抄録
The coffee sold by the cup from vending machines does not taste as good as that of drip coffee made at home or in coffee shops. The difference in taste is caused by various reasons such as brewing efficiency, the stain in brewers, the freshness of coffee beans, the roasting methods of beans and the particle size of ground beans, etc. Among these reasons, the brewing efficiency is probably the most important one. An experiment was conducted in order to improve the stability of brewed coffee concentration (Brix) using the parameter design approach.
