Freeze Drying Offers Profitable, Produce-Saving Benefits

Freeze Drying Offers Profitable, Produce-Saving Benefits A WWII medical invention might help today’s farmers get more value from their harvests. Freeze-drying, also known as lyophilization or cryodesiccation, uses extreme cold followed by heat to turn water in food products into vapor. The vapor is removed by a vacuum pump, and the food then undergoes a secondary drying process called desorption to remove up to 99% of any remaining moisture, creating a shelf-stable product. Rehydrate your freeze-dried foods, and they’ll retain their shape, color and taste better than dehydrated foods. Most foods can be freeze-dried, including dairy and meat. Foods high in both fat and sugar (like baked goods) are the exception. Freeze drying is a complex process that requires specialized equipment costing hundreds, even thousands, of dollars per unit. For this reason, many growers hesitate to invest in the technology, despite its profit potential. Shari Gallup, an Assistant Professor with Ohio State University Extension, has set out to find evidence-based information on freeze drying to help growers looking to expand their operations. “Freeze-drying is unique because it removes water without heat damage, preserving food closer to its original state than almost any other method,” Gallup says. “That’s why it’s widely used for space food, emergency supplies, and high-quality backpacking meals.” Freeze-dried foods are lightweight, shelf-stable, and portable. Commercial options can have a shelf life of 25 years. Home-scale freeze-dryers are likely to perform similarly, but they’re new enough that the research isn’t yet conclusive. “Freeze-drying can be a powerful tool for farmers, especially as markets shift toward value-added products, longer shelf life, and reduced waste,” says Gallup. “Fresh produce is fragile and time-sensitive. Freeze-drying lets farmers convert it into premium snacks, ingredients for cereals, smoothies, soups, and specialty products like pet treats.” Gallup notes that freeze-dried goods sell at much higher margins than raw produce. “Instead of selling raw commodities, farmers can build brands. Farm-grown freeze-dried snacks, anyone?” Freeze-dried foods can be prepared in a variety of sizes, making them useful as whole-vegetable snacks all the way to fine seasoning powders. These raw ingredients can be used to make backpacking meals, toddler foods, instant soups, and even pet foods and treats. Still, she’s quick to clarify that freeze-drying isn’t a magic solution for profitability. “Freeze dryers cost hundreds, even thousands, for commercial units, and their energy use is significant. Processing time is slow, often 24 to 48 hrs. per batch.” Likewise, a lack of heat treatment means microorganisms aren’t killed, so they might become active when moisture is reintroduced. The shelf life of any product is related to its moisture content, because removing water eliminates the potential for microbial growth. Overall moisture levels can vary, but they average around 3% for freeze-dried products. Gallup suggests that farmers take their time and conduct thorough research before venturing into freeze-drying. “Start with the market, not the machine. Consider who will buy your product. Will you sell direct-to-consumer or wholesale? And after the initial (expensive) unit cost, are you prepared to pay for the ongoing electricity, packaging, labor and time costs? Premium pricing is necessary to make this worthwhile.” All freeze-dried food should be stored in moisture-proof, hermetically sealed containers. Mylar bags, PETE resealable pouches, and vacuum-sealed Mason-style jars work well. For long-term storage, consider adding oxygen absorbers to extend shelf life by preventing color changes and reducing microorganism growth. To maximize safety, wash all produce before peeling and cutting, and cut it into uniform pieces to ensure even moisture removal. Thinner pieces freeze-dry more quickly. Determining when freeze-dried foods are done takes trial and error. Home units may process unevenly, so it’s important to verify multiple samples. You can cut pieces in half and inspect them for moisture or “dark spots” in the middle, which indicate they aren’t done. If you find them, return all trays to the freeze dryer. Contact: FARM SHOW Followup, Shari L. Gallup, OSU Extension-Licking, 771 E. Main St., Suite 103, Newark, Ohio 43055 (ph 740-618-6330; gallup.1@osu.edu).

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