[ intro ].

Everyone knows the sadness of biting into a fresh piece of fruit only to find the inside is dry and mealy. It happens to lots of produce: peaches, watermelons, tomatoes, you name it.

Some of the worst offenders are apples, like those shiny Red Delicious that are beautiful on the outside and all grainy when you take a bite. But these fruits aren't /inherently/ terrible. They can start off yummy, and /become/ grainy.

And a lot of the problem has to do with the way they're stored. When ripe apples are stored at cool temperatures, like inside your fridge, the cells making up the flesh of the fruit unstick from one another. But the tough outer walls of these cells stay strong, so when you take a bite, they don't break apart and release any juice.

So instead of a burst of flavor, you just get that mealy texture. That gets worse as the apple dries out. Without moisture, the cells shrivel— and biting into those shriveled cells is like trying to pop a deflated balloon.

The cells are less likely to burst and release their flavor. And the more mature an apple is, the more it dries out. Plus, the cold air inside a refrigerator speeds up the drying process, since it holds less moisture than warmer air.

So research suggests that if you want to save an apple for a few weeks, your best bet is to pop it in the fridge right away, before it becomes /too/ mature. But the same rule doesn't apply to all potentially-mealy fruits. Soft fruits, like peaches and nectarines, can become mealy if you refrigerate them /too soon/.

That's because their mealy texture is tied to the breakdown of a substance called pectin. Pectin is a carbohydrate in cell walls that fruit generates as it ripens. It strengthens cell walls and makes them stick together.

But pectin can dissolve in water. And over time, as it dissolves, the cell walls lose their strength. In some fruits, pectin doesn't /just/ dissolve, either— it also gets broken into pieces by enzymes.

And that's a good thing. Under normal conditions, the cell walls weaken through these processes, and the fruit becomes nice and soft. When you bite into it, the cell walls burst and release their juice.

Like a proper fruit. But as soon as you stick these fruits in the fridge, that natural process starts to veer off track. In general, low temperatures slow down chemical reactions, so if you keep fruit cold, its pectin molecules break down less.

And /that/ means the cell walls hold up when you bite into them, so whole cells break apart, rather than bursting. And you get a sad, mealy mouthful. But not all fruits will come out of the fridge equally pathetic.

Different kinds have different compounds attached to the pectin molecule, so they often ripen differently. And as a result, they /also/ react differently to refrigeration. Still, as a general rule, fruits that continue to soften after they're harvested— like peaches, nectarines, cantaloupe, and tomatoes— should only be refrigerated /after/ they're fully ripened if you want to avoid that gross, grainy texture.

Unfortunately, you can't always know what happened to your fruit before it got to the store. And from the outside, it's impossible to tell which fruit already has a mealy texture. But you can make sure it's not your fault that it becomes mealy by storing it at the right time.

Thanks for watching this episode of SciShow! If you liked this episode and you want to learn about another reason we end up with disappointing fruit, you might be interested in this video about why apples turn brown. You can watch that one next! [ outro ].