The Most Common Problems With Freeze Drying

Freeze Dried Fruits

Can’t get your gummies and jolly ranchers to puff when you freeze-dry them? Did your food items shrink after the process? We’ll talk about the common problems with freeze-drying that beginners encounter and how to avoid them.

 

Mixed Flavors Between Food Batches

Ever wonder why your freeze-dried bananas taste like onions? Or why do your freeze-dried apples have this unpalatable green bean flavor?

This puzzling mix of flavors is often due to freeze-drying two food types with different flavor profiles. To avoid this from happening, the best option is to freeze-dry one food item at a time. If you’re trying to save time and energy, freeze-dry those with similar flavor profiles. Also, avoid mixing light-flavored food with heavy-flavored ones.

Shrunk food or bubbling

This happens for two reasons. One, the sublimation stage is heated too fast. The second is that the sublimation stage ended too soon, and the adsorption phase started prematurely.

Basically, the excessive temperature causes melt-back or what is known as product collapse. This means the dry product melts into liquid, causing the freeze-dried product to shrink. This severe melting then produces bubbling.

Solution:

There are a few ways to solve this:

1. Reduce the temperature of the sublimation stage
2. Extend the sublimation phase
3. Increase the vacuum pressure of the chamber
4. Keep the product temperature to no more than 5°C.

Massive Mess in the Freeze Dryer

Have you experienced freeze-drying something and ended up having huge gunk of mess on every surface of the interior of your freeze dryer?

You get this when you freeze-dry something that has a high-fat content. Butter and mayonnaise are the best examples of food that will create such a mess. No matter how much elbow grease you put out, you won’t’ be able to get the smell out completely.

Solution:

• Avoid freeze-drying food items that have high-fat content like pure chocolate, peanut butter, mayonnaise, and butter.
• Remove as much fat as possible from meat products before freeze-drying.

Meat Tastes Like Leather

Freeze drying can preserve the texture and flavor of almost all food, and that includes meat. If your freeze-dried meat ended up tasting like leather, this means the freeze-drying process was too long. Usually, this is because the meat is too big that the process took quite a while to complete.

Solution:

Cut the meat into small pieces. It’s best to work with shredded, ground, or diced. This gives the freeze drier more surface area to work with for faster, efficient drying.

 

Food Stay Stuck On The Pan

What do playful kids experience when they mess around with a pole during winter? They get their tongues stuck on the surface.

That can also happen on food after freeze-drying on a metal pan. Sometimes they get so stuck, that it’s nearly close to impossible to get them out.

Solution:

Invest in good pan liners like reusable parchment to keep the food from sticking. Regular parchment can work, too; when used carefully, you can use it for a couple of loads.

Plastic wrap and the wax paper won’t work because they’re too thin and can tear apart.

 

Uneven Freeze Drying

This usually happens when you’re eager and excited to either use your freeze dryer or in a hurry to create your freeze-dried stash.

Most of the time, beginners don’t make the effort to prepare their food properly. The result is they have different shapes and sizes of food that get stacked unevenly in trays. What they end up with is that you have a mix of fully processed freeze-dried food and those that are still cold and wet in the middle.

Solution:

The solution here is quite simple but quite tedious. Take the time to slice up your food evenly, so you get the same-sized chunks or slices.

Another is to layer them evenly on trays and space them properly. This gives your freeze dryer a good surface area to work with.

Also, avoid stacking or layering the food too deeply. Let the freeze dryer do its work by giving it enough space to penetrate food items at the bottom. Remember, the deeper the layer, the less efficient your freeze dryer will work.

Problems With Freeze Drying Solutions

These common problems with freeze-drying can be avoided by observing the following:

• Watch the temperature of the freeze dryer by observing the right sublimation temperature.
• Keep your freeze dryer clean by avoiding food items that are high in fat.
• Slice meats into small cubes to retain the original taste and texture.
• Line the freeze-dry trays with good parchment paper to make it easy to take out processed food.
• Cut the food evenly, and don’t layer the food too deep so that the food will dry at the same rate.

Freeze drying food is an art and requires constant practice to get it right. Just follow these tips, and you’ll easily solve, if not avoid these common problems with freeze-drying.

What problems do you usually experience when you freeze preserve food? Let’s exchange stories and tips down in the comment section!