What’s the difference between extra virgin and virgin olive oil?
Aside from the difference in colour, extra virgin and virgin olive oils have different concentrations in oleic acid. The chemical definition of oleic acid is a fatty acid formed of a long chain of carbon atoms. Extra virgin olive oil has a concentration of oleic acid less than 0.8% in mass concentration. With time the fat in oil breaks down to fatty acids, a phenomenon that increases the concentration of oleic acid in the fluid. In soap production we use virgin olive oil, reason being that the saponification reaction requires fatty acids to react with the caustic soda. If the oil is extra virgin, then the reaction won’t start easily. In conclusion, if you read a label that mentions ingredients with extra virgin olive oil then most probably it either contains additives to jumpstart the reaction or the oil has been heated for an extended period of time. In both cases, this soap is not the best in class.