Safe Internal Temperatures for Food: The Science Behind USDA Numbers

Safe cooking temperatures feel arbitrary until you understand what they’re doing at the molecular level. 165°F is not a round number chosen for convenience. It’s the temperature at which Salmonella — the primary pathogen of concern in poultry — is destroyed fast enough to make the kill step reliable. Each USDA number targets a specific pathogen in a specific food structure.

The mechanism in every case is the same: heat denatures proteins. Bacterial cells are full of proteins — structural proteins that maintain cell shape, enzymes that drive metabolism, proteins embedded in cell membranes. At high enough temperatures, those proteins unfold and lose their function. The bacteria can no longer survive. This is the same process that changes the texture of a chicken breast as it cooks. Denaturation explains the chemistry in full.

The USDA Temperature Table

Why Poultry Needs 165°F

Poultry gets the highest minimum temperature for two reasons. First, Salmonella contamination in raw chicken is widespread and often deep in the muscle tissue — not just on the surface. Second, Salmonella Enteritidis in eggs can be internal contamination present before the shell even forms.

At 165°F, Salmonella is destroyed in under a second. The kill is essentially instantaneous. This gives the USDA a comfortable safety margin. If your thermometer is off by a couple of degrees, or if there’s a cold spot in the meat, there’s still a meaningful kill step.

The old guidance was 180°F for whole birds. The USDA lowered it to 165°F based on thermal death data showing that 165°F is sufficient and 180°F produces drier, overcooked meat without additional safety benefit. The science changed the number.

Why Ground Meat Needs 160°F

Ground beef, ground pork, and other ground meats require higher temperatures than their whole-muscle equivalents. The reason is the grinding process.

A whole beef steak is contaminated only on its surface — any bacteria that got onto the meat during slaughter and processing lives on the outside. When you sear a steak, the surface reaches temperatures far above 160°F quickly. The interior of an intact whole-muscle cut is sterile.

Grinding changes everything. The grinder takes surface meat from multiple animals and mixes it throughout the product. Contamination that was on the surface is now distributed through every part of the ground beef. Every bite in the center of a burger needs to reach 160°F to be safe.

The same logic applies to ground turkey, ground pork, and any other ground meat. If it’s been ground, the internal temperature standard is 160°F — not the lower temperature that applies to whole cuts of the same animal.

Why Steaks Get a Pass at 145°F

Whole muscle cuts (steaks, chops, and roasts) from beef, pork, veal, and lamb only need to reach 145°F, followed by a 3-minute rest. The interior is safe at lower temperatures because the interior is naturally sterile — bacteria can’t penetrate intact muscle tissue.

The 3-minute rest serves two purposes. First, it allows carryover cooking to continue raising the interior temperature by a few degrees. A steak pulled at 143°F may reach 147°F during resting. Second, sustained temperature over time produces additional microbial reduction at the surface. The combination of 145°F plus 3 minutes produces the same kill effect as higher temperatures with shorter exposure.

This is why medium-rare steak (125-130°F internally) is lower risk than medium-rare ground beef. The steak’s contamination is on the surface, which was seared. The ground beef’s contamination is throughout.

The Color Problem

Food color is not a reliable safety indicator. This is worth stating clearly because it’s one of the most common food safety misconceptions.

Chicken can turn white and appear fully cooked at temperatures below 165°F. Ground beef can appear fully browned at temperatures below 160°F. And both can remain slightly pink at fully safe temperatures — myoglobin chemistry and pH interact with heat to determine color independently of bacterial death.

A survey of home cooks found that most people rely on color rather than thermometers to judge doneness. That approach produces both unnecessary overcooking (because people cook past the point of apparent doneness “to be safe”) and actual undercooking (because they trust color instead of temperature).

A good instant-read thermometer inserted into the thickest part of the food gives you the actual internal temperature. Nothing else does.

Thermometer Placement

Where you measure matters. Insert the thermometer probe into the thickest part of the meat, away from bone (bone conducts heat differently than meat and will give you inaccurate readings). For a whole chicken, check the thickest part of the thigh without touching bone. For a burger, insert horizontally from the side and push to the center.

Check multiple spots in large roasts or dishes. A casserole or meat loaf may have cooler zones in the corners or center. Hot spots and cold spots are real, especially in microwave reheating.

Never Partially Cook and Finish Later

Partial cooking followed by a gap and then finishing cooking is a setup for bacterial growth. If you sear chicken and leave it out for 20 minutes before finishing in the oven, the partially heated interior — which never reached a kill temperature — has spent time in the danger zone where bacteria actively multiply. By the time the final cooking step happens, you’ve given bacteria a window to grow that the final temperature may not fully address.

If you’re cooking in stages, either complete the cooking in one session or keep the food below 40°F between stages. The temperature danger zone article explains why this 40-140°F window is the critical control point.

Sous Vide and Pasteurization by Time

Lower temperatures held for longer periods achieve the same bacterial kill as higher temperatures held briefly. This is the principle behind pasteurization — milk pasteurization historically used 145°F for 30 minutes (low-temp long-time) or 161°F for 15 seconds (high-temp short-time). Both achieve the same bacterial reduction.

Sous vide applies this principle to cooking. At 140°F held for 30 minutes, chicken reaches pasteurization levels adequate for safe consumption. This produces dramatically different texture — noticeably juicier and more tender — but requires precise time-temperature control. For home cooks without calibrated sous vide equipment, sticking to USDA minimums measured with a thermometer remains the reliable approach.