Dehydration Questions

by Susan on February 17, 2010

One of the questions that comes up consistently both in the comments and your emails, is about dehydration. Are there alternative ways to make raw food recipes with out a dehydrator? Dehydration times and temperatures also seem to be confusing. I will attempt to answer your questions, but I also want to encourage you to do research on the subject so you get to a point that you are comfortable with. Let’s start with the most frequently asked question:

Can I make the recipes without a dehydrator, in my oven? If you wish to try this method, there are a couple of things that I suggest you think about.

1. How important is it to you to follow the raw method and protect the enzymes, nutrients and vitamins. Some of the nutrients can withstand the higher temps, but not all. If you are just wanting to make the recipe, but don’t care about adhering to the raw temperature guidelines, it would make more sense to just “bake” them at the lowest temp possible and check your times.

2. If you want to make sure you are sticking with the temperature guidelines, this method will be difficult. You could purchase an oven thermometer, prop open the door and see what kind of results you can achieve. One of the questions you will have to ask yourself is whether or not you are comfortable running your oven for hours with the door open. Not too energy efficient.

I thought I had to make sure that I didn’t go over 105 degrees for maximum health benefits. A lot of people wonder why I start many recipes at a higher temperature and then reduce the temp after a period of time. This is why:

1. The temperatures that enzymes are destroyed at are food temperatures, not air temps. Starting at a higher temperature will benefit in two ways. First, it reduces the time needed for dehydration. Second, it helps pull out the moisture quickly, reducing the chances of fermentation taking place over longer periods of dehydration.

2. There is some mis-information out there about dehydration temps. This is a very good explanation from the Excalibur site:

“Ann (Wigmore) tested different dehydrators,… She found that the best technique for saving enzymes was to set Excalibur on a higher food temperature setting in the beginning and then turn it down after a few hours. However because most people may not know when to turn it down, and by leaving it on the higher setting may kill the enzymes she said to set your Excalibur on 105ºF setting throughout the entire cycle. That way the food temp will never go above 120ºF even after it is dry.

We believe this is why many have come to believe that 105ºF air temperature is the temperature at which the enzymes are destroyed, which is entirely inaccurate.

Just recently we spoke with Dr. John Whitaker who is a world recognized enzymologist, and former dean of the Department of Nutrition and Food Science at U.C. Davis. He said that every enzyme is different and some are more stable at higher temperatures than others but that most enzymes will not become completely inactive until food temperatures exceed 140ºF to 158ºF in a wet state.”

Why don’t you state an exact time for dehydrating recipes? Because dehydration takes place over a longer period of time and at lower temperatures, your dehydration time will be affected by different variables. Humidity, the type of dehydrator you have, etc. will cause the times to differ. You should always check what you are dehydrating so that you get the best results.

In the summer, I hardly use my dehydrator at all. But in the winter, it is a life saver. You can buy a small dehydrator, the Excalibur 4 tray is good for most, for around 100.00. If you are really interested in incorporating raw healthy foods into your diet, it is a great investment. You can find them in the Rawmazing store!

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{ 22 comments… read them below or add one }

bitt February 17, 2010 at 9:50 pm

so informative! I agree that a lot of people are confused about the temps. I’ve even put a thermometer in the dehydrator and the air was not as high as the knob indicated.

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Stacy February 17, 2010 at 10:12 pm

Oh boy this is a great insight to dehydrating! Thank you for the quote from John Whitaker…am passing this blog onto my dehydrating friends.
Bitt, I’ve done the same thing and actually the thermometer air was higher than the knob on mine…yikes ;P Our dehydrator from Cabella’s is right on the nose with the temp shown on the electronic display, the Excalibur is the one that varies for us. I think it is a good idea for everybody to test their dehydrators and see how accurate their setting is to the actual temp inside of the dehydrator.
Susan, where did you buy your red dehydrator screens?

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Susan February 17, 2010 at 10:21 pm

Check out this link from Excalibur. It will explain the varying temps…it is not something to worry about. http://www.excaliburdehydrator.com/enzymes_and_thermostat_control.htm They are the screens that came with my TSM dehydrator. I have 3 different ones.

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hihorosie February 17, 2010 at 10:42 pm

When we first started raw and attempting dehydrating we did the oven method. I didn’t think it worked that well but it did motivate us to save up for an Excalibur. So glad we have one! Also, another tip for those just starting out and looking to save is to check Craigslist or garage sales, etc. We scored on our Champion juicer that way. :)

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Dawn Hutchins February 18, 2010 at 9:45 am

Thank you so much for this post as this answered my questions I had since I’ve been browsing your site.

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Diane February 18, 2010 at 11:32 am

I’m getting the stainless sausagemaker as soon as we get through some more pressing bills. We’re lucky to have some stores nearby that carry the specialty dehydrated raw crackers and snacks, but the are really expensive. I’m sure even a spendier model like the one I want will pay for itself in no time if I dehydrate my own products vs. buying them pre-made. Now if I can just find a place to put it. Small bungalow, teeny kitchen, no laundry room, and I think the basement is out since it’s a bit moldy.

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K&M February 18, 2010 at 2:06 pm

Thank you, thank you, thank you for writing that!

Many rawfoodists and people trying out raw foods believe that all enzymes are denatured at or above 115F or 118F.

I learned early last year that different enzymes denature at different temperatures and was hoping to find more info on that. It would be nice to see a chart/table with this kind of data – the enzyme & temperature of denaturization. The same for freezing temperatures. Although, freezing generally does less ‘damage’, from what I understand.

Also, one cannot kill enzymes. They are not alive. They are a protein.

Again, thanks for posting this.

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Kelly Parr February 18, 2010 at 2:29 pm

Very informative and answered questiongs that I didnt even know I had! :)

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Polly Raichert February 18, 2010 at 7:52 pm

but you can destroy enzymes with cooking, right? Susan what are those delectable looking treats pictured?:-)

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Susan February 18, 2010 at 8:02 pm

Denature, kill, destroy…I think it is semantics….

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Susan February 18, 2010 at 8:03 pm

They are the beginning of an amazing treat…more to come!!

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Julie Lynn February 19, 2010 at 2:59 pm

Susan,

Stop by my blog when you get a moment. I left you an award. =)

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Elizabeth February 22, 2010 at 1:25 pm

Good info. I thought people turned up the temp on the dehydrator to save energy by finishing the food faster!
Thanks!!

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Lisa February 23, 2010 at 12:34 pm

Very nice article! … It’s disappointing to dehydrate something forever just to find it fermented …

K&M, freezing tends to just greatly slow both microbial and enzymatic action, rather than killing/denaturing either. Same for dehydrating at the lower temps.

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Wind March 28, 2010 at 10:21 am

I am very grateful to be educated on this subject. I have been playing with raw foods for seven years and have never come across this information. I thank you.

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Donna February 9, 2011 at 2:12 pm

Thanks for the info. My dehydrator has been my life saver this winter for raw foods. My problem has been using other recipe’s that say to dehydrate only at a lower temp. Some recipes ended up partialy fermented and took forever to dehydrate. Your recipe’s stated the higher temp. for a few hours then lower. I will try this next time and want to try some of your recipes to.

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Terry August 31, 2011 at 11:39 am

This is a great site with lots of good information. With regard to dehydrating … I’ve been 100% raw foodist for 8 years, and I dehydrate everything at the same temp and have never had a problem. My excalibur 9-tray is set at 110 — done. Many times I add other items when I’m in the middle of dehydrating a different recipe, so can’t be bothered with yo-yo-ing the temp up and down. Just put your stuff in, turn it when necessary. Keep it simple.

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Susan September 1, 2011 at 11:13 am

Starting with a higher dehydration temperature reduces dehydration time (using less electricity so it is better for the planet), and also helps prevent fermentation and the growth of bacteria that can happen when dehydrating at lower temps for longer periods of time. It is very humid in the summer where I live so the shortened times are very beneficial. But to each their own!

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amy April 14, 2012 at 6:57 am

Might be silly questions but just got a dyhydrator. (Excalibur). The wired sheets go on top of trays always? Teflex sheets on top of that? If I am using only 2/4 trays should I remove others?

THANKS

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Susan April 14, 2012 at 9:30 am

You can remove or leave them in. It is completely up to you. I am confused as to the stacking. The trays support either the non-stick sheets or the grids. I hope that helps!

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Carrie October 10, 2012 at 11:36 pm

Enzymes have a life span – just as with any living thing. So I’m wondering….if it takes 8,12, 14 and sometimes as much as 24 hours to prepare a raw dish via the dehydrator at 105 degrees, how many of those enzymes actually survive that amount of time? I’m not just asking about plain fruits and vegetables necessarily….my question also concerns more elaborate dishes like flax burgers (hemp burgers, veggie burgers, etc…), pizza, calzones – things are are blended, mixed, pureed, etc… and then dehydrated.

Thanks!

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Susan October 15, 2012 at 1:27 pm

It is my understanding that heat above 118 degrees destroys enzymes. You can pick an apple, let it sit for months and still have an apple that has nutritional value, enzymes intact. You can also cook that apple immediately after it has been picked and destroy all of it’s enzymes. I think that it is not the time in the dehydrator, it is the heat. Cheers!

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