Recent Studies Related to Microwave Processing of Fluid Foods

Abstract

Microwave heating is a convenient way to heat materials; it is considered to be a fast, clean, and easy to use technology. The use of microwaves for industrial food unit operations is the subject of research since several years ago. However, the application of microwaves depends, among other variables, on the dielectric properties of the material to be heated; otherwise, the efficiency of the process and the quality of the final product cannot be guaranteed. This paper reviews basic concepts related to microwaves and dielectric properties, and then it presents reported dielectric properties data for selected fluid foods and microwaveheating processes that have been recently studied. These processes are focused mainly on microbial inactivation, enzyme inactivation, chemical, physical, or sensory changes evaluation, or for reheating. The temperature uniformity is also discussed as a key issue for successful application of microwave heating, which is now applied by some companies.

Design of intelligent surfaces for energy intensive processing industry

“…A number of advantages exist in the use of microwave heating including: it does not rely on the diffusion of heat from the surface so can apply rapid & uniform heating of large volumes [151], selective heating of components possible [153], minimal come up time (CUT) required [152], energy saving due to the high degree of efficiency in microwave heating [165], One key disadvantage with most common microwave heating processes is the non-uniform heat distribution that can be generated that results in hot and cold spots [166]. This non-uniform heating is more common in solid food processing rather than in the heating of fluids [165]. Microwave drying offers the means to shorten the drying time of a product as well as improving the product quality compared to conventional drying processes [167].…”

“…In drying applications microwave processing has been found to reduce processing time due to the build-up of internal vapour pressure that drives out moisture of the product [161]. The improvement in product quality steams from the short processing time required, resulting in a decrease in the loss of heat sensitive compounds such as colours, nutrients and flavour [165]. Limitations of microwave drying processes include the possible development of scorching at the edges of a product due to the development of excessive heat at those points during the final stages of drying [168].…”

“…However, this rapid mass transport can result in a phenomenon known as 'puffing', which may or may not be deemed desirable in a final product [167]. Microwave or microwave assisted processing has been applied to a number of different fluid and solid food systems [165]. This includes: the drying of honey [169], minimal processing of apple puree [170], avocado puree [171], and the pasteurisation of orange juice [172].…”

Microwave Pretreatment

“…Since the first MW oven built in 1947 by Raytheon Corporation and an early commercial model introduced in 1954, MW heating has gained popularity in food processing because of its ability to achieve high heating rates, significant reduction in cooking time, more uniform heating, safe handling, ease of operation, and low maintenance [12,13]. Over the decades, this technology has spread widely to such applications as analytical chemistry, heating and vulcanization of rubber, plasma processing, chemical synthesis and processing, and waste remediation.…”

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

“…Upon the discovery that microwaves can cook food faster than conventional ovens by Dr. Percy LeBaron Spencer while researching on magnetron, it was a breakthrough in food technology and currently, microwave oven is an irreplaceable electronic appliance in every household due to its ability to achieve high heating rates, significant reduction in cooking time, more uniform heating, safe handling, ease of operation; low maintenance and energy efficiency (Zhang et al, 2006;Salazar-Gonzalez et al, 2012;Puligundia et al, 2013). Microwaves are wavelengths of electromagnetic radiation between 1 to 0.001 m (Decareau, 1985), in between infrared and radio frequency.…”