Why Does Ice Cream Float on Root Beer? And Some Other Stuff!

It is all about density! Ice cream has a high fat content, and fat is less dense than water, so a scoop of ice cream floats on water solution or a glass of root beer. More expensive ice creams are higher in fat, which gives their velvety texture, and are more ‘dense’ than their lower priced counterparts. Premium ones have the highest fat content and least air bubbles. Ice cream has a lot of air bubbles trapped in a matrix of fat and sugar molecules which also lowers its density.

Do an experiment about density and have a root beer float party! Buy a few different brands of ice creams, some root beer, and see if the kids can ‘guesstimate’ the fat content and density of each ice cream in each root beer float.

You can change the temperature of the root beer( or coca cola) by a tiny bit and see what happens to the float! An excellent way to have the kids think about science without going near a textbook.

For customers wanting more from their ice cream eating experience, functional ice cream is coming soon to mainstream grocery stores. Adding a probiotic culture instead of a stabilizer is fashioning ice cream into an attractive delivery tool for probiotics. A stabilizer is added to make ice cream melt slower, and to make it taste more smooth and creamy. Examples of routinely used stabilizers are gelatin, egg whites, guar gum and the like. Due to an increasingly health-conscious consumer market, food research is driven toward functional foods, improving taste and texture, while taking away additives that are viewed as ‘processed’. For alternative or nondairy, probiotic ice creams, coconut milk, and soy milk shows the most promise.

Here is a link to a probiotic, home-made ice cream recipe from www.homemademommy.net, which hints an utterly delicious result looking at the ingredient list. To a first-time ice cream maker (such as myself), I would suggest being conscious of the ‘beating continuously’ part of instruction in the recipe, as that is the process where air gets mixed in which determine the structure of the ice cream. Structure relates to taste because structure relates to how slowly or quickly flavor releases into the mouth. (Think of whipped cream vs. a spoon of liquid sweetened cream.) But this is a fitting summer project for perfecting in the kitchen!

P.S – If you are doing a density experiment with ice cream, and need more details about preparing a data and results table, contact me and I can provide one.


Reference: Aboulfazli, Fatemeh, Amal Bakr Shori, and Ahmad Salihin Baba. “Effects of the Replacement of Cow Milk with Vegetable Milk on Probiotics and Nutritional Profile of Fermented Ice Cream.” LWT – Food Science and Technology 70 (2016): 261-70. Web.