If you keep lemons and limes on hand to add a squeeze to your tea or a twist to your happy hour cocktail, then you might not have thought much about the difference between these two kinds of citrus fruits. They might, by and large, seem the same, or even interchangeable — but there are more differences between the two types of citrus than the color of their skins. According to US Citrus, one of the key differences between lemons and limes is that regular limes are a little less flavorful, so lemons or key limes are used for punchier recipes. However, limes pair perfectly with tropical dishes, while lemons better lend themselves to European recipes.
Concerning nutrition, limes are technically healthier because they tend to have higher amounts of vitamins and minerals like vitamins A and C, calcium, folate, as well as phosphorus. Lemons tend to be more acidic and have minerals like potassium and magnesium. The most surprising difference of all, however, might be that lemons float while limes sink. If you toss a few in a bowl of water, you should find out that this is true. If you think that perhaps the skin of the citrus has something to do with whether or not they sink or float, that’s not the case. In an experiment conducted by Best Food Facts along with RD Sarah Downs, they tested both kinds of citrus whole, peeled, and sliced. In all three cases, the limes continued to sink further and further down into the water while the lemons stayed reasonably close to the surface. Even after the pieces shed their skin, the flesh of the citrus continued to sink, even for lemons, though they remained closer to the top of the water.
The reason why limes sink and lemons float is their density or their mass per unit of volume. Any object will float if it happens to be less dense than the liquid it is placed in and will sink if it is denser than the liquid it is in. Limes and lemons both have densities that are very close to that of water, so we would expect to both float. However, limes are slightly more dense than lemons, which is why they sink instead and lemons float.” So, the next time you drop a slice of either into your drink, you’ll know why it sinks or floats.