With its numerous cultivated varieties, the sweet orange (Citrus sinensis Osbeck) constitutes one of the world's most popular and recognizable fruit crops. Sweet oranges are citrus fruits (Citrus spp.), which are regarded as high sources of vitamin C (ascorbic acid) and other fruit acids. These fruits are hesperidiums, because of their fleshiness and separable rind. Physically, citrus fruits consist of forty to fifty percent juice, twenty to forty percent rind and twenty to thirty-five percent pulp and seeds. They contain 86-92% water, five to eight percent sugars and one to two percent pectin with lesser amounts of acids, protein, essential oils and minerals (Janick et. al. 1981). Citrus fruits grow on small evergreen trees, many of which depend on root mycorrhizae and are cultivated as scions on rootstocks because they are interfertile.

In Studies:     Recent tests had shown orange peel extract (OPE), or more specifically, a key ingredient called d-Limonene which naturally occurs in citrus and a wide variety of other plant species, can prevent occasional heartburn, greatly reducing the number of occasional heartburn incidents.
There are currently two schools of thought on how OPE works to combat heartburn. On the one hand, OPE is thought to promote healthy peristalsis, the way in which the body moves food and fluids from one place to another. On the other, OPE is also thought to work as a surfactant, reducing the surface tension of the liquid contents in the stomach.
Studies had shown that OPE could give immediate relief for occasional heartburn but that long term use of the extract over a period of 20 days or more could provide long-lasting relief.

Technicals:     d-Limonene is found widely in citrus and many other plant species and is a major constituent of many essential oils. It is used extensively as a component of flavourings and fragrances, as a chemical intermediate and as an insect repellant.