蛋白质与多糖相互作用研究进展

作为食品重要组成成分,蛋白质与多糖间相互作用研究对食品体系结构和品质具有重要意义。该文概述蛋白质与多糖相互作用类型;蛋白质与多糖相互作用研究方法,包括糖芯片、毛细管电泳和质子共振技术;及蛋白质与多糖在可食性膜、乳状液、流体界面及起泡性方面相互作用研究。     

蛋白质多糖共价复合物的研究进展

介绍蛋白质多糖共价复合物的形成及分析方法,探讨共价复合物形成的影响因素,复合物对蛋白质乳化特性,溶解性,热稳定性及抗菌性的影响。     

蛋白质和多糖在界面处的相互作用研究进展

蛋白质和多糖两种生物大分子在界面处的相互作用对于乳状液和泡沫体系有显著影响。蛋白质和多糖混合后的协同效应可构建新的、功能性的纳、微或宏观结构,改变食品的力学和流动特性,对改良食品,降低生产成本具有重要意义。本文对近年来蛋白质的界面行为,多糖的界面行为以及蛋白质-多糖复合物的界面行为所做的一些研究进行综述。      

多糖与蛋白质相互作用及其复合物的功能特性

多糖和蛋白质是食品中共存的生物大分子,营养丰富,两者相互作用可以改善食品的品质,因此成为研究的热点内容。该文对国内外有关多糖与蛋白质相互作用的研究进行综述,介绍多糖与蛋白质相互作用的类型、影响因素和复合物的制备方法、功能特性,并对其在食品中的应用进行展望,以期为多糖-蛋白质复合物的进一步研究与应用提供理论参考。     

蛋白质与多糖类交互作用对食品乳状液稳定性的影响

论述了蛋白质的乳化性质及多糖类与蛋白质交互作用对食品乳状液稳定性的影响 ,共价结合及静电交互作用对乳状液稳定性产生有利影响 ,而弱的交互作用及无交互作用可能导致乳状液的分层等不稳定现象的发生。     

蛋白质—阴离子多糖相互作用研究进展

该文简要介绍蛋白质-阴离子多糖之间相互作用力及其影响因素和在食品中应用,并根据当前蛋白质-阴离子多糖之间相互作用研究现状和存在问题对今后研究方向进行展望。     

多酚的功能性质及与蛋白质、多糖相互作用研究进展

多酚是具有多种化学结构的多相分子群,具有很强的抗氧化性、抗菌性以及预防慢性疾病的能力,在食品和医疗领域具有广泛的应用价值。多酚由于含有多个酚羟基基团使其化学稳定性差,生物利用度低,在功能性食品中的应用受到了限制。蛋白质、多酚、多糖相互作用所形成的复合结构能够有效地提高食品的感官品质以及各生物大分子的功能特性。本文对多酚的结构与功能之间的关系,多酚与蛋白质、多糖三者相互作用的机理,多酚对二者功能性质及对改善乳化液性质的影响,进行了综述,以期为多酚在食品工业中的应用提供理论参考。     

美拉德反应制备蛋白质-多糖共价复合物的研究进展

蛋白质和碳水化合物通过美拉德反应形成糖基化产物,也称为共价复合物,可以改善蛋白质的功能特性。本文主要介绍了近年来通过美拉德反应制备蛋白质-多糖共价复合物的方法,共价复合物生成的主要影响因素,共价复合物结构与功能性质的分析方法及其应用。     

美拉德反应制备蛋白质-多糖共价复合物的研究进展

蛋白质和碳水化合物通过美拉德反应形成糖基化产物,也称为共价复合物,可以改善蛋白质的功能特性。本文主要介绍了近年来通过美拉德反应制备蛋白质-多糖共价复合物的方法,共价复合物生成的主要影响因素,共价复合物结构与功能性质的分析方法及其应用。      

蛋白质多酚多糖三元复合物的结构和功能特性研究进展

蛋白质-多酚-多糖三元复合物能够影响食品体系的感官、功能和营养等特性。本文主要关注在不同食品体系中,蛋白质、多酚和多糖三者之间通过非共价相互作用形成的三元复合物的结构和功能特性,总结蛋白质-多酚-多糖三元复合物对食品和饮料感官和功能等特性的影响,以及相关应用的科学问题,为更好理解蛋白质-多酚-多糖三元复合物在食品体系中的应用提供依据。      

Properties of oil/water emulsions stabilized by casein-acid polysaccharide mixtures

Properties of oil/water emulsions stabilized with the soluble casein-acid polysaccharide mixtures were investigated. Compared to initial protein solutions, higher emulsifying properties of the mixtures are demonstrated. A study is made on the influence of the properties of the mixtures for obtaining thermostable emulsions of hard consistency which could be applied in production of a great variety of foodstuffs. The role of the formation of protein-acid polysaccharide complexes is discussed.     

Infrared spectroscopic analysis of structural features and interactions in olive oil-in-water emulsions stabilized with soy protein

Lipid and protein structural characteristics of olive oil-in-water emulsions formulated with various stabilizer systems were investigated using Fourier transform infrared spectroscopy (FT-IR). Proximate composition, water binding and textural properties were also evaluated in these emulsions. Two different olive oil-in-water emulsions were studied: E/SPI prepared with soy protein isolate as a stabilizing system, and E/SPI + SC + MTG prepared with a combination of soy protein isolate, sodium caseinate and microbial transglutaminase as a stabilizing system. Results showed that textural properties (P < 0.05) were dependent on the stabilizing system. E/SPI + SC + MTG emulsion presented greater (P < 0.05) lipid chain disorder, more lipid-protein interactions, and more (P < 0.05) ??-helix and ??-sheet structures. A relationship between textural and structural properties was also observed as a function of the stabilizing system employed in the formulation of emulsions. A more thorough understanding of this connection could help improve the development of food products with appropriate physical properties.     

豌豆分离蛋白/卡拉胶复合物乳液的性质研究

为改善豌豆分离蛋白(PPI)在酸性乳液体系中的乳化稳定性,将PPI与阴离子多糖卡拉胶(CG)在酸性条件下混合,制备可溶性静电复合物乳液。通过测定PPI乳液和PPI/CG复合物乳液在不同pH(4～7)下粒径、ζ-电位、显微结构以及乳析指数的变化,判断两种乳液的稳定性。结果表明：pH 4～5时,PPI乳液粒径达到35μm以上,而pH 4～7时PPI/CG复合物乳液粒径均小于18μm;储藏14 d时,PPI乳液和PPI/CG复合物乳液粒径均稍有增加;酸性条件下,PPI乳液的ζ-电位绝对值均小于30 mV,而PPI/CG复合物乳液的ζ-电位绝对值均大于40 mV;酸性条件下,PPI/CG复合物乳液较PPI乳液分散性有明显改善;在储藏14 d过程中,PPI乳液乳析指数随储藏时间的延长而逐渐增大,而PPI/CG复合物乳液乳析指数基本为0。综上,PPI/CG复合物可显著改善PPI在酸性条件下的乳化稳定性。     

Comparison of properties of oil-in-water emulsions stabilized by coconut cream proteins with those stabilized by whey protein isolate

Coconut cream protein (CCP) fractions were isolated from coconuts using two different isolation procedures: isoelectric precipitation (CCP1-fraction) and freeze–thaw treatment (CCP2-fraction). The ability of these protein fractions to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). Protein solubility was a minimum at ∼pH 4, 4.5 and 5 for CCP1, CCP2, and WPI, respectively, and decreased with increasing salt concentration (0–200 mM NaCl) for the coconut proteins. All of the proteins studied were surface active, but WPI was more surface active than the two coconut cream proteins. The two coconut cream proteins were used to prepare 10 wt% corn oil-in-water emulsions (pH 6.2, 5 mM phosphate buffer). CCP2 emulsions had smaller mean droplet diameters (d₃₂ ≈ 2 μm) than CCP1 emulsions (d₃₂ ≈ 5 μm). Corn oil-in-water emulsions (10 wt%) stabilized by 0.2 wt% CCP2 and WPI were prepared with different pH values (3–8), salt concentrations (0–500 mM NaCl) and thermal treatments (50–90 °C for 30 min). Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CCP2 (pH ∼ 4.3); WPI (pH ∼ 4.8). Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for WPI, but CCP2 produced bimodal distributions at this pH. The CCP2 and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations ⩽50 and ⩽100 mM, respectively. In the absence of salt, both CCP2 and WPI emulsions were quite stable to thermal treatments (50–90 °C for 30 min).     

Ultrastructure of o/w emulsions stabilized by faba bean protein isolates

An ultrastructural comparison is given for dispersions of a protein isolate (FBPI) from faba beans (Vicia faba L.) and its highly acetylated derivative (AFBPI) as well as for various o/w emulsions stabilized by FBPI and AFBPI. Both protein isolates contain substantial amounts of surface-active phospholipids (about 3%) which occur as vesicles (diameter 30 … 500 nm). Their membranes and rather cores contain protein. Interfacial protein layers of Triolein/Water-emulsion droplets possess smooth external surfaces and rather coarse internal surfaces with peculiar paracrystalline structured areas. Tangible differences are found in the droplet-size distribution and ultrastructure of sunflower-oil/water emulsions due to both the homogenization process (high pressure homogenizer or ultrasonic disintegrator) and the acetylation of the isolate. The modification by acetylation increases the emulsifying activity of the isolate and prevents the strong aggregation of oil droplets observed in FBPI-stabilized emulsions.     

Characterization of cold-set gels produced from heated emulsions stabilized by whey protein

This paper reports the cold gelation of preheated emulsions stabilized by whey protein, in contrast to, in previous reports, the cold gelation of emulsions formed with preheated whey protein polymers. Emulsions formed with different concentrations of whey protein isolate (WPI) and milk fat were heated at 90 °C for 30 min at low ionic strength and neutral pH. The stable preheated emulsions formed gels through acidification or the addition of CaCl₂ at room temperature. The storage modulus (G′) of the acid-induced gels increased with increasing preheat temperature, decreasing size of the emulsion droplets and increasing fat content. The adsorbed protein denatures and aggregates at the surface of the emulsion droplets during heat treatment, providing the initial step for subsequent formation of the cold-set emulsion gels, suggesting that these preheated emulsion droplets coated by whey protein constitute the structural units responsible for the three-dimensional gel network.     

Oil-in-water emulsions stabilized by chitin nanocrystal particles

The aim of the present study was to investigate the oil-in-water emulsion stabilizing ability of chitin nanocrystals (colloidal rod-like particles) and the factors that may influence the properties of such systems. Chitin nanocrystal aqueous dispersions were prepared by acid hydrolysis of crude chitin from crab shells and oil-in-water emulsions were generated by homogenizing appropriate quantities of a chitin nanocrystal stock aqueous dispersion with corn oil, using an ultra-sonic homogenizer. The resulting emulsions were visually evaluated for their creaming behaviour upon storage. Additionally, the samples were studied with static light scattering, small deformation oscillatory rheometry and optical microscopy, under different conditions of nanocrystal concentration, ionic strength, pH and temperature. The chitin nanocrystals were proven quite effective in stabilizing o/w emulsions against coalescence, over a period of one month, as evidenced by static light experiments and microscopy, and this could be attributed to the adsorption of the nanocrystals at the oil–water interface. The rheological data provided evidence for network formation in the emulsions with increasing chitin nanocrystal concentration. Such a gel-like behaviour was attributed to an inter-droplet network structure and the formation of a chitin nanocrystal network in the continuous phase. The stability of the emulsions to creaming increased with an increase in nanocrystal concentration. Finally, by raising the temperature (20–74 °C), NaCl concentration (up to 200 mM) or pH (from 3.0 to 6.7) there was an enhancement of the emulsion elastic character and creaming stability.     

乳清分离蛋白-葡聚糖接枝物乳液冻融稳定性研究

研究冻融处理对乳清分离蛋白―葡聚糖接枝产物乳液稳定性的影响。颗粒尺寸数据结果表明,以接枝产物为基质的乳液冻融稳定性得到明显改善;表观形态和微观结构的测定进一步印证这一现象。ξ–电位的测定结果说明电荷不是决定接枝产物乳液体系稳定性的主要因素。这可能是由于接枝物在油滴表面形成的界面膜相对较厚,使得低温条件下的固体脂肪颗粒很难渗透和破坏界面膜,有效抑制低温状态下油滴之间的聚结和絮凝,从而改善乳液冻融稳定性。     

Beverage emulsions: Comparison among nanoparticle stabilized emulsion with starch and surfactant stabilized emulsions

Emulsions are widely used in beverages to impart desired appearance and flavor to the products. Ring formation in beverages with emulsions during thermal processing and storage is one of the key challenges. This study was aimed at comparing the relative effectiveness of silica nanoparticle based emulsifiers with surfactant and biopolymer based emulsifier (modified starch) in influencing physical stability of emulsions in a model juice. The stability of emulsions was measured by characterizing changes in emulsion droplet size, zeta potential, UV–vis absorbance and visual evaluation of phase separation or ring formation in both primary emulsions and beverage emulsions as a function of storage time. The influence of thermal processing on stability of emulsions both immediately after processing and upon storage was evaluated. The thermal processing conditions simulated both high temperature short time and low temperature long time pasteurization conditions. The results demonstrate that the mean droplet diameter of primary emulsions stabilized by selected emulsifiers was stable during storage for 21 days with and without pasteurization. Based on measurements of mean droplet diameter and visible ring formation, polyoxyethylene sorbitan monolaurate (tween-20) stabilized emulsion was not stable in a model juice and the stability of this emulsion was further reduced with thermal processing. In contrast, starch and silica stabilized emulsions in a model juice did not show significant changes in particle diameter or visible ring formation during storage with and without prior thermal processing, although starch stabilized emulsion did show a decrease in absorbance during storage. Zeta potential measurements in a model juice indicate that the surface properties of emulsions were significantly distinct from those of primary emulsion, indicating interaction of juice components with the emulsion interface influencing the surface charge at the interface. These changes in zeta potential of emulsion droplets did not correlate with reduced stability of the emulsions. Overall, the results demonstrate that nanoparticle stabilized emulsions can improve stability of emulsion in beverages as compared to surfactant and biopolymer stabilized emulsions and provides a comprehensive matrix to evaluate stability of emulsions in beverages.     

Heat-induced changes in oil-in-water emulsions stabilized with soy protein isolate

The physicochemical properties of soy proteins stabilized oil-in-water emulsions were studied after heating at two different temperatures, 75 and 95 °C. The effect of changing the order of the process (heating the solution before emulsification, or heating the emulsion) was also studied. The heating temperatures were chosen as they are known to selectively cause denaturation of the two major proteins present in the soy protein isolate: β-conglycinin and glycinin. The thermal transitions observed for soy proteins adsorbed at the interface were different from those measured in protein solutions, suggesting that some changes occur in the structure of the soy proteins upon adsorption on the oil droplet. Heating induces aggregation of the oil droplets, as shown by an increase of the particle size and the bulk viscosity of the emulsions, with a more prominent effect after heating at 95 °C. Transmission electron microscopy observations clearly demonstrate that heating induces the formation of large protein aggregates at the interface. In addition, the composition of the protein present at the interface changes depending on the order of heating and homogenization. While heating the solutions before emulsification results in all the protein subunits to be present at the interface in an aggregated form, when heating is applied after emulsification, a portion of the α and the α′ subunit of β-conglycinin as well as the acidic subunits of glycinin remain unadsorbed.