As you probably know an e-juice contains Propylene glycol, vegetable glycerin and nicotine as a base for the mixture that account for 85% and 15% is the flavour shot/aroma. In the vaping community there is a term called steeping where all ingredients blend together and create better flavour(like aging) and lasts between 1-4 weeks. As a chemist, do you think that this is a legit argument. Is it possible to “age” an e liquid?
Thank you in advance
Hi Dimitris, and thanks for the interesting question!
There are several factors behind the flavor changes during the steeping process. These include both physical and chemical factors.
The ones occurring quite quickly are evaporation of volatiles and degasification.
Flavor concentrates often contain certain amounts of volatiles, which may not contribute final, overall flavor perception.
Very often vapers say that flavor is “too fresh” or “too sharp” straight away after mixing. In most cases, this sensation is created by the presence of small volatile molecules and small amounts of gases in the liquid. Normally they disappear, during the evaporation and degasification processes, within a few days.
Shaking bottles, from time to time, and leaving liquids with the cap off (or at least not tightly closed) helps to achieve better results, quicker. That is why vapers say that they are “airing” their mixes.
Another physical factor is the homogenization on the molecular level (by diffusion).
E-liquids, straight after mixing on the large scale, or “shaking” a DIY-made bottle of juice, are well homogenized as a whole volume, in a macro-scale. However, diffusion will still be occurring on the molecular scale.
After a couple of days, e-liquids will get to the point of the equilibrium where not only all ingredients used are homogenized but where all the molecules coming with those ingredients re-arrange between themselves and the solvents (PG/VG).
The chemical factor of steeping probably involves, as normally happens in nature, reactions similar to the Maillard reactions or reactions occurring during the “browning process” or wine aging. In general, this means that new, more complex flavor compounds are formed – i.e. esters, or oxidized aldehydes. A good example is browning of the vanillin-containing liquids.
These more complex molecules are formed at room temperature. However, this process takes longer and (in general) first changes in the taste can be observed after 3-5 days at least and may be occurring, at a very slow pace, throughout the whole shelf life of the product. It is a natural process, and shouldn’t be considered as unwanted. However, this can be slowed down by storing e-liquids in a relatively cold and dark place.
We hope that helps!
Batch Chemistry Applications Specialist at Syrris