抄録
Metal oxide-based semiconductor gas sensors have been exploited for detecting various odorous components generated in the process of aging and/or putrefaction of beef, such as ethyl acetate, isoamyl alcohol, acetoin, and so on. Among various sensor elements tested, WO3(5wt%)-ZnO showed the highest sensitivity to ethyl acetate (20ppm in wet air) at 500°C. On the other hand, acetoin could be detected with excellent sensitivity and selectivity by WO3(0.5wt%)-ZnO element at 300°C. The effect of WO3 additive was evalutated in the catalytic oxidation of acetoin over ZnO-based materials. As a result, the increase in acetoin sensitivity was found to be correlated with the catalytic activity in oxidative dehydrogenation of acetoin to diacetyl. These two elements obtained appeared to be applicable to evaluate beef freshness. Actually, it was confirmed that the sensitivities of these sensors to the headspace volatiles of the beef kept at 5°C increased gradually during the preservation term of 5 days.
