An ester is a molecule that has undergone esterification. (Wow, that was clear, eh?) Esterification is a chemical reaction - for our purposes between a carboxylic acid (like a fatty acid from vegetable oils) and an alcohol - that leads to the creation of an ester and water (as a by-product).
The carboxylic acid loses its H - hydrogen - and the alcohol loses its OH, so we have H20! See below for a nice picture of this process!
So what does this all mean to us as bath and body creators? Esters are everywhere! They're fragrances and flavours, thickeners, protective emollients, non-occlusive emollients, dry and astringent emollients (like IPM), and more! So let's take an in-depth look at esters and how we use them in our amazing products!
FRAGRANCE AND FLAVOUR OILS
Yep, these are esters. In fact, the word ester refers to their fragrant - but not always lovely - scent. They are found in nature, and are the key chemicals we associate with certain fruits or flowers. Ethyl butyrate (pineapple), butyl acetate (apples), and methyl trans-cinnamate (strawberry) can be naturally found in those fruits or created in a lab. (So what a lot of what we're loving in the hydrosols and essential oils are esters!)
Oil of wintergreen is synthesized from salicylic acid and methyl alcohol to create methylsalicylate. (The illustration shows salicylic acid - the carboxylic acid - reacting with methyl alcohol to create methyl salicylate and water, the by product of the esterification process.)
So what does this mean in our creations? Honestly, nothing when it comes to fragrance or flavour oils. It's not like we can run out and get some carboxylic acid, alcohol, and a catalyst and make our own - well, none I'd trust using in a product, anyway - but it's an interesting thing to know...
What I'm really more interested in are the emollient, thickening, and dry or astringent esters that can change the way our products feel, thicken lotions or surfactants, and add some emolliency without adding oils.
Join me tomorrow for fun with dry and astringent emollients - isopropyl myristate or IPM!