Of the consumer calls I receive, the hardest to answer are those regarding how long food can be kept before it is not safe to use. Like many answers, this one depends on several factors: the type of food, the length of time the food sat on the store shelf before you bought it, the temperature of the food while it was in the store, its packaging, how efficiently your refrigerator or freezer runs, and the temperature in your cupboards.
While you can't control all these factors, there are some precautions you can take. For example, always read the package labels and buy the products with the most distant expiration dates. The calendar date on the packaging of a food that indicates the last date a food should be eaten or used. Foods that are purchased or used after the expiration date could contain spoilage bacteria or pathogens and may not be safe to eat.
Sell-by date: Indicates the last day the product should be sold, but there is some leeway for use at home. Properly stored, this would be up to seven days for most foods, three to five days for fresh beef or pork and two days for poultry, seafood and ground meats.
Use-by date: Indicates the last day the food should be eaten or used. It is found mostly on products such as refrigerated dough and yeast. You are likely to see a marked deterioration in product quality and safety after that date.
Best if used by: With emphasis on the word best, it means the product should retain maximum freshness, flavor and texture if used by this date. Beyond this date, the product begins to deteriorate, although it may still be edible.
For the most part, once opened, expiration dates become obsolete and the food is considered perishable. It is then advised to use the product quickly to avoid spoilage. To ensure a safe food supply:
Refrigerate leftovers within two hours of serving. Store in a covered container, not a can, and use within three to five days.
Most condiments like pickles and salad dressings will stay fresh tasting for quite awhile if refrigerated. Check the package to see if refrigeration after opening is necessary.
Many baking mixes contain dehydrated fats which can become rancid or leaveners that may loose their potency. Check their expiration dates.
Most home canned goods can be stored up to one year at room temperature. They may be used later but their quality will have deteriorated.
No matter what the food is or the circumstances are, if you ever doubt the safety of a food, throw it out.
More information on safe food storage and handling practices is available at your county extension office or on the web at (www.ag.ndsu.nodak.edu).
(Gail Slinde is a Ward County Extension agent. She can be reached by email at firstname.lastname@example.org).