Jeanne Goldberg, G59, N86, a professor at the Friedman School, on what the nose knows—and doesn't know
Taste and smell are not reliable indicators of food safety. Some bacteria that cause food-borne illness do not have off-flavors associated with them. Clostridium botulinum, for example, produces a tasteless but deadly toxin. One clue that it may be present is a bulging lid on canned food. Any cans with bulging lids should be discarded without opening, and disposed of beyond the reach of children and pets. However, botulinum poisoning is not limited to canned foods. It can occur in other foods stored improperly.
Similarly, the toxin produced by staphylococcus is tasteless and can cause typically short-term—but unpleasant—symptoms.
In other cases, spoilage organisms that cause off-flavors would deter you from eating a food before the microorganisms that cause food-borne illness have had a chance to do their work.
The “sell-by” date on a package provides guidance to the store, not the consumer. It is the date by which the store should remove a food from the shelf, not the date by which the food must be used. For consumers, a “use-by” date is more helpful, but even that is not an absolute guide.
In the case of fresh, raw poultry, beef or fish, it makes sense to use them within a few days to preserve freshness. If that is not possible, freeze them, or cook them thoroughly to kill any harmful bacteria, and use them for a dish that requires cooked meat.
Chicken, in particular, has been identified as a source of salmonella bacteria, which generally does not affect the taste or smell of food. The good news is that salmonella bacteria are destroyed by heat. To prevent salmonella infection, always prepare chicken on a clean surface, cook it thoroughly, and once it is done, put it on a clean serving dish.
The fundamental key to food safety is to keep hot foods hot (that is, more than 140 degrees) and cold foods cold (less than 40 degrees). That will prevent bacteria from thriving and help keep your meal out of the danger zone.