Q: What are soapnuts?
Soapnuts are fruits from a shrub that grows in parts of Asia and the Americas. Alternative names include soapberry and sapindus. The fruits are dried and then boiled to release a natural detergent for washing (Ind. Eng. Chem.,pp712-713, 1939). The detergent is used not just for washing hair but also even more 'serious' tasks such as laundry.
Q: Really can you just boil a dry fruit and get shampoo?
For those of you who read my oat and bean water shampoo article, this will not come as a surprise to you. Soapnuts naturally contain a chemical known as saponin (sounds a bit like soap!). Saponins are detergent like in behaviour because they are amphiphilic.
Amphiphilic means that on a single molecule you have both a part that is attracted to water and a part that is attracted to oil. Why is this important? It all boils down to the fact that oil and water do not mix, and in order for oil to be removed (i.e cleansing to occur), you need a molecule that can attach to oil and at the same time force it to mix with water so that it can be rinsed off. Therefore you need both a water loving and oil loving part on the same molecule.
If you are a visual learner, here is an old diagram, showing you how SLS behaves, the process with saponins would be similar in principle except of course that saponins from soapnuts are a little larger and can be extracted by you boiling the dry fruit. (If you want more details, read how surfactants work in full - here).
|Demonstration of how hair cleansing works from a chemical perspective|
Q: What is the pH of the soapnut shampoo water?
I have not done any experiments myself but I have seen some commercially extracted saponin with a pH of around 4-5when dissolved in water.
Q: Ok, so you really are saying we can boil some dry fruit and use that water to wash you hair?
I am indeed, here is a helpful video guide!
Have you heard of or have you used soapnuts? What is your experience, does it clean well? Have you done a pH test?