Ultrasonic spectroscopy could be used to evaluate the quality of so-called functional foods, say scientists in Canada.

Concerns over healthy eating and diet-related disease have seen an increase in the number of functional foods - foodstuffs with ingredients added to increase the food's health benefits. 

However, according to John Page and colleagues at the University of Manitoba, Winnipeg, added ingredients can disrupt the structure of the food and impair its quality, which affects consumer satisfaction with the product.

Page's team have now shown that ultrasonic spectroscopy can be used to investigate how the structure of aerated foods such as bread, cakes and desserts is disrupted by the inclusion of additional components. The scientists used an agar gel to mimic the food and added bubbles, polystyrene beads (to mimic added ingredients), and a mixture of both to the gel to test how easily these disruptions to the structure could be detected.

Ultrasonic spectroscopy is a non-invasive technique in which ultrasonic pulses are directed into the material. The structure of the material affects the propagation of the ultrasonic pulses allowing structural disruptions to be detected.

The scientists showed that the bubbles had a large effect on the acoustic properties of the model aerated food system. They also found that the scattering from the polystyrene beads, which were a similar size to the bubbles, was observed at much higher frequencies. The spectra could be successfully modelled and the size distributions and concentrations of the inclusions could be obtained. 

Because the solid and gas inclusions could both be detected at the same time, the researchers believe that ultrasonic spectroscopy is a promising technique for evaluating foodstuffs that are impaired when the added nutrients interact with the food's structure. This, they believe, will lead to more control over the microstructure of the foods while maximising the food's nutritional benefits.

Caroline Moore