The soap nut (Sapindus trifoliatus and Sapindus mukorossi), which originates from India, has been used as a vegetable detergent in everyday life since time immemorial. After ten years, the tree produces its first fruits: orange-coloured, sticky nuts, which are harvested in September. After drying, the fruits are red-brown to dark brown and no longer sticky. Only the shells are used, which contain up to 15% wash-active saponins, whereby the quality is determined by the harvest time and the age of the tree.
Use as detergent
The fruits are traditionally used in India to wash clothes and hair. The shells of the nuts release a soapy lye as soon as water is added. This ensures gentle and thorough cleaning. Soapnuts are traded as whole nuts, as well as in powder form, as ready-to-use halved shells or as liquid detergent.
For washing, the nuts are cracked, the black kernel is disposed of and the shells are placed in a cotton sack (or an old sock) for washing in the drum. Depending on the washing temperature and the hardness of the water, the quantity required varies from 3 to 7 nut shell halves. The washing nuts can be used for two washes at temperatures of up to 40°C, after which the rest is also composted. When washing whites, it is advisable to add an additional bleaching agent (or alternatively a teaspoon of baking powder) from time to time to prevent a grey haze, as soapnuts do not contain optical brighteners. Depending on water hardness, a water softener should be added (or alternatively citric acid) as the detergent saponine glycoside is also effective in acidic solutions. Laundry washed with soap nuts is odourless, so you can add a few drops of essential oil (lavender, lemon, verbena) in the fabric softener to give your laundry the desired scent.
As a shower gel or shampoo, boil a few wash nuts in water and pour the liquid into a bottle. The soapnut liquid can also be used as an all-purpose household cleaner. Soapnuts ground into powder are used as a hair shampoo or body cleanser. In use, it hardly foams at all, yet has very good cleaning power. Another advantage is that it is able to wash out chemical residues. This is why it is also used in the countries of origin to wash fruit and vegetables. In this way, dangerous pesticide residues can be significantly reduced.
Soapnuts are also used in Chinese and Ayurvedic medicine.