Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Abstract

Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the nonuniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.

Effects of Microwaves on the Germination of Weed Seeds

“…Aladjadjiyan (2010) researched the effects of microwave radiation on lentil seeds. Vadivambal (2010) determined that improper temperature distribution of microwave energy during food heating decreases food quality.…”

Design of whey protein nanostructures for incorporation and release of nutraceutical compounds in food

“…This nonuniform heating along with the complexity, high equipment costs, inability to ensure homogeneity and lack of suitable packaging materials are the major draw-backs in the MW prospecting. Thus, may result in several issues related not only with safety, but also with poor final quality and overheating (Vadivambal and Jayas, 2010). Applications include the use of pulsed electric fields (PEF) for nonthermal sterilization (Toepfl et al, 2007) or electric fields to change protein molecules (Cramariuc et al, 2005;Zeng et al, 2008).…”

Survivability of Salmonella and shiga-toxigenic Escherichia coli (STEC) O157 in microwave heated ready-to-eat (RTE) foods

“…Microwaves generate heat from the transformation of alternating electromagnetic field energy into thermal energy by affecting the polar molecules of a material, particularly polar water molecules and charged ions in food (Vadivambal and Jayas, 2010). Heat is being created internally by the polar molecules after microwave absorption to generate a volumetric heating effect, leading to faster heating rate (Vadivambal and Jayas, 2010), which is not achievable by any other conventional means (Fu, 2006). Conventional heating occurs by convection whereby heat is transferred from the surface to the interior of the food and requires more time.…”