As I get more and more familiar with the beverage, I begin to see how much there is to cider that we might not immediately perceive. Particularly here in the Northwest, where nearly every orchard apple was planted for eating, we tend to think of cider as a crisp, sweet drink characterized mainly by a light apple flavor. Because that's what eating apples produce. There's more to it than that.
In the old traditions, cider should actually be a more complex drink. The humble apple comes in a variety of types, and many of them are, as Abram Goldman-Armstrong calls them, "little gnarly, scabby things" no one would eat. But these apples are full of important compounds that give a proper cider its holy trinity of balance: tannins, acidity, and sweetness. Indeed, among these, perhaps the least important is sweetness. Sweet apples are loaded with sugar, but sugar is easily fermentable, so what you're left with is a neutral beverage. (Cider makers can "back-sweeten" a cider by adding apple juice back to the fermented cider to give it more flavor--and sweetness.)
But cider apples have tannins and acids that stay behind. Tannins are a group of phenolic compounds that come from the skin and seeds of the fruit (not all phenolics are tannins, but you can look into the chemistry if it interests you) and gives a character that you can feel as well as taste. Tannins are astringent and drying and contribute to the sense of body. Sometimes people call them "bitter," but for beer geeks this may be confusing. They're bitter like kale is bitter. Astringent is better, because in your mouth, you'll detect tannins when you swallow--your mouth will have a chemical kind of dryness. Those phenols in the apple, incidentally, can contribute the band-aid/medicinal character you find in some wild and wheat ales.
|My July 4th cider: a Dupont.|
Residual sweetness has its place in ciders--tannins and acids are strong players, and they need softening by a bit of the fruit's native sugars. Even dry ciders will have a bit of sweetness for balance.
One final note. Rarely will a single apple variety have a perfect balance of all three of these elements. Blending apple varieties is one of the great skills of cider-making. In this way, it's a lot like brewing a lambic. Blending isn't used to moderate or soften a beverage, as in whiskey, but to find richer balance points not available in single varietal or unblended stocks.