What’s The Best Way To Freeze Dry Large Batches?

“I recently started a small farm in New Zealand and have been growing my own veggies for a while now. I keep hearing about freeze-drying as an excellent storage method, especially for big harvests, and I want to use this technique for larger batches. But I have no idea where to start. Any tips for freeze-drying large quantities effectively would be really helpful! Also, are there any specific things I should watch out for?” Thanks, Sarah, Canterbury, New Zealand.

How Freeze Drying Works

Freeze drying is a fantastic way to preserve food for the long term—think years rather than months like with canning or dehydrating. The food is first frozen at a very low temperature, and then a process called sublimation removes the water. This means the ice inside your veggies (or whatever you’re freeze drying) turns directly from a solid into water vapor without passing through a liquid state. How cool is that?

That means you’re left with light, crisply dried food that’s packed with nutrition. It’s great for large batches because it removes 98-99% of moisture, so your harvest will stay preserved for years and take up much less space than other methods like freezing.

Where to Start with Freeze Drying

Sarah, since you’ve got a plentiful harvest, the first thing you’ll want to do is make sure you’ve got plenty of time and space. Freeze drying large batches isn’t quick—it can take anywhere from 20 to 40 hours for a single batch depending on what you’re drying. But don’t worry: once you set it up, it’s mostly hands-off until it’s done.

Choosing Your Equipment

There are two real options for freeze-drying large quantities at home: investing in a home freeze dryer or outsourcing it to a service. If you’re serious about preserving your harvests year-round, a home freeze dryer might be worth the investment. They can handle multiple trays at once, meaning you can run big batches in one go, which is ideal for farmers like yourself.

• Small freeze dryers: Good for a family-sized garden, but might not be enough if you’ve got entire rows of crops to deal with.
• Medium-to-large freeze dryers: These are perfect for bigger operations or if you’re handling a variety of different veggies, fruits, and even herbs or meats. Some can handle over 10 pounds of food per cycle.

Prepping Your Food For Freeze Drying

The prep work is as crucial as the drying itself. Here’s what I like to do:

• Chop food into even sizes: Your pieces don’t have to be identical, but keep them close enough in size to ensure they freeze and dry evenly. For veggies like carrots or onions, you can slice them thinly for best results.
• Blanch certain veggies: If you’re freeze-drying veggies like green beans, broccoli, or anything with a high water content, blanching them helps retain color, flavor, and texture. It also helps maintain the nutrient value.
• Pre-freeze large batches: This is a time-saver, Sarah! Before placing food in the dryer, spread it in a single layer on trays and freeze it. Freezing beforehand reduces the time it’ll spend in the freeze dryer, cutting down on machine workload and energy use.

Freeze Drying Tips for Large Batches

Tackling lots of food at once can be a challenge, but with a little strategy, it gets easier each time. Here are some tricks:

Load Trays Strategically

Getting maximum efficiency depends on how you load your trays. Freeze dryers work best when the food is arranged in a single layer. Stacking or overloading can slow the process or worse, leave you with partially dried batches.

• Cut food to save space: You can save space by cutting bulkier items like cauliflower into smaller pieces.
• Don’t overcrowd trays: Tempting as it may be to cram all you can in one batch, leaving space between the pieces ensures proper air circulation, which speeds up the drying.

Batch Similar Foods Together

Avoid mixing different types of food in the same load, especially if they take different times to freeze dry. For instance, strawberries and green beans have vastly different water contents and won’t freeze dry at the same rate. Mixing them can result in under- or over-dried foods.

Monitor The Machine

Even though the freeze drying process is mostly hands-off, it’s still a good idea to check it occasionally. Some cycles can run long, so just pop in once or twice a day to make sure everything’s going smoothly. If you notice condensation on your food, it likely needs more drying time.

Storing & Rehydrating Freeze-Dried Food

Once your batch is done, Sarah, you’ll want to store your freeze-dried food carefully to avoid moisture creeping in and undoing all your hard work.

Best Practices for Storage

• Use mylar bags with oxygen absorbers: These are the gold standard for storing freeze-dried food. Oxygen absorbers help prevent oxidation, which can spoil your food.
• Glass jars with proper sealing: If your batch is smaller or you know you’ll be using the food in the coming months, glass jars work great, especially for snacks like freeze-dried apples or kale chips.
• Keep in a cool, dark place: Light and heat speed up spoilage, even with freeze-dried food, so find a pantry or cellar without too much fluctuation in temperature.

Rehydrating Your Food When You’re Ready to Use It

Now let’s talk about bringing those freeze-dried foods back to life. Rehydrating veggies for soups or stews is remarkably simple. Just toss them into hot water or broth, and they’ll plump right back up in 15-20 minutes. For fruits that you’re eating as snacks, no rehydration is necessary (though you can drop bananas or berries into a smoothie as-is for a nutritious boost).

Troubleshooting: What If The Food Isn’t Dry Enough?

If you notice certain foods feel a bit soft or spongy, this means there’s still moisture left inside. No worries—just pop them back in the freeze dryer. If this happens a lot, you might want to double-check that your freeze dryer isn’t overloaded or needing maintenance.

Cost Considerations For Freeze Drying

Freeze drying does come with costs—both in terms of time and resources. The machine is the biggest upfront cost, but after that, energy use can add up, especially when doing multiple, long batches. To help manage energy costs:

• Pre-cool your food by freezing it yourself before using the machine.
• Run the machine during off-peak energy hours if your electric company offers a reduced rate at night or weekends.

I’d also suggest prioritizing your crops based on storage necessity. Foods that you want to retain their texture (like fruit or snacks) are prime for freeze drying, but other items might be fine in the freezer or dehydrated.

Benefits of Freeze Drying Large Batches

There are several reasons freeze drying large batches is the way to go, especially for someone like you with a bountiful harvest out of Canterbury.

• Extended Shelf Life: Freeze-dried goods can last up to 25 years if properly stored, so it’s a great solution for preserving your hard-earned harvests.
• Minimal Nutritional Loss: Unlike canning or other heat-based methods, freeze drying keeps most vitamins, minerals, and antioxidants intact.
• Lightweight and Space-Saving: Freeze-dried food weighs much less than its original form, making it easier to store and transport.

Alternative Methods For Large Batches

While freeze drying is fantastic, it’s not the only way to preserve large amounts of food. For variety (or when the freeze dryer is busy), consider these alternatives:

Dehydrating

Dehydrators use heat to pull moisture out of the food, similarly shrinking its size but with a different texture. Dehydrating isn’t as efficient for long-term storage as freeze-drying, but it’s quicker for some veggies and fruits. You’ll still want airtight containers and dry conditions for storage, though.

Canning

For things like tomatoes, cucumbers (pickles!), or sauces, canning can be a great alternative, though you’ll lose some of the texture. It’s more labor-intensive with all the sterilizing and equipment / timer checks but works wonders for more acidic foods.

Final Thoughts…

Sarah, freeze drying large batches is an investment in both time and resources, but it’s absolutely worth it for the long-term storage and preserved quality you get. Whether you’re tucking away green beans or apples for the winter or prepping entire meals for later, once you get the hang of it, you’ll be amazed at how efficiently you can store all those garden goodies. Thanks so much for your question—I hope this helps guide you through the process!