By: Diane Wright Hirsch, Extension Educator/Food Safety
Whether you are someone who wants to store away a cache of food in case of an emergency or weather disaster or if you simply want to preserve some green beans from your garden or freeze some chicken from the farmers’ market, you may have considered purchasing a vacuum packaging machine, or maybe you already own one.
Along with the quest for more information on preserving food at home SAFELY, Connecticut food preservers are also on the look out for ways of preserving food more effectively and easily. At the same time interest has piqued in the use of vacuum packaging devices made for use in the home kitchen. So what about these little machines? Are they a good addition to the food preservation toolbox?
What is vacuum packaging?
When you use a vacuum packaging device, you are removing the air from the package of food. This air contains oxygen; which is needed by some microorganisms in order to survive and multiply. By removing the oxygen, you will limit the growth of these “aerobic” organisms that can include bacteria and fungi that cause food spoilage and foodborne illness.
In addition, the oxygen in a package can promote certain reactions that can spoil foods. This might include causing a food to become rancid or to darken in color. Both of these reactions are a type of “oxidation” that will be minimized if oxygen is removed from the package.
But, don’t run out and purchase a vacuum packaging device until you also know the disadvantages to packaging this way.
Vacuum packaging can be expensive. The machinery can cost well over $100. In addition, you must then purchase special bags, which are not reusable.
There are some new hand-held devices that may be battery operated or a simple manual pump that resembles a bicycle tire pump. These are much cheaper and users report that they are effective and easy to use. However, these bags are also not reusable.
If you decide to go ahead (you might argue, “hey, it will save me from throwing away food that becomes inedible in my freezer”), there are a few more things to think about.
There is a risk for botulism or other bugs that actually like an oxygen free environment—and they will not tell you when they are there!
When spoilage organisms are present, they are certainly more than willing to let you know. They cause a food to look peculiar, they might make a food slimy or smelly or turn funny colors. This is good. Then we know to throw the food out. But, the biggest fear we food safety types have regarding the use of vacuum packaging equipment in the home is that some pathogenic or disease causing bacteria also prefer the anaerobic (oxygen free) vacuum packaging environment.
One of these is the Clostridium botulinum—the organism that causes botulism poisoning. These bacteria may give the consumer no sign that they are growing in a vacuum packed food. The food can look, smell and taste perfectly fine. Botulism is most likely to result from low-acid, moist foods canned or vacuum packaged in an air-free environment. Think chili in a can, mushroom soup or smoked seafood. Also, think low acid veggies or meats vacuum-sealed on your kitchen table.
So, can these machines be used safely?
Vacuum packaging machines will extend the storage time of refrigerated food, dry foods, and frozen foods. However vacuum packing machines or sealers are NOT a substitute for heat processing of home canned foods.
Perishable foods packed in a vacuum package must be refrigerated between 34 and 38°F or frozen at 0° F. They cannot be safely stored at room temperature. Keep in mind also that when you defrost foods frozen in vacuum bags, additional precautions must be taken. I like to recommend that people open the package, allowing some air to enter when removed from the freezer. Then defrost in the refrigerator. Thawed, unopened vacuum-packaged foods are a recipe for a food borne illness disaster—maybe even botulism poisoning.
Dry foods such as crackers or rice can be stored in vacuum bags safely at room temperature. You can also use them for dehydrated foods including dried fruit or tomatoes, nuts, or meat jerky. These foods contain little moisture to support the growth of bacteria. But it might be cheaper to simply use glass jars or plastic or metal containers with air tight lids that can be used over and over again.
Also, keep in mind that any foodborne illness causing bacteria that might have been present on something like raw chicken or unwashed blueberries will still be there when these vacuum packaged frozen or refrigerated foods are prepared for eating. Be sure to handle them as you would any perishables. Wash fruits and vegetables before eating or preparing, use good cleaning and sanitation practices, and cook raw meat, poultry and fish thoroughly before eating.
For more information about vacuum packaging food for home storage, go to the National Center for Home Food Preservation at http://nchfp.uga.edu or contact the Home and Garden Education Center at firstname.lastname@example.org or 1-877-486-6271.