If you’ve ever wondered if there was an easy way to tell if your blueberries are ripe or not, @onlybsides has a hack for you.

The millennial mom explained that both she and her kids are “texture” people and have a hard time eating blueberries without knowing what they are going to get because blueberries are “notoriously not the same” when it comes to taste and texture.

But when washing blueberries one day, she noticed that some of the blueberries floated while others sank to the bottom of the bowl.

She discovered that when blueberries are ripe, their “specific gravity” changes, causing them to sink to the bottom, while the less-ripe berries stay floating.

“Now I know that all of these blueberries are going to be more sour than the ones in the bottom, and I can put them in a separate container. That’s rad!” she explained and exclaimed in the video.

Why ripe blueberries sink

As a 2020 study in Foods found, the soluble solid concentration of blueberries increases as they ripen, which makes the berries heavier, causing them to sink.

The knowledge of how the specific gravity of blueberries affects their ability to float is even part of how many berries are sorted to sell.

“It is known that ripe blueberries have a specific gravity greater than that of water and that unripe berries have a specific gravity less than that of water,” explains a patent of a blueberry sorting product.

“A common practice when harvesting blueberries is to pour the ripe and unripe mixture of blueberries into a tank of water to not only wash them, but also cause ripe berries to sink and green or unripened berries to float on the surface to be skimmed off and separated.”

You can also get clues about a blueberry’s ripeness by a visual inspection as well. For instance, the United States Department of Agriculture (USDA) also defines a ripe blueberry as having “firm, not soft or mushy” skin that “yields very readily to slight pressure” but is not soft or mushy.