What is THE most sour candy?

Okay so if your son randomly said “I tried the most sour candy in the UK” , hilariously (referring to barnetts mega sours), and then continually obsessed about finding the most sour candy’s in the world,

Aside from just dipping stuff in malic acid directly,

What would you get?

Toxic waste hazardously sour, Black Death, and cry babys have come up. I think I’m just going to tell him black deaths are the most sour? They’re like $30 for 10 of them, and that’s cash he’s gotta earn by reading and shit