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A comprehensive study on thermophysical material properties for an innovative coffee drying process
Publikationstyp
Journal Article
Date Issued
2011-08-11
Sprache
English
Author(s)
Institut
Journal
Volume
29
Issue
13
Start Page
1562
End Page
1570
Citation
Drying Technology 29 (13): 1562-1570 (2011)
Publisher DOI
Scopus ID
Publisher
Taylor & Francis
In the present work a series of physico-chemical and transport properties of coffee extract were determined that are required for developing a new process of drying instant coffee solutions. The influence of temperature and dry matter content on density, viscosity, thermal conductivity, heat capacity, and surface tension is shown systematically bringing light to the contradictory literature data, especially in the case of heat capacity. To specify feasible conditions of liquid feeding in the drying process, the freezing point of the solution was analyzed as a function of dry matter content. Further, the surface free energy, surface roughness, and thermal conductivity of some belt materials were investigated. In addition, the wettability of these materials was determined applying coffee solutions at different dry matter contents. Due to the presence of surface active components, the wettability was found to depend on the drop age revealing a spreading kinetic. As a consequence, dynamic and static measurements result in different contact angle values. © 2011 Taylor & Francis Group, LLC.
Subjects
Coffee extract
Contact angle
Density
Freezing point
Heat capacity
Surface tension
Thermal conductivity
Viscosity
DDC Class
530: Physik
540: Chemie
600: Technik
620: Ingenieurwissenschaften