This paper examines the engineering and application of different sensor methods to demystify the art that surrounds coffee roasting. Coffee roasting is an important step in the process of bringing coffee from green bean to cup. It is the roasting process that takes the green coffee and develops the flavours and aromas for which coffee is so valued, and it is the step that imparts the greatest added value. The sensor methods of, Online Calorimetry, Microwave Aquametry, and Raman Spectroscopy are analysed. The results are used to identify how expert coffee roasters manage to roast the perfect coffee.