Classification of the Coffee Roasting Level Based on Electronic Nose

Coffee beans must be roasted before serving for drinks. While the taste of coffee is largely determined by the quality and results of the roasted beans. So far, testing the aroma of coffee is still using the eyes, tongue and nose of people who are experts in their fields. Electronic nose exists as a device with the design to imitate human smell. This instrument can be used classify coffee's aroma based on the roasting level that is commonly used as a non-subjective method. Four types of Arabica coffee bean roasting level which are green, light, medium, and dark are used as an input to the electronic nose. Ten gas sensors as detector system, and the data acquisition consist of one cycle per sample which includes five phases of collecting phase. After pre-processing and feature extraction has been done to the data set, analysis is carried out using Principal Component Analysis (PCA) and K-Nearest Neighbour (KNN). The Results show the best K value of the KNN method for the sample is K=5, a system performance evaluation shows the test data and training data into 5-fold with an accuracy value of 67.5%, a precision value of 70.22%, and a recall value of 67.5%.