The short answer - there is not really a sour flavor on the market as of the writing of this article, but there are some options and alternatives we can discuss
So to date there is not a an actual sour flavor that exists. WHY?
Because we are using a vapor and not actually tasting the flavor. Producing a sour like sensation is extremely difficult in vapor. Sourness is one of the six tastes our tongue can interpret, and with vaping, it really more about our olfactory sense Therefore sour can’t quite be produced through vapor.
What are our options then?.
Malic Acid is a compound that was first created from an apple. It is used mostly in fruit/candy food products to generate a sour-like taste. Malic acid is what creates that sourness in most candies. If you look at certain sour candies like sour patch you’ll notice that there is a grainy, sugar like substance all over them. Most of the time, its just malic acid . So can this work in vaping? Well TFA Sour is just malic acid diluted in PG.
Malic acid at a low level and carried with sucralose seems to work best as the sucralose tends to carry that sensation more . The issue is at higher percentages it is harsh and destroys the mix and at lower percentages it tends to fade and becomes more of a tartness. There is also the issue of muting flavors which is similar to using Ethyl Maltol. Basicly TFA Sour is not that useful. There are situations where adding a touch of Malic Acid can help bring a bit more “tartness” to your candy recipes. Keeping it low .25 % is often best, where anything too high becomes harsh. Most likely though if you’re making a sour candy recipe, you’re using flavors that inherently have a sourness to them, chances are Malic Acid is already within them. In general there’s no point in adding any extra sourness to your mix. Save your money and save your time. Skip TFA Sour.
So what can I use ?
I think look for flavors that have an inheret tartness, while the tartness in these flavors may fade they make for good candy shake and vapes
1. Citric Acid - This is closest we can get a “sourness” from . Many citrus concentrates contain citric acid and often that will provide a sour like note . But if you wanted that citrus taste to your recipes without any citrus flavor, you can use 0.25-0.5% of citric acid .
But I would try some lemon or lemondae first. VT sour lemon is a a very solid concentrate for this ( but sadly it does fade slightly)
VT sour lemon
CAP Pink Lemonade
FA Lemon Sicily
2. Green Apple - Green Apple is another concentrate that can add some type of tartness to your mixes. These flavorings usually contain some type of Acid that does provide a slight sourness to your recipes which can help with authenticity. That sour green apple flavor also seens to support a candy profile better then most of the other flavors.
FLV sour apple
Cap Green apple hard candy
FW Green Apple
TFA Green Apple
FLV Green Apple
3. Some additional flavors
WF sweet and Sour rhubarb
CAP Tart cherry
And I’m sure there are a few more profiles out there that can produce a tart-like sensation. These are just the ones I consider and have used me when making sour candy profiles.
Credit to Wayne walker - see Article " stop using TPA sour"