How to tell if food is done -- both for food safety and personal preferences.
The great taste of food hot off the grill is a reward to be savored. Knowing when to pull it off the grill is important for a great eating experience and also to ensure safety. Determining "doneness" in terms of texture, appearance, and juiciness is often a matter of personal preference. However, in terms of safety, foods are "done" when they are cooked to an internal temperature high enough to eliminate harmful microorganisms. The best way to measure internal temperature is with a food thermometer.
The most accurate and safe way to determine doneness is to use a thermometer. To achieve an accurate reading, use the following guide to determine where to insert the thermometer.
Source: USDA FSIS