Use of NIR spectroscopy for the study of seasonality: from the green coffee beans to the final product

Seasonality of coffee is a problem that has always been considered affecting its production process but never scientifically approached. In this thesis work, conducted in the Lavazza plant in Torino, the chemical variations of coffee over the months were studied, performing chemical and NIR spectral analyses in three different production steps: the green coffee beans from June to October, the roasted coffee from April to October and the finished product (capsules) from February to October. For the last two groups, it was decided to analyse both 100% arabica blends and blends with also the robusta coffee variety. Principal Component Analysis (PCA) was used to evaluate the spectra, acquired by two different Near-InfraRed (NIR) spectrometers: the Termofisher instrument was used to get both the spectra of the green coffee and the finished product, while the Buchi one was utilized to collect those of the roasted coffee. These two instruments have different acquisition ranges, therefore at first the full spectrum, and then only the wavenumber range shared by both the spectrometers, were studied. In addition, a focus on specific parts of the spectra (focused spectra) was performed to highlight differences among samples. The obtained results led to conclude that seasonality is not experienced on green coffee, but it is very evident on roasted coffee and final product. The inspection done on the NIR spectral intervals, responsible of such a behaviour, suggests that this phenomenon is due to a different lipid, protein and moisture content, which can reasonably be correlated with the roasting process. To confirm this hypothesis a compositional analysis on the finished product was deemed necessary and therefore performed by an external laboratory, confirming that seasonality is directly proportional to protein and moisture content and inversely proportional to lipid content.