hybrid solar dryerFruit preservation is essential in Jamaica and Haiti due to relatively brief bearing seasons that produce popular fruits like mangos and breadfruit. Additional factors such as extreme poverty and natural disasters significantly increase Caribbean food insecurity. According to the World Food Programme, 30% of the Caribbean population lives in poverty. Michael McLaughlin, the co-founder of Trees That Feed, designed a hybrid solar dryer to combat food insecurity and preserve approximately 100 pounds of fruit in nearly four to eight hours. Trees That Feed is a nonprofit organization based in Winnetka, IL that planted close to 25,000 fruit trees across Jamaica, Haiti, Ghana, Kenya, Puerto Rico, Uganda and Barbados in 2019.

Hybrid Solar Dryer Design

Trees That Feed distributed 12 hybrid solar dryers in Jamaica and Haiti. Each dryer comprises six modules to ease assembly and material transportation. The modules include three solar collectors, a lower and an upper cabinet and a roof. The three solar collectors capture heat and feed warm air into an upper cabinet that holds five shelves of sliced or shredded fruit. The roof of the hybrid solar dryer contains a solar exhaust fan to pull moisture from the air and protect against harsh weather conditions, dust and insect contamination. Excess space is provided in the lower cabinet to include an optional fueled heater that functions in the absence of sunlight.

Passive Solar Thermal Technology

Solar thermal technology captures heat energy from the sun and uses it to produce electricity or provide heat. Likewise, the hybrid solar dryer uses passive solar thermal technology to rely on design features when capturing heat. The dryer operates without photovoltaic panels or fuel to provide an efficient, hygienic and inexpensive method of food preservation. However, the hybrid design includes space for an optional kerosene or propane heater to incorporate alternative forms of heat energy. While fuel increases the cost of operation, it prevents crop spoilage that can occur on a day with minimal sunlight.

Fruit Dehydration Benefits

Fruit moisture content must be reduced below 20% to ensure a secure shelf life.  The design of the Trees That Feed dryer decreases fruit moisture content by 60% and increases fruit shelf life for over a year. Temperatures between 130 to 140 degrees Fahrenheit dehydrate fruit at a rapid rate that removes moisture content and inhibits the growth of mold or bacteria.

The benefits of fruit dehydration in developing countries include:

  • Access to fruit consumption during non-bearing seasons
  • Reduced dependence on imported fruit and grain
  • Increased variety of food production
  • Access to sustainable production methods
  • Increased shelf life that retains nutritional value

Breadfruit is a highly perishable fruit grown in Jamaica and Haiti. Tropical regions across the world cultivate over 120 varieties of the high-yielding breadfruit crop. The hybrid solar dryer extends the initial three-day shelf life of breadfruit to approximately one year.

Dehydration preserves the nutritional benefits of breadfruit such as riboflavin, protein, potassium and vitamin C. Also, dehydrated breadfruit is ground and used to produce high-value products such as flour, pastries and pasta that sell across local and national markets.

Moving Forward

McLaughlin reported the success of a hybrid solar dryer located at the Sydney Pagon STEM Academy, a Jamaican agricultural school in the parish of St. Elizabeth. Once Sydney Pagon extended dryer access to members of the community, St. Elizabeth locals noticed the efficiency of the hybrid solar dryer and requested an additional model. Trees That Feed recently provided the parish of St. Elizabeth with a second dryer to increase access to food preservation in the community.

Trees That Feed has designed a dryer that provides opportunities for economic activity in impoverished nations like Jamaica and Haiti. Efficient and successful food preservation allows Caribbean farmers to make small profits by selling excess dehydrated fruit. In turn, farmers can increase their economic independence and stimulate their local economy by selling surplus dehydrated fruit across community markets.

McLaughlin told The Borgen Project that “empowering people to become independent” is a crucial step in alleviating poverty and increasing economic opportunity. While Jamaica and Haiti are the only nations with current access to the hybrid solar dryer, Trees That Feed plans to implement its design in Kenya and Uganda to extend this unique method of food preservation to additional countries in need.

– Madeline Zuzevich
Photo: Flickr