Enzymatic degradation of ochratoxin A: the role of ultra-pure water

Abstract

Ochratoxin A (OTA) is a toxic mycotoxin, making its removal from food essential for public health. This study examines OTA degradation by porcine pancreatic lipase (PPL) in ultra-pure water versus buffer systems through in vitro assays and molecular modeling. The results show that PPL fully degrades OTA in ultra-pure water within 7 h at 44 °C, whereas only partial degradation occurs in phosphate buffer. After 4 h, PPL in water degrades 91% of OTA, compared to only 12% in buffer. The enzymes half-life is longer in water (~4 h 4 min) than in phosphate buffer (~2 h 30 min), suggesting better stability in water. Other buffers, including acetate, citrate, and borate, confirmed higher degradation efficiency in low-conductivity, acidic environments similar to ultra-pure water. Additionally, using the model compound p-nitrophenyl octanoate (p-NPO), it was found that p-NPO degrades faster in buffer, likely due to a salting-out effect. Molecular modeling and circular dichroism analysis indicate that PPLs secondary structure in water promotes an ideal conformation for OTA binding. This study suggests ultra-pure water as a greener, sustainable option for reducing mycotoxins in food, with broad industrial applications.