An Advanced Centrifugal Technique to Characterize the Sticking Properties of Tomato Pulp during Drying

Abstract

An advanced centrifugal technique was developed to characterize the stickiness of tomato pulp at various moisture contents and temperatures. To provide tomato pulp samples with different moisture contents, tomato powder produced by a laboratory spray dryer was wetted to six different moisture levels. By noting the rotational speed for a tomato pulp droplet detachment and weighing the mass of the droplet remaining on the surface it is possible to gauge the approximate attachment forces holding the droplet to the substrate. The effects of droplet mass and centrifugation time after reaching the desired rotor speed on the detachment rate were also studied. The detachment force was found to increase at the beginning and then started decreasing as the moisture content decreased presenting a maximum at moisture content of about 34%. In addition, the higher the droplet temperature, the higher the attachment force.

Keywords:

• Adhesion
• Centrifuge method
• Cohesion
• Glass transition
• Stickiness

ACKNOWLEDGEMENT

A. M. Goula would like to thank the State Scholarship Foundation (IKY) of Greece for awarding her a postdoctoral scholarship. The authors thank Dr. D. S. Achilias and Dr. G. Z. Papageorgiou for conducting the DSC measurements.