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研究概要

Exploring the Heating Patterns of Multiphase Foods in a Continuous Flow, Simultaneous Microwave and Ohmic Combination Heater

研究機関名

University of Hawaii, USA

http://www2.hawaii.edu/~soojin

代表者

Dr. Soojin Jun

本研究の主旨

A novel continuous flow microwave and ohmic combination heater was designed and fabricated for uniform heating of particulate foods without any pretreatment steps. Design of the combination heater was examined by numerically analyzing the electric field and potential heat distributions under microwave and ohmic heating. Heating patterns of liquid-particle mixtures containing sodium chloride solutions (0.2-0.5%) and carrot particulates were monitored and compared for individual and combination heating methods. At a steady state level, maximum solid-liquid temperature differences under individual microwave and ohmic heating methods were about 8.1 and 8.0℃, showing that either solids or liquid would be under-processed, risking food safety. However, when microwave and ohmic heating were applied simultaneously, there was no significant temperature difference between solid and liquid phases. Energy efficiency of combination heating was higher than microwave heating, yielding a maximum increase of 12.8%. The findings opened new and very promising opportunities to thermally process particulate foods (i.e. soup and chunky mixed fruit juice) with improved uniformity, organoleptic, nutritional quality and reduced food safety problems.

A schematic diagran of microwave and ohmic heating combinatino heater

Fig.1 A schematic diagran of microwave and ohmic heating combinatino heater

Distrubution electrice field in the heater

Fig.2 Distrubution electrice field in the heater

Electrical conductivities of Nacl solutions and carrot

Fig.3 Electrical conductivities of Nacl solutions and carrot

Heating patterns of liquid particl mixtures

Fig.4 Heating patterns of liquid particl mixtures