If there's one thing we all know about blueberries, it's that they have a wide spectrum of flavors. Ripe blueberries, for instance, have a nice sweetness, maybe a note of acidity. On the other hand, under-ripe blueberries can be tart enough to make your mouth pucker. Although you can guess a blueberry's flavor from its color and firmness (ripe berries are softer and a blue-gray color; less ripened berries are firmer and may have hints of purple or green), you usually can't know for sure until you eat them. Or can you?
Interestingly enough, you can easily separate sweet blueberries from the tart ones by pouring them all into a bowl of water. Sweeter, riper berries will sink to the bottom of the bowl, while the berries that are less ripe and more tart will float. Weird, right?
One thing to be mindful of when using this trick is that you should only rinse blueberries right before you intend to eat them. To keep blueberries fresh, they need to remain dry, with their natural waxy coat intact.
The Science Behind Blueberries Floating Or Sinking
Being that ripe blueberries consistently sink and less-ripe blueberries consistently float, there's got to be some sort of science involved here. As expert Heather Arndt Anderson explains, the sink-or-float situation actually has more to do with specific gravity than anything else.
In an interview with AllRecipes, Anderson noted that "a ripe blueberry has a greater specific gravity than water" due to the sugars it contains. In other words, ripe berries are denser than water, so they sink. Conversely, the less-ripe berries contain less sugar, resulting in a lower specific gravity than water. Being less dense than water, they float.
That being said, this method is not entirely foolproof, so many blueberry-processing machines simply rely on visual inspections to weed out damaged blueberries. After all, sweet blueberries and tart blueberries are equally safe to eat, so there's no real reason for manufacturers to separate them anyway. If you try this hack at home, just be sure to not make the blueberry mistake of throwing out the less-ripe ones –- they're still perfectly suited to a blueberry muffin recipe!
Read the original article on Mashed.