Researchers have developed an efficient method for drying pomace, which prolongs the viability of the material and opens the door for further development of new uses. The project was a collaboration between the U.S. Department of Agriculture (USDA) and UC Merced and was funded through the California Department of Food and Agriculture’s Specialty Crop Block Grant Program, which looks to enhance the markets for fruit, vegetable, and nut products in California.
“In our particular project we focused on processed fruit and vegetable products, and even more specifically, the coproducts of those products,” said Rebecca Milczarek, Research Agricultural Engineer for the USDA Agricultural Research Service. “Pomace is kind of a wet, damp material. This material is commonly used as livestock feed, or other low value uses. We’d like to see it used in human food products.”
The challenge with the material is based on its moisture content. It must be used very quickly during the harvest and processing season before it becomes moldy and subsequently discarded. The heavy puree material is comprised of the seeds, skins and other fibrous parts of fruits and vegetables that were processed. Milczarek noted that they were able to convert tomato, prune and carrot pomace “into a dried stable material using only energy from the sun to create the heat for that process.”
The drying method that was developed involves a solar thermal-powered drum dryer which generates all of the required heat that is necessary for the process directly from sunlight. Traditional dehydrating methods required burning natural gas and was not a cost-effective means for processing the material. With the development of a solar heat processing method with no carbon emissions, there is significant interest in expanding the technology on a larger scale.
“There’s already been a lot of research showing that there are some very good, positive nutritional components to this,” said Milczarek. “If we can dry it down with this solar thermal technology that would stabilize it and then open the opportunity that it could be a standardized food ingredient that could be used throughout the year by food processors.”