3 Freeze Dryer Sizes Compared – Freeze Drying Corn

How do the 3 different Harvest Right freeze dryers compare in efficiency?

With this test, we chose corn because it’s relatively easy to freeze dry. Corn is generally cheap, which makes it the perfect food to compare against our pork cost analysis. It’s also a simple food item that regularly goes on sale. Needless to say, we picked up a bunch of these bags:

Setting up the test

We tried to eliminate a bias by filling the machines equally based on the tray capacity. After calculating the tray sizes, we determined the correct amount of corn to fill each machine with trays of (close-to) equal densities. As you can see from the sq.in/lb (square inches per pound), we got close. The “perfect” amount might have been more or less than this, but it was a good guess for the test.

It’s interesting to note that the tray capacity of the 5-tray freeze dryer is more than the combined capacity of the 3- and 4-tray units. To be able to compare the total cost, I measured the cost of each freeze-dryer cycle and then totaled each of them. The results are shown in the table below.

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The Freeze Dryer Doesn’t Store the Data Logs Forever – Lesson Learned

I had a great plan

As you can see from my sticky notes, I’ve been a bit behind in recording the freeze drying cycles. The plan was to use the sticky notes as a simple way to keep track of the food as I take it out. After I had collected a few cycles, I would come back and match the freeze dryer log to each note, and connect that information back to the pictures I took of the batches.

It was a great plan

The idea was/is great, but I let it build up too much. The biggest flaw in the whole plan: I thought my freeze dryer would keep all the data logs. Well, that didn’t quite work out as I had planned.

Read more The Freeze Dryer Doesn’t Store the Data Logs Forever – Lesson Learned

Freeze Drying Watermelon sticks

Make even slices

Make sure to cut the slices as equal as possible. The freeze dryer cycle will take as long as the thickest part of the food. With watermelon, it wasn’t as important (because watermelon has a simple structure), but the freeze-drying process of other foods can be complicated by drying variable food thicknesses.

We decided to make sticks with our first watermelon test. We tried to cut them the same thickness as the original slices.

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Chopping potatoes quickly for freeze drying

We found that the Vidalia Chop Wizard cut the potatoes to the perfect size for freeze drying. Before using the chopper, we cleaned the potatoes (of course), then sliced the them into ~1/2 inch pieces. The best part is that the potato chunks are now perfectly consistent, which will help them freeze dry evenly.

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Making silicone mats for the 3-tray freeze dryer

Why use silicone mats for Freeze Drying? Some food glues itself to the freeze-dryer trays

See the silicone mat in action.

Here is the silicone mat we used for our small freeze dryer trays.

Before we bought our own freeze dryer, we used my dad’s standard size, 4-tray unit. It’s was older one with the simple, non-touch display with two control knobs. We bought the small, 3-tray unit because it’s just the three of us. We’ve freeze dried leftovers, homemade baby food, random fruit boxes that we bought from our local farmer’s market, and half of our food from Costco.

We love white peaches. We had to run between 5-6 separate cycles to finally finish drying all the slices of white peaches we had. The one step of the process that took longer than anticipated was removing the peach slices from the trays. The peaches were quite ripe, and we blanched them to remove the skin, so they were a bit slimy. After the freeze drying cycle, they were glued to the trays.

Read more Making silicone mats for the 3-tray freeze dryer

Making Freeze-dried Strawberry Powder

This post starts after already having freeze dried strawberry puree.

We filled our freeze dryer trays almost to their max, which made for a very long dry cycle, but it produced a decent amount of strawberry powder. We have found the freeze dryers to be most cost efficient when they are loaded as much as possible.

Quick tip: When freeze drying purees (especially fruits), make sure not to overload the machine. If your machine is overloaded, you’ll have to defrost mid-cycle, and restart to get a completely dry cycle.

Once the freeze-drying cycle is complete, make sure the puree is completely dry…and then get it powdered and into jars before things get sticky (which can happen quickly.)

Read more Making Freeze-dried Strawberry Powder

Food temperature monitor – take-1

This post is a bit of a blast from the past.

This freeze dryer was the first step into our new adventure. If you’re familiar with the Harvest Right products, you’ll notice the older units have two knobs and no touch screen. They only came in the Standard size.

When I first started freeze drying, Harvest Right had a simpler screen that provided little detail about what was going inside the unit and did not have an USB port. I was curious about exactly what was going on inside, so I bought this wireless digital thermometer.

Read more Food temperature monitor – take-1

How much does it costs to freeze dry Pork Chops?

How much does it costs to freeze dry Pork Chops?

The raw pork chops were $1.99/lb. It costs about $0.47/lb. to freeze dry and package it using the Large, 5-tray Harvest Right freeze dryer. The total costs were $2.46/lb.

We freeze dried 9.2 lbs. of pork chops, and analyzed every cost aspect that went into the process. See the cost table below for a cost breakdown of each freeze drying cycle. Our cost per kilowatt hour is $0.10 (this number came off our power bill). With some "simple" analysis of the data we pulled from our freeze dryer logs, we calculated the cost per stage of the cycle. You can also see the exact stages of the cycle.

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