Preserving food when plentiful, to prepare for leaner times, is an ancient practice. There’s evidence cultures in the Middle East and China were using the sun and wind to preserve food such as fish, meat, fruit and vegetables, as far back as 12,000 years ago.
Widely use by combat troops during World War II, dehydrated food, unsurprisingly, fell out of favor with the public after the war. It wasn’t until the cultural revolution of the 1960’s, with a renewed focus on all things natural, that dehydrating foods experienced a renaissance of sorts.
As with all food preservation methods, there are certain steps along the way that present safety issues. Sourcing, producing and storing dehydrated fruits, vegetables and other produce correctly is important. It keeps the food, and the humans who consume it, safe.
Dehydrated food is cool again. You only need to check the fruit, veggie and health food aisles. People are living busy lives and want portable, tasty and healthy snacks. And not just snacks. Meals resembling grazing tables are almost the norm in some homes and offices around the world.
With the seemingly endless array of food and diet fads, if people can’t make their own food, they want to know what goes into the foods they do buy.
So, it goes without saying, that means sourcing quality produce.
There’s never been a better time to support local business and buy locally grown, seasonal produce as often as possible. Farmer’s Markets are a great place to start and more than 8,600 markets are currently registered with the U.S. Department of Agriculture (USDA) National Farmers Market Directory.1
Buying in season means you’re:
Not sure what’s in season? Check out the Seasonal Food Guide4 to see what’s in season in your part of the United States.
A 2018 New York Times5 article noted:
It’s obvious to anyone who visits an American supermarket in winter — past displays brimming with Chilean grapes, Mexican berries and Vietnamese dragon fruit — that foreign farms supply much of our produce.
Imports have increased steadily for decades, but the extent of the change may be surprising: More than half of the fresh fruit and almost a third of the fresh vegetables Americans buy now come from other countries.
Although local, seasonal and farm-to-table are watchwords for many consumers, globalization has triumphed in the produce aisle.
The U.S. Food and Drug Administration6 (FDA) adds:
‘… other countries now supplying approximately 32 percent of the fresh vegetables, 55 percent of the fresh fruit, and 94 percent of the seafood that Americans consume annually’
To import fruits and vegetables into the U.S., you’ll need to confirm your import is compliant with both FDA6 and USDA2 regulations.
The FDA7 website states:
American consumers seek a safe, diverse, and abundant food supply that is simultaneously affordable and available throughout the year. To help meet these consumer demands, the United States imports about 15 percent of its overall food supply.
Along with this increase in demand for fresh fruit and vegetables all year round, came the risk of disease so, in 2011, Congress passed the FDA Food Safety Modernization Act (FSMA)8, moving the focus from responding to contamination to preventing it. The agency created new food standards relevant to food importation and developed an ongoing strategy designed primarily to prevent food safety problems from occurring, preferably before the food arrives at our border or reaches the plates of U.S. consumers.
The strategy9 (available to download) is guided by four goals:
The USDA issued handbook The Commercial Storage of Fruits, Vegetables, and Florist and Nursey Stocks3 aims to maintain the safety and quality of food products as they’re handled, transported and stored.
This includes the cold chain, which as The Global Cold Chain Alliance10 says:
‘The cold chain refers to the management of the temperature of perishable products in order to maintain quality and safety from the point of slaughter or harvest through the distribution chain to the final consumer.
The cold chain ensures that perishable products are safe and of a high quality at the point of consumption. Failing to keep product at the correct temperatures can result in a variety of negative attributes including, among others, textural degradation, discoloring, bruising and microbial growth.
Each sector of the chain, from the point at which product is harvested to the point at which it is sold, shares responsibility.’
Recommended temperatures for transporting fresh fruit and vegetables range from freezing at 32°F to as high as 50-60°F.
Those in the cold chain should also regularly review policies and operating procedures as part of Hazard Analysis Critical Control Points (HACCP) and internal Food Safety Programs.
Originally developed by NASA and a group of food safety specialists in the ‘60s, Hazard Analysis Critical Control Point (HACCP) is an internationally recognized food safety and risk assessment plan. The plan outlines seven key principles in food safety:
Following HACCP plans isn’t mandatory. However, with many farms shifting towards production, more kinds of food businesses may need to adopt HACCP plans.
Some fruits, such as apples, bananas, nectarines, pears, peaches and apricots will benefit from some pre-treatment before drying. Pre-treating with an acidic solution like citric acid or ascorbic acid will:
Other methods of pre-treating are:
The drying process removes moisture from the food. This also hinders the growth of mold, bacteria and yeast and ensures the dehydrated fruit and vegetables don’t easily spoil.
A major contributor to drying food is humidity. As drying involves removing the moisture from the food and releasing it into the surrounding air, low humidity helps the drying process. This is why the drying of foods originated in the warmer and drier countries around the planet. Higher humidity will slow down the drying process as the air would also be heavy with moisture. Increasing air flow can speed up the drying process.
Water activity (aw) is a measure of available water in food. That’s not as simple as how much water is in the food though, as some water is bound to other ingredients – like sugar or salt – and isn’t available. In the context of dehydration, this is important as it is the available water11 that microorganisms will use to facilitate growth.
When too much water is available, microorganisms can grow. Pure water has aw = 1.00 and fresh fruits and vegetables have aw = 0.98. The FDA9 recommends drying fruits to aw = <0.85 to 0.60 and drying vegetables to aw = <0.60.
The safest and most accurate way to monitor water activity is by using a water activity meter. It is also possible to measure weight loss to determine moisture loss, but this is not recommended for commercial applications.
According to the FDA Food Labeling Guide10:
Raw agricultural commodities, such as fresh fruits and vegetables, are exempt from the stringent Food Allergen Labeling And Consumer Protection Act of 2004 (FALCPA) labeling requirements.
If fresh fruit or vegetables form part of a package:
Nutrition labeling is not required when the entire package is made up of fresh fruits (which fall under the voluntary nutrition labeling program) or when the fruit is packed with other processed foods that are intended to be eaten separately. However, if the fruit is included as one part of a kit with more than one ingredient, and some of the other ingredients are not subject to the voluntary labeling exemption, nutrition labeling is required (e.g., apples and caramel sauce)
Fruits and vegetables in the FDA’s Top 2010 most frequently consumed list fall under the voluntary labeling category. Nutrition labeling values for foods not on FDA's lists are subject to the compliance provisions of 21 CFR 101.9(g). Please check the guide for more details.
Correctly prepared, dehydrated and stored dried fruits and vegetables typically last a year or even longer. Vegetables tend to have a longer shelf life than fruit. Stored at stable temperatures in a cool, dark spot will increase their shelf life. Those foods with the least moisture content will last the longest and vegetables that are cooked prior to dehydration tend to last longer as well.
Should a package show condensation or other signs of moisture, if it looks unusual or smells funny, it’s likely to have spoiled. And if it’s moldy, throw it away immediately.
There’s a few basic principles to adhere to in any environment where meat and food products are being prepared. These include:
The highest hygiene standards should be maintained every step of the way.
Best practice is to clean it between every batch. The trays in our dehydrators are dishwasher safe and the insides of the dehydrator should be cleaned using a cloth and warm soapy water (being careful not to splash water onto the electrical parts). We recommend using a food-safe sanitizer spray to eliminate microbial growth.
Any cleaning chemicals should be appropriately stored. Staff should be trained how to use cleaning chemicals safely, so as not to cause accidents or contaminate foods.
It’s also important to ensure equipment is thoroughly dried after cleaning to prevent Listeria contamination.
As well as daily cleaning, including throughout the day, regular cleaning and sanitizing should be scheduled for things like cool rooms and drains. It’s also a good idea to regularly clean shelving in chillers, door handles, door seals, switches.
All equipment used for monitoring should be regularly checked and calibrated to ensure accuracy. This includes:
If you’ve any questions about cleaning your commercial dehydrator, recommended settings, or other aspects to ensure a safe final product, let us know. We’re here to help guide you to producing dehydrated foods that are delicious and healthy.
U.S. Department of Agriculture USDA, Local Food Directories: National Farmers Market Directory, URL: https://www.ams.usda.gov/local-food-directories/farmersmarkets
U.S. Department of Agriculture USDA, Animal and Plant Health Inspection Service, URL: https://www.aphis.usda.gov/aphis/ourfocus/planthealth/sa_import/sa_permits/sa_plant_plant_products/sa_fruits_vegetables/ct_favir/
U.S. Department of Agriculture USDA, The Commercial Storage of Fruits, Vegetables, and Florist and Nursery Stocks, URL: https://www.ars.usda.gov/arsuserfiles/oc/np/commercialstorage/commercialstorage.pdf
Seasonal Food Guide, FInd what's in Season Near You, URL: https://www.seasonalfoodguide.org/
The New York Times, Most of America's Fruit is Now Imported. Is that a Bad Thing?, URL: https://www.nytimes.com/2018/03/13/dining/fruit-vegetables-imports.html
Food and Drug Administration, FDA Strategy for the Safety of Imported Food, URL: https://www.fda.gov/media/120585/download
Food and Drug Administration, FDA Strategy for the Safety of Imported Food, URL: https://www.fda.gov/food/importing-food-products-united-states/fda-strategy-safety-imported-food
Food and Drug Administration, Food Safety Modernization Act (FSMA), URL: https://www.fda.gov/food/importing-food-products-united-states/fda-strategy-safety-imported-food
Food and Drug Administration, Hazard Analysis and Risk-Based Preventive Controls for Human Food: Draft Guidance for Industry1, URL: https://www.fda.gov/media/99572/download
Food and Drug Administration, A Food Labeling Guide, URL: https://www.fda.gov/media/81606/download
Global Cold Chain Alliance, The Cold Chain, URL: https://www.gcca.org/about/cold-chain
Food Crumbles, What is Water Activity (in Food)?, URL: https://foodcrumbles.com/water-activity-in-food-the-theory/
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