Microwave technology in drying

Lead University: University of Birmingham

Professor Serafim Bakalis, Professor Peter Fryer, Dr Georgina Zimbitas, Ms Faiqa Shazeaa Modh Salleh



Microwave heating has gained popularity as an alternative rapid drying method that can be used for expansion of food products. Microstructure and physical characteristics of the expanded starch products were examined. The 3D microstructure was analysed using the X-ray micro CT-scanning technique. Upon heating moisture within the sample generates superheated steam, resulting in a fast release and puffing by creating volume expansion. Maximum size expansion was achieved with highly gelatinized pellets. In this project the structural parameters focusing on volume, porosity, number of pores, structure thickness and structure separation of expansion were observed and compared between samples in order to correlate to the optimum conditions for obtaining a highly puffed product with uniform distribution of air cells throughout the inner structure of the sample. Thus the recommended structure quality by consumers, uniformity and controllability of the expansion of food puffing products are highly desirable findings for food industries.

Aims and objectives

In this project the effect of (i) pre-treatment of different types of starch (ii) processing conditions during microwave heating on starch puffing. The main objectives of the project are:

  • To understand the effect of expansion and puffing on porosity during microwave heating through time for different shapes of the starch samples.
  • Optimising formulation, processing and packaging of gluten-free products


Microwave experiments covering different pre-treatments, process conditions (times, power) and samples size and shape; microstructure analysis using micro CT-Scan imaging method.


  • Preliminary analysis of puffed microstructures conducted.
  • Porosity parameters and morphology studies needed to control puffing.

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