pgrs are plant growth regulators. if you use them properly, they don't effect taste.
there are a load of pgrs that all do different things,
https://www.ncbi.nlm.nih.gov/pubmed/20355716
the amount of gibb is too small to matter, kinetins are the thing in seaweed that really effect weed, and what they do is make for short bushy plants with a lot of bud sites. auxins are what make a plant grow tall.
the only problem with kinetins are if you over do them, even a little, you get midget bushes with leaves stacked right on top of each other. i doubt your seaweed will have enough of anything to make that happen, though. before you start using something like pgrs, you really ought to do some reading, they can have profound, and unwanted effects, if not used properly.
that being said, i use synthetic pgrs, ( triacontanol, brassinolide, IBA, 6BAP) and theres no taste to any of them that i've ever detected, but i did bother to do some research and learn what to use before i started