Six Tips for Extending the Shelf Life of Foods

Do your blueberries or cheeses get moldy within a few days of purchase?  Does the milk you opened 5 days ago already smell sour? Shelf Life Advice can come to your rescue with seemingly endless tips on ways to keep your food fresh longer. The site’s “search” feature can lead you to money-saving info on hundreds of specific products—scientific data on the best ways to select, handle, wrap, store, and refrigerate specific foods to keep them from spoiling prematurely.  In this article, we’ve pulled together some general guidelines on extending shelf life, based upon the expertise of our Advisory board food scientists.  We’ve also provided links to several other Shelf Life Advice write-ups dealing with best food handling practices.

Tip #1: Get the most out of your refrigerator.

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- Note that we did NOT recommend getting the most INTO your refrigerator.  A tightly stuffed fridge doesn’t have the proper air circulation for sufficient cooling of all the contents. Bacteria that cause illness and those that cause spoilage grow faster in a fridge that’s kept above 40°F.  Be sure you have a refrigerator thermometer to check the temperature of your fridge.  Leave a little “breathing” space between foods and keep them from blocking fans so that there’s proper air circulation.

- To protect food from the growth of pathogens and spoilage bacteria, it’s often recommended that the temperature be 38°F. Or, at least, no higher than 40°F. But note that foods will last longer in a fridge that’s on the cool side of safety. But if you can keep your fridge at 36-37°F, you’ll be helping to extend the shelf life of the contents. (But don’t make it so cold that the beverages develop ice crystals and lettuce leaves begin to freeze.) “The refrigerator temperature is very important,” says food scientist Dr. Joe Regenstein.  “The difference between 33 and 41 can almost double or halve the shelf-life.”

­­- Find the cold and hot spots in your fridge. Food scientist Dr. Catherine Cutter points this out:  “Some foods may start to freeze at a higher temperature than others.  It’s a good idea to take a temperature profile of your refrigerator by moving the thermometer around from time to time to locate the hot and cold spots.  The coldest spots are probably near the walls, back, and bottom.  Put foods less likely to freeze, such as a roast, in the coldest spots. Note: newer, better refrigerators may have the same temperature throughout.”

- “Many foods that don’t require refrigeration (such as apples and some types of cakes) will last longer if they are refrigerated,” Dr. Regenstein points out.

- “If you’re keeping raw fish in your refrigerator for a day or so after purchase, it’s a good idea to put some ice on top of the wrapped fish.,” Dr. Regenstein suggests.  Ice, he explains, will help to keep it fresher and tastier.  A plastic bag over fish that’s wrapped in paper will protect the fish from the melting ice.

- Keep your refrigerator very clean so that pathogens and spoilage bacteria don’t spread to foods.  Wipe up spills promptly, and, every month or two remove all foods and clean and sanitize the entire interior. For tips on how to do this, click here. Remember to dust off the coils.  Dirty coils retard adequate air flow. 

- Every week or so, check the fridge contents to be sure that you haven’t kept some foods too long.  Be on the look-out for old luncheon meats, moldy fruit, and forgotten gravy-laden leftovers that got shoved to the back. Remember, low-sugar or sugar-free products will deteriorate faster than conventional products.

- Buying a new refrigerator?  Get one with plastic or glass shelves rather than wire racks because plastic or glass is easier to clean and keep germ-free.

Tip #2: Give different fruits and vegetables the special care they need.

- Don’t refrigerate most fruits until they’re ripe. Most won’t ripen further once refrigerated.

- There’s no point in keeping strawberries, blackberries, raspberries, or blackberries out on the counter to ripen; once they’ve been picked, they will not ripen further, so into the fridge they go as soon as you bring them home. 

- Most fruits can be tightly wrapped because (unlike vegetables) they are too acidic for the bacteria that cause botulism to grow on them.  Tight wrapping keeps out oxygen, which is protective since mold growth requires oxygen.  Fruits that give off a lot of moisture (especially berries) should be loosely wrapped to prevent the growth of mold or spoilage bacteria that make them slimy.  Leave them in their perforated store containers, or, if they’re not packaged that way, cut a slit in the plastic top.

- Don’t put apples close to other fruits.  Apples give off ethylene gas, which will make other fruit become overripe.

- Blanch and freeze leftover uncooked vegetables that you’re not going to use soon.  They’ll last much longer than if kept in the refrigerator and not blanched. 

- Fresh vegetables should be wrapped loosely and washed immediately before preparing them to cook or serve, not before refrigeration. Root vegetables (potatoes, carrots, etc.) will last longest if kept at about 55ºF, but, if you don’t have an area (a basement, crawl space, etc.) about that temperature in your living quarters, these vegetables will last longer in the fridge than at room temperature. For more information about handling fresh vegetables, click here.

Tip #3: Handle dairy products right to keep them fresh.

- Refrigerate all dairy products as soon as possible after use.

- Don’t pour leftover milk from your pitcher back into the original store container.  Doing so will hasten spoilage.

- Wrap cheese tightly to keep it tasty and mold-free longer.

- Regarding eggs:

1) Don’t store eggs in the refrigerator door; the temperature is too varied there.

2) Be sure that eggs are not stored in a refrigerator section that’s cold enough to freeze them. Frozen raw eggs turn gummy when thawed and are unusable. However, according to the Chicago Tribune “What’s Cooking” section, leftover egg yolks  (when your recipe calls for egg whites only) can be frozen if they’re first beaten with a little salt or sugar. 

3) Remember that eggs are good for 3-5 weeks after the sell-by date printed on the carton.    Don’t confuse a sell-by with a use-by date and throw out perfectly good eggs. 

Tip #4: Use a vacuum sealer to lengthen the shelf life of many foods.

A good vacuum sealer is an investment, but it will probably save you money in the long run if you remember to use it.  Vacuum packaging removes air, seals in flavor and quality, and prevents freezer burn.  It’s great for protecting and food made in advance and leftovers, for food going into the pantry, fridge, freezer, or picnic basket.  The FoodSaver (www.foodsaver.com) is one you’ll find in many stores, and it works well, according to Dr. Cutter. 

Tip #5: Read labels!

This may seem too obvious to say, but preservatives extend shelf life. Food labels often tell consumers that a particular ingredient is a preservative. Sugar and acidic ingredients are natural preservatives. A product called nison is also a natural preservative and an anti-microbial that protects against many bacterial strains.  You might find nisin in your dairy products, canned foods, cured meats, and processed cheese as well as in beer, wine, and salad dressings. If you are avoiding the purchase of foods with artificial preservatives, keep in mind that these “natural” items will not last as long as those containing preservatives, especially after the product has been opened.

Remember that use-by dates refer to the QUALITY (not safety) of foods, and they’re about the UNOPENED product.  To find out how long a product will be of good quality once it’s been opened, check the specific product on Shelf Life Advice.

Tip #5: Freezing is a great way to extend shelf life—if the food is wrapped right.

Many newlyweds freeze a chunk of their wedding cake and save it to celebrate with on their first anniversary.  You’ll enjoy your defrosted wedding cake (or any other food) more if you’ve wrapped it well to avoid freezer burn.  Use freezer bags or double-wrap the food.

Don’t wait a few days to freeze leftovers.  They taste better if frozen when they’re fresher. 

Tip #6: Don’t throw out leftover fresh fruit.  Dry it. 

Drying foods for preservation is growing in popularity because the benefits are many.  For starters, finding a use for leftovers or inexpensive, in-season fresh fruits and vegetables is a great way to avoid waste, save money, and do well for the environment.  Moreover, drying food is easy.  The sun, the oven, or your dehydrator does most of the work.  All you have to do is eat it, which is a treat because drying food intensifies the flavor. 

Furthermore, dried foods require no refrigeration, are compact and lightweight, and pack a lot of nutrition, so they’re very handy to have along on a long car ride, a hike, a camping trip or even a trip to the movies with a bunch of insatiable kids. Nibbling on brought-along dried fruit is healthier (and cheaper) than candy from the movie concession.  And drying your own is a lot cheaper than purchasing store-bought (or movie-counter) dried fruit. 

The shelf life of dried fruit is about a year if stored at 60ºF and about 6 months at 80ºF. Dried vegetables last about half as long. And if you’ve dried more than you can use for awhile, you can freeze them for longer preservation. 

To learn more about the types of food commonly dried, methods of drying food, and types of dehydrators, click here.  

Sources (in addition to the hyperlinks in the article):

Catherine N. Cutter, Ph.D., Pennsylvania State University, Dept. of Food Science

Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science

Susan Brewer, Ph.D. University of Illinois, Dept. of Food Science and Human Nutrition

FoodSaver.com

http://www.foodsaver.com/product.aspx?pid=8793

profoodinternational.com   “What is Nisin?”

http://www.profoodinternational.com/nisin-profood.html

Chicago Tribune   What’s Cooking section “What about those yolks?”

June 29, 2011.