Even though pasteurization kills hazardous bacteria in milk, bacteria can still grow if left out of the fridge. If milk smells or tastes sour, stop drinking it. "Best before", "use before" and "sell by" dates aren't much help.
Any pack date is irrelevant when determining berry safety; mould is the main factor. Officially, soft fruits with mould development should be discarded since their high moisture content can harbor invisible pests.
Raw chicken should only be refrigerated for one to two days before cooking. The US does not require chicken to have a sell by or use before date, although retailers may add one freely.
Unfresh or improperly stored and handled fish can cause food illness. Fish should only be refrigerated for one to two days before cooking or freezing. Use by dates on packaging should be followed
Minced beef is more likely to cause food poisoning than a piece of steak because bacteria like E. coli, salmonella, and staphylococcus aureus can be mixed up.
Check the use-by date on spinach leaves, but avoid eating uncooked spinach after it starts to wilt. Wilted leaves cook well, but dark or slimy ones should not be eaten.
Soft cheeses breed listeria, so don't eat them after their expiration date.Undated deli soft cheeses should be eaten within two weeks.
Keep bread until mold appears, then throw it out. You may be tempted to cut out the mold, but bread is porous and may have bacteria under the surface.