Chai Liwen, Shi Wei, Tan Yunxia, Che Xudong, Lu Jiankang, Bai Bingyao, Zhang Chunlan
College of Food Science and Engineering, Tarim University, Alar 843300, China.
Production & Construction Group Key Laboratory of Special Agricultural Products Further Processing in Southern Xinjiang, Alar 843300, China.
Foods. 2025 May 15;14(10):1754. doi: 10.3390/foods14101754.
This study aims to explore the effect of pH on the solubility of walnut protein isolate (WPI) across a pH range of 7.0 to 12.0. The findings reveal that WPI solubility increased with rising pH levels, reaching a maximum solubility of 61.13% (4.79 mg/mL) at pH 12.0. Building on these results, WPI was subjected to compound heating at pH 12.0, with temperatures ranging from 60 °C to 100 °C (maintained for 30 min), to evaluate its structural and functional properties. Compared to the control group, WPI solubility peaked at 80.56% when heated to 90 °C. Additionally, its foaming capacity rose to 118.22% ± 7.34, accompanied by improved foaming stability. The average particle size decreased to 151.93 nm, while the surface charge increased to -28.33 mV. The protein subunits progressively aggregated within the range of 20.0 kDa to 14.1 kDa, and the surface hydrophobicity decreased. Scanning electron microscopy revealed that the surface morphology of the WPI became increasingly smooth with rising heating temperatures. Moreover, significant changes were observed in the secondary structure of the WPI. This study underscores the potential of pH-shifted compound heating treatment as a promising processing technique for WPI, offering key insights into the optimization of walnut protein processing.
本研究旨在探究pH值在7.0至12.0范围内对核桃分离蛋白（WPI）溶解度的影响。研究结果表明，WPI的溶解度随pH值升高而增加，在pH 12.0时达到最大溶解度61.13%（4.79毫克/毫升）。基于这些结果，在pH 12.0条件下对WPI进行复合加热，温度范围为60℃至100℃（保持30分钟），以评估其结构和功能特性。与对照组相比，加热至90℃时WPI的溶解度峰值为80.56%。此外，其发泡能力升至118.22%±7.34，同时发泡稳定性得到改善。平均粒径降至151.93纳米，而表面电荷增加至-28.33毫伏。蛋白质亚基在20.0千道尔顿至14.1千道尔顿范围内逐渐聚集，表面疏水性降低。扫描电子显微镜显示，随着加热温度升高，WPI的表面形态变得越来越光滑。此外，WPI的二级结构也发生了显著变化。本研究强调了pH值调节复合加热处理作为一种有前景的WPI加工技术的潜力，为核桃蛋白加工的优化提供了关键见解。
