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.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, with DOI 10.54499/UIDB/04469/2020 and by LABBELS—Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020. This research was also funded by FEDER (European Regional development fund)-COMPETE-QRENEU through the Chemistry Research Centre of the University of Minho (UID/QUI/00686/2020), contract CEEC INST/00156/2018/CP1642/CT0011. Joana Santos also thanks FCT for funding (UI/BD/152286/2021).info:eu-repo/semantics/publishedVersio