Rheology of milk foams produced by steam injection.

Unlabelled: Rheology of milk foams generated by steam injection was studied during the transient destabilization process using steady flow and dynamic oscillatory techniques: yield stress (τ(y) ) values were obtained from a stress ramp (0.2 to 25 Pa) and from strain amplitude sweep (0.001 to 3 at 1 Hz of frequency); elastic (G') and viscous (G″) moduli were measured by frequency sweep (0.

Release kinetics of volatile organic compounds from roasted and ground coffee: online measurements by PTR-MS and mathematical modeling.

The present work shows the possibilities and limitations in modeling release kinetics of volatile organic compounds (VOCs) from roasted and ground coffee by applying physical and empirical models such as the diffusion and Weibull models. The release kinetics of VOCs were measured online by proton transfer reaction-mass spectrometry (PTR-MS). Compounds were identified by GC-MS, and the contribution of the individual compounds to different mass fragments was elucidated by GC/PTR-MS.

Interactions of water with roasted and ground coffee in the wetting process investigated by a combination of physical determinations.

Three complementary techniques were used in this study to investigate the physical changes during wetting of roasted and ground coffee. Scanning electron microscopy (SEM) was found to provide indirect evidence of the presence of liquid water in the coffee particles. The effect of wetting on coffee closed porosity was studied by helium pycnometry, and finally, particle sizing was used to determine the swelling kinetics of coffee after wetting.