College of Food Science and Technology, Henan Agricultural University, Zhengzhou, China.
Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China.
Food Sci Technol Int. 2024 Oct;30(7):671-679. doi: 10.1177/10820132231158278. Epub 2023 Mar 2.
An increased interest has been observed in the application of soybean protein isolate (SPI) into O/W emulsion because of the amphipathic characteristics of SPI. However, at pH around 4.5, SPI was almost lost its hydrophilic characteristic, thus greatly limiting its application in emulsion under an acidic environment. Therefore, this drawback of SPI needs to be urgently solved. This study aims to investigate the effect of γ-polyglutamic acid (γ-PGA) on physicochemical properties of SPI-stabilized O/W emulsion. The results suggested that the interaction between γ-PGA and SPI improved the SPI solubility in solution, and increased emulsifying properties of SPI in the pH range of 4.0-5.0 via electrostatic interaction. Meanwhile, the charge neutralisation between SPI emulsions with γ-PGA was confirmed via ζ-potentiometry. With the presence of γ-PGA in emulsion at pH 4.0 and 5.0, the electrostatic complexation between SPI and anionic γ-PGA exhibited decreased the viscosity of SPI emulsion, which might be related to the phenomenon as indicated by the confocal laser scanning microscope measurements. Therefore, the electrostatic complexation between SPI and γ-PGA suggested that the promising potential of γ-PGA to be used in SPI-stabilized O/W emulsion under an acidic environment.
人们对大豆分离蛋白（SPI）在 O/W 乳液中的应用越来越感兴趣，这是因为 SPI 具有两亲性特征。然而，在 pH 值约为 4.5 时，SPI 几乎失去了亲水性，从而极大地限制了其在酸性环境下的乳液应用。因此，SPI 的这一缺点亟待解决。本研究旨在探讨 γ-聚谷氨酸（γ-PGA）对 SPI 稳定的 O/W 乳液理化性质的影响。结果表明，γ-PGA 与 SPI 之间的相互作用通过静电相互作用提高了 SPI 在溶液中的溶解度，并在 pH 值为 4.0-5.0 范围内提高了 SPI 的乳化性能。同时，通过 ζ-电位计证实了 SPI 乳液与 γ-PGA 之间的电荷中和。在 pH 值为 4.0 和 5.0 的乳液中存在 γ-PGA 时，SPI 和阴离子 γ-PGA 之间的静电络合降低了 SPI 乳液的粘度，这可能与共聚焦激光扫描显微镜测量所表明的现象有关。因此，SPI 和 γ-PGA 之间的静电络合表明，γ-PGA 有望在酸性环境下用于 SPI 稳定的 O/W 乳液。
