This article on producing #vanillin in clean enzymatic reactions by oxidation of vanillyl alcohol with pure oxygen results from a very fruitful collaboration of us (#InnoSyn) with the researchers of the Autonomous University of Barcelona (UAB) in the framework of the EU project #ROBOX on the development of robust biooxidation methods using enzymes. The partners at UAB developed efficient immobilization methods for the Eugenol Oxidase (EUGO) enzyme that we had produced in high-cell density E. coli fermentations. The free and immobilised EUGO was applied to oxidise vanillyl alcohol to #vanillin using molecular oxygen with high productivities. The catalases we initially applied proved to be insufficient to quench all of the by-product hydrogen peroxide. Even the low concentrations of H2O2 still present in the reaction mixtures lead to considerable formation of colourfull side-products. This could however be solved by our #InnoSyn developers by replacing the catalase by low amounts of sodium sulfite, which is an antioxidant also present and applied in wine. So the enzymatic EUGO oxidation technology we developed can be applied to cleanly oxidise natural vanillyl alcohol produced by fermentation enzymatically to vanillin using only pure oxygen (from air) as oxidant. Direct fermentative production of natural vanillin is impaired by its toxicity towards the production organism already at low concentrations, while vanillyl alcohol can be fermented to high titers.