Because it's made from oranges.

Orange juice is a fruit juice obtained by squeezing, pressing or otherwise crushing the interior of an orange. The largest exporter of orange juice is Brazil, followed by the United States.

One orange will typically produce about 90 grams of juice, and when freshly squeezed, orange juice has a slightly spicy and somewhat acidic taste.[citation needed] Besides water and sugar, it is an excellent source of vitamin C (ascorbic acid) and potassium. It is also an important natural source of folic acid (Vitamin B9), which is recommended for women who are pregnant or may become pregnant.[1] Citrus juices contain flavonoids that are believed to have beneficial health effects. However, if drunk on an empty stomach, orange juice can exacerbate present gastro-intestinal conditions and/or cause mild and temporary stomach upset. Due to the citric acid, orange juice typically has a pH of 3.5. [2] Drinking, or sipping, orange juice over a long period of time can therefore potentially erode tooth enamel.

Food Lover

:)