Constitutive Properties of Soft Aerated Food Materials

许多食品和饮料需要气泡来创造独特的质地和味道。如果你不相信这一点，试着用一罐新开的可乐和一罐刚喝了一天的可乐进行品尝。但是，此外，起泡食品和食品泡沫显示出一些非常有趣的特性，我们还不完全了解它们是如何产生的。例如，为什么特定频率的超声波可以用来激发面包团中的气泡，从而使气泡真正产生共鸣，而不是饼干面团中的气泡？我想用材料科学的方法来回答这样的问题，以便更好地理解气泡对食品特性的影响。然而，这并不容易，需要使用一些相当复杂的科学工具(正如我建议我的学生进行的两项研究所表明的那样)。气体在有气泡的食物中分布不均，这导致不同气泡之间存在非常小的压力差。但是，尽管压力差很小，但气泡大小的分布变化如此之快，以至于我们必须使用地球上最强的光束之一(加拿大光源)来成功地研究这些变化。创造良好的食物泡沫需要正确的配料。食品泡沫中使用的蛋白质分子(例如乳蛋白)表现良好，因为它们在同一分子上既具有极性特征，也具有非极性特征。但是，如果我们将蛋白质挤压到8000个大气压的压力下，极性会发生什么变化？当你考虑到高压处理正越来越多地被用来确保我们的食品安全时，这个问题就不那么奇怪了。在这项研究的五年中，我希望量化某些物理特性对充气食品特性的影响。更多地了解充气食品材料的性质将有助于生物科学，因为它建立了简化原则，可以应用于更好地了解其他软生物材料的性质。加拿大人将从中受益，因为更好地了解如何处理气泡和食品原料将使食品制造商能够在不降低原始口感的情况下，创造出含有更多健康成分的高质量食品。

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.