College of Food Science and Nutritional Engineering, China Agricultural University; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture; National Engineering Research Centre for Fruits and Vegetables Processing, Beijing 100083, China.
J Sci Food Agric. 2013 Mar 30;93(5):1105-11. doi: 10.1002/jsfa.5857. Epub 2012 Aug 30.
Walnut (Juglans regia L.) is a good source of protein that has potential application in new product formation and fortification. The main objectives of this study were to investigate the effects of high hydrostatic pressure (HHP) treatment (300-600 MPa 20 min) on physicochemical and functional properties of walnut protein isolate (WPI) using various analytical techniques at room temperature.
The results showed significant modification of solubility, free sulfhydryl content and surface hydrophobicity with increased levels of HHP treatment, indicating partial denaturation and aggregation of proteins. Differential scanning calorimetry and fluorescence spectrum analyses demonstrated that HHP treatment resulted in gradual unfolding of protein structure. Emulsifying activity index was significantly (P < 0.05) increased after HHP treatment at 400 MPa, but significantly decreased (P < 0.05) relative to the untreated WPI with further increase in pressure. HHP treatment at 300-600 MPa significantly decreased emulsion stability index. Additionally, HHP-treated walnut proteins showed better foaming properties and in vitro digestibility.
These results suggest that HHP treatment could be applied to modify the properties of walnut proteins by appropriate of pressure levels, which will help in using walnut protein as a potential food ingredient.
核桃（Juglans regia L.）是一种优质蛋白质来源，具有在新产品形成和强化方面的潜在应用。本研究的主要目的是使用各种分析技术在室温下研究超高压处理（300-600 MPa 20 min）对核桃分离蛋白（WPI）的物理化学和功能特性的影响。
结果表明，随着 HHP 处理水平的增加，溶解度、游离巯基含量和表面疏水性有显著的变化，表明蛋白质的部分变性和聚集。差示扫描量热法和荧光光谱分析表明，HHP 处理导致蛋白质结构逐渐展开。在 400 MPa 下进行 HHP 处理后，乳化活性指数显著增加（P < 0.05），但随着压力的进一步增加，与未处理的 WPI 相比，乳化稳定性指数显著降低（P < 0.05）。HHP 处理在 300-600 MPa 下显著降低了乳液稳定性指数。此外，经 HHP 处理的核桃蛋白具有更好的泡沫性能和体外消化率。
这些结果表明，HHP 处理可以通过适当的压力水平来改变核桃蛋白的性质，这将有助于将核桃蛋白用作潜在的食品成分。
