In this study, tender coconuts were treated with high-intensity ultrasound (US) for 20 min at a frequency of 20 kHz and a power of 2400 W. Compared with control group, US treated coconut water had a higher content of total soluble solid and sugar/acid ratio along with a lower pH value and conductivity, and the contents of sucrose, fructose and glucose were also higher. Results from HS-SPME/GC–MS showed that there was no significant difference in the content of volatile compounds in coconut water before and after US treatment. The activities of sugar metabolism enzymes such as sucrose phosphate synthase, sucrose synthase, acid invertase (AI) and neutral invertase were inhibited by US, of which AI had the strongest inactivation. Circular dichroism and fluorescence spectra showed that the secondary and tertiary structure of AI molecule were destroyed with the increase of US intensity and time, which was confirmed by the change of particle size distribution pattern and scanning electron microscopy. Molecular docking and molecular dynamics showed that US treatment prevented the recognition and binding of sucrose and AI molecules, thereby inhibiting the decomposition of sucrose. In conclusion, our results indicate that US can inhibit the activity of AI and maintain the sugar content to increase the quality as well as extend the shelflife of coconut water, which will bring more commercial value.

在这项研究中，用高强度超声波（US）处理嫩椰子20分钟，频率为20 kHz，功率为2400 W。与对照组相比，经过US处理的椰子水的总可溶性固形物含量更高，糖酸比、pH值和电导率较低，蔗糖、果糖和葡萄糖的含量也较高。HS-SPME/GC-MS 结果表明，US 处理前后椰子水中挥发性化合物的含量没有显着差异。US对蔗糖磷酸合酶、蔗糖合酶、酸性转化酶(AI)和中性转化酶等糖代谢酶的活性有抑制作用，其中AI的失活作用最强。圆二色性和荧光光谱表明，随着超声强度和时间的增加，AI分子的二级和三级结构被破坏，粒度分布模式的变化和扫描电镜证实了这一点。分子对接和分子动力学表明，US处理阻止了蔗糖和AI分子的识别和结合，从而抑制了蔗糖的分解。总之，我们的研究结果表明，US可以抑制AI的活性并保持糖含量，从而提高椰子水的品质并延长其保质期，这将带来更多的商业价值。