Limonene is a clear liquid that smells of freshly peeled oranges. It can be used in biodegradable cleaning soap, biofuel, botanical insecticide, insect repellent, and it is said to relieve gastroesophageal reflux disease and heartburn.
This video shows how to extract limonene without having to waste lots of energy on distillation or having to use toxic solvents such as liquid carbon dioxide.
The world market for soaps and detergents is valued at $38 billion, the equivalent of 35 million tons of products so for those having acces to citric fruits like oranges or lemons, making soap can be a good way to earn some money.