Cider apple
Cider is made in several countries and can be made from any apples. Historically the flavours preferred and varieties used to produce cider have varied by region. Many of the most traditional apple varieties used for ciders come from or are derived from those from Devon, Somerset and Herefordshire in England, Normandy in France, and Asturias in Spain, and these areas are considered to have their own broad cider styles although the many exceptions make this more of a historic footnote. Normandy cider is usually naturally carbonated and clear: Asturian cider apple varieties are mainly 'sharps' or mild 'bittersweets', producing a mildly acidic cider which is customarily served by being poured from height into the glass to oxygenate it.
Citric acid
In 1917, American food chemist James Currie discovered certain strains of the mold "Aspergillus niger" could be efficient citric acid producers, and the pharmaceutical company Pfizer began industrial-level production using this technique two years later, followed by Citrique Belge in 1929. 
In this production technique, which is still the major industrial route to citric acid used today, cultures of "A. niger" are fed on a sucrose or glucose-containing medium to produce citric acid. The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch or other inexpensive sugary solutions. After the mold is filtered out of the resulting solution, citric acid is isolated by precipitating it with calcium hydroxide to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid, as in the direct extraction from citrus fruit juice.