Why does fresh pineapple make my mouth tingle?

The answer

Fresh pineapple contains an enzyme that breaks down protein, which can irritate the mouth for some people. The effect is usually temporary and is common. The same enzyme is why raw pineapple stops gelatin from setting and why it is sometimes used in marinades. Cooking or canning generally deactivates it. Cooked or canned pineapple does not have this effect, so you can still enjoy it in baking, sauces and cooked dishes.