Can snails smell preservatives/pesticides?

Hello all! I’m a college student in a rural area and sometimes I’m not able to get fresh veggies from the store for my snail. I have tried giving my snail things from the school’s dining hall salad bar but he refuses to eat anything from there. I’ve tried spinach, bell peppers, mushrooms, and whole apples that I have sliced for him. I always wash and boil the things I give him to get rid of any harmful stuff. But anything that comes from the school is a no go.

He’ll crawl over it or outright refuse to touch it. He never has a problem eating the same things from the grocery store though. I imagine the school treats their fruit and vegetables with preservatives to make them last longer or maybe they’re grown with pesticides? I wonder if he can smell these things and instinctively knows they’re bad for him? I tried googling it but all I get are articles about how to get rid of snails :’)

Much thanks in advance!