Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=216114
Story Retrieval Date: 5/25/2013 3:16:52 PM CST
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Emily Wasserman/MEDILL
Researchers at the University of Wisconsin-Madison are studying how structures found in milk affect how ice cream melts.
Here’s the scoop: Researchers at UW-Madison study ice cream
by Emily Wasserman
Feb 19, 2013
Maya Warren/University of Wisconsin-Madison
The size and number of fat globules in ice cream may affect how it melts and drips, say researchers at the University of Wisconsin-Madison.
Fun Facts about Ice Cream
U.S. Department of Agriculture:
- Ice cream in the U.S. by definition must contain at least 10 percent milk-fat
Researcher Maya Warren unravels the meaning of icy desserts:
- Ice creams in the U.S. generally range from 10 percent to 16 percent milk-fat.
- “Overrun” is how much air ice cream manufacturers pump into their product.
- The legal limit for overrun in the U.S. is 100 percent
- Custard by legal definition in the U.S. must contain 1.4 percent or more egg yolk
- Sherbert is a combination of ice cream and sorbet. It contains 3 to 4 percent milkfat
-Gelato has less air than ice cream, creating a stiffer product
- Sorbet does not contain any dairy ingredients; it consists of sugar, water, flavor or fruit
International Dairy Foods Association:
- Vanilla is America’s favorite flavor of ice cream
- America’s top five flavors of ice cream are: Vanilla, Chocolate, Cookie ‘n Cream, Strawberry, and Chocolate Chip Mint
-
The U.S. dairy industry produced approximately 20 quarts per capita in
2010. That’s 20 x 314 million people in the U.S. = 6.3 billion quarts.
-
The central region of the U.S. led production of ice cream and related
frozen products in 2011 (Source: USDA, National Agriculture Statistics
Service)
- In 2011, the central region of the U.S. produced 726 million gallons of ice cream
- The U.S. ice cream industry generated total revenues of $10 billion in 2010 (Source: MarketLine)
Few consider the science behind this phenomenon, but researchers at the University of Wisconsin-Madison are getting beyond the cone to study how ice cream melts.
“If you’ve ever had an ice cream cone on a hot, sunny day, you know that, often, before you get halfway through the cone it’s dripping down your hand,” said Rich Hartel, professor of food engineering at the University of Wisconsin-Madison. “So we’re trying to understand better what factors affect that, and surprisingly, after however hundreds of years of making ice cream, we still don’t know.”
Hartel and his team take samples from different brands of ice cream to study the melting process. Brands include Haagen Daas, Chocolate Shoppe, Ben and Jerry’s and Edy’s.
Because their data has not yet been published, researchers chose not to disclose the melting behavior of specific brands, said Maya Warren, a Ph.D. student in Hartel’s lab.
Researchers place slices of frozen ice cream on a mesh screen, and measure how much of the product “drips through” the mesh after two hours.
Researchers also measure the height of the ice cream to determine how much of it stands up.
“All ice creams will melt because they all have ice in them,” Warren said. “However, not all ice creams will fully collapse or deflate or come through the screen like you would expect through gravity.”
Warren and Hartel said the reason why certain ice cream does not melt through the screen has to do with structures - called fat globules - found in milk. The globules partially bind together, or coalesce, forming an internal structure that literally holds the ice cream up.
If there are a large number of partially coalesced fat globules in an ice cream sample, or the globules are large themselves, they can withstand the force of gravity, Warren said.
Warren added that different brands of ice cream have varying concentrations of fat globules, which affects the rate at which they drip through the screen. For example, an ice cream with large partially coalesced globules has a very low drip-through rate.
“Literally after two hours, after a day of sitting there, only about 10 percent of its weight would have come through the screen,” she said.
Ice creams with small partially coalesced fat globules results in a much different “meltdown” and “drip through” rate, said Warren.
“The very large difference in size and the small number of globules will allow for the ice cream to completely flow through the screen just as if it’s soup or an ice cube that literally just melts,” Warren said. “Basically 98 percent will go through.”
However, Hartel emphasized that the quality of the product does not play a role in its drip-through and melting rates.
“You can find ice creams that have no stand-up, that melt right through, and you can find products that stand up completely and don’t drain through, and both of them are very good commercial products,” Hartel said.
According to the U.S. Department of Agriculture, 1.53 billion gallons of ice cream and related frozen desserts were produced in the United States in 2011. In 2010, the average American consumed 11.9 pounds of ice cream.
Despite the high demand for ice cream, Hartel said few companies consider the structural components of their products.
“I don’t think any ice cream manufacturer thinks about what they’re doing, in terms of meltdown and drip through,” he said. “I think they just make their ice cream, and develop the formulation to make their ice cream and taste it. And if it’s okay, then they’re happy with it.”
Hartel and his team have yet to find conclusive evidence to explain the differences between meltdown and drip through rates. He said this work could potentially appeal to companies who want to better control their product.
“I think that some companies, bigger companies in particular, would use this kind of information and say well, we really want an ice cream that doesn’t drip through,that even though it’s melting, it’s not dripping. And design a product like that,” Hartel said.
He added that further research could lead to a practical application of their findings.
“In this case the application would be ice cream makers actually controlling what they make as opposed to just taking what they get,” Hartel said.
