Intelligent green tea fixation with sensor fusion technology

Abstract Fixing, shaping, and drying are three major processing procedures after green tea's harvest. Among them, fixing is the first and key step for the formation of green tea's specific appearance and fragrance. With traditional methods, only trained experts with years' experience can produce good green tea products, which is backward in the industrial age. In this study, intelligent green tea fixation is designed to automatically and continuously adjust the processing parameters. Aroma is online measured with an electronic nose and a few sensors' signals are selected to represent the fresh fragrance, enzymatic reaction, charring occurrence, respectively. Image information is captured with machine vision and G, R, B values are carefully processed to reflect the color changes. The original aroma signals and processed image information were fed into an adaptive fuzzy logic controller to automatically control the pot temperature continuously. With a controlled high temperature at the beginning, the enzymatic reaction could be suppressed and more polyphenols and chlorophyll were retained. In the later phase the temperature was decreased to minimize charring, and more aroma and contents were retained. The final product quality was hence greatly improved in terms of appearance, liquor color, fragrance, taste, and residue color.