In the early 2000s Professor Sun and FRCFT at UCD published details of a new approach: using ultrasound to assist freezing.
“Ultrasound has the ability to produce bubbles of vapour in a liquid, this is called cavitation,” he explains. “And when we apply ultrasound during the freezing process it can help to reduce the size of ice crystals that form in the internal structure of the food.”
Professor Sun and his team were the first to develop this freezing technology internationally, and their experiments showed that using ultrasound when freezing helped to preserve the internal structure of many larger fruits and vegetables, including potatoes and apples.
Not all foods suit the new freezing technology – meat, chicken and foods with more porous internal structures do not demonstrate the same level of benefit – but where it works, the results are good.
“We were able to show that, compared to conventional methods, the ice crystals that form are smaller with ultrasound-assisted freezing,” explains Professor Sun. “We could see that the damage inside the foods was minimised.