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United States Department of Agriculture

Agricultural Research Service

Research Project: NEW TECHNOLOGIES TO PROCESS VALUE-ADDED, HEALTHY FOODS FROM FRUITS AND VEGETABLES Title: Infrared Stage Drying of Onions

Authors
item Gabel, Michael - UC DAVIS, DAVIS, CA
item Pan, Zhongli
item Amaratanga, K.S.P. - UC DAVIS, DAVIS, CA

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2004
Publication Date: July 16, 2005
Citation: Gabel, M., Pan, Z., Amaratanga, K. 2005. Infrared stage drying of onions. Meeting Abstract No. 99C-11. IFT Annual Meeting. July 2005. New Orleans, LA.

Interpretive Summary: Stage drying is a common practice for dehydrating onions. In this process, drying air temperature decreases over the drying progression. This type of drying compensates for moisture loss and reduces detrimental changes to the product. Many stage drying schematics exist for the conventional forced convection drying of onions but none exist for newer infrared drying methods. This research examined optimization of stage drying using infrared drying technologies.

Technical Abstract: Stage drying is a common practice for dehydrating onions. In this process, drying air temperature decreases over the drying progression. This type of drying compensates for moisture loss and reduces detrimental changes to the product. Many stage drying schematics exist for the conventional forced convection drying of onions but none exist for newer infrared drying methods. This research examined optimization of stage drying using infrared drying technologies. Sliced onions were dried using a catalytic flameless gas-fired infrared dryer. Drying rate along with quality indicators, namely pungency and color, were measured over the drying process with different product temperatures. Based on the drying rate and quality results, several time and temperature schematics were created and evaluated. The drying schematic that resulted in the highest product quality was drying at 80' for 11 minutes, 70' for 17 minutes and 60' for 91 minutes. The drying time was shortened significantly compared to a commercial forced convection drying operation. Product quality was comparable to retail onion samples. These results demonstrated that infrared drying could effectively be used to reduce drying time in onion dehydration while maintaining a high level of product quality.

Last Modified: 10/30/2014
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