Emulsifying properties of protein–pectin complexes and their use in oil-containing foodstuffs

The emulsifying properties of proteins have been well studied as they are important for the preparation of creams, mayonnaises and other oil/fat-containing foodstuffs. The emulsifying action of a protein is not always sufficient to obtain stable emulsions of good quality. The use of chemical stabilisers in the food industry is not desirable. One of the best ways to improve the quality of emulsions and to produce emulsions with high nutritive value is to use protein-polysaccharide complexes as emulsifiers. Varying the protein-polysaccharide ratio in the complex, and also the kind of the polymers, would vary the quality and the nutritional value of the foodstuff. Four non-conventional protein preparations were tested as emulsifiers and their emulsifying properties were improved by the addition of pectin. This makes it possible to create new foodstuffs with low oil content and high nutritional value.     

乳清分离蛋白-甜菜果胶共价复合物理化特性分析

蛋白质-多糖通过Maillard反应生成共价复合物,其乳化稳定性等功能特性得到提高,为研究与开发新型食品添加剂提供了一条新的途径,但共价复合物的乳化稳定性提高机理尚不明确。本研究通过界面张力仪测定界面张力、红外光谱分析二级结构,并结合GPC-动态光散射法考察其分子量分布,初步探讨乳清分离蛋白(WPI)-甜菜果胶(BP)共价复合物乳化稳定提高原因。研究结果表明:WPI-BP共价复合物与混合物相比,界面张力降低;WPI-BP共价复合作用使得蛋白质分子中的羟基含量增加,亲水性增强;共价复合物的分子量增大,dn/dc降低,分子量分布更集中,提高其在乳状液界面上的空间位阻作用,从而提高其乳化稳定性。因此,界面张力降低、亲水性增强与空间位阻增大是WPI-BP共价复合物乳化稳定性提高的主要原因。     

复凝聚反应及其应用研究进展

复凝聚反应是指胶体溶液中的两种带不同电荷的聚电解质通过静电相互作用发生相分离而产生沉淀的一种现象,目前研究和应用得最多的复凝聚体系是蛋白质-多糖体系和多糖-多糖体系。由于参与复凝聚反应的聚电解质来源广泛、安全性高、可生物降解、反应可控性强,而且所得复合物有望获得新的功能性质,因此复凝聚反应及复凝聚相在医药、化工、食品等领域具有极其广阔的应用前景。本文对常见的复凝聚反应体系、影响复凝聚反应的因素、复凝聚相的性质、复凝聚反应及其产物复凝聚相在食品工业中的应用等进行了综述,以便为开发新型的复凝聚体系及拓展复凝聚反应的应用提供参考。     

Glycation of whey protein with dextrans of different molar mass: Effect on immunoglobulin E–binding capacity with blood sera obtained from patients with cow milk protein allergy

A growing concern around the world is the number of people who are suffering from food protein allergies. One potential approach to decrease protein allergenicity is to block IgE-binding epitopes of the protein allergen by attachment of polysaccharides via the Maillard reaction (i.e., glycation). Protein glycation has been extensively studied to modify various functional properties. We wanted to examine whether glycates could reduce IgE binding in patients with cow milk protein allergy and to explore how the size (molar mass; M_W) of the polysaccharide affects this IgE-binding capacity. Glycation was performed using the initial step of the Maillard reaction performed in aqueous solutions. The specific goal of this study was to reduce the IgE-binding capacity of whey protein isolate (WPI) through glycation with dextran (DX). Blood sera were obtained from 8 patients who had been diagnosed with cow milk protein allergy, and a composite sera sample was used for IgE-binding analysis by the ImmunoCap (Phadia, Uppsala, Sweden) method. The WPI was glycated with DX of M_W ranging from 1 to 2,000 kDa, and the M_W of purified glycates was determined using size-exclusion chromatography coupled with multiangle laser light scattering. The WPI to DX molar ratios in the glycates made from DX that had M_W values of 1, 3.5, 10 (G10), 150, 500, and 2,000 kDa were 1:4, 1:3, 1:2, 1:1.5, 1:1, and 1:1, respectively. With the increase in the M_W of DX, there was an increase in the M_W values of the corresponding glycates but a decrease in the number of bound DX. The WPI-DX glycates had lower whey protein IgE-binding capacity than native WPI, with the lowest IgE-binding capacity obtained in the G10 glycate. The DX binding ratios and morphology results from atomic force microscopy images suggested that glycation of WPI with small-M_W DX resulted in extensive protein surface coverage, probably due to the attachment of up to 4 DX molecules per whey protein. The lower IgE binding of the G10 glycate was likely due to greater steric hindrance (or a physical barrier) at the surface of the protein. In summary, our results demonstrate that glycating WPI with DX via Maillard reaction can potentially be used to decrease the allergenicity of whey protein.     

美拉德反应合成蛋白质-多糖复合物及其应用

该文综述利用美拉德(Maillard)反应制得蛋白—多糖复合物性能,该复合物主要是在干燥状态下利用自发进行美拉德反应所制得,与传统商业使用乳化剂相比,该复合物具有优良乳化性、热稳定性和抑菌性。因此,该复合物在工业上可用作天然乳化剂、无毒抑菌剂;同时如为多糖与过敏原蛋白复合还具减轻蛋白致敏性效果。     

不同方法在蛋白-多糖复合反应中的应用现状

蛋白-多糖复合物的生成主要是依靠美拉德反应,传统的方法主要为干热法和湿热法,但这两种方法均存在一定的不足。随着科技的发展和技术的改进,微波、高静水压、超声波以及超临界CO2等新兴技术被逐渐应用到食品的蛋白-多糖复合反应中。本文对这些不同方法在蛋白-多糖复合反应中的应用研究现状进行了综述。     

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(Ⅱ)反应机制的理论分析

采用凝胶过滤色谱和红外光谱(FT-IR)分析了反应前后蛋白与多糖Maillard反应产物分子结构特征,证实反应后SAPP与葡聚糖产生了共价结合;并通过凝胶渗透色谱(GPC)技术对干热反应后所得共价复合物的分子量分布进行分析,结果表明液相体系所得蛋白-多糖共价复合物与干热法所得产物的数均分子量和重均分子量非常相近.     

黄原胶对酪蛋白酸钠乳状液稳定性的影响

研究了一定pH条件下,黄原胶浓度及剪切稀化效应对酪蛋白酸钠乳状液稳定性的影响。结果表明,在酸性条件下,黄原胶无法抑制酪蛋白的变性沉淀,乳液在制备之初,即产生严重絮凝。在中性和弱碱性条件下,黄原胶在一定浓度范围内,诱发了乳状液的排斥絮凝;体系的pH显著影响了乳状液的稳定性,pH6条件下,较低的黄原胶浓度(0.2wt%)便可赋予乳状液良好的稳定性。均质过程大大降低了黄原胶的粘度,导致乳状液的稳定性下降,与添加未经均质处理的黄原胶相比,添加量增大近一倍,才能获得稳定的乳状液。     

Protein glycosylation: a promising way to modify the functional properties and extend the application in food system

Abstract

Modification of functional properties by glycosylating with polysaccharides is an effective solution to improve the internal disadvantages of native proteins. Generally, protein glycosylation belongs to the first stage of the Maillard reaction in essence. Dry-heating, wet-heating, and their combination are the major methods for the preparation of protein-polysaccharide conjugates (PPC). Spectrophotometry, spectroscopy, electrophoresis, calorimetry, chromatography, and mass spectrometry are confirmed to be the most effective methods for the identification of PPC. After glycosylation, functionalities of the native protein, including solubility, rheological properties, emulsifying properties, foaming properties, gel property, film-forming properties, thermal stability, antioxidant activity, allergenicity, and antibacterial properties, are improved. The PPC is extensively used as an encapsulation or a delivering material in order to improve the bioaccessibility of bioactive compounds in food system. Some new applications in food processing could be explored using PPC as an ingredient based on the improved functional properties, such as 3-dimensional printing food, gelled food, and colloid food. Furthermore, the model of protein glycosylation and the application of PPC in food processing could be extended to other protein modification to broaden the exploitation of native protein resource for the processing of novel foods.     

Extracellular matrix–inspired gelatin/hyaluronic acid injectable hydrogels

Gelatin injectable hydrogels have attracted attention for soft tissues regeneration; however, their poor mechanical properties limit their applications. The authors present a versatile strategy to enhance mechanical properties by mixing gelatin (Gel) with different proportions of hyaluronic acid (HA). The protein-polysaccharide systems are inspired by extracellular matrix and benefit from adhesive properties of RGD sequences in Gel and enhanced hydration and stiffness of HA. The authors were able to raise the Young’s modulus from 4?kPa to 6?kPa and gelation times can be tuned between 4 to 9?min, giving surgeons the option of adapting the material to specific requirements.