Apple Texture

From from http://www.cooksillustrated.com/, Published September 1, 2008

Why do some apples turn to mush and others stay firm when cooked?

As anyone who has made applesauce or an apple pie knows, some types of apples turn mushy when cooked and others remain quite firm. And sometimes even the same type of apple will produce different textures.

Differences Among Apple Types

The texture of apples depends on three things: the thickness and composition of the cell walls, the amount of acid in the apple, and the amount of air between the apple cells.

The first factor is the composition of the cell walls, which are made of cellulose and are held together with pectin. The crunchier, crispier varieties (such as Granny Smith) contain more cellulose. Even before cooking, you can clearly see the difference between crunchy Granny Smith apples and softer McIntoshes. As an apple is cooked, the pectin melts and the cells fall apart. The varieties with more cellulose will remain more firm, while those with less cellulose will become softer.

The next factor is acid. Acid strengthens pectin and keeps it from dissolving so readily when heated. Naturally acidic apples, such as Granny Smiths, are thus more likely to hold their shape than other varieties.

Finally, the air. Apples have lots of air pockets between their cells (25 percent or more of their volume may consist of air), which is why they float. When apples are cooked, the air escapes and the air pockets collapse. As a result, there is a loss of firmness and volume. The less air an apple has to begin with, the firmer it will be, both before and after cooking.

Differences In the Same Apple Type

While developing our Skillet Apple Pie recipe, we noticed that the apple filling occasionally turned mushy. Our science editor explained that apples that aren’t going to be sold within a few weeks of harvest are placed in refrigerated “controlled atmosphere” (CA) storage with regulated levels of oxygen and carbon dioxide. Because apples continue to ripen after harvest, these conditions are designed to halt the ripening process. The problem is that once the apples are removed from CA storage and put on display at the grocery store, they begin an accelerated ripening process. The apple’s structure will then quickly break down upon cooking. The longer the apples are kept in CA storage (and they may be stored as long as 10 months), the faster they ripen once removed, and the more likely they are to turn mushy during baking.

Because it is impossible to know how long or under what conditions supermarket apples have been stored, your best bet is to use fresh, local apples whenever possible. If you purchase fresh apples, refrigerate and use them as soon as you can.

From Seriouseats.com

These are the results of J. Kenji Lopez-Alt's (he used to work for Cook's Illustrated) apple pie tests. He used 10 different kinds of apples and compared the results. He found Golden Delicious and Braeburn (descendent of Granny Smith) are the best for cooking when you want the apples to hold some shape: pies, apple crisp, etc.

Red Delicious

Flavor: Very sweet and one-dimensional.
Texture: Mealy flesh that turns to mush when cooked. Skin is thick and can be quite bitter. They may look good on the supermarket shelf for a long time, but are only really tasty when fresh picked.
Pie Rating (1-10): 1; Completely mushy with a very one-dimensional, cloying flavor. This reminded me of bad applesauce.
Best uses?: Eating out of hand, but only when very fresh.

McIntosh

Flavor: Sweet and mildly tart with very white flesh.
Texture: Tender and slightly grainy.
Pie Rating (1-10): 3; it holds up better than, say, Red Delicious in pies, but still turns quite brown and mushy.
Best uses?: Apple sauce or eating out of hand.

Braeburn

Flavor: Very sweet and mildly tart with a unique citrusy aroma, similar to Granny Smith (of which it is a descendent). It becomes almost pear-like in flavor when it cooks.
Texture: Quite crisp and not much graininess. This texture seems to indicate that indeed it has a fairly strong structure of pectin.
Pie Rating (1-10): 7; it manages to soften fully while still retaining a good deal of texture when baked into an apple pie due to its density. It could be slightly firmer when baked. Great golden color.
Best uses?: Pies, tarts, sauce, eating plain.

Rome

Flavor: Very mild when eaten out of hand, not very sweet, but develops in flavor when cooked.
Texture: They have a thick skin and very firm flesh. Despite having a reputation as being a good baking apple, I found them unsuitable.
Pie Rating (1-10): 3; They turn dark brown and mushy as they baked.
Best uses?: Sauce.

Fuji

Flavor: Quite sweet and fresh tasting, not cloying.
Texture: Crisp flesh that stays good for a long time. The texture is almost pear-like in its moisture level and crunchiness.
Pie Rating (1-10): 2; The mild flavor does not get enhanced by baking. Watery but tart.
Best uses?: Eating out of hand.

Golden Delicious

Flavor: Sweet, tart, and almost buttery. Well balanced and rich, especially when cooked.
Texture: Very fresh it's quite crisp, but can border on mealy when held for too long off the tree. When baked, it softens but retains a bit of texture
Pie Rating (1-10): 8; the best flavor I got out of any single apple—this is what apple pie should taste like. I just wish it were slightly firmer.
Best uses?: Pies, sauce, apple butter.

Cortland

Flavor: Similar to a McIntosh, but much sweeter and tarter. Like its cousin, it's got very white flesh and a mild flavor.
Texture: Tender and slightly grainy,
Pie Rating (1-10): 4; it does quite well in pies texturally—softening without breaking down—but lacks in flavor.
Best uses?: Apple sauce or eating out of hand.

Empire

Flavor: Very sweet and very tart with a good level of juiciness, they are a cross between a McIntosh and a Red Delicious, and show flavors from both.
Texture: Despite their tender/grainy ancestry, their texture is quite firm and crunchy.
Pie Rating (1-10): 3; when baked, they have nice texture, but become cloyingly sweet. The acid is still present, but it's not enough to fight against the sugar level.
Best uses?: Eating out of hand.

Royal Gala

Flavor: Mild and sweet with a fair amount of tartness, they're one of the most popular apples around for their small size and good resistance to bruising.
Texture: Very thin-skinned with a grainy texture.
Pie Rating (1-10): 6; when baked, they hold their shape, but the graininess can get overwhelming. I prefer my pie apples to be supple and smooth-textured.
Best uses?: Eating out of hand.

Granny Smith

Flavor: Very bright and tart with a distinct citrus aroma and white wine-like nose.
Texture: Very firm, crunchy, and slightly grainy.
Pie Rating (1-10): 5; it holds up almost indefinitely when cooking. They have good brightness, but not much apple-y flavor.
Best uses?: Eating out of hand.