Pretty sure they should be able to smell that. Red pepper sap has a distinct acrid smell that rankles my nose even when they are uncut.
The moment Marisa bites she should have smelled the spiciness not to mention taste how spicy it is in the few seconds the capsaicin hits her tongue or even skin.
@Yuno; In my opinion, the father Marisa is saying that the peppers are sweet in a more matter-of-fact way. He's 100% confident that it's red like a strawberry which means its sweet. But that's just my inference anyway, it might not even be true. I don't think there's a need to change anything, so I'll just remove the "translation_request" tag.
The current translation is correct, as it closely follows the original. Marisa is really saying "because it's red like a strawberry then you can eat it".
Little one, here's a mister vegetable for you to munch-munch noze
Because its red like mister strawberry it must be sweet-sweet and delicious nozeBhut JolokiaRemyu too
Remyu wantsh to mwunch-mwunch shweech-shweech mishter vegetable tooooo!Mmmm-mwunch-mwunch!
Mishter vegetable, quickwy come to Maricha nanoje!