Temperature affects storage time the most. The cooler the better. Most official guideline statistics for shelf life are based on ‘room temperature’, or 70 degrees F (21 C).
Each drop of 10 degrees F (5.5 C) will double the shelf life! That is pretty significant.
60 F instead of 70 F will double a 1 yr storage to 2 yrs, which may simply be the difference between storing your food upstairs in the pantry or downstairs in the basement (assuming you have a basement).
Likewise, when foods are stored in warmer temperatures, you will lose shelf life at the same proportion. 80 F instead of 70 F will halve the storage life. This fact may be more of a concern for those that don’t have a basement to conveniently store food in a cool environment.
One thing that I miss, having moved from the Northeast US to California more than a decade ago, is having a basement. Many homes here are built on slabs, where outdoor temperatures don’t freeze to extremes like other parts of the country (where deep foundations are required, and thus a basement). Without a basement, use your common sense and simply beware of storing food in places where temperatures will be higher than normal.
The process of dehydrating removes most of the moisture from foods while retaining much of the nutritional value and flavor. It is a great method to preserve your harvested fruits and vegetables for later consumption off-season.
Fruits will typically contain about 75 percent moisture when fresh, and should be dehydrated to a 20 percent moisture level, the point at which they become leathery and pliable. Apparently, it is OK for fruits to be dried to this ‘pliable’ level rather than a lower ‘brittle’ moisture level because the natural sugars and acids in fruit act as an added preservative.
Vegetables must be dehydrated to a moisture level around 5 percent, the point at which they become crisp and brittle, and will break if bent.
Oxygen will interact with, and break down fats and proteins resulting in poor flavor and eventual spoilage. Fruits and vegetables only have small amounts of fat and protein but will still oxidize over a period of time when stored in an environment containing oxygen. Oxygen absorbers are commonly used inside long term food storage containers.
Photons from light will also eventually break down fats and proteins as well as vitamins in the food, resulting in poor flavor and possibly eventual spoilage.
Dehydrated Fruit and Vegetable Shelf Life
‘Shelf Life’, when referring to survival food storage, is typically defined as the maximum amount of food storage time whereby the food will not spoil and still contribute to keeping you alive. Shelf Life, when referring to grocery store and typical food packaging labels, is defined as the length of time that the food will still taste its best and retain most all of its nutritional value, usually far before actual spoilage. Having said that, shelf life is a subjective thing, and may fall somewhere in between the two extremes.
Generally speaking, home dried fruits will have a shelf life of about 6 months to 1 year, if stored in glass mason jars and in a dark, dry, and cool environment (the cooler, the better).
The shelf life of home dried vegetables vary depending on the vegetable itself, but some say it is about half that of home dehydrated fruit. I believe it’s safe to say that it will generally be between 6 months to 1 year. Some claim storage life success of several years, but again, storage conditions will change storage life by either increasing, or even decreasing if stored poorly.
Store-bought dehydrated fruits and vegetables processed specifically for long term storage will be prepared, dried, and packaged in processes that bring moisture content down to as low as 3 percent, and will store much, much longer (I’ve seen claims of 25 years in #10 cans if stored properly).
My opinion and experience with home-dehydrated storage and shelf life is that 6 months to 1 year has been fine for me because the following growing season I am growing all new foods. So as long as they last during the off-season, which is quite simple to achieve, then I’m personally okay with that (some of my long term food storage supplies are not home dried, but professionally manufactured). As long as I am able to grow my own food each year, our home dehydration method works just fine.
Vacuum Sealing, Mason Jar, or Zip Lock Bag
In my opinion it is debatable whether vacuum sealing home-dehydrated food will add significant shelf life in most practical situations. Common sense tells me that it will definitely add some storage time, but I’m not so sure how significant that will be assuming we’re talking about foods that are already dehydrated, and are being stored in normal conditions (cool, dark, dry – mason jar), and will be replenished during the following growing season.
Granted that opening and closing a mason jar lid to remove some of the product when needed, will reintroduce fresh air and oxygen into the jar. However, so long as the air in the room isn’t laden with moisture, it would seem not to be such a big concern. If you live in a very humid environment, I can see an advantage though. Some vacuum sealers also have an attachment for mason jars to remove the air. Vacuum sealing in vacuum seal bags will definitely save space too.
Having said all that, I just don’t think it is a huge difference to vacuum seal versus using a mason jar when we’re talking about foods that will only last a year or so anyway… (although some claim to get several years from home dehydrated fruits and vegetables when stored well).
I believe that Zip Lock Bags are a fine alternative too. They take up less space than jars. I am a little leery about the effectiveness of the seal when compared to a mason jar with the nice lid. Quite often I have experienced these bags not holding a nice seal, even after ‘burping’ the bags quite efficiently.
I personally like the mason jars because I can easily see the foods inside while on the shelf, and they are convenient and easy to handle and use. Again, since I’m only dealing with shelf life requirements of 1 year maximum for my home grown foods, I don’t feel a need to use vacuum sealed bags. Don’t get me wrong, we love to use vacuum sealed bags on other items around the homestead, like on some of our other storage items such as 5 pound bags of flour – for convenience – although storing in 5 gallon buckets with Mylar is even better for longer term storage. We’ll save all that for another post some other time