Sun Peng-Peng, Liu Ying, Wang Wei, Song Guo-Jun, Ren Yuan-Yuan
College of Life Science, Yangtze University, Jingzhou, Hubei 434023, PR China; Institute of Food Science and Technology, Yangtze University, Jingzhou, Hubei 434023, PR China.
College of Life Science, Yangtze University, Jingzhou, Hubei 434023, PR China.
Food Chem. 2023 May 30;409:135300. doi: 10.1016/j.foodchem.2022.135300. Epub 2022 Dec 24.
In this study, regulation mechanism of magnetic field on pectinase was investigated and it was preliminarily applied in postharvest sapodilla. Results indicated pectinase activity decreased by 44 % when treated by magnetic field (3 mT, 0.5 h) with kinetic parameters V/K decreasing from 0.799 to 0.366 min. The optimal temperature (48 °C) and pH (4.8) of pectinase was not altered by magnetic field but Ca at 0.05 mol/L strengthened its regulation effect. Ultraviolet and fluorescence spectra suggested tyrosine and tryptophan residues in treated pectinase became more hydrophobic while opposite in phenylalanine. CO, CNH, COO groups in pectinase were also influenced, resulting in decreased β-sheet (from 53 % to 49 %), increased random coil (from 20 % to 22 %) and β-turn content (from 27 % to 29 %). More importantly, the firmness of treated sapodilla remained 45 % of maximum at 12 days' storage. Our findings provided new insights to illustrate the role of magnetic field in fruit preservation.
本研究对磁场对果胶酶的调控机制进行了研究，并初步将其应用于采后人心果。结果表明，在3 mT磁场处理0.5 h后，果胶酶活性降低了44%，动力学参数V/K从0.799 min降至0.366 min。磁场未改变果胶酶的最适温度（48℃）和pH（4.8），但0.05 mol/L的Ca增强了其调控效果。紫外光谱和荧光光谱表明，处理后的果胶酶中酪氨酸和色氨酸残基变得更疏水，而苯丙氨酸则相反。果胶酶中的CO、CNH、COO基团也受到影响，导致β-折叠减少（从53%降至49%），无规卷曲增加（从20%增至22%），β-转角含量增加（从27%增至29%）。更重要的是，处理后的人心果在贮藏12天时的硬度仍保持在最大值的45%。我们的研究结果为阐明磁场在水果保鲜中的作用提供了新的见解。
