Mechanism of folic acid radiolysis in aqueous solution

•Folic acid is a sensitive compound easily degraded by ionizing radiation.•Electron-beam processing induced folic acid radiolysis into several degradation products.•Folic acid breakdown increased with increasing radiation doses.•Most of folic acid degradation products showed increasing concentrations mainly up to 1.0 kGy.•Two new folic acid radio-degradation products were identified by LC/MS.

Folates compounds are a B group vitamin vital for important biochemical processes like DNA synthesis and repair and in certain biological reactions as a cofactor. Folic acid (FA) is composed of a pteridine ring, p-aminobenzoic acid and glutamate moieties. Separately, the three moieties have no vitamin activity. Folate deficiency can lead to increased risk of several pathologies. FA is known to be a sensitive compound, easily degraded by pH, light, heat and food processing. Food irradiation is a process exposing food to ionizing radiations to reduce storage losses, extend shelf life and microbiological safety. Radiation treatment produces oxygen radicals and thereby induces oxidative damage in biomolecules such as proteins, lipids, DNA and vitamins. In the present work, aqueous FA solutions are submitted to electron-beam (E-beam) radiation in a dose range of 0.25-10 kGy. Upon irradiation, main FA radio-products are quantified by HPLC. E-beam processing undergoes radiolysis to yield some known FA photoproducts and also new radio-products are formed: 6-(hydroxymethyl)pterin and N-(4-nitrobenzoyl)-l-glutamic acid. A radio-degradation pathway of FA is also discussed.