I'm not sure you'd say 'added minimal sugar', rather 'a minimal amount sugar'. It feels more natural.
I would say 'minimal sugar'. Seems more natural to me.
A minimal amount of sugar
The smallest amount of sugar should also be accepted, I think. "minimum sugar" sounds awkward.
I would like 'very little ' as well
I've added it.
Formally, but more used than the opposite μέγιστος. I have this sense.
You don’t say minimal sugar but minimal quantity of sugar or very little of sugar
Maybe "barely any" for ελαχιστον ?
Interesting suggestion! This expression has no direct equivalent in Greek. I think it would most closely be translated as "σχεδόν καθόλου" but ελάχιστος probably works here as well.