The Buyer’s Guide to Freeze Dryers

While freeze-dried foods have long been popular among restaurateurs and packaged-food manufacturers, freeze dryers are also becoming essential in other sectors of society—including the nascent cannabis concentrates market. The good news is that it has never been easier to compare a wide range of freeze dryers for home, commercial, or laboratory use.

If you’re thinking of purchasing a freeze dryer for your own personal or commercial needs, the trick is understanding what to look for. The specs you’ll find in a freeze dryer comparison are quite a bit different than for other types of products, so we’ve created this overview to help you make sense of it all.

Freeze-Drying Overview

Freeze-drying, or lyophilization, is defined by the Food and Drug Administration as “a process in which water is removed from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase.”

There are three steps involved in the process:

• Freezing
• Sublimation (the initial drying)
• Desorption (secondary drying)

First, the contents inside the freeze dryer are frozen to a temperature far below 0°F, sometimes close to -50°F. This is how the foods or products are prepared for sublimation.

The sublimation step is what makes freeze-drying unique. This process transforms the ice from a solid to a gas, bypassing the liquid phase entirely and allowing the original moisture to be removed in the form of gaseous water vapor. For this process, a high vacuum is used to reduce pressure inside the freeze dryer. Heat is also applied to assist in the conversion from ice to water vapor.

For the final step, a vacuum pump removes the air and vapor from the chamber, eliminating about 95% of moisture from the foods. At this point, the foods can be removed from the chamber and stored at room temperature.

Benefits of Freeze-Drying

The benefits of freeze-drying are many, but they vary depending on the purpose for which the freeze dryer is being used.

Benefits of Freeze-Drying Foods

Freeze dryers are popular among campers, survivalists, culinary experts, and restaurant owners for several reasons.

• Freeze-drying allows for conditions where foods can safely be stored at room temperature. Freeze-dried food is shelf-stable and food-safe for up to 30 years in some cases.
• Freeze-drying allows foods to retain most of their original flavor and texture when rehydrated. This is because freeze-dried foods rehydrate more readily than dehydrated foods.
• Freeze-drying locks in the nutrients of fruits, vegetables, and meats, ensuring that they retain most of the nutritional value that they had when fresh.
• Home freeze dryers are more affordable in the long-run than purchasing commercially freeze-dried foods. Commercial producers of freeze-dried foods have markups as high as 85%, so a home freeze dryer can be an excellent investment.
• Foods are easy to prepare for freeze-drying. Vegetables just need to be cleaned and blanched in some cases, and certain fruits may need to be pretreated to prevent browning. Meats can be freeze-dried in a cooked or raw state.
• Freeze dryers can preserve foods that are otherwise non-preservable, like eggs and dairy products.
• Freeze dryers are easy to use. In many cases, it’s as simple as arranging foods on the trays and pressing a button to start the freeze cycle. Many freeze dryers, though, do have custom settings and controls for users who want precision freeze-drying.

Benefits of Freeze-Drying Cannabis Concentrates

Cannabis processors, and especially hash makers, are also relying more on freeze dryers as they offset many of the challenges associated with making modern ice water hash (bubble hash).

• Freeze dryers eliminate the residual moisture from ice water hash while maintaining temperatures below freezing.
• Freeze dryers can dry hash up to 7 times faster than air drying.
• Freeze-drying preserves the cannabinoids and terpenes, contributing to better flavors and aromas and a better overall experience for consumers.
• Freeze dryers can lighten the color of the hash, contributing to a more attractive and marketable aesthetic.
• Freeze-drying can dramatically extend the shelf life of hash concentrates.
• Freeze dryers take the difficulty and labor out of the hash drying process. Just set it and forget it.

Pictured: placing wet hash in a Large Harvest Right Pharma Freeze Dryer at the Papa's Select lab

Types of Freeze Dryers

When shopping for freeze dryers, you’ll often find them labeled according to the intended customer. Harvest Right, for instance, uses categories like Home, Pharmaceutical, and Commercial. Some manufacturers also offer Scientific freeze dryers.The meanings of these terms can vary from one manufacturer to the next, so it’s always important to check the specs.

Home Freeze Dryers

As the name suggests, these are intended for freeze-drying foods at home. They tend to be smaller in size and capacity, more affordable than the alternatives, and simple in their design. You won’t find as many customization settings with this type of small freeze dryer. In some cases, they have a single button to activate the freeze-drying cycle.

Pharmaceutical Freeze Dryers

Pictured: Large Harvest Right Pharmaceutical Freeze Dryers in the Papa's Select lab 

Commercial Freeze Dryers

Scientific Freeze Dryers

Scientific freeze dryers are often used in research labs and equipped with precise customization settings.

For example, Harvest Right and Labconco make scientific freeze dryers that can be programmed for custom processes, giving the user complete control over the timing of the condensing

unit and vacuum pump and the ability to input custom temperature settings throughout each step of the freeze-drying process.

The rate of freeze can be sped up or slowed down as needed. This type of control allows for maximum precision and the use of custom recipes.
To see a more detailed comparison of the types of freeze dryers and the benefits of each, please refer to our Harvest Right freeze dryer fact sheet and our Labconco freeze dryer fact sheet.

What’s Required in a Freeze Dryer?

A freeze dryer isn’t like other types of freezers. When shopping for a freeze dryer, you want to keep certain requirements in mind:

• The collector coil of your freeze dryer must be at least 15 to 20 degrees colder than the freezing point of the types of foods or concentrates you want to freeze dry. Conventional freezers can’t compete here.
• You’ll need a vacuum pump that can reach a minimum 0.20 mBar. This is how you achieve the necessary vacuum levels to remove the sublimated water vapor from the chamber and into the collector coil.
• Each freeze dryer should contain a manifold, tray dryer, or other drying accessories.

When breaking down your needs on an individual level, consider the following:

Temperature Needs

First, it helps to know the freezing point of the material you’re freezing. For instance, a lot of fruits have a freezing point between 10°F and 32°F, but it’s generally recommended that fruits and vegetables be stored at temperatures below 0°F.

In any case, your freeze dryer will need to reach temperatures that are 15 to 20 degrees colder than the freezing point of your sample. If you’re freeze-drying bubble hash, the customary freezing temperature is -30°F to -50°F. Most quality freeze dryers can reach temperatures around -50°F, which is suitable for most applications. It’s still important to check the product specs, though.

Purpose

If you just want to freeze-dry foods for personal use and for long-term food storage, go with a home model. If you’re using it to dry ice water hash, a pharmaceutical model will serve you well.

Pharmaceutical and scientific models like the Labconco FDry-8L Freeze Dryer System also work well for other herbs, oils, and medicines. If you need maximum control over the times and temperatures for each drying cycle, scientific models work best.

Capacity Needs

Freeze dryers vary substantially in their capacities, from small home models to large commercial models.

The first step is to determine how much surface area you’ll need for each drying cycle, depending on the quantity and size of your samples. Then, as you compare freeze dryers, you can calculate the total surface area therein by multiplying the tray size by the number of trays. Extra tray kits are available for some models to expand your capacity.

Freeze Dryer Comparison

Below are a few of our top-recommended freeze dryers along with their basic specs:

Capacity Per Batch

Tips for Finding the Perfect Freeze Dryer

Even when you find a freeze dryer that offers all the right specs, there are still a few more variables to consider before making your purchase:

• Does the freeze dryer have programmable shelf temperatures and vacuum levels?
• Is it fast enough to meet your needs? While some users are fine with 24-hour freeze-drying circles, some commercial operations require the shorter 6-to-8-hour cycles offered by the Labconco FDry-8L.
• Does it offer vacuum pump protection that preserves your samples in the event of a power outage?
• How much maintenance is required? Ideally, you want a machine with a high-quality vacuum pump like the Leybold SOGEVAC NEO D 16, which requires maintenance as infrequently as every 3 years.
• Does it come with a warranty? It should include at least a 1-year manufacturer’s warranty.
• What are the shipping costs? This will need to be factored into the total cost of the unit.
• What is the total lead time? In some cases, these units can come with shipping delays when ordered online. If you urgently need your freeze dryer, expedited shipping may be available.

Most importantly, be sure to purchase your own freeze dryer from a reputable manufacturer or retailer that stands by its products. As long as you do your homework when buying, this is one purchase you won’t regret.

If you have questions about freeze dryers, contact us today. Our expert team can help you select the best unit to suit your needs.