Ultrasound helps processors to measure food crunchiness

Leading biscuit and crisp manufacturers have been in discussions with Professor Malcolm Povey, a food physicist at Leeds University, about how they can benefit from a groundbreaking system that measures product crunchiness.

Povey discovered that pulses of ultrasound are released when crunchy food is consumed that tell humans whether or not they like a product. “People have been trying for a long time to measure food sound,” he said, “but they assumed we interpreted crispy sounds acoustically. Instead, the frequency range goes so high that even bats and dolphins cannot hear it.”

He realised that if the ultrasound produced by crunching food could be measured by a microphone, while taste panellists simultaneously rated the crunchiness of food products, then he could detect which ultrasound levels people found acceptable. The microphone could then be used as a texture analysis device.

“This is a cheap way to control quality,” said Povey. “Before now, manufacturers have had to rely on taste panels and consumer complaints to indicate texture alterations, because mechanical testing tends to be expensive, but this new method offers economical testing of large quantities of product.”

Povey also claimed that his discovery will lead to more accurate product discrimination: “The English only have two words to describe crispy, crunchy texture, whereas the Chinese have 17, so there are obviously many different levels of crunchiness that we can use the ultrasound recordings to pinpoint,” he said. There will also be a reduction in waste because manufacturers will be alerted to texture flaws as soon as they occur and can deal with the matter immediately, he claimed.

Although the system will be useful for day-to-day quality control, Povey said that the equipment would not replace taste panellists: “At the end of the day, humans can change their minds - learn to like or dislike things, so machinery will never completely take over human taste panels, because it needs to be calibrated.”

“Maybe I should have patented the process,” he added, “but in the long run it’s better for the industry that I haven’t, because now everyone can benefit.”