Taguchi analysis for quality stabilization of coffee roast

Coffee is a healthy drink rich in a variety of vitamins beneficial for human beings. The coffee drinking population increases year by year, and it seems to have become a new world trend. According to International Coffee Organization (ICO), the production of green bean in 2015 has reached 8.6 million tones with its output value reaching USA 50 billion, which is the world's second largest bulk second only to oil. The coffee industry chain from the cultivation, green bean production, transportation, roasting, to coffee extraction, each stage are following a basic principle 'only focus on stability, to show the value'. Hence, the development of professional roaster and cup tester need to go through a rigorous training and specialized inspection processes, respectively. The primary goal of roasting coffee is to stabilize the initial point of caramelization, referred to as the middle roastinging point, which is the beginning of the emergence of alcoholic flavor. In the middle point, coffee beans remains in a dry and high temperature environment where artificial roasting method is difficult to accurately grasp the correct time to withdraw roasted beans. The current commercial roasting machines uses gas source so that there exists a crisis of unsafe food and environmental pollution due to incompletely burned gas. The AVR-1000 is a programmable electric roaster developed by the 18h Coffee Company (http://18hcoffee.com/index.php/ en/product?productsublayout=0), which can have good heat insulation and stable heat sources. In this paper, the dominate factors affecting the roasting quality are analyzed by Taguchi method. They includes bean weight, steaming temperature, roasting temperature, and fan speed. The quantitative analysis can effectively improve the stability of the automated coffee bean roasting process and the quality of roasted beans.