Barbecue masters know that grilling meat at high temperatures can burn or char the outside and leave the inside underdone. Medium or low heat produces tastier, healthier food -- whether on a gas or charcoal grill.

On a charcoal grill, that's when coals have a slight red glow and are covered with gray ash. If you can hold your hand above the heat at cooking height for 4-5 seconds, you should be good to go.

You've probably heard about "pink slime," the low-cost beef filler that is treated with ammonia to kill bacteria . But how can you avoid it?

Since "ammonium hydroxide" is considered a processing aid, it doesn't need to be listed on food labels. But many fast food chains and grocery stores have stopped selling beef that contains it. Check the web site of your favorite store, or ask at the meat counter.

Bacteria on the surface of ground beef can get mixed inside when you make hamburger patties. So don't skimp on the cooking time. As a rule of thumb, cook a 4-ounce ground beef patty that is about 1/2 inch thick and 4 inches wide over medium coals for 11 to 13 minutes. With a gas grill, check the manual for cooking times.

If you don't want to flavor that juicy steak with chemicals, skip lighter fluid and self-starting charcoal. They contain toxic substances that may pass into grilled food. Lighter fluid is made from petroleum products, which also pollute ground-level air.

So fire up the grill with a chimney or electric starter. Instead of briquettes, burn wood chips or lump charcoal, which are chemical free.

To avoid spoiling, cook refrigerated beef ribs or steaks within three to five days of purchase or before the "use by" date, if there is one on the label. Poultry and ground meat go bad faster, so cook them within one to two days.

Otherwise, freeze meat to keep it safe until you're ready to cook it.

The temperature inside chicken needs to reach 165 degrees F or more to kill bacteria. As a general rule, that means grilling chicken thighs, legs, or a 6-ounce breast with bones for 10 to 15 minutes each side. You can flip a boneless breast after 6 to 8 minutes and wings after 8 to 12 minutes.

Steaks, roasts, and chops should reach an internal temperature of at least 145 degrees F and ground meats 160 degrees F.

You can't really go by inside color, and if you cut into the meat, the juices will pour out, drying it out. Grill master Bobby Flay goes by touch: The longer meat, fish, or poultry cooks, the firmer it gets. So a steak cooked medium should be springy, not squishy (rare) or taut (well done).

Of course, the only surefire way to check for doneness is with a meat thermometer.

Low and slow is the way to go with fresh sausages, like Italian and fresh bratwurst. Over low heat, the skin won't burn before the inside is cooked through. That also keeps the skin from splitting and dripping juices, which flare up flames. 

For a flavor kick and to cut grill time, simmer sausages in water and beer for about 15 minutes first and finish them over medium-low heat.

Bacteria can grow on food that's left out to defrost. For safety, slow thawing in the refrigerator is best. Most food will thaw in a day or two in the fridge.

If you forget or you don't have time, you can quick-thaw food in a sealed bag in cold water or in the microwave if you're going to cook it right after. If you use cold water, change it every half-hour and keep it cold.

The risk is pretty small, but cooking meat over hot open flames can cause some harmful chemicals to form. Fortunately, it's easy to reduce the risk:  

• Don't eat well-done or burned parts of meat.
• Trim fat. Remove skin from chicken.
• Partially cook meat in the microwave or oven or simmer it in liquid so it isn't on the grill as long.
• Flip meat on the grill often.
• Grill fish and chicken on top of foil.
• Grill fruits, vegetables, and veggie burgers, which don't have those cancer-causing chemicals.

Marinating meat, even for just 10 minutes, is a triple-win for grillers. It brings out flavor and moisture and helps reduce possible cancer-causing chemicals. Thin, oil-free marinades, especially with vinegar or citrus, are best. Thicker, store-bought marinades and those with honey, sugar, or tomato tend to char. Use those only in the last minute or two of grilling.

It is a good idea to put about ½ inch between chunks of food on your kebab. (It can help everything cook through more quickly). But the very best way would be to cook meat and vegetables on different skewers. That’s because veggies and meats can need different cooking times to be done, says chef and food science whiz Alton Brown. Plus, it cuts back on the chance of germs moving between the meat and veggies.

Try putting slow-cooking veggies like sweet potatoes on one kebab, fast-cookers like zucchini and mushrooms on another, and meat on another.

However, most people cook them all together. That’s OK. The risk of germ mixing is small when you make sure everything is well-cooked. Keep cooking and turning your kebabs until the meat is “firm, but yielding.”

Grilling close to a house, deck railing, eaves, or overhead branches is a serious fire hazard. And grilling in an enclosed or partially enclosed space can expose you to deadly carbon monoxide fumes, so don't wheel the grill into the garage, a camper, or tent to cook. 

Propane and charcoal grills should be used outdoors only. If it rains on your party, move it inside and finish cooking on the stove.

When juice from meat drips on hot coals, it increases smoke and flares up flames, which may leave harmful chemicals on food. So keeping the juices in burgers is both tastier and healthier.

To avoid squishing out juice and drying hamburgers out, don't flatten them with a spatula while they're cooking. Flipping burgers frequently cooks them more evenly and also avoid drips.

Ancient grease and food are health hazards, not flavor enhancers on the grill. Brush burnt bits of food off grates while they're still warm with a wire brush. Then soak the grates in warm sudsy water and rinse.

Dump used charcoal to cut down on smoke and bad flavors. Wipe off grease or fat buildup in the trays below the grill to prevent fires and flare-ups. Clean gas grills according to the owner's manual.