Effects of high pressure on functionality of whey protein concentrate and whey protein isolate

Abstract

-The objective of this study was to evaluate the influence of high-pressure treatments on the solubility, surface hydrophobicity, foaming and emulsifying ability of whey protein concentrate (WPC) and whey protein isolate (WPI). Dispersions of WPC and WPI powders (10% (w/w)) were processed at 300 MPa and 600 MPa, for 5 and 10 min at 40 ± 2°C. Changes in protein solubility were determined as solubility at pH 7.0 and at pH 4.6. Assessment of foaming properties was based on the foam expansion during prolonged whipping, and foam stability. Emulsifying properties were characterised by emulsion stability and emulsifying activity indices. The results show significant (P < 0.05) modification of solubility and surface hydrophobicity with increasing intensity and duration of applied pressure, indicating partial denaturation and aggregation of proteins. It was found that high-pressure treatments significantly (P < 0.05) improved the foaming behaviour of WPI, while the foaming ability of WPC was diminished. However, foams formed with high-pressuretreated WPC and WPI exhibited significantly prolonged stability (P < 0.05) compared with control samples. There was a significant trend of decreasing emulsifying efficiency and emulsifying stability related to the intensity of applied pressure and treatment time for both WPC and WPI. emulsifying properties / foaming properties / high pressure / whey protein concentrate / whey protein isolate / solubility / surface hydrophobicity 摘要 -高压处理对乳清浓缩蛋白和乳清分离蛋白的影响。本文研究了高压处理对乳清浓缩 蛋白 (WPC) 和乳清分离蛋白 (WPI) 的溶解性、表面疏水性、发泡性和乳化性的影响。在 40°C 下，乳清浓缩蛋白 (10 %, w/w) 和乳清分离蛋白 (10 %, w/w) 的分散液分别在 300 MPa 和 600 Mpa 下高压处理 5 min 和 10 min。在 pH 7.0 和 pH 4.6 测定了两种蛋白质溶解性的变 化。以长时间搅打后形成的泡沫膨胀度和泡沫稳定性来评价蛋白质的发泡性能；根据测定 乳液稳定性指数和乳化活性指数评价两种蛋白质的乳化特性。试验结果表明，经过高压长 时间的处理后，由于蛋白质发生了部分变性和凝聚作用，使得蛋白质的溶解性和表面疏水 性发生了显著的改变 (P < 0.05)。高压处理能够显著地改善 WPI 的发泡性 (P < 0.05)，而 WPC 的泡沫形成能力则降低。然而与对照样品相比，经过高压处理后的 WPC 和 WPI 形成的泡 沫稳定性有显著提高 (P < 0.05)。随着处理压力和作用时间的增加，两种蛋白质的乳化性和 乳化稳定性均呈下降的趋势。 乳化性 / 发泡性 / 高压 / 乳清浓缩蛋白 / 乳清分离蛋白 / 溶解性 / 表面疏水性 * Corresponding author (通讯作者): Greta.Kresic@fthm.hrArticle published by EDP Sciences and available at http://www.edpsciences.org/lait or http://dx

Combined effect of dynamic heat treatment and ionic strength on denaturation and aggregation of whey proteins – Part I

“…Preliminary results have shown that the viscosity of the solutions was not significantly modified by ionic strength and heat treatment. The weak influence of dynamically heat treatment on solution viscosity could be attributed to their low protein content that did not allow the formation of heat-induced gels (Krešić et al, 2006). This result is important because viscosity may affect the other properties of protein solutions (Glicksman, 1986).…”

“…(a) hydration properties that have an important effect on wettability, swelling, adhesion, dispersibility, solubility, viscosity, water absorption and water holding; (b) interfacial properties including emulsification and foaming characteristics; (c) aggregation and gelation properties which are related to protein-protein interactions (Krešić , Lelas, Herceg, & Režek, 2006).…”

Effect of high hydrostatic pressure on bovine α-lactalbumin functional properties

“…The tertiary structure is also affected at pressures over 200 MPa due to changes in hydrophobic and ionic interactions, while the quaternary structurewhich depends on non-covalent unions -is affected at pressures of 150 MPa or less (Huppertz et al, 2004). These changes in molecular structure alter physical properties such as solubility and viscosity, and influence protein functionality, especially the role they play in processes such as gelation, emulsification, and foaming (Krešić et al, 2006). In general, HHP induced changes depend on factors such as temperature, pH, type of solvent used for processing and the applied pressure (Nabham et al, 2004).…”

“…LG (López-Fandiñ o, 2006), whey protein concentrate (WPC) and whey protein isolate (WPI) (Bouaouina et al, 2006;Krešić et al, 2006). However, little is known on the effect of HHP on the functional properties of a-LA, which is the subject matter of this paper.…”

Influence of high isostatic pressure on structural and functional characteristics of potato protein

“…Size and shape of the molecule influence the hydrodynamic properties of the protein and might thereby alter its ability to form a visco-elastic and stable foam lamella (Damodaran, 1994). Aggregation of whey protein during high pressure treatments enhanced the thickness of the lamella and decelerated thereby drainage and foam decay (Kresic, Lelas, Herceg, & Rezek, 2006). The positive effect on foam stability decreased for protein in solution with progressing time between treatment and analysis, indicating that the modification is not stable.…”