Modelling of ochratoxin A photo-degradation by a UV multi-wavelength emitting lamp

- A mid-pressure multi-wavelength lamp was used to degrade ochratoxin A.
- A reaction mechanism was proposed, concluding a first-order kinetic.
- The power absorbed by the solution was evaluated.
- The kinetic constants were obtained for aqueous solutions and must.

The aim of this work is to study the degradation of ochratoxin A using UV radiation from a mid-pressure lamp with emission wavelengths between 250 and 740 nm and to propose a mechanism that describes the degradation as three stages: excitation of the ochratoxin A molecules which can desorb the energy to its fundamental state or degrade to photo-products. It is shown that this mechanism is in line with a first-order kinetic that best describes the process.Considering the linear spherical emission model and using the Simpson integration method, the spectral radiant power absorbed by the whole solution is evaluated, with its dependence on the ochratoxin A concentration and the incident spectral radiant power at different depths.The first-order kinetic constants for aqueous solutions of 100 μg/L of ochratoxin at pH = 4 and pH = 7 and temperatures of 15, 25, 35, and 45 °C were obtained. In order to know the effect of the must on the photodegradation process, the kinetic constants for clarified 12°Brix must containing 100 μg/L of ochratoxin were obtained at the same pH and temperature values. The photo-degradation in must showed lower kinetic constants probably due to the global photo-protector effect of the other substances present.