TY - JOUR
T1 - Hole and vacuole formation during drying of sessile whey protein droplets
AU - Bouman, Jacob
AU - Venema, Paul
AU - de Vries, Renko J.
AU - van der Linden, Erik
AU - Schutyser, Maarten A.I.
PY - 2016
Y1 - 2016
N2 - Morphological development from droplet to particle during drying has strong influence on powder structure and functionality. We study the evolving morphological properties of whey protein droplets during single sessile droplet drying experiments as a well-defined model for spray drying. Sessile drying droplets were visualised with a camera and subjected to varying drying conditions such as temperature, initial protein concentration, presence of airflow and droplet rotation. The final particles were imaged by SEM and X-ray tomography. Under all conditions used, the droplets initially shrink steadily while at a specific point a hole nucleates. Subsequently, a vacuole develops until a rigid hollow particle is obtained. The location of the hole was found strongly dependent on the presence and the direction of the applied air flow. We hypothesise that in the early drying stage a skin forms, which becomes more rigid when the hole nucleates. The hole forms at the position where the local modulus of the skin layer is minimal and/or at the point below the skin where the local pressure is minimal, and that after the hole has nucleated, the vacuole develops mainly by evaporation of water through the hole.
AB - Morphological development from droplet to particle during drying has strong influence on powder structure and functionality. We study the evolving morphological properties of whey protein droplets during single sessile droplet drying experiments as a well-defined model for spray drying. Sessile drying droplets were visualised with a camera and subjected to varying drying conditions such as temperature, initial protein concentration, presence of airflow and droplet rotation. The final particles were imaged by SEM and X-ray tomography. Under all conditions used, the droplets initially shrink steadily while at a specific point a hole nucleates. Subsequently, a vacuole develops until a rigid hollow particle is obtained. The location of the hole was found strongly dependent on the presence and the direction of the applied air flow. We hypothesise that in the early drying stage a skin forms, which becomes more rigid when the hole nucleates. The hole forms at the position where the local modulus of the skin layer is minimal and/or at the point below the skin where the local pressure is minimal, and that after the hole has nucleated, the vacuole develops mainly by evaporation of water through the hole.
KW - Droplet drying
KW - Dynamics
KW - Morphology
KW - Process conditions
KW - Protein solution
U2 - 10.1016/j.foodres.2016.03.027
DO - 10.1016/j.foodres.2016.03.027
M3 - Article
AN - SCOPUS:84962023044
VL - 84
SP - 128
EP - 135
JO - Food Research International
JF - Food Research International
SN - 0963-9969
ER -