I've been contemplating getting a vaccum sealer. I think that would be the best option, and then putting the vaccum sealed packages in another sealable container with O2 absorbers in that. That should give your dehydrated food (fruits, vegetables, and nuts)about 15 years. I think meat is a lot less likely to make it that long. I am about in the same boat you're in. I have a dehydrator (American Harvest Nesco). I read that my dehydrated fruits, vegetables, and nuts can last five years, but I think you can squeeze more time out of it if you take a few extra steps mentioned above.

 

That's the one I received for Christmas. I'm trying to become as knowledgeable as possible before I begin. I'm just worried about botulism since the spores aren't destroyed as in canning and pressure canning.

 

The clostridium spores are not destroyed by dehydrating, but neither can they grow in a low-moisture environment. Any organism requires a minimum level of moisture to live and reproduce (water activity or aw) , which for Clostridia botulinum is actually pretty high, at about .93 aw.

The water activity scale runs from 0.0 (bone dry) to 1.0 (water). Dry corn is about .14, dry milk is about .2 aw, dried fruit is about .6, aged cheddar is about .85 , bread is about .95.

As a rule of thumb, if a food will support the growth of mold, the aw of that food is above .75. If your food won't grow mold, then it absolutely won't grow botulism.

So the answer is, yes your dehydrated foods are safe, whether on a shelf in a dry cave or in a mylar bag with O2 absorbers.

 

THAT is the main piece of information I was looking for! Thank you so much!

 

Some of you scare me you are so smart. Good info thanks.

:

 

The past few months we have been using some home dehydrated veggies that I put up 5 years ago. All of it was done with a nine tray Excaliber. What we have been doing is making soups and stews with it.

Only a small was amount was vacuum packed with O2 absorbers and the rest was in mylar with O2 absorbers. Of the following veggies only celery has been an issue. We figured out that it needs to be sliced really thin.

Onions
celery
mushrooms
garlic
leaks
corn
greenbeans
peas
carrots
bell peppers
jalapeno peppers

 

So, since my concern for botulism has been eliminated, as for shelf life, there's really nothing to be worry about when eating dehydrated food that has been stored (in mylar with O2 absorbers) for a decade other than taste and perhaps some loss of nutrition? If it's moldy, don't eat it. If it's not, there's nothing to worry about?

 

Your ancestors used to store dried fruits and veggies in the attic and strung on the walls of the kitchen and the stuff lasted quite well.

As long as your foodstuffs remains dry and away from light, they will be safe to eat, well, basically *forever* and still nutritious for a long, long time.

 

I dehydrate bananas and apples and only store them in double-bagged heavy Ziploc bags. I've eaten them up to three years later with no ill affects or change in texture/flavor.

 

Another point is that your dehydrated fruits and vegetables will not really store any better or longer because its packaged in in vacuum bags or mylar with 02 absorbers.

You will see a benefit using mylar/02/vacuum with foods that contains protein or fat, or that are finely ground like flour, but dried garden stuff is extremely stable.

If time and cost are a consideration, remember that the fruits and veggies only need dark and dry to stay good, and a Ziplock inside a paper bag can do that for you.

FWIW

 

Interesting link regarding 'water activity'.

http://extension.psu.edu/food-safet.../food-preservation/issues/water-activity-of-foods/water-activity-of-foods-table

 

And while we're on the subject, a cheap and quick dehydrator can be made out of a square box fan and a bunch of pleated paper furnace filters that are approximately the same size as your fan.

Lay the box fan on its back across two chairs or something so that there is free space under the fan. Stack one furnace filter on the "blow" side of the fan. Lay down a layer of cotton cloth or cheesecloth and a layer of fruit , another furnace filter,cloth, layer of fruit, furnace filter,cloth, layer of fruit and so on. Put a filter on the very top and bungie cord the whole thing together. Turn the fan on high and let her rip.

You need to balance the number of layers so that enough air is blowing through all of them (not too many, in other words).
You could also make your own racks with 1x1s and window screen or fabric- its much cheaper this way than buying a new dehydrator, and you can do a LOT of fruit at one time.

 

Just because food doesn't grow mold does not mean the water activity is too low to grow mold - mold spores may have been killed or inhibited due to other factors or may be present but not obvious. People eat botulism contaminated food without being tipped off by the obvious presence of mold.

Conditions that favor the growth include low acid foods (pH
above 4.6), high moisture content (water activity above 0.93), low salt, food devoid of
oxygen and food stored unrefrigerated.
http://doh.state.fl.us/environment/medicine/foodsurveillance/pdfs/3_panel_Botulism.pdf

Read that carefully. Does it say that water activity over 0.93 is required? No it does not. also water activity is very different than moisture content. I water activity requirement of 0.93 does not mean 93% moisture. It is more equivalent to humidity levels at equilibrium. Bread has a water activity of around 0.95. And commercially dried fruit around 0.6.

Most microorganisms grow well at 0.91 to 0.99. Clostridium botulinum will grow and produce deadly botulism toxin if the pH is above 4.6 and the water activity is above 0.85.
http://extension.psu.edu/food-safet.../food-preservation/issues/water-activity-of-foods/water-activity-of-foods-table

Another site suggests it takes far less water for botulism too be an issue.

Warning: Botulism poisoning may result if moist products are stored in packaging that reduces oxygen. When stored in airtight containers with oxygen absorbers, products must be dry (about 10% or less moisture content) and low in oil content.
http://www.newfluwiki2.com/diary/1419/

This one quotes a higher level but still much lower than the post above.

In order to grow, bacteria need moisture, some as little as a 20% moisture content. For dry grains, legumes, powdered milk and other low moisture foodstuff bacterial spoilage will seldom be a problem so long as the moisture level in the foodstuff remains too scant to support its growth. For this reason, it is imperative that such products be drier than 20% and preferably below 10% to ward off mold growth as well. The botulism bacteria need moisture in the 35% range to grow. Thus, using desiccants in your food packaging is also an excellent idea.
http://www.survival-center.com/foodfaq/ff15-bot.htm

Bear in mind that allowable levels of water activity are lower the longer the intended shelf life - consider these comments on mold growth:

When these foods spoil, it is usually the result of surface mold growth. Most molds cease to grow at a water activity level below about 0.8, but since some molds will grow slowly at this aw, it is usually recommended that products of this type do not have an aw greater than 0.75.

While this will not ensure complete freedom from microbial spoilage, those few yeasts and molds which do grow at lower water activities need only to be considered when special shelf life conditions must be met For example a commercial shelf life over twelve months might be required for confectionery; in these circumstances an aw below 0.6 would be required.

http://drinc.ucdavis.edu/dairychem4_new.htm

Whether botulism is an issue or not, moisture content has a substantial effect on storage life and moisture content and water activity is often poorly controlled in home dehydrated foods.

 

LDS Recommends <10% moisture w/O2 to avoid Botulism

My goal with my new dehydrator is to dry staples such as onions, bananas, apples, etc... My concern is botulism. I thought I would store them in mylar bags with O2 absorbers . . . how do I know that my food has been adequately dried to keep this from happening?

LDS' Longer-term Storage site says 02 absorbers should only be used for foods having less than 10% moisture - otherwise there's a risk of botulism . LDS Longer-Term Food Storage Site HERE "Warning: Botulism poisoning may result if moist products are stored in packaging that reduces oxygen."

Long page of w/lots of info, but it basically lists the 30+ year foods that have less than 10% moisture (wheat, white rice, corn, sugar, pinto beans, rolled oats, pasta, potato flakes, dehydrated apple slices, non-fat powdered milk, dehydrated carrots).

Their list of products that are NOT suitable for longer-term storage because their moisture content is too high & creates the risk of botulism includes:
- Dehydrated Vegetables and fruits (unless dry enough, inside and out, to snap when bent
- Pearled barley, Dried Eggs, Whole wheat flour, Milled grains (other than rolled oats), Granola, Dried Meat (like jerky), Nuts, Brown Rice, Brown Sugar

 

The foods that I'm interested in dehydrating for long term storage are items that don't can well; specifically bananas and onions, but also items like potatoes, apples and strawberries because I can dehydrate them cheaper than canning them or buying them commercially dehydrated in #10 cans.

I think all of these foods will dry to the point of 'snap when bent'. I don't know if that satisfies the less than 10% moisture rule for using 02 absorbers though. I guess that's the main question now: whether to use the 02 absorbers at all or just put the dried food in mylar and allow a small amount of oxygen to remain? Would that be safer? If a small amount of oxygen compromises the longevity, wouldn't that be preferable to an increased risk of botulism in an airless environment?

 

If they're dry enough to snap, botulism is not a worry. Long term food storage companies have been packing them with O2 absorbers for a very long time. In order to sell food to the public, those foods and their packaging methods have to be accepted by the FDA as safe. These same companies sell powder milk, eggs, barley and a number of other things on the above list. So until I can find further info, I doubt the validity of that list.

 

NickiTX, don't bother with 02 absorbers in fat-free dried foods. No particular benefit in terms of longevity.

In the normal universe, botulism organisms WILL NOT GROW in dehydrated foods. Will. Not. Grow.

To make you ill, these organisms must reproduce and grow- because it is during the growth phase that the toxin is produced. You don't get sick simply by ingesting the organism and the organisms cannot grow at low moisture levels.

The SPORE (which is a protected, dormant stage) itself is very durable, and is the reason why canning is done at high temps/pressures, but you have eaten those spores all your life without effect- very common in soils.

Even the toxin itself is not durable- it is easily destroyed by by heating it to 185 F for 5 minutes (10-15 minute boil is the rule of thumb to make sure all parts of the food is heated.)

**And FYI for the previous poster and anyone else who cares: moisture content and water activity may not the same (water activity being how much moisture is AVAILABLE for biological reaction, which is related to particle size, among other things) but aw score can N.E.V.E.R be higher than moisture percentage. Quit trying to get a food chemistry degree via Google.**

No offense, but your most serious danger of food borne illness is because you didn't scrub your hands properly after pooping.

And color me skeptical at the LDS recommendations quoted above- I think they are erring on the far, far side of caution.

But far be it from me to keep anyone from panicking over an activity that humans have been doing safely for thousands of years...

 

NickiTX, don't bother with 02 absorbers in fat-free dried foods. No particular benefit in terms of longevity.

Fats are not the only thing that oxidizes. The long term food storage companies use O2 absorbers. Their lab tests verify long storage life and adequate nutritional levels. Something our taste buds can't tell us. Dry foods don't "rot" so they may be edible long term without an O2 absorber, but they can also be nutritionally void because of oxidation.

I always defer to how the decades old long term food storage companies are packing foods. They know what they're doing and have lab tests to prove it. It's easy to make mistakes with home improvised solutions and too many things that "seem like they should work" don't. They use O2 absorbers and either mylar or metal cans. Food storage is too important to cut corners, or try to improvise a solution that may not work.

 

ZombieHoneyBadger, thank you so much for your advice. You have been extremely helpful.

 

Okay, one more quick question about storing dehydrated food. I'll be making jerky for the first time tomorrow. I have thinly sliced lean round steak marinating/curing in the fridge. One of my books says to cook it first for 10 minutes in a 350 degree oven, then put it in the dehydrator for 6-8 hours, so that's what I'm doing. Because of the fat/moisture content, about what can I expect for a shelf life if stored in mylar with 02 absorbers? Should I refrigerate it too?

 

In order for jerky to last, it has to be dried to the brittle stage. It's not fun to eat straight like that. For true long term storage, dry meats are usually cured rather than just salted and dried. That's a little more involved.

For jerky I'd just suggest making it the way you enjoy snacking on it, and consider it a short term food and rotate it. Homemade jerky is so yummy that NOT rotating it is the hard part! :

But there are a lot of ways of curing meats. Look up charcuterie, brining and smoking meats, etc. There are some really delicious meats that last pretty well. But they're fairly involved to make.

 

I make jerky all the time as it's my favorite snack (have 25 lbs of venison marinating as we speak )

Mike is correct, unless you really like super dry jerky, it will not be a good LTS food.

I do like my jerky dry, and if I don't eat it all (very hard not to do) I will still last for 6+ months just in ziplocks in the fridge with no problems at all.

Btw drying times are different based on many factors. The first four hours are pretty much worthless, afterwards you should be checking on the pieces every 30-45 min, rotating them to make sure you get even drying on all pieces. It's a long process. I usually make jerky at 155 and depending on the thickness of the slices, it takes between 8-12 hours. Again, times will vary based on how you like your jerky to be made.

 

It's been in for about three hours and I've been blotting the oil about every hour. It's still pliable. It's finished when it cracks but doesn't break when bent, right? It smells wonderful, but I used Nesco spice/cure packs and realized too late that they contain MSG. Next time I'll make my own marinade.

 

Put your dehydrated foods in a jar, drop a small piece of dry ice in the bottom. Let the jar fill up with CO2 and after it's pushed all the air out, put the lid on. At that point, it will last longer than it will be for you to eat it.

 

Not sure on what kind of dehydrator you're using but I never blotted the oil on mine, what temp are you using btw?

I do like my jerky drier so when it cracks and almost breaks when bent is what I like.

Definitely make your own marinade! It took me about 2 years to get the exact ratios to what I want in my jerky lol.

 

I'm using a Nesco. It's round and has eight trays. It's on 160 degrees and some of the pieces seem ready after just four hours. I did pre-cook the meat for 10 minutes in a 350 degree oven per The Dehydrator Bible. That's also where I got the blotting info. I'd love to have your recipes if you're willing to share.

 

If you're going to continue doing a lot of dehydrating I would definitely recommend upgrading to an excalibur dehydrator. They are absolutely phenomenal! It uses horizontal drying instead of vertical so you get a lot more even air everywhere. Trust me, you won't regret it.

I have no problem sharing recipes, I love it!

I slice it with an electric slicer and put them into gallon ziplock bags. Marinade for 5 days mixing up the bags and rotating them every day to make sure all slices get an equal distribution and fully saturated.

This is for ~2 - 2.5 lbs of meat
2/3 cup soy sauce
2/3 cup Worcestershire
2 tsp liquid smoke
2 tsp black pepper
2 tsp garlic powder
2 tsp onion powder
2 cloves minced garlic
1 tsp red pepper flakes

To add extra spice/flavor in a couple of the bags I will add 2 tsp Sriracha as well.

Hope your jerky comes out great!

 

Oh, this sounds wonderful! I will definitely use this recipe next time. Do you add nitrate/nitrite? My jerky is finished and it's pretty darn good. I ended up with about 2-1/2 pounds and started with 5 pounds of round steak. Better than I expected.

 

I've never added nitrate/nitrite to my jerky, never saw the need honestly.

Glad your jerky came out good!

 

Dehydrated foods are pretty much safe from botulism.



http://edis.ifas.ufl.edu/fs104
Look on this page just below the topic:

"What sanitation methods are used to prevent infection?"

 

Just wanted to say thank you for all the wisdom. especially Ms. Badger and Mike

 

Thanks Friends for all the great info, especially Ms. Badger, Mike and others for the wonderful questions.

 

One thing I am curious about - Is it possible for dehidrated food to partially rehidrate from air humidity?