Pruno or prison wine is an alcoholic liquid variously made from apples, oranges, fruit cocktail, ketchup, sugar, and possibly other ingredients — including bread. It originated in (and remains largely confined to) prisons, where it can be produced cheaply, easily, and discreetly. The concoction can be made using only a plastic bag, hot running water, and a towel or sock to conceal the pulp during fermentation. The end result has been colorfully described as a "vomit-flavored wine-cooler", although it should be noted that flavor is not the primary objective. Depending on the time spent fermenting, the sugar content, and the quality of the ingredients and preparation, pruno's alcohol content by volume can range from as low as 2% (equivalent to a weak beer) to as high as 14% (equivalent to a strong wine).
Typically, the fermenting mass of fruit — called the motor in prison parlance (from "promoter") is retained from batch to batch, to make the fermentation start faster. The more sugar that is added, the greater the potential for a higher alcohol content — to a point. Beyond this point, the waste products of fermentation cause the motor to die when the yeasts outgrow their food supply. This also causes the taste of the end product to suffer. Ascorbic acid or Vitamin C powder is sometimes used to stop the fermentation at a certain point, which, combined with the tartness of the added acid, somewhat enhances the taste, by reducing the cloyingly sweet flavour associated with pruno.
Inmates are not permitted to have alcoholic beverages, and prison authorities confiscate pruno whenever they find it. The beverage, if made improperly — such as in 'tin cans' — can cause severe illness and possibly blindness. In an effort to eradicate pruno, some wardens have gone as far as banning all fresh fruit from prison cafeterias. But even this is not always enough; there are pruno varieties made almost entirely from sauerkraut and orange juice.
A variety of other alcoholic prison-made potables are known to exist. These include crude wines, famously fermented in toilet tanks. Sugary beverages like orange drink may also be fermented slowly using a radiator or other available heat source. Though popularized in prison fiction, these techniques are slow and laborious, and generally result in a low alcohol content.
In 2004 at the American Homebrewer's Association's National Homebrew Conference in Las Vegas, a pruno competition and judging was held.