Food poisoning bacteria usually do not affect the appearance, smell, or taste of food, so it is generally not possible to tell if food has enough bacteria to cause food poisoning just by sensory inspection. Bacteria that cause food poisoning can multiply quickly under favorable conditions such as the right temperature (between 5°C and 60°C), time, moisture, and nutrients in food. Even food that looks, smells, and tastes normal can contain harmful levels of bacteria. High-risk foods include dairy, egg products, meat, poultry, and seafood. The best way to prevent food poisoning is to handle, store, and cook food properly and avoid consuming food that has been improperly stored or handled.
In summary, there is no reliable way to tell if food has enough bacteria to cause food poisoning simply by checking its sensory qualities; the risk is more about conditions and handling than outward signs.
