Fang Wenyu, Yi Ling, Azarakhsh Nima, Wang Liping, Ramaswamy Hosahalli, Duan Hanying, Wang Chao
Department of Food Science and Technology, Jinan University, Guangzhou, 510632, China.
International School, Jinan University, Guangzhou, 510632, China.
Curr Res Food Sci. 2025 Aug 12;11:101169. doi: 10.1016/j.crfs.2025.101169. eCollection 2025.
5-Methyltetrahydrofolate (5-MTHF) is considered as a safer fortifier than folic acid (FA), but still unstable and less bioavailable. To investigated the soy protein isolate (SPI) or high hydrostatic pressure (HHP) treated SPI on the thermal stability of 5-MTHF and interaction of protein with 5-MTHF, the thermal stability of 5-MTHF in SPI-5MTHF complexes and HHP treated SPI-5MTHF complex was firstly investigated, and then revealed the effect of HHP on the structure and micromorphology of SPI by circular dichroism spectroscopy, free sulfhydryl content and scanning electron microscopy. Finally, the effect of HHP on the ability of the SPI to bind to 5-MTHF was also investigated by fluorescence spectrometry and isothermal titration. The results showed that the SPI-5MTHF complex was more thermally stable than free 5-MTHF in the thermal environment, and the retention of 5-MTHF was increased by about 306-fold. HHP also improved 5-MTHF stability in the HPP-SPI-5MTHF complex, with the highest retention of 5-MTHF of 104.77 ± 0.22 % at 300MPa. HHP increased apparent binding constants (4.83-26.78-fold) and binding sites (9.22 %-15.60 %) of SPI with 5-MTHF at pressures of 100-300 MPa. The interaction between SPI and 5-MTHF is a spontaneous exothermic reaction driven by enthalpy change. 5-MTHF is mainly bound to SPI by van der Waals forces and hydrogen bonding to form a complex. This study lays the foundation for further application of SPI or HHP-SPI as an encapsulation material to improve the stability and bioaccessibility of 5-MTHF.
5-甲基四氢叶酸（5-MTHF）被认为是一种比叶酸（FA）更安全的强化剂，但仍然不稳定且生物利用度较低。为了研究大豆分离蛋白（SPI）或经高静水压（HHP）处理的SPI对5-MTHF热稳定性以及蛋白质与5-MTHF相互作用的影响，首先研究了5-MTHF在SPI-5MTHF复合物和经HHP处理的SPI-5MTHF复合物中的热稳定性，然后通过圆二色光谱、游离巯基含量和扫描电子显微镜揭示了HHP对SPI结构和微观形态的影响。最后，还通过荧光光谱和等温滴定量热法研究了HHP对SPI结合5-MTHF能力的影响。结果表明，在热环境中，SPI-5MTHF复合物比游离5-MTHF更具热稳定性，5-MTHF的保留率提高了约306倍。HHP还提高了HPP-SPI-5MTHF复合物中5-MTHF的稳定性，在300MPa时5-MTHF的最高保留率为104.77±0.22%。在100-300MPa压力下，HHP增加了SPI与5-MTHF的表观结合常数（4.83-26.78倍）和结合位点（9.22%-15.60%）。SPI与5-MTHF之间的相互作用是由焓变驱动的自发放热反应。5-MTHF主要通过范德华力和氢键与SPI结合形成复合物。本研究为进一步应用SPI或HHP-SPI作为包封材料以提高5-MTHF的稳定性和生物可及性奠定了基础。
