Fermented apple juice is a fruit-based alcohol otherwise known as hard cider in the US, or cyder in the UK, and is made from certain strains of apples known as cider apples. It usually contains from 2% to 8.5% alcohol, as opposed to varieties of beer which contain around 5% alcohol. While cider is a common name for fermented apple juice, another type of cider that contains no alcohol content is known as sweet cider. Making fermented apple juice also can involve freezing apple cider or distilling it further to produce variations such as applejack and a form of brandy liquor known as apple brandy.
Fermented products such as beer, hard cider, and bread have been made by humanity since at least the time of the ancient Egyptians several thousand years ago. Hard cider was first produced in Europe around 55 BC when the invading Romans found natives to England drinking a version of it, and, as of 2011, the fermentation process has diversified to include the production of such products as antibiotics and vitamins. Cider fermentation itself is a relatively simple procedure that involves picking and aging cider apples for a week and then crushing them to obtain the juice that they hold. This apple juice contains its own natural sugars and yeast to start the fermentation process and produce alcohol.
Once apple juice has started fermenting, it is stored in wooden barrels for several weeks and fresh juice is added to the barrel to keep it continually full, as gas is released during aging by the yeast and reduces the volume to a degree. While fermentation is a natural type of aging or decay, apples with bad spots or mold have to be removed before making hard cider, as they will speed up the fermentation process and spoil the end product. Once the fermented apple juice has reached its maximum level of alcohol content, the barrels are then sealed for about six months more, as the volume will now stay relatively level.
Cider juice may be cloudy due to yeast residue and other impurities in it, and if green or unripe apples were used, it will have a relatively flat, unsweetened taste. Making fermented apple juice, therefore, sometimes involves adding ingredients after fermentation is done to improve the flavor. Often carbonation will be added to give it a soda-like taste, or, in locations like France, it is often refined further into various types of apple-flavored wine.
One of the benefits of fermentation is that it protects the end product from a type of spoilage. This is due to the fact that cider is usually pasteurized before being fermented, by heating it to 160° Fahrenheit (71° Celsius), which kills off harmful bacteria such as E. Coli or Salmonella. Fermented apple juice can also be frozen for an extended period of time without losing its quality.