Even though I am not a big fan of the use of them in my mixes, Cooling Agents are a topic that have always fascinated me. How is it possible to feel something is cold when the temperature of the vapor is warm? What is the difference between the variety of compounds, and why they feel different? How do they affect flavor and why?
The Asian cultures had been using peppermint for medicinal application for more than 200 years, but it wasn't until the late 18th century that we were able to isolate the menthol compound and the late 1880s that we started using it in pharmaceutical and cosmetic preparations.
Between the 1960s and 70s the prices of menthol derivatives were very high and the tobacco industry (among others) needed a cheaper alternative for their products. The Wilkinson Sword company began an extensive research on the behavior of various cooling agents in order to develop compounds with a lower cost. They also wanted to ensure that they do not have the negative effects from the use of older derivatives.
It is because of that company that we now have the most used cooling agents in the market and the “WS” initials in their names.
How do they work?
This is a very complex topic, especially for someone with no chemistry background, so I will try to explain only the basics to understand how they work.
The process that allows us to get the feeling of being in contact with something hot or cold is called thermoreception. This mechanism depends on ion transport across the protein ion channels in the cellular membranes. The flow of ions and their concentration produce electrical signals that excites primary afferent sensory neurons of the dorsal or trigeminal ganglia.
We identify different thermoreceptors (TRPV) according to the temperature-sensitive reception. Among others related to heat sensation, we find that the TRPM8 (<~28°C) and TRPA1 (<~18°C) channels are activated by cold and that certain types of chemical agonists activate these thermoTRP channels to produce the cooling effect.
Commonly known as Koolada, the WS-3 is one of the most widely used cooling agents on the market alongside the WS-5. Although it is a derivative of menthol, it is usually classified as a less volatile product with less flavor or odor.
The effect is immediate, with greater intensity than WS-23 (at the same percentage) but its duration is shorter.
The sensation of cold that it generates is accentuated in the upper and rear part of the palate and in the part of the tongue closest to the throat.
WS-5 / WS-12
These two are the strongest commercially available cooling agents and they are also menthol derivatives. It has been found to have approximately two and one-half times the cooling intensity of WS-3.
Both of these agents are mostly used in the candy industry, and the main difference is that the effect of the newest developed WS-12 do not affect flavors that much and has a longer longevity, which makes it perfect for products like chewing gum, but it is also harder to produce and more expensive.
The use of this cooling agent is not recommended in vaping due to its intensity and how difficult it is to use in small percentages. It also carries a bitter aftertaste and can mute delicate or weaker flavors very easily.
WS-5 has been found to cool primarily at the roof of the mouth and the back of the tongue.
Butanamide, N, 2,3-trimethyl-2- (1-methylethyl) -
WS-23 is not derived from menthol but shares the same characteristic of not having odor or flavor and low volatility.
The cooling effect is incremental in its initial stage, taking longer than WS-3 to reach its maximum peak, which doesn't last as long, but it's average cooling effect duration is longer and the sensation drop less pronounced.
Unlike the WS-3, the effect is more present on the front of the mouth and tongue, which in some applications can be translated as a fizzy sensation, similar to carbonation.
It is understandable that WS-3 and WS-5 have greater importance in the food market in general, especially for the production of mint confectionery and oral hygiene products, due to its greater intensity and immediate effect. However, many people notice a plastic or chemical taste in liquids with Koolada, and some may even feel roughness and burning depending on the used percentage.
For its part, the WS-23 is softer and silkier. It does not add any new flavor to the mix and it does not block other flavors to develop like Koolada does, although it can mute the effect of sweeteners and you may need to use more than without the use of this agent.
Due to the corresponding presentations of 10% for WS-3 to 30% in WS-23, the use of either of these two concentrates is usually at the same percentage of the final product (0.5% - 1%) due to the difference in intensity between them.
Although there is an important quota of personal preference in choosing one over the other, it is advisable to use WS-3 for recipes where mint or menthol is the main note, as long as you are not one of the people who notice an unpleasant taste with the use of this concentrate.
WS-23 is more versatile in fruit and beverage recipes without having to worry about flavors changing or fading, knowing that they may need to increase the percentage of sweetener.
A last option, is to use a mixture of both products (WS-3 and WS-23) in order to obtain an immediate effect with a wider sensation in the mouth and without sacrificing flavors thanks to the low percentage in the use of both agents.