Many people are surprised to learn that orange juice naturally contains a small amount of alcohol. The alcohol has not been added to the juice, but is produced by fermentation which occurs when yeasts or bacteria convert sugars into carbon dioxide and alcohol. There are many naturally-occurring yeasts on the orange peel, and some of them get into the juice when the orange is handled or squeezed.
Paul Davis from the USDA Market Quality Research Division measured the amount of ethanol in citrus fruits at harvest (ethanol is the “drinking alcohol”—the main form of alcohol in wines, beers and spirits). He found large variations according to the variety of fruit and also according to the month of harvest. Fruit picked towards the end of the harvest season was highest in ethanol (because the yeasts have had longer to convert sugar to alcohol). The exception was the Valencia Orange, which had a fairly constant alcohol content throughout the season.
The amounts that Paul Davis measured were very low, the highest being just under 0.07% alcohol by weight (equivalent to around 0.09% alcohol by volume) in Valencia Oranges.
After the orange is picked the ethanol content continues to increase, depending on how long and in what conditions the orange is stored. To reduce spoilage, fruit is sometimes stored in an artificial atmosphere. Davis also treated his fruits with fungicide. After eight weeks of storage he obtained ethanol readings up to 0.31% ABW (0.39% ABV).
In many countries any drink with less than 0.5% ABV can legally be described as non-alcoholic, because your body can metabolise the alcohol as fast as you consume the drink. Although all orange juice contains alcohol, the quantity is low enough that you won’t get intoxicated from it, even if you drink many glasses of it. However in places with zero-tolerance rules against driving with any measurable alcohol in your blood, you might need to be careful if you are a very heavy orange juice drinker.
Paul Davis focused his research on citrus fruits, but other fruits such as grapes and peaches also have alcohol in their juice.
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