Changes in particles of coffee powder and extensions to caking. http://dx.doi.org/10.1016/j.foodchem.2006.11.029

Abstract

Changes in the projected area (PA) of particles of an instant coffee powder were followed in real time by videomicroscopy and image analysis. Particles were placed inside a transparent acrylic chamber (7x7x3 cm) where the relative humidity RH (43, 52, 67 and 74%) and temperature T (20, 25 and 30°C) were controlled and measured in the head space. A “caking index”  was defined as the change in PA at any time t with respect to the initial PA. At any temperature there was an increasing effect in as RH increased and the shape of v/s time curves followed closely that of caking measured by sieving techniques. The exponential kinetic model fitted adequately the data. The PA method could be used as a first approximation to predict the tendency to caking of amorphous particles.