Public Release:  The science of the scoop: Wheat proteins for ice cream?

American Association for the Advancement of Science



Low-temperature scanning electron micrograph of ice cream after the initial aeration, whipping and freezing step. Numerous air bubbles can be seen, each about 40 µm in diameter. Ice cream is a frozen foam, about half its volume is air.

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BOSTON, MASS - Ice-modifying proteins extracted from winter wheat may help ice cream stay smooth and creamy during long periods in the freezer, suggests new research by food scientist Douglas Goff of the University of Guelph, in Canada.

It's not just the ice cream of the future that will benefit from research, however. The last time you polished off a double-decker cone, you were enjoying the results of some serious scientific investigation.

Today, Goff and other ice cream experts presented the science, technology, and cultural trends that go into making the perfect scoop, at a session on "The Science of Ice Cream," at the American Association for the Advancement of Science (AAAS) Annual Meeting.

Ice cream gets its creamy texture from the way that fat molecules, air bubbles, and ice crystals are assembled within a highly concentrated mixture of sugar-water. Getting this assemblage right is no easy task, according to Goff, who uses electron microscopy to zoom in on ice cream's molecular makeup.

"Ice cream is a very complex product to manufacture, especially since the industry has changed considerably over the last couple of decades," Goff said. "You can make a very good gallon of ice cream in the kitchen without knowing anything about the science [of the process]. But, if you're trying to send ice cream around the world and make it last, so that the person who eats it gets a smooth product, there is a lot to learn."



Line forms to buy ice cream at the Penn State Creamery. credit: Greg Grieco, Penn State

Goff's microscopy images of ice cream reveal a matrix of tiny fat globules, surrounding air bubbles and ice crystals. Ice cream is an emulsion-like oil and vinegar salad dressing-so the matrix of fat particles must be stabilized by milk proteins to prevent the fat from clumping together. The other component of the emulsion is a solution of sugar-water, from which the ice crystals form during freezing. The solution never freezes completely, allowing ice cream to be scooped and chewed at freezer temperatures.

Goff and his colleagues are investigating possible new ways to improve ice cream quality by introducing new ingredients and manipulating its structure. Recently, he discovered a possible use for certain proteins in winter wheat, which help the plant survive winter by modifying the growth of cell-damaging ice crystals. This research was done in collaboration with Ice Biotech, Inc, who developed and patented the proteins. Using these proteins in ice cream production has made for some ?really smooth? batches of ice cream, said Goff, who will soon propose new processes to dairy industry officials.

The process of manufacturing ice cream is a science unto itself, according to Bob Roberts of Pennsylvania State University. When the ingredients are blended together, they form an "ice cream mix," but turning ice cream mix into the beloved frozen dessert is more complicated than one might think.

The mix must be pasteurized, then homogenized. Homogenization induces changes in the physical structure of the fat, decreasing its particle size, and adding stabilizer proteins to the particles' surfaces. In the ensuing refrigeration step, the fat must be crystallized right away, to achieve the desired liquid and crystal proportions.

The mix is then frozen, changing much of the liquid water into ice and incorporating air into the mixture. The smaller the air bubbles, fat particles, and ice crystals are, the smoother the ice cream will feel in the mouth, according to Roberts. Homemade ice cream generally has larger ice crystals, because the mix freezes more slowly and the crystals have more time to grow.

"You've got gas, liquids, and solids, and as the temperature changes, then so do the volumes of each phase. So it's a tough system. On the other hand, it works, and people are able to make it," Roberts said.

He and his colleagues are investigating possible ways to improve ice cream consistency through manufacturing. For example, they have narrowed down the range of possible mixing speeds during the freezing process that would produce the ideal ice crystal size.

"The manufacturing system is constantly under study," Roberts said.

Ice cream culture has also changed with the times, according to food anthropologist Merry White of Boston University.

In recent years, ice cream has been adopted by many cultures around the world, and made to feel right at home. Thus it's possible to eat gelato, say in China, and be eating a Chinese dessert, according to White. She calls this phenomenon "glocalization," as foods lose their initial local identities and get reassigned new ones.

"Ice cream reveals a great way of looking at how foods change. We think ice cream is all-American, but you really have to look further," she said.

Even on its home turf, ice cream's identity is constantly in flux, helped along by innovators like Gus Rancatore, owner of Toscannini's Ice Cream, in Cambridge, Massachusetts. Some of Rancatore's flavors were once unheard of, but nowadays, they make perfect sense. Rancatore kept Boston's changing demographics in mind when dreaming up flavors such as cardamom ice cream, which draws from Indian cuisine. The same goes for Guinness ice cream, which is reminiscent of some West Indian desserts, according to Rancatore.

Ultimately, no matter how much ice cream changes, thanks to technological advances in the ice cream factory or flavor experiments at the ice cream shop down the street, it's always recognizably itself. It doesn't take a Ph.D. to recognize the sign of a true classic.

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