Control of coffee bean roasting by optical measurement of colour value

摘要

On-line control of the coffee roasting process is new. The progress, or degree of roasting is inferred from the tristimulus colour value of the beans. When the colour correlates with the required degree of roasting, the process is terminated. An inspection glass allows process monitoring without interruption or sampling. Any contamination of the glass is compensated for. To do this, the colour value of raw coffee is determined through the glass, and compensation is applied, based on the known correlation between degree of roasting and colour. Also claimed is the apparatus used. The colour measurement unit (5-8) determines the coffee (4) colour through the inspection glass (3). An evaluation unit (12, 17) monitors the degree of roasting and prompts termination as appropriate.