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Smart Combination of Heating Modes for Improved Quality, Speed and Safety of Food Processing

Although microwave ovens have provided several benefits in terms of its speed and convenience, the full potential of microwave heating is far from being realized due its disadvantages such as non-uniformity of heating, edge overheating, soggy texture and lack of browning. Several ways to improve these situations have developed through the years, in terms of the turntable and the mode stirrer that improve the uniformity of heating, changes in food composition and placement, using active packages like shields and susceptors, and combining microwaves with other modes of heating. Increasingly, combination of microwaves with other modes of heating is seen as a practical solution to improve the uniformity of microwave heating while simultaneously increasing the speed of heating.

Project Summary

Microwave combination ovens are ovens that heat food by a combination of heat transfer methods such as infrared radiation, convection, jet impingement, high temperature bottom contact plates, etc in addition to microwave propagation. Exploiting novel combination heating to its fullest potential requires knowledge of the engineering fundamentals that govern the relationship between combined modes of heating and the final quality and safety of heated foods. A physics based computer model is, therefore, needed to study combinations like microwaves with infrared and forced hot air heating for cooking of foods. The use of different food systems ranging from simple gels to the most complex food system, meat, is essential for modeling the cooking process using microwaves and combination microwaves. Validation of the mathematical model developed is equally important. Magnetic resonance imaging (MRI) technique provides an efficient and precise way to map heat and moisture transfer and thereby can be used to validate the model and complement understanding.

Method

MRI temperature measurements were made in 3D for preconditioned TX151 gel samples with different concentrations of salt heated in the oven. Maxwell's equations of electromagnetics were solved and coupled with the energy equation to obtain temperature distribution in the samples using finite element method. Dielectric and thermal properties required for the model were measured experimentally. Temperature contours at different cross sections across the height of the samples obtained from MRI were found to match with the simulation results. Average temperature rise in microwave assisted baking and broiling was observed to be 30% greater compared to conventional heating modes. Better overall heating uniformity was found in samples heated using combined microwaves. In addition, samples with higher dielectric loss had higher surface temperatures and were less uniformly heated during microwave assisted baking indicating the dependence of the quality of microwave heating on the product composition. The results show that microwaves can be used to our advantage for speeding up conventional cooking methods such as baking and broiling. Microwaves tend to heat foods more uniformly due to their ability to reach deeper locations and thus complement conventional heating. However, uniformity in microwave assisted heating is more food composition dependent compared to conventional heating.

For more details on the project, please see the presentation below.

Combination Heating

Arts Quad

Computed tempertaure contours inside the gel sample for 30s of heating in the speed broil mode

 


Ashim K. Datta

Ashim K. Datta

  • Professor
    Biological & Environmental Engineering
    Cornell University
    208 Riley-Robb Hall
    Ithaca, NY 14853-5701
  • Tel: (607) 255-2482
  • Fax: (607) 255-4080