What are the benefits of continuous microwave processing?
By Andrew Bosman - 30 May 2019
Microwave heating refers to the use of electromagnetic waves of certain frequencies to generate heat in a material. Continuous microwave processing uses this mechanism to heat a product as it continually flows through a chamber, for example, a pumpable soup through a pipe.
The demand for high-quality food has put pressure on manufacturers to trial new thermal processing technologies. By rapidly heating a product, continuous microwave processing (CMP) is one such technology that can achieve this.
CMP rapidly heats pumpable products which can reduce the overall time the product remains at elevated temperatures. This prevents over-processing and ultimately better preserves colour, texture and nutrients, while maintaining a safe pasteurised or sterilised product.
Our recent feasibility study found microwave processing an effective method of preserving the vibrant green colour of pea and ham soup, shown below.
Conventional heating of products with scraped surface heat exchangers relies on conduction to heat up the particulates. Microwave processing, however, can rapidly heat both the liquid and particulates simultaneously, minimising the risk of over-processing the product.
Reduced cleaning and longer runs
Microwave processing instantly delivers energy throughout the product rather than via its surface. This heats the product without relying on a hot surface, reducing the potential of fouling. Reducing the risk of burnt on food will reduce cleaning time and/or chemicals, allowing longer run times.
With CMP, energy penetrates directly into the food product and heats through interactions with polar molecules (e.g. water) and ionic compounds (e.g. salt). Heating the entire volume of a flowing product is known as volumetric heating. It avoids relying on heating through conduction and convection alone which circumvents the issue of the heating apparatus's surface becoming much hotter than the product itself.
We have an AMT continuous flow microwave at Campden BRI and use it to conduct energy comparison and product trials. We have conducted trials alongside Brunel University to investigate the comparison of quality and energy of various processing techniques.