Dear Mr. Scientist,
How do fabric fresheners like Febreze work? From what I can tell they actually get rid of the bad smell and aren’t just covering it up.
—Chris G.
The active ingredient in these sprays is a ring-shaped molecule made of seven sugars called beta-cyclodextrin. This acts as sort of a circular cage and can trap other molecules. In the bottle, the cyclodextrins have pleasant smelling perfume molecules inside their rings. Once you spray something, any “bad smelling” molecules that the cyclodextrin rings encounter will swap places with the caged perfume molecules. Now that the unpleasant smelling odor molecules are trapped inside the rings, you are no longer able to smell them, and instead smell the pleasant perfume molecules that have been released.
Dear Mr. Scientist,
Being a Wisconsinite, this may be blasphemy, but how are they able to make nonalcoholic beer?
—Brian J.
The phrase “nonalcoholic” is kind of a misnomer, as it contains up to 0.5 percent alcohol. A really easy way to brew a beer with such a low alcohol content is to simply stop the fermentation process earlier than normal, so not as much alcohol is produced. Unfortunately this also prevents many of the flavor compounds people like from developing as well. Alternatively you can brew the beer like normal and remove the alcohol afterwards through distillation, reverse osmosis, or evaporation. In theory, these processes should leave the flavor molecules untouched and the end product should taste just like normal beer, but many popular opinion seems to disagree.
Ask Mr. Scientist is written by Michael Leitch. If you have a burning science question you want him to answer, tweet @DC_Science or email it to science@dailycardinal.com.
