RESUMO
Gold (Au) nanoparticles (NPs) supported on SiO2 (Au/SiO2) were prepared by a practical impregnation method and applied as an adsorbent for 1,3-dimethyltrisulfane (DMTS), which is responsible for an unpleasant odour in drinks, especially Japanese sake. Compared with a conventional adsorbent, activated carbon, Au/SiO2 selectively reduced the DMTS concentration in Japanese sake without decreasing the concentrations of other aromatic components. DFT calculations revealed that the selective adsorption of DMTS occurred through the formation of a stable intermediate. The size of the supported Au NPs was controlled by the preparation conditions and determined from TEM observations and XRD measurements, and the size was ranged from 2.4 nm to 30 nm. Au/SiO2 having Au NPs with a diameter of 2.4 nm adsorbed DMTS the most efficiently. Smaller Au NPs showed better DMTS adsorption capabilities because larger amounts of Au atoms were exposed on their surfaces in the size range of this study. Langmuir-type monolayer adsorption and one-to-one binding of Au-S are proposed to occur based on an adsorption isotherm experiment. Even though significant differences of the fruity aroma score were not observed in the sensory evaluation between Au/SiO2 and activated carbon for this less aromatic Japanese sake, Au/SiO2 selectively decreased the DMTS concentration in the instrumental analysis.
