19 February 2002
As you contemplate the wonders of science, consider ice cream. Far from the soft, cold product produced by hand-cranked freezers of old, today's commercial ice cream is a complex product designed and engineered for the best attributes.
At the recent American Association for the Advancement of Science convention in Boston, I heard a guy talking about a partly frozen foam with ice crystals and air bubbles, with flocculated fat globules surrounding the air bubbles, and proteins and emulsifiers surrounding the flocculated fat globules. My mind began drifting until I realized he was actually talking about ice cream, one of my favorite topics. Only then did I begin to realize that ice cream scientists take their work as seriously as brain surgeons and rocket scientists, maybe more so.
"Not only is the chemistry of the ingredients important, but the physics plays an incredibly important role as well in terms of how those components are all put together," said food scientist Douglas Goff of the University of Guelph in Canada. He says ice cream gets its creamy texture from the way that the fat, air and ice crystals are assembled in a highly concentrated mixture of sugar water, which, because of its salt content, never freezes completely, allowing it to be scooped and chewed at freezer temperatures.
"You can get vast differences in the textural properties of ice cream based on differences in structure," said Mr. Goff. "So we've used microscopic techniques to examine the structure and to look at things like ingredient variability and process variability and how that affects structure."
Mr. Goff says you can make a good bucket of the stuff in your kitchen without knowing any of this. But if you want to send it around the world and make it last so people who eat it still get a smooth product, there is a lot to learn.
Lately, his laboratory has been investigating proteins in winter wheat that control the size of ice crystals when the plant is exposed to freezing temperatures. He wants to see how the protein might retard ice crystals from growing larger in ice cream and giving it a grainy texture over time.
"The plant in nature doesn't die because it has an ability to deal with the detrimental effect of ice formation in the cell. So we've been rather interested in the potential for extracting these and using them in ice cream to maintain very small ice crystal sizes and to maintain smoothness and texture over a longer shelf life," Mr. Goff says.
Mr. Goff says several different companies have received patents in the last decade for similar anti-freeze proteins from other plants, arctic fish, and even a winter insect. None, however, has advanced to commercialization.
Although ice cream is a snack, some researchers want to make it useful as a real food or source of medicine for patients who cannot swallow easily. Pennsylvania State University food scientist Bob Roberts says this could benefit, for example, cancer patients undergoing treatments that make them nauseous.
"People like to eat ice cream. Even people who through chemotherapy or other types of therapy that don't feel like eating are able to eat ice cream. You can modify ice cream as a delivery vehicle for nutriceuticals, for pharmaceuticals if that's the most appropriate delivery vehicle," Mr. Roberts says.
Did he say nutriceuticals? That's a scientist for you. I think he meant just plain old nutritional ingredients.
Anyway, anthropologists have something to say about ice cream, too. At Boston University, Merry White says many cultures around the world have adopted it, even in places such as Asia where intolerance to the milk protein lactose is high. Ice cream is another example of globalization especially in terms of the flavors people prefer.
"What's true is that vanilla, chocolate and strawberry are the three most popular flavors in the world pretty much everywhere, especially in China," Ms. White says.
Ms. White says flavors like green tea or ginger ice cream are not Asian inventions, but Western ones to please the palate of local patrons at Asian restaurants.