Botany: Bitter orange is an evergreen glabrous tree with long but not very sharp spines and very fragrant flowers. It grows up to 10 m high. It is native to southern China and north-eastern India. It is cultivated in China, southern Europe and USA. Membranes and pulp of the fruit are very bitter and sour. Parts used are the peel of the fruit, freshly picked flowers and leaves and twigs.
Sweet orange is a smaller tree than the bitter orange tree, less hardy, and with few or no spines. The fruits are smaller, with sweet pulp and non-bitter membranes. It is native to China, and is extensively cultivated worldwide, especially in USA (Florida and California) and Mediterranean countries. Parts used are the peel of the partially or fully ripe fruit.
Best known products of the bitter orange tree are bitter orange oil, neroli (orange flower) oil and petitgrain oil (extracted from the green twigs by steam distillation).
Best known products of the sweet orange tree are sweet orange oil and terpeneless orange oils.
Anti-inflammatory, antibacterial, and anti-fungal activities.
Bitter and sweet orange, neroli, and the petitgrain oils are extensively used as fragrance components in soaps, detergents, creams, lotions, and cosmetics. The highest concentration used is 1.0% reported for bitter orange oil in perfumes.
Bitter orange oil is reported to have distinct phototoxic activity, while none is reported for expressed sweet orange oil even though both oils contain coumarins.
Expressed sweet orange oil, bitter orange oil, and neroli oil are generally reported to be non-irritating and non-sensitising to humans. However, limonene present in citrus oils has been known to cause contact dermatitis in humans.