Ice Cream Science: Researchers Find A Way To Prevent Crunchy Ice Crystals

Have you ever experienced being excited to eat ice cream, only to find that it has become crunchy because of ice crystals? A team of researchers has found a better way to stop the ice crystals from forming, thereby retaining ice cream's creamy texture.

Fresh ice cream has tiny ice crystals, but the ice tends to melt and regrow during storage and transport, the American Chemical Society (ACS) explained in a news release. If the ice crystals become bigger than 50 micrometers, this leads to that crunchy and grainy texture that isn't exactly what most consumers enjoy in ice cream.

So far, polysaccharides are "commonly used" to prevent ice recrystallization (IR).

"However, their ice recrystallization inhibition (IRI) effects are dependent on measurement conditions, such as concentration and type of sweeteners and storage temperature and time," the ACS noted. In other words, they can work well in some products, but not in others.

Nature has its own way of preventing the formation of ice crystals.

"Some fish, insects and plants can survive in sub-zero temperatures because they produce antifreeze proteins that fight the growth of crystals," Tao Wu, Ph.D., the principal investigator of the project presented Sunday at the ACS' spring meeting, said, as per the news release.

However, antifreeze proteins are quite expensive and limited, so it's not exactly practical to use them. Instead, the researchers simply used these antifreeze proteins to inspire their work.

As the ACS explained, these antifreeze proteins are ampiphilic. This means that they have a polar end that's attracted to water and a non-polar end that's hydrophobic. Nano-sized crystals of cellulose are also amphiphilic, so the researchers sought to determine if they can also stop ice crystals from forming in ice cream.

Initially, the Cellulose nanocrystals (CNCs) didn't have an effect on the model ice cream. But after a few hours of storage, it actually "completely shut down" ice crystal growth. On the other hand, the untreated ice cream had continued ice crystal growth, the ACS noted.

CNS did not only protect ice cream better than the stabilizers currently being used when faced with fluctuating temperatures, but it also caused the ice crystals to melt slower. This means that the ice cream also melted slower. And since CNCs are derived from the plant cell walls of agricultural and forestry by-products, they are "inexpensive, abundant and renewable," ACS noted.

This could then help the ice cream industry to develop "new materials and recipes to control ice recrystallization." Further work will also look at its possible benefits on other frozen products such as frozen fish and dough, and even to help preserve organs for transplant.