Meat has various colours, depending on the environment it is stored in. The bright red colour of fresh meat is due to a pigment called oxymyoglobin that turns red when in contact with oxygen. But meat that is not subject to oxygen will be brown. Even cooked meat has a range of colours, from pink to brown to black. This makes it hard to tell if cooked or raw meat is spoiled just by looking at it. There are several causes of meat spoilage, including exposure to air, improper freezing methods, the process of fat in the meat oxidising into aldehydes and micro-organisms such as bacteria festering inside the meat. The best way to determine the viability of a piece of raw or cooked meat is to smell it.
Find the "use by" date on the original package of a piece of raw meat. This date is the retailer's best judgment as to how long the meat will be tasty and wholesome for consumption. No food suddenly becomes rancid the day after the expiration date. If it has only been a few days, the meat may still be good. If the date listed has long gone by, it is a good indication that the meat is spoiled.
Smell the meat. Spoiled food can have a normal appearance but still be unsafe to eat. If the meat smells terrible or has a sulphur or ammonia-like smell, it is spoiled. If the meat smells unusual, throw it away. This applies to raw or cooked meat.
Look at the meat. If there is a layer of slime on the surface, it is spoiled. If there are whiskers or green fuzzy spots, there is mould growing and it is unsafe to eat. A black, green or creamy surface discolouration is also a sign of mould growth.
Touch the surface of the meat with a plastic utensil. If the meat is sticky, it is spoiled. Immediately throw the plastic utensil away to avoid contaminating other items in the kitchen.
Throw it out, when in doubt. Eating spoiled meat can cause illness, so always stay on the safe side and discard questionable meat items.
Cooked meat and raw meat are examined the same way for freshness. Always wash your hands after handling raw or spoiled meat to prevent the spread of bacteria. Cooked meat stored in the refrigerator should be consumed within three to four days, before bacteria has a chance to develop. Cooked and raw meat can be wrapped airtight and stored in a freezer for several months or longer.
Any meat, no matter what colour or age, can be contaminated by pathogenic bacteria if not properly handled. Food poisoning is the result of eating spoiled meat filled with bacteria. Symptoms of food poisoning include stomach cramps, nausea, vomiting and diarrhoea.