Microwave puffing: mathematical modeling and optimization

Abstract

Increased interest in microwave puffing is due to its ability to obtain low-fat healthy foods and ready-to-eat products that emulate deep fried foods. Determination of optimal conditions for this complicated process has been difficult and as a result, although several patents exist on the concept of microwave puffing, we are yet to see any large scale commercial use of it. A fundamental physics based computational modeling approach integrated with relevant experimentation, as used in this work, is an ideal framework to understand and optimize microwave puffing. Coupled porous media transport and large deformation model, describing complex physical phenomena occurring during the process such as electromagnetic heating, heat and moisture transport, evaporation and structural changes, was formulated and solved. Temperature (using infrared camera and fiber optic probes), moisture and volume measurements were performed in potato samples to validate the model. The effect of various processing and operating conditions on the puffed potato quality was studied. It was found that infrared addition to microwave puffing leads to a better quality product. Hot air can be used with microwaves to reduce the final moisture content; although the change is not as significant compared to addition of infrared. Heating of sample using forced air convection may lead to decreased volume products. An initial moisture content near 1.4 db may be optimum for puffing. Relative humidity of the surroundings had no effect on the puffing characteristics. The study provides critical guidelines to food product and process developers for successful development, control and automation of microwave puffing process, thereby leading to a value-added nutritious product.