Why do sweet Mini bell peppers turn bitter when cooked in a crockpot? I make chicken with tomatoes and put some Mini peppers in and they were horribly bitter
In commercial cooking, the skin is often removed from the pepper due to issues with bitterness and difficulty digesting. Charring the peppers over an open flame or blanching then shocking in cold water is a common technique for removing the skin.
As mentioned in the comments, it's difficult to say without knowing how bitter the raw product was, red or green, etc... Green peppers tend to be considerably more bitter than their sweet counterparts.