Interaction of dietary polyphenols with bovine milk proteins: molecular structure-affinity relationship and influencing bioactivity aspects

Scope : Dietary flavonoids and stilbenes are important polyphenols in foods, such as, e.g. fruits, vegetables, nuts, and tea as they are of great interest for their bioactivities, which are related to the anti‐oxidative property. Methods and results : The relationship between the structural properties of dietary polyphenols and their affinities for milk proteins (MP) was investigated. Methylation and methoxylation of flavonoids decreased (or hardly affected) the affinities for MP. Hydroxylation on the rings A and B of flavones and flavonols enhanced the interaction slightly. The hydroxylation on the ring A of flavanones significantly improved the affinities. Glycosylation of flavonoids weakened the affinities by 1–2 orders of magnitude. The hydrogenation of the C2?C3 double bond of flavonoids decreased the binding affinities by 7.24–75.86‐fold. Galloylation of catechins significantly improved the binding affinities by about 100–1000‐fold. Glycosylation of resveratrol decreased its affinity for MP. Esterification of gallic acid increased its binding affinity. MP significantly weakened the DPPH radical scavenging activity of polyphenols. The decreasing DPPH scavenging percentages of polyphenols increased with increasing affinities of MP–polyphenol complexes. Conclusion : The binding affinities with MP were strongly influenced by the structural differences of dietary polyphenols. The MP–polyphenol interaction weakened with the DPPH free radical scavenging potential of polyphenols.     

多酚与蛋白质相互作用的研究进展

蛋白质是人体必须的营养素,也在调控人体生物学功能中扮演了重要的角色。多酚类物质能和食品体系中的膳食蛋白发生相互作用,影响蛋白质的功能特性和营养价值,也能与生物体内激酶、转录因子、受体等功能蛋白相互作用,调控不同信号通路中靶基因的表达,进而发挥健康效应。本文综述了多酚类物质与膳食蛋白及体内功能蛋白相互作用的研究现状,分析了多酚与蛋白的互作机制及常用的研究方法,以期为进一步揭示多酚类物质的生理功能,拓展多酚类物质在食品和医药领域中的应用提供参考依据。     

环境因素对米糠不溶性膳食纤维吸附蓝莓多酚的影响

为了研究影响米糠不溶性膳食纤维吸附蓝莓多酚的环境因素,以时间、温度、p H、离子强度、尿素浓度、乙醇浓度为变量,蓝莓多酚吸附量为指标进行了吸附实验。蓝莓多酚的吸附量随时间先增加后趋于平衡,30 min时基本达到平衡;低p H环境有利于吸附,吸附量在p H4~5时达到最大值;吸附量随溶液中离子强度的增大而增加,随温度升高,尿素、乙醇浓度增大而减少。吸附蓝莓多酚后,米糠不溶性膳食纤维的抗氧化活性得到提高,其IC50为3.53 mg/m L,结果表明:米糠不溶性膳食纤维与蓝莓多酚的共混物是一种理想的新型高效的天然抗氧化剂。      

植物多酚与蛋白质互作机制表征方法研究进展

多酚化合物是食物中对人体健康有促进作用的功能活性成分,其功能作用的发挥与食物中其他营养成分(如蛋白质、多糖)之间的相互作用密切相关。为深入研究食品加工过程中功能营养成分的相互作用与变化,本文综述了多酚与蛋白质的相互作用机制及表征方法,包括荧光光谱法、傅里叶变换红外光谱法、拉曼光谱法、圆二色谱、等温滴定量热法、核磁共振法、原子力显微镜、激光扫描共聚焦显微镜、分子对接和分子动态模拟等。多酚与蛋白质之间的相互作用主要是氢键、疏水相互作用、静电相互作用和范德华力,应用多种表征方法可全面地解析植物多酚与蛋白质相互作用机制。     

食品多酚与蛋白相互作用及其对多酚生物可利用性影响的研究进展

多酚和蛋白质的相互作用是近几十年来多酚类化合物与生物大分子作用研究的重点。食品多酚具有多种功能活性,但是由于受其他食品组分、加工条件和消化环境等各种因素的影响,其生物可利用率较低,对人体的健康功效受到严重影响。因此,该文综述了近些年来国内外关于食品多酚与蛋白的相互作用类型及其对多酚生物可利用性影响的研究进展,以期为提高多酚类食品的健康功能品质提供一定的指导依据。     

多酚与蛋白质、消化酶相互作用的研究进展

近年来,随着人们对营养和功能性食品的需求逐渐增长,果奶、奶茶、可可奶和咖啡奶等含有乳蛋白和多酚的复合产品备受青睐,而复合体系中乳蛋白与多酚的相互作用及其对产品营养健康性的影响也成为目前的研究热点。消化道是影响食品营养健康特性发挥作用的重要场所,在消化环境食品多酚与乳蛋白、多酚与消化酶存在相互作用,它们之间的竞争性作用会影响乳蛋白的消化性和多酚的健康功能性,然而有关此方面的研究较少。因此,该文主要概述了国内外关于多酚和乳蛋白、多酚和消化酶间相互作用的研究进展,分析在消化环境中多酚功能性质的改变,以及研究乳蛋白与多酚复合体系蛋白消化性、抗氧化性和生物利用性的变化情况,以期为提高此类产品的营养和功能品质提供一定的指导依据。     

牛乳蛋白抗原性研究现状概述

乳蛋白是衡量乳制品营养价值的重要指标。文中介绍了牛乳蛋白的种类、结构、性质和抗原性强弱,比较了不同蛋白抗原的免疫抗体的特异性、交叉性、采用不同检测方法的检测限等。对酶联免疫吸附测定乳蛋白的优缺点进行了阐述,并展望了其应用前景。     

蛋白质与多酚的相互作用在食品运载体系中的研究进展

由蛋白质与多酚相互作用形成的食品运载体系因其良好的生物相容性和抗氧化活性而受到越来越多的的关注。本文主要阐述了蛋白质与多酚相互作用的机制及其复合物的功能特性,重点介绍了蛋白质-多酚运载体系的特性以及其在功能活性物质缓释载体、乳液稳定剂和功能性薄膜中的应用,并基于目前与蛋白质-多酚相互作用有关的食品运载体系形式较少、配合物研究单一以及复合物缺乏安全性评估等问题提出了见解,以期为拓展蛋白质-多酚复合物在食品运载体系中的应用提供参考依据。     

Association between the bovine milk metabolome and rennet-induced coagulation properties of milk

The milk metabolomes of 407 individual Swedish Red dairy cows were analyzed by nuclear magnetic resonance spectroscopy as part of the Danish-Swedish Milk Genomics Initiative. By relating these metabolite profiles to total milk protein concentration and rheological measurements of rennet-induced milk coagulation together using multivariate data analysis techniques, we were able to identify several different associations of the milk metabolome to technological properties of milk. Several novel correlations of milk metabolites to protein content and rennet-induced coagulation properties were demonstrated. Metabolites associated with the prediction of total protein content included choline, N-acetyl hexosamines, creatinine, glycerophosphocholine, glutamate, glucose 1-phosphate, galactose 1-phosphate, and orotate. In addition, levels of lactate, acetate, glutamate, creatinine, choline, carnitine, galactose 1-phosphate, and glycerophosphocholine were significantly different when comparing noncoagulating and well-coagulating milks. These findings suggest that the mentioned metabolites are associated with milk protein content and rennet-induced coagulation properties and may act as quality markers for cheese milk.     

Binding of zinc to bovine and human milk proteins

Zn binding by whole bovine and human casein and by purified bovine caseins and whey proteins was investigated by equilibrium dialysis. Bovine alpha s1-casein had the greatest Zn-binding capacity (approximately 11 atoms Zn/mol). Protein aggregation was observed as Zn concentration was increased and the protein precipitated at a free Zn concentration of 1.7 mM. Zn binding increased with increasing pH in the range 5.4-7.0 and decreased with increasing ionic strength. Competition between Zn and Ca was observed for binding to alpha s1-casein indicating common binding sites for these two metals. Bovine beta-casein bound up to 8 atoms Zn/mol and precipitated at a free Zn concentration of approximately 2.5 mM, while kappa-casein bound 1-2 atoms Zn/mol. Whole bovine and human casein bound 5-8 atoms Zn/mol and precipitated at a free Zn concentration of approximately 2.0 mM. Scatchard plots for Zn binding to caseins showed upward convexity, possibly due to Zn-induced association of caseins. Apparent average association constants (Kapp) for all caseins were similar (log Kapp 3.0-3.2). Enzymic dephosphorylation of alpha s1- or whole bovine casein markedly reduced, but did not eliminate, Zn binding. Thus, phosphoserine residues appeared to be the primary Zn-binding sites in caseins. With the exception of bovine serum albumin, which bound over 8 atoms Zn/mol, the bovine whey proteins, beta-lactoglobulin, alpha-lactalbumin and lactotransferrin, had little capacity for Zn binding.     

三种多酚与牛血清蛋白相互作用的初步研究

采用紫外光谱法、荧光光谱法、圆二色谱法、同步荧光光谱法等方法分析异荭草素、鞣花酸和安石榴苷与牛血清蛋白(bovine serum albumin,BSA)的相互作用。结果表明,三种多酚类化合物对BSA的荧光猝灭机制主要为静态猝灭;与3种多酚结合后,BSA的构象发生变化,异荭草素与BSA的结合位点比例约为2∶1,安石榴苷、鞣花酸与BSA的结合位点比例约为1∶1;异荭草素、安石榴苷、鞣花酸与BSA相互作用的主要作用力初步确定为疏水作用力,并且此3种多酚与BSA之间的结合主要是吸热和熵驱动的反应。3种多酚均与牛血清蛋白产生不同程度的结合,为蛋白质与多酚复合物的研究提供了理论支撑。     

Antioxidative and antibacterial peptides derived from bovine milk proteins

The search for alternative preservatives is on the rise due to safety issues linked with the application of synthetic antioxidants and the extensive increase in bacterial resistance to several conventional antibiotics. Therefore, the quest for finding suitable alternatives including bioactive peptides has received attention. This article reports a comprehensive insight concerning antioxidative and antibacterial peptides derived from milk proteins, a prolific source of peptides having various bioactivities. Caseins and whey proteins have also been evaluated for antioxidative and antibacterial potential using the BIOPEP database. A notable number of potentially active peptides are present in milk proteins. Technological approaches are here reported for the production of these peptides. The findings of this review show potentiality of utilizing dairy derived antioxidative and antibacterial peptides in the development of a superior alternative to the current generation of preservatives and therapeutic agents, as well as a functional ingredient in dietetic or pharmaceutical applications.     

牛羊乳蛋白组分比较研究

羊乳被国际营养学界誉为"奶中之王",逐渐被人们列为日常生活的营养保健佳品。该文对羊乳和牛乳的蛋白组分(主要是酪蛋白和乳清蛋白)含量、氨基酸组成及变异体等方面的差异进行了综述,并且对两者酪蛋白胶束的差异进行了比较,为羊乳检验和加工提供理论依据。     

Interactions between milk proteins and polyphenols: Binding mechanisms,related changes,and the future trends in the dairy industry

The biological activity and techno-functional properties of phenolic compounds have gained great importance due to the epidemiologically-proved health benefits. Use of polyphenols as fortification agents for functional food production and nanotechnological approaches using natural vehicles for polyphenol delivery have been recently discussed. In this respect, milk proteins and dairy products represent unique characteristics for polyphenol studies. The conflicting results on the functionality of polyphenols interacting with milk proteins either in model systems or in complex dairy matrices reveal the need for future studies.     

Molecular modification associated with the heat treatment of bovine milk

Raw bovine milk was heated using common industrial heat treatment conditions to determine how treatment conditions modify proteins and lipids. Processing temperature and time were found to affect both the degree and type of molecular modification. An early and consistent protein marker of heating was identified, namely the presence of the Maillard modification (carboxymethyl or carboxyethyl) at the Lys22 residue in the whey protein glycosylation-dependent cell adhesion molecule 1 (GLCM1). Observable chemical protein modifications generally initially increased with increasing temperature but decreased then under more extreme conditions. For lipids, the concentrations of free fatty acids, methylketones, and oxidised fatty acids were directly correlated with pasteurisation temperature. However, mirroring the trend for protein modification, phosphatidylcholine hydroperoxide levels first increased and then decreased at higher temperature. These protein and lipid modifications are potential markers of milk modification during processing and product development.     

High-pressure-induced interactions between milk fat globule membrane proteins and skim milk proteins in whole milk

The association of beta-lactoglobulin (beta-LG) and alpha-lactalbumin (alpha-LA) with milk fat globule membrane (MFGM), when whole milk was treated by high pressure in the range 100 to 800 MPa, was investigated using sodium dodecyl sulfate (SDS)-PAGE under reducing and nonreducing conditions. In SDS-PAGE under reducing conditions, beta-LG was observed in the MFGM material isolated from milk treated at 100 to 800 MPa for 30 min, and small amounts of alpha-LA and kappa-casein were also observed at pressures >600 MPa for 30 min. However, these proteins were not observed in SDS-PAGE under nonreducing conditions. These results indicate that beta-LG and alpha-LA associated with MFGM proteins via disulfide bonds during the high-pressure treatment of whole milk. The amount of beta-LG associated with the MFGM increased with an increase in pressure up to 800 MPa and with increasing time of pressure treatment. The maximum value for beta-LG association with the MFGM was approximately 0.75 mg/g of fat. Of the major original MFGM proteins, no change in butyrophilin was observed during the high-pressure treatment of whole milk, whereas xanthine oxidase was reduced to some extent beyond 400 MPa. In contrast to the behavior during heat treatment, PAS 6 and PAS 7 were stable during high-pressure treatment, and they remained associated with the MFGM.     

膳食多酚类化合物的研究进展

该文归纳了近十年来国内外关于膳食中多酚类化合物在人体内发挥抗氧化、清除自由基、控制人类慢性病的发病率、保护DNA和抗突变、抑制癌症发生等方面的功效。重点探讨了膳食多酚类化合物的构效关系。资料显示膳食多酚类化合物由于备受关注而大有成为的人类"第八大营养素"的趋势。     

Two-dimensional gel electrophoresis of proteins and peptides in bovine milk

Proteins and peptides in bovine milk and colostrum were separated by two-dimensional gel electrophoresis (2-DE). The proteins were separated in the first dimension by isoelectric focusing in the pH ranges 4–7 and 6–11, and in the second dimension by sodium dodecyl sulphate polyacrylamide gel electrophoresis on 12.5% T homogeneous gels. The peptides were separated in the pH range 3–10 in the first dimension, while 15% T homogeneous gels were used in the second dimension. 2-DE evaluation of samples with various somatic cell counts showed an increased number of peptides with increased cell count. 2-DE analysis of samples heated at 65 and 85 °C for 30 min showed a decrease in the number of proteins and peptides with increased temperature. Colostrum exhibited a peptide pattern in which the intensity and number of spots decreased with time postpartum. These results show that 2-DE is a useful tool to detect variations of proteins and peptides in milk.