To soak meat, fish, vegetables, or other foods in a seasoned liquid, the marinade, to add flavour and often to tenderise. Typical marinades combine an acidic component such as vinegar, citrus juice, or yoghurt with oil, herbs, spices, and salt. Acids and enzymes gently break down surface proteins, allowing flavours to penetrate, though contrary to popular belief, marinades penetrate only a few millimetres. Food safety rules apply: marinate in the refrigerator, never at room temperature, and discard used marinade or boil it before reuse as a sauce. Marinating times range from minutes for delicate fish to overnight for robust cuts.