HomePhilippine Journal of Material Science and Nanotechnologyvol. 8 no. 1 (2022)

Effect of Embryo Surface Morphology and Grinder Type on the Particle Size Distribution of Coffee

Emmanuel Garcia | Franz Gabriel V. Quidlat



There has been a growing trend in research where scientists conduct their experiments with industry partners to create a more pertinent output. The coffee industry is particularly interested right now in the Particle Size Distribution (PSD) of coffee grounds. The PSD of coffee grounds has always yielded a bimodal spectrum – it contains a small fines peak with a major peak where the majority of the particle sizes appear. This study aims to investigate what causes this bimodal nature and the factors such as surface morphology, and variations in grinder type affect the PSD of coffee. Particle size plays a crucial role in maintaining and controlling the intensity of flavors extracted from the coffee bean. Moreover, PSD is a major contributing factor in producing consistent cups of coffee – a primary concern of industry members. To evaluate the surface morphology of the beans a manual focusing Scanning Electron Microscope (SEM) was used, while an LS13 320 laser diffraction apparatus was used to evaluate the PSD. SEM analysis revealed significant differences in the surface morphologies of the embryo as compared to the rest of the bean. These differences however did not show to play a role in the bimodal nature of the PSD. Different grinder types showed a marked difference in PSD wherein flat burrs produced less fines when compared to conical burrs. This could mean that flat burrs produce more consistent cups.