KATHRYN L. McCARTHY, Associate Professor

Ph.D., Food Engineering, University of California, Davis, 1987
Department of Food Science and Technology / Biological and Agricultural Engineering
222 Cruess Hall
Phone: 530-752-1487
Email: klmccarthy@ucdavis.edu

Current Research

Professor McCarthy's research program focuses on flow of and mass transfer in foods products. She and her research group collaborate with NMR spectroscopists using magnetic resonance imaging (MRI) and ultrasonic Doppler velocimetry (UDV) to characterize rheological properties. These techniques combine a fluid velocity profile, obtained by UDV or MRI, and simultaneous pressure drop to evaluate rheological properties of fluids flowing in viscometric pipe flow. The objective of this research is to provide in-line sensors to improve the control and efficiency during processing.

In food processing, there are a number of applications that incorporate the movement of fluid through porous media. Porous media is the term applied to material that has interconnected non-solid space (or pores) within a solid matrix. Examples include the flow of solvent through solid particles in extraction processes (e.g., coffee, tea, and sugar), wort separation in a lauter tun (e.g., beer production) and whey separation from cheese curd. The hydraulic conductivity characterizes the flow through these systems at steady state and is the proportionality constant in Darcy's law. Work is being performed in McCarthy's group to characterize and quantify flow in these porous media systems; the results will ensure higher food quality through the ability to better tailor processing conditions and product formulation.

In addition, a magnetic resonance imaging methodology has been developed to follow mass transfer of oil in food products. Specifically, work has been performed to evaluate oil migration in chocolate products that have two or more oil-containing components in contact. Oil migration is a common problem in composite chocolate confectionery products resulting in softening of chocolate and hardening of the filling, leading to unwanted changes in texture, color and flavor. Spatial and temporal changes in the liquid oil content of a two-layer peanut butter and chocolate model system were evaluated as a model system. The work provides insight to manufacturers regarding key factors that affect quality. Research results will be used to increase economic benefits due to higher quality products.

Representative Recent Publications

Choi, Y. J., K.L. McCarthy and M.J. McCarthy. September 2002. Tomographic techniques for measuring fluid flow properties. Journal of Food Science 67(7):2718-2724.

Yoon, W.B. and K.L. McCarthy. November 2002. Rheology of yogurt during pipe flow as characterized by MRI. Journal of Texture Studies 33(5):431-444.

McCarthy, M.J. and McCarthy, K.L. 2002. Integration of tomographic data in process analysis, modeling, and control. IN: E. Balsa-Canto, J. Mora, J.R. Bang, E. Onate (eds.) Computational Techniques in Food Engineering, International Center for Numerical Methods in Engineering, Barcelona, Spain.

Yoon, W.B. and McCarthy, K.L. 2003. Flow behavior of processed cheese melt. Journal of Food Process Engineering 26(6):559-576.

Wang, L., McCarthy, K.L., and McCarthy, M.J. 2004. Effect of temperature gradient on ultrasonic Doppler velocimetry measurement
during pipe flow. Food Research International. 37(6):633-642.

Choi, Y.J., McCarthy, M.J., McCarthy, K.L. 2004. MRI for process analysis: co-rotating twin screw extruder. Journal of Process
Analytical Chemistry 9(2): 72-85.

Membership in Professional Societies

Institute of Food Technologists
American Institute of Chemical Engineers
Society of Rheology

Courses Offered

EBS 175 - Rheology of Biological Materials
FST 203 - Food Processing
FST 109 - Principles of Quality Assurance in Food Processing

Research Support

CPAC (Center for Process Analytical Chemistry)
DMI (Dairy Management, Inc.)