Review of Tart Blast Flavor-FLV:

I love tart recipes! The unfortunate thing is that most sour or tart additives don't really work very well. LA Tart and Sour has been my go to for years but since Tart Blast came out I find myself reaching for it less and less. Basically it adds a nice lemony tartness to just about anything. It's very potent so you don't need much at all. This is perfect for something like tarting up a lemonade recipe or lemon candy recipe. It works great with other flavors as well. If you want your raspberry flavor to lean more to the tart side, this will do the trick. Tart Blast also works extremely with Blue Raspberry flavors. It adds that citrus kick most BR flavors lack plus it adds to the tartness any good BR should have. 
If you need a good tart/sour additive this is probably the best option out there. I still reach for LA Tart and Sour when working with candy flavors outside of lemon candy but for everything else I go with FLV Tart Blast.