Efficient Degradation of Ochratoxin A by Zn-Metal-Organic Framework Immobilized Lipase

To enhance the stability of Amano lipase A (ANL) and its degradation efficiency toward ochratoxin A (OTA), ANL was immobilized on a Zn-metal-organic framework (Zn-MOF) carrier by a one-step in situ method, yielding ANL@Zn-MOF. Based on OTA degradation rate, the optimal immobilization conditions were determined as 8 mg, 2 h and 400 r/min for enzyme loading, immobilization time, and stirring speed, respectively. ANL@Zn-MOF was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results confirmed the successful loading of ANL onto Zn-MOF. ANL@Zn-MOF exhibited superior alkali tolerance, thermal stability, and ionic strength stability compared with free ANL. ANL@Zn-MOF degraded OTA more rapidly. Specifically, it (containing 20 ng/mL ANL) completely degraded OTA in 8 h, which was shortened by 66.7% compared with free ANL. Moreover, in a 500 mL reaction system, ANL@Zn-MOF degraded 69.3% of OTA in 12 h. Additionally, ANL@Zn-MOF exhibited excellent reusability, retaining 78% of its activity after five cycles of reuse. This study establishes a foundation for the application of ANL@Zn-MOF in degrading OTA in food systems and provides a reference for the use of MOFs in enzyme immobilization.