A research team led by Prof. LI Boqiang from the Institute of Botany of the Chinese Academy of Sciences has developed an immobilized enzyme preparation with high efficiency, stability, safety and easy separation, which can degrade patulin in contaminated apple juice without any adverse effect on juice quality.

The study was published in Journal of Hazardous Materials.  

Patulin is one of the most important mycotoxins contaminating fruit-derived products and causing acute or chronic toxicity in humans. However, methods to reduce patulin by adsorption, irradiation and chemical modification suffer from potential limitations such as safety issues and loss of nutritional quality. Biodegradation based on microbial enzymes is considered one of the promising ways to control patulin contamination.  

The researchers have previously identified a short-chain dehydrogenase/reductase (CgSDR) with the function of degrading patulin. In the present study, a novel patulin-degrading enzyme preparation was further constructed by covalently linking CgSDR to dopamine/polyethyleneimine co-deposited magnetic Fe₃O₄ particles.  

The researchers found that the immobilized enzyme possessed combined effects of patulin adsorption by Fe₃O₄ particles and biological degradation by CgSDR, and exhibited a detoxification rate of 100% in phosphate-buffered saline and a detoxification rate of more than 80% in apple juice.  

In addition, they demonstrated that compared with the free enzyme, the immobilized CgSDR significantly improved thermal and storage stability, proteolysis resistance, and reusability.  

"Notably, this novel patulin-degrading enzyme can be easily separated from apple juice by external magnetic field and retains more than 50% detoxification rate after seven consecutive reuse cycles, which significantly reduces the cost in future application," said Prof. TIAN Shiping, corresponding author of the study.

Application of a magnetically recoverable enzyme formulation in patulin detoxification in fruit derived products. (Image by LI Boqiang)