Exploring low-tech food dehydration to increase profits on small farms

2014 Annual Report for FNE13-789

Project Type: Farmer
Funds awarded in 2013: $14,915.00
Projected End Date: 12/31/2015
Region: Northeast
State: Maryland
Project Leader:
Tanya Tolchin
Jug Bay Market Garden

Exploring low-tech food dehydration to increase profits on small farms


Our grant explores low-tech solutions for dehydrating crops on our farm to help reduce waste and increase farm profit from new value added products. In the early 2013 we built two dehydrator models to test on our farm. The first model is a passive solar stack dryer that utilizes the chimney effect to dry products with increased air flow. Since we have such high humidity in our area, we also built an electric cabinet style food dryer.

Beginning in late July 2013, we began testing both dryers using greens, tomatoes, flowers, sweet potatoes, eggplant, hot peppers, basil and other herbs. Overall, we found both dryers to be a great asset to our farm and each has particular strengths and weaknesses depending on the crop we are drying, weather and other factors.

We packed our products using a vacuum sealer in plastic and glass, and held tastings in December 2013 to get feedback on six of our dried products: 2 kale chip recipes, dried tomatoes, basil, spearmint and sweet potato chips. We received useful feedback and made adjustments and continued testing in year 2014.

Since we are not yet certified to sell the dried food products, we did some experimental marketing of decorative dried products. Upcoming goals include getting our kitchen certified as a “farm kitchen” and beginning to clear some of our recipes with the Maryland Department of Health so we can start marketing food products in 2015. 

So far our biggest hurdle has been getting our products approved for sale by the Maryland Department of Health. In a meeting with the state inspector, we learned the solar dryer cannot pass health inspection in our state because it is too exposed to the outdoors. We will therefore only use it for drying flowers, for which it is very well suited. The electric dryer can pass the health inspection but we must first construct a better building for it. The inspector found the shed in which it is now in too exposed to the outdoors. We plan to erect a building in 2015 for the dryer.

Objectives/Performance Targets

Building and Testing

Objectives/Performance Targets

Building Phase (Winter/Spring 2013)

We relied heavily on two existing plans to build the dryers. We made a few modifications based on our judgment and consultation with the Maryland Food Safety team. One dryer is passive solar and one includes an electric heating element.

The passive solar model follows UC Davis plans for a passive solar stack or chimney dryer. The second dryer utilizes electric heat and a fan, and it also based on plans from UC Davis. It was more expensive to build and run but played an essential role in drying this season.

We decided to use stainless steel trays instead of plastic and to modify the specs so we could use the same trays interchangeably between the two dryers. This worked out well because most of the time we used one dryer or the other.

Testing the Dryers (Summer/Fall 2013 and 2014)

Solar Dryer Performance Notes

The solar dryer was amazing during our tests on hot days in June, July and August. We were able to dry greens and herbs within hours and pull them out before nightfall. The color remained vibrant and the materials appeared fully dried and crumbly to the touch.

Later in the season we ran into several challenges with this dryer, especially when trying to dry tomatoes. The tomatoes required more than one full day in the dryer and if left overnight would attract insects to the fruit. When the dryer is hot, insects seem to stay out but as it cools at night they will be drawn to the residual warmth. Unloading and reloading is labor intensive so it seems ideal to dry products in the solar dryer that take one day or less like the herbs and flowers.

A second problem with this dryer is that the area did not drain well after big rains. Since we dug around the area to create a raised bed area for drying, the rain tended to pool near the dryer and take a few days to dry after a hard rain. In 2014, following the advice from the designers of the solar dryer, we built a platform to dry the product on. This reduced moisture and helped create a cleaner drying area. The platform was also much higher and much more ergonomic.

In both 2013 and 2014, the solar dryer excelled at drying herbs and flowers with an initial low moisture content. The basil, rosemary and spearmint all dried within hours and had similar color to the herbs dried in the electric dryer. Another advantage to the solar dryer is the elbow room and variable headspace. The plastic cover could be raised and lowered and larger items could span more than one tray. In this way we were not limited by tray size and could pile on some awkward large items like three foot stems of larkspur, branching basil, hard neck garlic with stalks etc.

Electric Dryer Performance Notes:

In both 2013 and 2014, the electric dryer did very well for us, with just a few little hitches along the way. Everything we put in the dryer dried very nicely within 24-48 hours. The dryer is very clean and pest free. On the downside, we were limited to the tray size which meant a little more prep for loading the dryer efficiently was needed.

In 2013, we put the electric dyer in the corner of a high tunnel. On hot days, having the dryer in the tunnel must have saved energy by speeding drying times. However, there were also a few times when it was so hot in the greenhouse we had to make sure the dryer was not going above 140 degrees. During the 2014 season, we relocated the electric dryer to a cooler packing shed and replaced the fan. The dryer continued to run very well and dry products successfully. 

In 2014, we dried a large amount of tomatoes in the electric dryer. We dried several varieties, including Big Beef, Mountain Magic and Iron Lady. The tomatoes lost virtually all their weight to evaporation. On August 15, nine pounds of sliced tomatoes on one try, went down to 5oz. The before and after weights of four trays that day are given below. We may be drying the tomatoes more than necessary and are still experimenting to find the right level of drying. The ability of the dryer to adequately dry the tomatoes and other high moisture crops is clear. Sample data is below.

August 15 Before and After Weights of Large Sliced Tomatoes


Wet Weight

Dry Weight

Tray 1



Tray 2



Tray 3



Tray 4




Licensing and Legal Hurdles:

Our biggest hurdle has been getting licensed to market our dried products by the State of Maryland. We had two meetings with a MD State department of health inspector and while he is willing to license our kitchen as a farm kitchen for prepping crops for the dryer, he did not like that the dryers are not located in a building.

He thought he could approve the electric dryer for use in 2015 if we move it into a building that includes running water and a fully enclosed space. Since we do not have an appropriate farm building with a washing sink and walls completely impenetrable to pests, we need to build an adequate structure. While plan to construct a small building for the dryer in 2015. We are also exploring obtaining a small shipping container or box from a box truck. The inspector advised us that both are good alternatives.

The health department inspector did not see a way to approve tomatoes or kale from our solar dryer because the design requires the product to be outside during the drying process. He did think it is possible to approve drying tea herbs that are intended to be boiled before they are consumed.  This was discouraging, because we were able to dry greens like kale quite well in the solar dryer on hot days.

He also provided feedback on our packaging and raised concerns about the potential to grow botulism spores in our vacuum packed dried tomatoes. In 2013, we sealed bags of dried tomatoes and basil tightly by vacuuming out as much air as possible. The inspector advised we seal the bags with some air to avoid an anaerobic environment hospitable to botulism. During 2015 year, we will do lab testing on all of the products before they can be approved for sale and will likely focus on the electric dryer for all products except teas and dried flowers.

Over all, we found the meetings with the health inspector very constructive and are now much more ready to market the dried products than in 2013. While we did not get to the point of bringing our product to market in 2014, we should be able to gain approval in 2015. Farmers in other states with different health department requirements may be able to gain approval faster.



We met our goals of building and testing the two dryers during the 2013 and 2014 seasons. We were able to build the two dryers at a very low cost and remain within our planned budget. Our electric cabinet dryer is comparable to units that sell from upwards of $25,000 and was constructed for less than $500 in materials. The solar dryer cost even less to construct and is free to run.

We tested the two dryers on various crops including tomatoes, kale, herbs, sweet potatoes, and flowers.  During 2014, we made modifications to both dryers to improve operation and developed a protocol for successful use of the two dryers. We were able to create attractive and tasty value added products from the excess produce on our farm including dried tomatoes, kale and herbs.

During the winter of 2013, we held a successful tasting event where participants tried six of our products. We included our chef consultant Tom Meuller in the tasting. We were quite pleased with the results of our tasting (attached) and we feel we can be responsive to the feedback. The tomatoes, kale and basil all received great reviews and we hope to have these products market ready in 2015.

The dried flowers have enormous potential for us. Unlike with fresh flowers, there is no issue with needing to sell a large amount of blooming flowers at one time. Nor are there concerns with vase life. The dried flowers are a product we can potentially wholesale to florists or floral distributors in large numbers without the time pressure associated with fresh flowers. Some of the dried flowers like the cornflower have potential for sale as decorative food items like such as confetti for catering trays.


We completed the outreach phase of this grant in early 2014 in three key events. I spoke at two regional conferences and published an article in a national magazine. In all of these venues, I shared our experience, our dryer plans and information about the SARE program and grants.

1) I spoke on a SARE panel at the Future Harvest/Casa conference in College Park Maryland. This is a gathering of organic and sustainable farmers, advocates and educators from the whole Chesapeake Bay region. I created a Powerpoint presentation and shared my experience using the two driers. There were 30 participants in the panel.

2) I presented a similar presentation at the Maryland Organic Food and Farmers meeting in Annapolis, MD in February 2014.   There were about 30 farmers in attendance and there was time for discussion and questions. I will offer follow up information at the 2015 MOFFA meeting.

3) I published an article in Acres USA in March of 2014 about the grant and my experience using the dehydrators. As a result of the article, I responded to several email inquiries from farmers in the US who were interested in more information and plans.

4) We shared our dryers with local farmers and friends who were interested in learning and drying some of their own excess crop like hot peppers.

Impacts and Contributions/Outcomes

I believe we were able to demonstrate that for a small capitol investment farmers can build commercial scale food dehydrators that work well on various products.  We were also able to sucressfully spread the word about our work to many other farmers both in the region and nationwwide.

While the project did not go as far as we hoped in the first two years, our struggles with licencing are also instructive. The food safety landscape is rapidly changing for farmers, and making on farm value added products may require more capitol investment than is feasable.  In our case, we were hoping to add a line of products without a small investment but it seems we will have to take another route, either partnering with an existing commercial kitchen or building a new packing shed that can accommodate the electric dryer and packing area.

While we were not able to get to the point of selling our food products, we do know what is needed to get there for the 2015 season. We now need to consider the additional investment to decide if we want to use our dryers for food products.  We are in discussion with a couple of chefs and we might move the operation to an existing commercial kitchen.

We are so grateful to SARE for this opportunity. We will definately continiue to build on what we learned and hopefully get some food products to market in 2015 or 2016.  We will have more information on next steps in the final report to be submitted in early 2015.


Brian Clark

[email protected]
Agent, Agriculture & Natural Resources, Horticulture
UMD Extension
6707 Groveton Drive
Clinton , MD 20735
Office Phone: 3018688780
Website: http://extension.umd.edu