How Do You Tell If Liver and Kidney (Offal) Have Gone Bad?

The quickest way to tell whether liver or kidney has gone bad is the smell test: fresh liver has a faint iron-like scent, while spoiled liver gives off a sour or sharp, ammonia-like odour. That ammonia smell is even more obvious in kidney, since kidney tissue naturally contains urea and that smell intensifies quickly once it starts to spoil.

What should fresh liver and kidney look like?

Fresh liver is a deep reddish-burgundy colour, with a glossy, moist but not sticky surface, and a mild, metallic scent. Fresh kidney is a lighter reddish-brown, and feels firm and springy when touched.

In both cases, a loss of shine, dark patches or fading colour is an early sign that freshness is declining; the smell may not be obvious yet at this stage, but the texture has already begun to change.

What are the signs of spoilage?

Spoiled liver turns a grey or greenish shade, and the surface becomes tacky and slimy; the smell turns sour or sharply ammonia-like. Spoilage in kidney shows up in the smell first: a mild ammonia scent is normal for kidney, but once it sharpens enough to sting the eyes, it should no longer be eaten.

With either one, a slippery film left on your fingers can signal spoilage has begun even before it's visible to the eye.

Why does it spoil faster than other meat, and how should it be stored?

Offal has more enzymes and moisture than muscle meat, which makes it more hospitable to bacteria; that's why red meat keeps for 3 to 5 days in the fridge while liver and kidney should generally be used within 1 to 2 days. If it won't be cooked soon, freezing offal delays spoilage by 3 to 4 months.

When buying it, it's also worth checking whether the offal has stayed in the cold chain; liver left out on a counter for a long time may already be well into spoiling by the time it gets home.

Is there a difference between beef and lamb offal?

Lamb liver and kidney tend to have a finer texture than beef offal and start spoiling somewhat sooner, which is why cooking lamb offal the same day you buy it matters even more than it does for beef. Beef liver has a slightly denser texture, so signs of spoilage can appear roughly a day later.

In both cases, kidney spoils faster than liver; so if a shopping trip includes both and they won't be cooked the same day, eating or freezing the kidney first is the safer order to follow.

When buying offal, it's also worth noting how much bloody liquid has collected under the packaging or on the counter; more than usual can be a sign the product has sat around longer than it should have. Cooking offal from the butcher the same day, or at the very latest the next day, is the safest approach.

Soaking liver and kidney briefly in cold water and changing it before cooking reduces the faint blood smell that's normal even in fresh offal; this is an optional prep step for a natural smell, not a fix for offal that has actually spoiled. This small prep step also has a positive effect on the overall flavour of the offal once cooked.