Unfortunately, the Internet age has made this type of experimentation a lot less common. Remember when game help hotlines were popular? It's crazy to think that people used to pay to call a help line to get past a difficult part in a game. (I admit that I did it a few times. Damn you Quest for Glory!)
I have a feeling that rather than trying things, a majority of players will just google it and instantly know which fruit is dangerous/beneficial. To combat this, you could do what some roguelikes do and change the properties of potions each game (ie - the blue potion might heal, poison, cloak, etc on different play-throughs)
This might require a little more planning and development time on your part though.