Constitutive Properties of Soft Aerated Food Materials

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Many foods and drinks need bubbles to create unique texture and flavour sensations. If you're not convinced of this, try a taste test with a freshly-opened and a day-old can of cola. But, in addition, bubbly foods and food foams display some really interesting properties and we don't yet fully understand how they arise. For instance, how come ultrasound of a specific frequency can be used to excite the bubbles in a bread dough so that the bubbles will actually resonate, but they won't in a cookie dough? I want to take a materials science approach to answering questions such as this so that the influence of bubbles on food properties can be better understood. However, this is not easy and requires the use of some fairly sophisticated scientific tools (as illustrated by two studies I am proposing my students do). Gas is distributed unevenly within bubbly foods, and this causes very small pressure differences to exist between different bubbles. But, even though pressure differences are small, the distribution of bubble sizes changes so rapidly that we have to use one of our planet's most intense beams of light (the Canadian Light Source) to successfully study these changes. Creating a good food foam demands the right ingredients. The protein molecules that are used in food foams (think dairy proteins, for example) perform well because they have both polar and non-polar characteristics on the same molecule. But, how does the polarity change if we squeeze the protein to a pressure of 8000 atmospheres? The question isn't so bizarre when you consider that high pressure processing is being increasingly used to ensure that our food is safe. Over the five years of this research, I expect to quantify the influence of certain physical properties on the properties of aerated foods. Learning more about the nature of aerated food materials will benefit the biological sciences by establishing simplifying principles that can be applied to get a better understanding of the properties of other soft biological materials. Canadians will benefit because a better understanding of how to process bubbles and food materials will allow food manufacturers to create high quality foods with more healthy ingredients without cutting down on the original taste.