How to Preserve Tomatoes with Dehydration

The end of the summer is the time for tons of tomato production, and preservation becomes necessary. There are many ways to preserve tomatoes, but dehydrating is definitely my favorite because it is simple and dried tomatoes taste great in soups, on top of winter salads, or even plain as chips.



1. Choose a high acid tomato. Most heirlooms are high acid. Low acid tomatoes will turn black when dehydrated. Ideally your tomatoes are fresh, dark red, with meaty walls.

2. If you wish to remove the skins, boil the tomatoes for a minute then put them in an ice bath. The skins should come off easily after that. This step is a pain, so I don’t bother with it. I will cut the top and bottom of the tomato and feed those parts to the chickens. This gets rid of a lot of the skin

3. Cut cherry tomatoes in half, and cut large tomatoes in ¼ inch slices.

4. Spray your dehydrator trays with olive oil cooking spray. This will stop the tomatoes from sticking.


5. This is optional, but I like to add some basil and sea salt before putting the tomatoes in the dehydrator. This gives them a nice flavor if you want to eat them as chips.

6. Dry at 155 degrees for 7-9 hours until brittle. I have found that it takes me around 11 hours to get my tomatoes completely dry. I may be cutting my tomatoes a little thick.

7. Place tomatoes in an air tight container with an oxygen absorber. I use food grade paint cans with oxygen absorbers, or my vacuum packer for storage.



~ Phil Williams

Phil Williams is a permaculture consultant and designer and creator of the website  His website provides useful, timely information for the experienced or beginning gardener, landscaper, or permaculturalist. Phil's personal goals are to build soil, restore and regenerate degraded landscapes, grow and raise an abundance of healthy food of great variety, design and install resilient permaculture gardens in the most efficient manner possible, and teach others along the way.

This is a companion discussion topic for the original entry at

This could be a bit off-topic…
My wife and I do a lot of preserve and the vacuum sealing is one of the techniques we use.

We tried three different vacuum sealers and none was satisfactory: The first one was really cheap and did not properly seal. it was in fact cutting the plastic. The second was better, but bags are too expensive and the vacuum pump gave up after one year of light service. The third is similar to the second.

We buy milk in 4 liters packages. There are three 1.33 liters bags in it. We started using these bags instead of the more expensive ones. The machine is ok when sealing. But since these bags have no grooves, they cannot be vacuumed. So, we devised a setup with a plastic straw that allows air to be sucked before sealing. While working it is a pain. So, we did some search on the Internet and found the perfect machine: good price; clever design; accepts regular bags, good prices; strong vacuum.

We found the machine on aliexpress. It is a Chinese product for the Chinese market: Chinese manual, Chinese serigraphy. But simple to use.

Now we use regular milk bags. We can use any other bags. We can even make our own bags in any arbitrary size with plastic sheets as long as we have the assurance the plastic is food-grade.

The machine has a can to catch any liquid that may be sucked. The vacuum pump do not really like liquids.

One day we tried to vacuum seal a bag of flour. Never do that!!! The flour get sucked into the pump and you have to disassemble the whole pump to remove all the dust that prevent the valves to work properly.

When I disassembled the machine, I could see that the build quality is durable. The design is simple and efficient. We expect this machine to last many years. Compared to machines sold in Canada, it is ugly, but it surpasses all of them when it comes to performance and cost.

I hope this helps the ones that are looking for a performant vacuum sealing machine.

Below are some pictures of the machine and a bag full of tomatoes that are very tightly vacuum packed.

"We found the machine on aliexpress. It is a Chinese product for the Chinese market: Chinese manual, Chinese serigraphy. But simple to use."
SorbentSystems sells the same model in the US:

FWIW: I modified mine for Nitrogen gas flushing to remove all of the oxygen and reduce water vapor for long term storage.

"One day we tried to vacuum seal a bag of flour. Never do that!!! The flour get sucked into the pump and you have to disassemble the whole pump to remove all the dust that prevent the valves to work properly."

You can do flour, you just need to put a piece of paper or something in front of the vaccum blade to prevent flour (or other powder like materials) from getting sucked in. Also don't flll the bag to maximium capacity.

TechGuy,Thanks for the hint: We thought adding a dust filter in the liquid container, but having a filter BEFORE the intake is a much better option.
Can you describe the modification you did?
Is this operation effective with plastic bags? I know that they are not impervious to air. You must be using mylar bags. In that case, why not use an oxygen absorber?

You can use your dehydrator to make tomato leather also. Just chop the tomatoes and dry the pulp on the silicone dehydrator sheets. Drop a roll or two into a pot of whatever and the rich tomato flavor is melted right in. Yum.

"Can you describe the modification you did?I inserted a tap between the intake blade using at tubing tee ( and connected to to a nitrogen bottle and use a valve to turn on an off the gas. I turn on the vaccum pump to remove the air from the bag, then back fill the bag with nitrogen. I repeat the process three of four times to make sure I get all the oxygen.
"Is this operation effective with plastic bags? I know that they are not impervious to air. You must be using mylar bags"
I am using the Iron shield bags sold on SorbentSystems. These bags have two layers of plastic (one of mylar the other is polypropylene (I think) and a aluminium foil. The bags arent' cheap, buy you can reuse them by cutting off the sealed edge and resealing them (although with less storage capacity with each reseal)
"In that case, why not use an oxygen absorber?"
Well the oxygen absorbers have a limited shelf-life, in the sense that you have unseal the your stash of absorbers to put them the bags your packaging, and then reseal the stash, unless you use the all up when your packaging. Everytime you expose the oxygen absorbers to air they start to absorb oxygen. In addition you also need to use a desccant to remove moisture too. The issue is that if you store your bags in a hot environment the desicannt and release moisture back. This is for packaging non food items, such as tools, spare parts that I don't necessary or can't store in a temperatue controlled area. Using a bottle of dry nitrogen just is a cheaper and easier solution. The other advantage is that you can slightly pressurize the bag so that it prevents sucking in air. The Nitrogen will outgas from the bags, but prevent oxygen and moisture from getting in. 
I had started work on a more robust design for a bag sealer, that would accomiidate much larger bags. The idea was two use two pieces of square stock aluminum (about 26 in x 1 in). Use pair of Quick release clamps that would apply pressure between the alum bars. use a heating element from a 24 in bag sealer ( Ordered a replacement kit). I have a cheap harbor freight vaccum pump and use a small diameter brass tubing as the intake. I milled out a grooves in the alum. to accomidate a 1/8 pvc tubing that will serve as the flex rubber to provide a seal for the bag. I was able to pull a good vaccuum in the bag with some initial testing. But I never finished the project by adding the sealing heating elements and setting up for permanment use (I just did a few test to see if it would work). I also purchased a single action three way valve so I could switch between Vacuum and Nitrogen. Perhaps this winter, I've finish it up. I need to do a tear-down on my 24 inch heat sealer so see how much voltage and current I need to apply to seal the bags for my DIY design. 
The reason why I am going DIY is I looking for a way to flush and seal large pail size bags to store bulk dry food (oats, beans, sugar, etc) in 5 gallon pails with mylar bags. The little vac. sealers you and I have are too small and the vacuum pump is under sized for doing 5 gallon size bags. The commercial vac. sealers are big $$$. 

Thanks for the description.
I like the idea of using nitrogen to remove oxygen and moisture.

Actually the bags you describe are called (improperly) Mylar bags.

Moisture, I mean little, doesn't bother me as long as I vacuum the bag and insert an oxygen absorber. Example: Wheat grain is never totally dry. The moisture content is around 14-15%.  

About oxygen absorbers: When I purchase, let's say a bag of 200, I immediately store them in smaller bags to avoid unnecessary manipulations. Ex: I pack them 20 by 20 in small vacuumed "mylar" bags. Each time a new bag is open, I use it completely. This reduces the total exposure time to the air.

My septic system at home uses an air pump for the bio-reactor. This is exactly the same pump technology. An idea would be to use such type of pump for vacuuming larger bags. Some modifications (inversing internal tubing) would be required to inverse the air flow (