaccharides and iodine and their products have been explored for a long time. Due to the complex factors that can influence these reactions, a clear-cut mechanism has not yet been developed. Starch-iodine complexes, especially the amylose-iodine complex, are the most investigated of the polysaccharide-iodine reactions, and the study of this reaction can be used as a basis for the investigation of other polysaccharide-iodine reactions. In this paper, significant aspects of the reaction were introduced, including the influence of the polysaccharide structure on the properties of the resulting complexes, the relationship between the concentration of CaCl_2 and formation of the final products, as well as the form of the polyiodides in these complexes. The interior structure and the surface morphology of the complexes were discussed, along with the progress in research related to this reaction.     

酪蛋白非磷酸肽对大豆多肽的修饰及复合物的乳化性表征

通过Plastein反应利用酪蛋白非磷酸肽（casein non-phosphopeptides,CNPPs）对大豆多肽进行修饰,对制备出的CNPPs-大豆多肽复合物进行电泳、乳化性质和微观结构分析。结果表明：反应最佳工艺参数为：反应温度42 ℃、pH 4.8、时间3 h、凝乳酶添加量5 g/100 mL,该最优条件下产物的产率为（45.26±0.62）%,电泳结果证实CNPPs和大豆多肽发生了组合。对复合物功能性评价发现,CNPPs-大豆多肽复合物乳化性为0.28±0.02,乳化稳定性为（13.44±0.47）min,均高于大豆多肽的乳化性和乳化稳定性。微观结构较未修饰的大豆多肽呈现出更多的、均一的球形乳化微粒,证实通过CNPPs对大豆多肽的修饰可以有效提高蛋白质的乳化性和乳化稳定性。     

添加顺序对β-乳球蛋白与EGCG及葡萄糖三元复合物结构和功能的影响

采用碱法和美拉德反应将β-乳球蛋白（β-lactoglobul in,β-LG）、表没食子儿茶素没食子酸酯（epigallocatechin gallate,EGCG）及葡萄糖（glucose,Glc）通过不同添加顺序获得2 种共价复合物β-LG-EGCGGlc con和β-LG-Glc-EGCG con,与直接混合形成的非共价复合物β-LG-EGCG-Glc mix和β-LG-Glc-EGCG mix进行对比,研究添加顺序对三元复合物的结构和功能性质的影响。结果表明：不同添加顺序对共价复合物的影响大于非共价复合物。β-LG-EGCG-Glc con与β-LG-Glc-EGCG con在结构和功能性质上有较大差异,而β-LG-EGCGGlc mix和β-LG-Glc-EGCG mix在结构和功能上差别不大。聚丙烯酰氨凝胶电泳和紫外吸收光谱结果显示不同添加顺序对三元复合物的共价结合过程具有较大影响。结构表征发现,共价复合物的荧光猝灭和疏水性都高于非共价复合物。相较于β-LG-EGCG-Glc con,β-LG-Glc-EGCG con有更强的猝灭程度以及更高的疏水性,而β-LG-EGCG-Glc mix与β-LG-Glc-EGCG mix两者差距不明显。此外,2 种共价复合物的功能性质都优于非共价复合物。β-LG-Glc-EGCG con的乳化性、乳化稳定性和起泡性、起泡稳定性都优于β-LG-EGCG-Glc con,而非共价复合物之间差距不大。     

共固定化纳米酶的制备及其在级联催化反应中的应用研究进展

级联酶复合体可通过构建底物通道的方式加快催化效率,已经成功应用在合成医药、化妆品、功能性食品等不同工业领域。生物酶可参与的催化反应种类丰富而且是现代合成化学中的绿色经济型可持续生产工具,但在工业化生产中,固定化级联酶复合体更适合大规模生产,因为固定化技术不仅能够提高酶催化反应效率,还有利于提高酶稳定性以及简化生物催化剂的回收使用。最值得注意的是,酶催化性能、固定化方法、相关反应动力学特性均是酶复合体的活性和稳定性的关键影响因素。综合生物学和材料学领域的研究进展,如兼具纳米特性和稳定性能的载体材料的研发,级联酶共固定化技术将充分平衡各催化组分,从而设计出理想的酶复合体催化机器。因此,该研究结合键联方式和载体材料就近年来多酶的共固定化技术研究发展和相关领域应用进行了综述。     

Preparation and properties of phytosterols with hydroxypropyl β-cyclodextrin inclusion complexes

In order to enhance the solubility and bioavailability of phytosterols (PS), cyclodextrin–PS (CD–PS) inclusion complexes were prepared and the properties of PS-β-cyclodextrin (PS-β-CD) and the inclusion mechanism of its derivative hydroxypropyl β-cyclodextrin (PS-HP-β-CD) in solution were also evaluated. The effects of crucial parameters on cyclodextrin–sterol inclusion efficiency were optimized, including solvent type, β-CD/PS molar ratio, temperature, PS content and reaction time; 92–98?% inclusion efficiency was achieved under the conditions of HP-β-CD/PS ratio 3:1–4:1, PS concentration 15–20?mM, temperature 50–55?°C, reaction time 12?h. For β-CD host, butanol was a good solvent for PS inclusion reaction. The properties of CD–PS inclusion complexes were characterized by differential scanning calorimetric, scanning electron microscopy, UV–Vis scanning spectrophotometer (UV–Vis) and fourier transform infrared spectroscopy (FT-IR), which demonstrated that there are intermolecular hydrogen bonds between PS and HP-β-CD in inclusion complex, resulting in the formation of amorphous form. To clarify the mechanism of the increase in the solubility and bioactivity of HP-β-CD–PS inclusion complexes, the structure of CD as well as the interaction of the HP-β-CD–PS inclusion formation was elucidated. The conclusions indicated that PS-HP-β-CD showed higher water solubility with greater solubilizing and complexing capabilities than PS-β-CD and PS itself.     

偕胺肟双金属配合物纤维的制备及物理性能

通过控制金属离子的浓度和反应时间制得一系列不同金属含量的双金属配合物纤维。分别对不同金属含量的单、双金属配合物的断裂强度、断裂伸长率、初始模量、回潮率等物理机械性能进行了分析。结果表明,各种配合物的断裂强度、断裂伸长率与配合物中金属含量密切相关,金属含量很低时,其值比聚丙烯腈纤维(PAN)的低,随金属含量增加可达与PAN相当值;与PAN相比,回潮率增大,初始模量减小,双金属配合物具有良好的可纺性能。     

Influence of Lipids Isolated from Soybean Seed on Different Properties of Cassava Starch

The effect of lipids isolated from soybean seeds on the properties of cassava starch was investigated. Both polar and non‐polar lipid fractions were complexed with starch and the physicochemical and rheological properties were examined. The FTIR spectra of the complexed starches showed all the absorption bands characteristic of native starch with an extra minor peak at 2355 cm^‐1.The complexes prepared using the polar lipid fraction in diethyl ether as solvent exhibited a swelling volume of 32.5 mL/g compared to 36.9 mL/g for petroleum ether as solvent. A similar effect was observed with the non‐polar fraction. The apparent amylose content of the complexes was found to be lowered as a result of complexation. Total and soluble amylose contents and water‐binding capacity of the complexes were higher while their enzyme digestibility was noticeably lowered. The peak viscosity of the complexes was suppressed as a result of complexation. The polar layer exhibited a greater influence on the viscometric properties of the complexes with a higher breakdown ratio and hence higher stability. When compared to native starch, the percentage light transmittance of the complexes was noticeably reduced. The results indicate a considerable influence of the isolated lipid fractions on starch properties which can be useful in food and industrial applications.     

脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物结构和热性能的影响

本文研究了脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物热性能、微观结构、粒径分布及Zeta电位的影响。结果表明,高直链玉米淀粉与脂肪酸形成复合物后热稳定性降低,且复合物的热稳定性随脂肪酸不饱和度的增加而降低;高直链玉米淀粉与脂肪酸形成复合物的结晶结构为V型,结晶度随着不饱和度的增加而减小;高直链玉米淀粉-脂肪酸复合物有两种存在形式,分别为颗粒表面凸起的球晶和嵌在颗粒表面的层状或絮状结构,后者存在形式随脂肪酸中双键个数的增加而减少;高直链玉米淀粉与脂肪酸形成复合物后淀粉颗粒变小,分散液稳定性增加。总之,脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物的结构和热性能具有明显影响。     

甘氨酸及其小肽配合物的pH电位法研究

利用ｐＨ 电位法研究了甘氨酸及其二、三肽与锌、铜元素的配位作用,测定了相应的配合稳定常数,结果表明,氨基酸和二、三肽的配合行为不同,而小肽之间配位作用基本相似．ｐＨ 电位法研究还表明,铜与肽的配合过程中存在着明显的晶体场稳定化能效应,表现在配合滴定过程中出现特征颜色变化（双缩脲反应）．     

大豆蛋白-黄芩素的结合机制及蛋白构象和功能变化

探索大豆蛋白组分中β-伴大豆蛋白（7S）/大豆蛋白（11S）与黄芩素的结合机制,考察复合物构象及功能特性的变化。傅里叶变换红外光谱表明黄芩素诱导蛋白的β-折叠转化为α-螺旋和无规卷曲。内源荧光光谱证实了黄芩素的加入使7S、11S结构变得更紧密。黄芩素与蛋白的反应自发进行,并通过静态方式猝灭蛋白荧光。7S、11S蛋白分别通过氢键和疏水相互作用与黄芩素结合。分子对接结果表明,黄芩素对11S的亲和力高于7S。扫描电子显微镜显示了7S、11S与复合物的微观结构差异。此外,与黄芩素结合后,7S、11S的表面疏水性下降,热稳定性及其他功能特性提升。     

Pro-oxidative effects of melanoidin–copper complexes on isolated and cellular DNA

High molecular weight Maillard reaction products (melanoidins) are described to possess metal-chelating properties. Whereas in food systems, this ability contributes to antioxidant properties, the consequences on biological systems are not quite clear. The study was aimed to evaluate the implication of metal complexation by melanoidins on DNA damage. Melanoidins prepared with d-glucose and different l-amino acids under water-free reaction conditions were charged with cupric ions. The effect on isolated DNA was investigated by the PM2 assay and on cellular systems in the human colon carcinoma cell line HCT-116 by alkaline unwinding. Independent of the amino acid composition, pure melanoidins (MW >14 kDa) did not cause significant DNA damage. By charging melanoidins with Cu²⁺ ions, a considerable DNA strand breaking activity was detectable, which was again amplified in an oxidative milieu (addition of hydrogen peroxide). Since Cu²⁺ normally does not provoke the formation of reactive oxygen species (ROS) via Fenton-type reaction, the results obtained have to be attributed to reducing properties of melanoidins. Thus, in melanoidin–copper complexes redox cycling may take place leading to Cu⁺ which subsequently undergoes Fenton-type and Haber–Weiss reactions. As a consequence, ROS are formed, which may explain the generation of DNA strand breaks.     

Characterization of modified high-amylose maize starch-α-naphthol complexes and their influence on rheological properties of wheat starch

Amylose can form inclusion complexes with diverse small molecules. Modified starch has different and unique properties compared with its native counterpart. In this study, chemically/enzymatically modified high-amylose maize starches were used to make inclusion complexes with α-naphthol, and the physical properties of complexes and their influences on the rheology of wheat starch were characterized. The results showed that modification of starch had little influence on the wide angle X-ray diffraction pattern of complex (eightfold single helix), but did so on the complexation index and precipitation yield. Inclusion complexes with chemically modified starch showed a lower range of thermostability and recrystallization temperatures. Addition of complex considerably influenced the rheological properties of wheat starch, and the effect was dependent on the type of modified starch used. It may be concluded that starch inclusion complexes, with a range of properties and potential food applications, may be feasibly prepared by using diverse modified high-amylose maize starches.     

Emulsifying Properties of Whey Protein-Carboxymethylcellulose Complexes

ABSTRACT: Proteins/polysaccharides complexes could improve emulsifying properties of proteins by thickening the layer at the interface of the oil droplets. Emulsifying properties of whey protein-carboxymethylcellulose complexes (WPI/CMC) were compared with those of a whey protein isolate (WPI). Ingredients were incorporated into oilinwater emulsions with various protein and oil contents. Visual observations, protein load, protein distribution and rheological measurements were used to evaluate emulsion stability. Protein load up to 26.1 and 48.9 mg protein/g oil were obtained for WPI and WPI/CMC emulsions, respectively. The higher protein load of WPI/CMC emulsions and visual observations indicated that WPI/CMC complexes had greater emulsifying properties against coalescence than whey proteins. However, complexes enhanced flocculation of oil droplets.     

Complex gels of proteins and acid polysaccharides]

The authors studied the thermomechanical properties of complex gels of gelatin and sodium alginate which had been produced on the basis of their insoluble (type I) and soluble (type II) complexes. Compared to gelatin gels of the same concentration, the complex gels I have higher melting points. The latter depend on the pH value at which the insoluble complexes of gelatin and sodium alginate were separated. Up to temperatures from 70 degrees--80 degrees C., no melting of the complex gels II was observed. The aging time and the composition of the soluble complexes of gelatin and sodium alginate exert no marked effects on the properties of the complex gels II. The soluble complexes of gelatin and sodium alginate can form gels in 7 M urea solutions.     

Interaction between proteins and oxidized lipids]

Oxidized lipids react with proteins to form lipoproteid complexes in which the lipids are bound to the proteins in part by physical forces, in part by covalency. The free radicals resulting from the cleavage by hydroperoxides are the major precursors of the lipoproteid complexes. The interaction is associated with protein denaturation and oligomer formation. The lipids contained in the lipoproteid complexes are only in part extracted by chloroform-methanol; in part not until after acid or alkaline hydrolysis. The nutritive value of the protein moiety is diminished by the reaction of the hydroperoxides with methionine and cysteine and by the reaction of the peroxidic radicals and aldehydes with lysine and other basic amino acids. Secondary reactions of the lipoproteid complexes lead to brown coloured, only partly soluble compounds which often impair the organoleptic value. The rancidity products of the fats are neutralized by the reaction with proteins. The action of highly unsaturated oxidized lipids on proteins results in the development of a fishy aroma.     

大豆分离蛋白-黄原胶-茶多酚复合物的制备及其乳液性质表征

以大豆分离蛋白（SPI）、黄原胶（XG）、茶多酚(TP)为原料,改变原料的添加顺序制备三元复合物SPI-XG-TP和SPI-TP-XG,研究了不同复合物的结构与乳化特性的差异。结果表明：蛋白质与多糖、多酚复合之后其结构发生一定程度的改变,且复合物的乳化特性都得到了改善,两种三元复合物中SPI-XG-TP稳定的乳液粒径更小,电位绝对值更大,乳化活性更高,但乳化稳定性略低于SPI-TP-XG稳定的乳液。大分子间能够相互交联形成三元复合物并改变蛋白质的结构,不同原料添加顺序的复合物的结合过程不同     

动态高压微射流处理顺序对果胶-乳铁蛋白复合物结构及性质的影响

采用动态高压微射流（dynamic high pressure microfluidization,DHPM）分别以不同的处理顺序：DHPM预处理乳铁蛋白（lactoferrin,LF）后与果胶（pectin,P）混合（MLFP）、DHPM预处理果胶后与乳铁蛋白混合（MPLF）以及乳铁蛋白与果胶混合后再经DHPM处理（MLFP）,制备3 种乳铁蛋白-果胶复合物,探究DHPM的处理顺序对复合物结构及性质的影响。结果表明：DHPM处理使复合物的分散性增大,乳化性减小。且经DHPM处理后的3 种复合物中,MLFP的分散性和乳化性最强,而MLFP的分散性和乳化性最低,这与界面张力测定结果一致。经DHPM处理后复合物粒径也显著减小（P＜0.05）,且MPLF＜MLFP ＜MLFP＜空白对照组复合物。ζ-电位和荧光光谱结果表明,果胶和LF复合物主要通过两者间静电作用结合,且DHPM处理促进果胶与LF的相互作用。本研究为探讨食品组分在食品加工过程中的结构和性质变化提供一定的理论依据。     

Reaction of Starch and Cellulose with Products of Thermal Decomposition of Mono- and Disaccharides

D(—)-Fructose, dextrose and sucrose were thermally decomposed in the presence of native and pregelatinized corn starch, cellulose as well as its mixtures with native corn starch. Several products were obtained in which reactive intermediates thermally generated from lowmolecular saccharides were involved. When starch either was not gelatinized or it could not gelatinize on reaction, the preference for the formation of a physical mixture of caramel with starch and starchsugar complexes was observed. Otherwise products of substitution of starch with reactive intermediates and inclusion complexes were formed. Cellulose appeared to be more reactive. It was grafted to starch by reactive intermediates thermally generated from dextrose.