Thermophysical and Dielectric Properties of Salsa Con Queso and its Vegetable Ingredients at Sterilization Temperatures

Abstract

Aseptic processing of a low-acid multiphase food product using continuous flow microwave heating system can combine the advantages of an aseptic process along with those of microwave heating. The objective of this study was to determine the thermophysical and dielectric properties of salsa con queso and its vegetable ingredients (tomatoes, bell peppers, jalapeno peppers, and onions) at a temperature range of 20 to 130°C to design a safe process for aseptic processing of salsa con queso using a continuous flow microwave system. The influence of temperature on apparent viscosity of salsa con queso was described by an Arrhenius-type relationship. Second order polynomial correlations for the dependence of thermophysical and dielectric properties (at 915 MHz) of salsa con queso and its vegetable ingredients on temperature were developed. The results showed that the dielectric constant decreased with an increase in temperature and the dielectric loss factor increased with an increase in temperature.

Keywords:

• Aseptic processing
• Microwave heating
• Salsa con queso
• Multiphase foods
• Thermophysical properties
• Dielectric properties

ACKNOWLEDGMENTS

Support for the research study undertaken here, resulting in the publication of paper No. FSR-06–09 of the Journal Series of the Dept. of Food Science, NCSU, Raleigh, NC 27695–7624, from USDA National Integrated Food Safety Initiative Grant No. 2003–51110–02093, titled: Safety of foods processed using four alternative processing technologies and USDA Grant No. 2003–01493, titled: mathematical modeling and experimental validation of continuous flow microwave heating of liquid foods are gratefully acknowledged. We would also like to thank Dr. Mari Chinn, Penny Amato, and Sharon Ramsey for their help in conducting the experiments. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, or criticism of similar ones not mentioned.