We’ll take a break from this instructional series tomorrow before returning for a few more posts on the fundamentals of dehydrating food.  Feel free to add additional questions to the comments below and we’ll try to add them to this series of key dehydrating concepts.

The question of temperature comes in many different forms.  Know that some dehydrators don’t have a thermostat, some people want touse their ovens (understandable if that’s what you have) and others are wondering what temperature to set the dial for their dehydrator on.  We’re going to assume, for this article, that you have the ability to change your temperature and are using a dehydrator. 

If you are using an oven, the same knowledge applies (the difficulty being that many ovens don’t drop below 200 degrees which is hot enough to cook your product without drying it).  We’ll have a separate post later in the week (or next) to discuss oven drying.

Dehydrators with a variable temperature setting offer so much flexibility to the home preserver.  Namely:

• They allow you to dehydrate things hotter than most fixed temperature units which allow you to dry things like jerky without needing to finish in the oven at a higher temperature.
• They allow you to dehydrate things cooler than most fixed temperature units which allows you to dry things like herbs without turning them brown and losing their flavor.
• They allow you to precisely dry food below 105-158 degrees (more on this key temperature in a moment).

Many people don’t understand the thermostat on their dehydrator (I didn’t for a long time).  The temperature on the dial generally (always in the case of the Excalibur line of dehydrator that we use) refers to the temperature of the FOOD and not the air inside the box.  It is, of course, an approximation but it’s very different from the setting on your oven which refers to the ambient temperature of the air around your food.  The air temperature is generally 20 degrees warmer than your product while dehydration is happening (the process of evaporation will lead to cooler food temperature). 

Another consideration is that the natural enzymes in food (these are good for you) are destroyed with a certain amount of heat.  I’m certainly not an expert in the field of RAW food but understand this to be a core component of the diet (there’s a great FAQ here) which describe the benefits of raw food. 

Key concepts involved in cooking food under very hot temperatures:

• Too much heat kills healthy enzymes in food
• Destroys vitamins
• Changes the pH level of food

The actual temperature at which this happens is still debated.  Some claim:

• Enzymes die when food temperature raises higher than 105 degrees
• Enzymes die when food temperature raises over 120 degrees
• Enzymes will die when food reaches more than 140-158 degrees in a wet state
• Enzymes are much more resilient when food is in a dry state

The ability to use a thermostat is a significant advantage if you’re trying to preserve much of the nutritional benefits from your dried foods.  I can’t tell you which of the four contradicting statements above are correct but will point you to this article from Excalibur which details their research and names scientific sources they have used to reach their conclusions (and the ones I follow).  This isn’t about safety – it’s simply about preserving as much of the ‘goodness’ that you can.

 Having said all of that, here’s some rough guides for dehydrating different things and the food temperatures I use:

Pasta 135 Degrees
Fruit 135-145 degrees
Vegetables 125-135 degrees
Herbs 95-100 degrees

These are rough guides and many recipes will call for starting at one temperature and then reducing as the process goes on.  The key is to understand the advantages of varying your temperature and to know that there is a point when heat can kill much of the benefits of the produce you are working with (though it will still be safe and tasty).

This is part of a series of posts dedicated to the fundamentals of dehydrating and sharing tips that will ensure success as well as traps to avoid.  Make sure to check out the comments as they add to the discussion.  Additional information can be found through some of our posts on dehydrating or in our Facebook Group where a vibrant community with plenty of discussion can often be found! 

There is nothing more frustrating than losing product that you worked long and hard on.  In the case of dehydrating food, it’s even more painful as a small amount of mould can ruin a tremendous amount of produce.  As an example, we recently dehydrated fire-roasted jalapenos and the 26 pounds of original produce now sits in only 2 mason jars on our counter.  If one were to go mouldy we would lose about 13 pounds of jalapenos in a single jar.

There is only one reason why dried food goes mouldy: moisture.  There’s also some fine print here – there are many ways for your product to become too moist. 

It’s very important to understand that drying your product is only the first step.  Think of dehydrated goods as moisture sponges – they love to absorb liquid and humidity and can easily absorb moisture from the atmosphere and become less ‘dry’ and susceptible to mould.

Here’s a list of the things that I can think of that can result in too much moisture (and how to avoid it):

• Not drying the product enough in the first place. The National Center for Home Food Preservation (NCHFP)has many articles on how to tell when something is dry enough (I really like the link that you’ll find to Colorado State University which has a single ‘cheat sheet‘).  General idea (with exceptions): you are trying to remove 75%-95% of the moisture from produce (generally vegetables are dried more than fruit and end up crispy and brittle compared to leathery and slightly mailable).
• Different thickness of product resulting from slicing/ cutting.  Items of different thicknesses take different times to dry and become very difficult to obtain consistency with.  We shared the importance of using a mandoline here and this will resolve this issue for most fruit and vegetables (though soft items like ripe peaches and tomatoes won’t take well with it).  I believe a mandonline (and it’s safe use) is a tool that will save so much frustration, effort and spoilage that I can’t imagine drying without it (personal opinion).
• Not conditioning your product.  Once out of the dehydrator, some of your slices are more moist than others (this is especially true if you didn’t use a  and have items of different thickness).  Thinner slices will pull moisture from the thicker slices (assuming they are moister due to dehydrating the same length of time) until all product in the jar is roughly the same moisture content.  The NCHFP recommends placing dried goods in glass jars (only fill about 2-3rds of the way) and leave with the lid off for 4-1mandoline0 days.  Check the product daily, jostle it around to ensure there’s lots of air circulation and let them settle in (this is complicated if it’s very humid and you’ll have to check that things aren’t rehydrating).  If moisture appears in the jar or things appear to be too moist, return them to the dehydrator.
• Improper storage.  The safest is the freezer in sealed bags but we don’t have nearly enough room and use the product too often.  We store the product in a dark place in mason jars with the lid on to prevent more humidity from entering.  If you conditioned them in humid weather you may want to check as humidity breaks.
• Wet hands.  Cleanliness is a virtue of the kitchen – in the case of dealing with dehydrated food, clean also equals dry.  If you touch a dried product with a wet finger, it will gladly drink in some of that moisture which raises its water content and can put the jars contents in danger.

A final piece of best practice: when we dehydrate vegetables (or some fruit) that we plan to rehydrate when cooking, I’m not worried about making them ’too’ dry.  Since the intent is to rehydrate them (or, in many cases, turn them to powder), I’m not concerned about the texture of the final product.

This probably isn’t the definitive list – though it is the best practice that we follow in our house and we’ve never suffered a lost product of any sort and store our dried goods for long periods of time.

What tips would you add to the list?  If you’ve lost product before, is there something above that may have helped you avoid spoilage that you’ll try next time?

This is part of a series of posts dedicated to the fundamentals of dehydrating and sharing tips that will ensure success as well as traps to avoid.  Make sure to check out the comments as they add to the discussion.  Additional information can be found through some of our posts on dehydrating or in our Facebook Group where a vibrant community with plenty of discussion can often be found!

We don’t really get this as a question that often – but we should.  For there is only one answer and knowing it will change your relationship with drying food:

Buy a mandoline.

I have a $20 hand slicer (the OXO Good Grips) that has 3 width adjustments.  There is no replacement for this tool when it comes to drying food.

Consider that a slice of apple may go in to the dehydrator at 3mm (approximately 1/8th of an inch) thick.  If the piece beside it is 4 mm (1/6th of an inch), it could take up to 33% longer to dehydrate.  Unless your knife skills are accurate to a smaller margin than 1/25th of an inch, a mandoline is a giant time saver.

A mandoline starts saving you time because of the speed which you can accurately slice – but that’s just the beginning!  Once your product is drying in the dehydrator, things dry evenly which takes away the need to constantly check each and every piece for doneness through the process.  A quick visual scan will confirm that a tray is drying consistently and you won’t need to pull out each tray and remove individual pieces as they complete.  This is a massive deal if you have a larger unit (our has 9 trays and more than 20 square feet to dehydrate with).

When using a mandoline, it’s essential to use extreme care.  I’ve cut myself with them 3 times (all in the first 3 months of using one and only once when not using the guide) and each time was very painful.  These tools, like chainsaws and nailguns, can save you a great deal of time but require unyielding focus and care to harness their power safely.

It takes some time to get comfortable with using this tool.  I am amazed at how often I find myself using it (several times a day) and how much work it’s taken away from my use of knives in the kitchen.  I could not dehydrate the amount of food we do without one.

What’s your essential tip for dehydrating to share with others?

This is part of a series of posts dedicated to the fundamentals of dehydrating and sharing tips that will ensure success as well as traps to avoid.  Make sure to check out the comments as they add to the discussion.  Additional information can be found through some of our posts on dehydrating or in our Facebook Group where a vibrant community with plenty of discussion can often be found!

We’ve been getting more and more great questions about dehydration lately.  I think the timing coincides with cool evenings and fears of frost and the need to put up the last remains of our gardens and crops before the depths of fall (and all of it’s awesomeness) set in.  We’re going to try to answer a few of the most common questions over the coming days (add questions in the comments and we’ll attempt to add them to this series).

One of the most common questions is “How long will it take to dry _______?”  My answer is rather frustrating at first: “It depends.”

I know there’s a lot of books and resources which will tell you how long it takes to dry something.  I believe most of these to be guesses at best.  And a guess is better than anything.  But it’s still a guess.

The time it takes to dehydrate something varies drastically on many factors including:

• The type of dehydrator you have
• The amount of space between product
• The ability for your dehydrator to circulate air compared to other models
• Thickness of the product you are drying
• The moisture of the actual thing you are drying (we’ve all seen very juicy and very dry watermelons as an example)
• The moisture and humidity in the air when you are drying things
• Depending on the quality of your dehydrator, the relative temperature around it could affect drying times in extreme circumstances (I know some people who dehydrate outside in winter – their dehydrator allows the unit to produce variable amounts of heat that allow it to stay a consistent temperature while a mono-heat unit without a thermostat may not).
• The amount of trays and space between them.
• Your preparation method – cooked goods (including blanched) generally dehydrate faster than raw goods
• The different things being dehydrated and the relative amount of moisture in each (herbs are faster than tomatoes)

We recently shared a post about drying jalapenos - 7 pounds of pepper became 10 ounces of dried awesomeness.  This also means that almost 6.5 pounds of spicy water was released into our apartment.  Yes, you can taste and even feel a gentle tingle of heat on your lips when you dry hot peppers en masse like this.  No, it doesn’t burn.

The generic answer is that dehydrating generally takes 8-24 hours with the majority of it falling between 12-18 hours.  It is one part technique and one-part art.  You are generally trying to remove 75%-95% of the water content (source: National Center for Home Food Preservation).

Unlike cooking, you check for completion by looking, feeling and breaking your food.  Most vegetables are dried until brittle while many fruits are stopped while still leathery.  If you insist and want a more accurate guesstimation of timings, the NCHFP has a link to Colorado State University and a great document on dehydrating which features it’s timing and how to check doneness on the last page.

When we dehydrated more than a bushel of tomatoes (50+ pounds) in our apartment last year, each batch took subsequently longer than the previous as the air filled with water.  If I were to do such a large batch again, I would likely look at a dehumidifier to remove moisture from the air and reduce cooking time further.

This is part of a series of posts dedicated to the fundamentals of dehydrating and sharing tips that will ensure success as well as traps to avoid.  Make sure to check out the comments as they add to the discussion.  Additional information can be found through some of our posts on dehydrating or in our Facebook Group where a vibrant community with plenty of discussion can often be found!