Uh-oh, time to eat this for the morning coffee break: Swiss dark chocolate ice cream in its half-empty carton is forming telltale ice crystals, center top
LAUSANNE, SWITZERLAND – If you’ve never considered the instability of your ice cream beyond the fact that it disappears too quickly, you are clearly not an ice cream manufacturer.
We thought we were finished writing about the work of WSL, the Swiss avalanche and snow research insititute, now that the ski season is ending, but Nestlé has brought them back with news that the food multinational is collaborating with the WSL on ice crystals research, using a one-of-a-kind x-ray machine.
Nestlé hopes to uncover the holy grail of ice cream makers: how to keep its texture and structure and therefore quality for longer. Initial research results published 9 March in the journal Soft Matter.
A follow-up study is now underway with the SLF and a research group at the Paul Scherrer Institute in Switzerland, the company notes in a press release.
“The study found that as some ice crystals grow in size they fuse together, creating bigger crystals which cause the texture of the ice cream to coarsen,” says Cédric Dubois, a scientist working on the project for the Vevey-based food company.
“We already know the growth of ice crystals in ice cream is triggered by a number of different factors. If we can identify the main mechanism, we can find better ways to slow it down.”
A too-short slippery slope towards hard and icy or chewy ice cream
Closeup: Ice crytals come from the milk itself: not what mother cow intended
If you store ice cream too long in your freezer it develops ice crystals and, often, an inconsistent quality, with some bits going chewy and others hard. The ice crystals are the water that is in the ice cream itself.
“Ice cream is an inherently unstable substance,” says Hans Joerg Limbach, a scientist at the Nestlé Research Center in Switzerland. “As part of its natural aging process, the ice will separate from the original ingredients such as cream and sugar.”
Limbach says that temperature variations, which are clearly not good for ice cream, can occur at different stages of the product’s transportation and storage.
“For example, most home freezers are set at minus 18C, but the temperature doesn’t remain constant. It fluctuates by a couple of degrees in either direction, which causes parts of the ice cream to melt and then freeze again. The ice cream can sometimes become chewy due to loss of water or air, or icier and harder to scoop.”
WSL and the art of staying cool while studying ice crystals
Enter the WSL, which has the world’s only x-ray tomography machine “that allows long-term observation of tiny particles in a substance at temperatures of zero to minus 20 degrees Celsius,” Nestlé notes in its statement about the partnership. They “monitor the evolution of ice crystals in snow and how this affects its properties: key factors for understanding avalanche formation. Ice crystals affect the properties of ice cream in a similar way, altering its texture and structure as they grow and change shape.”
The WSL is one of the world’s top avalanche and snow research centres. The Davos-based institute, which in 2011 celebrated its 75th anniversary, is a well-known name to Swiss back-country and off-piste sports fans, thanks to its excellent snow condition maps and bulletins. GenevaLunch includes the group’s daily bulletins every Friday during the ski season when we issue a Swiss resorts weekend snow and winter sports report.
Ice cream people in Vevey, with its fine view of the snowy Alps, naturally turned to the WSL with their dilemma. The difficulty until now has been finding a way to examine material at -20C without destroying the sample. “This method is non-invasive and does not disturb the product,” says Dubois. “X-ray technology is normally used at room temperature, but this machine works within exactly the right range for frozen food.”
The new work with the Paul Scherrer Institute is giving the researchers “access to technology that should enable them to examine even higher resolution images of the microscopic particles in ice cream.”
