Cider
Cider is an ancient beverage. No-one knows when or where it was first made, because the native distribution of its principal component, the apple, is so widespread, from the Near East to Northwestern Europe. In the cider market, ciders can be broken down into two main styles, standard and specialty. The first group consists of modern ciders and heritage ciders. Modern ciders are produced from culinary apples such as Gala. Heritage ciders are produced from heritage, cider specific, crab or wild apples, like Golden Russet. Historically, cider was made from the only resources available to make it, so style wasn't a large factor when considering the production process. Apples were historically confined to the cooler climates of Western Europe and Britain where civilization was slow to develop record keeping. Cider was first made from crab apples, ancestors of the bittersweet and bittersharp apples used by today's English cider makers.
Cider
The acids in cider play a vital role in both the cider making process and in the final flavour of a finished cider. They are present in both apples and cider, and add a sour taste and a pungent odor to these respective substances. Acids also serve as a preservative in the cider since microbes grow less in lower pH environments and contribute to the fermentation process. Most ciders have a pH of between 3.3 and 4.1. The primary acid found in apples is malic acid which accounts for around 90% of the acid content in apples. Malic acid contributes to the tart and sour flavours found in cider, and typically between 4.5 and 7.5 grams of malic acid per liter of cider is preferred. Malic acid is also used to determine apple ripeness for harvesting, as its concentration decreases as the fruit ripens. Lactic acid is also commonly found in cider, and it is mainly formed from malo-lactic fermentation, a process that converts malic acid into lactic acid. This process rounds out the flavour of the cider while reducing a lot of the acidity and producing carbon dioxide as well. Other acids such as citric acid can be used to add taste after fermentation, but these acids are not typically found in high concentration in apples naturally.