Could your client take an unflavoured whey and just blend in small amounts of fruit to taste?
Sometimes I flavour my whey with a couple of strawberries and that tastes fine to me.
Just a thought.
230 strict press @ 220; bodyweight+187 X 4 dips @ 180; 403 front squat @ 210; 10 000 push-ups.
Ignoring irrelevant credentials since I was 17.