Environmentally friendly method in determining the water content of coffee by NIR Spectroscopy

Abstract

Coffee quality could be determined from several aspects, one of those is the water content inside. Along the storage, it must be low and for coffee export it must be below 12.5%. Nowadays, the determination of water content is conducted by the chemical method like the gravimetry method which spend time, destructive also can not represent all of the products. Therefore, it is not in line with the industries which need an actual measurement that could measure all of the products nondestructively and also keep considering the environment. This study aimed to develop a PLS model to determine the water content of green bean coffee, nondestructively. This study used green bean coffee from several region in Indonesia with a high range data concentration (7.18% - 12.16%), a NIR wavelength of 1000-2500 nm, followed by determination of water content using gravimetry method. After that, the NIR data was processed using data pretreatment such as normalization, first derivative, second derivative, multiple scatter correction and standard normal variate and followed by the calibration using PLS and validation. Result showed that NIR spectroscopy could be used to calculate the percentage of water inside coffee beans, indicated by high R value above 0.8% and high consistency above 90%.