Carbonated Beverages

Sucralose is supposed to be clean tasting like sugar.. maybe you overdosed it that you got excessive sweetness resulting a so cslled aftertaste?

Because you are making a syrup, probably your sucralose amount used is high as well.
You may want to check back on the ingredient used in your beverage , as @Roy already suggested sucralose is without any aftertaste if used in minimal dosage.

Try starting with 0.01% on the final RTD. So you will need to adjust it in your syrup concentration.

Out of curiosity, what aftertaste are you getting and is any of this flavour present in the syrup without the sucralose added?

@Nicolas_Tsisios Nicholas okay noted thanks. @PEICAN Peican this kind of after taste is not available when the sucralose is absent

@Dalse please describe the aftertaste exactly from your sensory experience...Your previous comment is so vague.......