Cooking · Safety

How to tell if steak is bad

A raw steak has gone bad when it smells sour, rotten or of ammonia, feels sticky or slimy, or shows mould; colour alone is not a reliable sign, because beef turns brown or grey simply from contact with air. Kept at 4 °C / 40 °F or below, raw steaks last 3–5 days in the fridge and ground beef 1–2 days, whatever the sell-by date says.

Also known as: Spoiled steak · Carne en mal estado · Thịt bò bị hỏngLast reviewed 22 Oct 20266 sources

Spoilage and danger are not the same

Two different kinds of bacteria matter in raw beef. Spoilage bacteria (mostly Pseudomonas and lactic acid bacteria) grow on the surface in the fridge and produce the off smells, slime and sourness that make meat unpleasant; they rarely make people ill. Pathogens such as Salmonella or E. coli O157:H7 can make people ill in small numbers and give no smell, colour or texture at all.

This is why the senses work in one direction only. A steak that smells or feels wrong should be thrown away. A steak that looks and smells fine is not proven safe: what keeps pathogens in check is time and temperature, which is why fridge times and the cold chain matter more than any inspection.

Colour: what is normal and what is not

The colour of beef comes from myoglobin, a pigment in the muscle that changes with oxygen. Freshly cut beef is purplish red; after 15–30 minutes in air it "blooms" to bright cherry red (oxymyoglobin); after days, or in the centre of a pack where little oxygen reaches, it turns brown or grey (metmyoglobin). All three are normal.

So a purple steak in a vacuum pack is fresh, and turns red a few minutes after opening. Grey inside a pack of ground beef, where the outside is red, is lack of oxygen, not spoilage. A brown surface on a steak that has been in the fridge for a few days means it is ageing, and is a reason to cook it soon, not to throw it away if smell and texture are fine. A rainbow sheen on sliced meat is light breaking on the cut fibres, not decay.

What is not normal: green, grey-green or black patches, fuzzy spots of mould (white, green or black), and a dull colour that comes with a bad smell or a sticky surface.

Smell and texture

Fresh raw beef smells faintly of iron and fat, or of almost nothing. Spoiled beef smells sour, cheesy, sulphurous, of ammonia or plainly rotten, and the smell gets stronger near the surface. Vacuum-packed beef is the exception to remember: on opening, the trapped gas can give a slightly sour "confinement odour" that fades within a few minutes; if it does not fade after 10–15 minutes in air and a rinse, the meat is spoiled.

The surface of fresh beef is moist but not sticky. A slimy or tacky film that stays on the fingers is a colony of bacteria and a sure sign of spoilage. A swollen, puffy vacuum pack means bacteria have produced gas inside it: discard it without opening.

Dry-aged beef follows other rules: its dark, hard crust and nutty, slightly funky smell are the point of the process, and the crust is trimmed away before cooking; see dry-aging.

How long it keeps

Dates on the label

In the United States, most dates on meat are about quality, not safety: a sell-by date tells the shop how long to display the product; a best-if-used-by date marks peak quality. USDA advice is to cook or freeze fresh steaks within 3–5 days of purchase and ground beef within 1–2 days, whatever the sell-by date. In the European Union and the United Kingdom, a use-by date on fresh meat is a safety date and should not be passed.

Freezing stops the clock: meat frozen at −18 °C / 0 °F stays safe indefinitely, though its quality slowly falls. Freezer burn, the dry grey-brown patches on badly wrapped meat, is a loss of moisture, not a hazard; the affected part can be trimmed before or after cooking.

Time out of the fridge

Bacteria multiply fastest between 4 °C and 60 °C / 40 °F and 140 °F. USDA guidance is that raw meat should not stay out of the fridge for more than 2 hours, or 1 hour above 32 °C / 90 °F. Taking a steak out 20–30 minutes before cooking is within that limit.

Cooking does not rescue spoiled meat. Heat kills most bacteria but not the smell, and some bacteria leave toxins that heat does not destroy. The rule of the food safety agencies is short: when in doubt, throw it out. Cooking to the right temperature is covered in steak temperatures.

Frequently asked questions

Sources

6

1. USDA Food Safety and Inspection Service. Safe Minimum Internal Temperature Chart. 2023. www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/safe-temperature-chart
2. McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen, rev. ed. New York: Scribner, 2004.
3. Toldrá, Fidel (ed.). Lawrie's Meat Science, 8th ed. Duxford: Woodhead, 2017.
4. USDA Food Safety and Inspection Service. The Color of Meat and Poultry. Washington, DC.
5. USDA Food Safety and Inspection Service. Food Product Dating. Washington, DC.
6. USDA, Cornell University and Food Marketing Institute. FoodKeeper (storage times). FoodSafety.gov. www.foodsafety.gov/keep-food-safe/foodkeeper-app

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