Optimization of flat plate drying of carrot pomace (abstract)

Authors: Alleyne, Fatima; FERRY, JONATHAN - University Of California; Milczarek, Rebecca; Olson, Donald; WINSTON, ROLAND - University Of California

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/18/2016
Publication Date: 7/18/2016
Citation: Alleyne, F.S., Ferry, J.J., Milczarek, R.R., Olson, D.A., Winston, R. 2016. Optimization of flat plate drying of carrot pomace (abstract). American Society of Agricultural and Biological Engineers Annual International Meeting - Orlando, FL - July 17-20, 2016.

Interpretive Summary:

Technical Abstract: Carrot (Daucus carota var. sativus) pomace is a co-product of the carrot juice and cut-carrot industry; it has high nutritional value but is currently underutilized. Drum drying is one method that could be used to dry and stabilize carrot pomace. However, optimum conditions for the dryer surface temperature, product dwell time, content of carrier, and content of added water (to aid in application of the pomace to the dryer surface), have not yet been explored. In this work, a flat plate heater was used to simulate the surface of a drum dryer. Industrially-produced carrot pomace of initial moisture content of 80.3% (wet basis) and initial water activity of 0.985 was used as the starting material. Based on a split plot response surface design, various feed blends of pomace, maltodextrin (carrier), and water were dried on the flat plate at varying surface temperatures for varying lengths of time. The surface temperatures (92°C to 132°C) and drying time (2 min to 4 min, plus a 1 min heat-up time) represented conditions that would be achievable on a typical drum dryer. Regression equations were generated for both moisture content (R2 = 84.0%) and water activity (R2 = 84.0%). Both moisture content and water activity were sensitive to the maltodextrin content, dwell time, and plate surface temperature and insensitive to amount of added water. Considering a target water activity of 0.6 or less (to ensure no growth of yeast and mold in the dried product), it was found that, even with an optimum amount of added water, maximum amount of maltodextrin carrier, and maximum heating time, this target could not be reached unless a minimum plate surface temperature of 118°C was used. Thus, this work demonstrated that carrot pomace can be effectively dried and stabilized on a flat plate heater under a variety of feed and process conditions, provided that a minimum surface temperature of 118°C is used. The results of this work will inform the design of a solar thermal-powered drum dryer for use in drying specialty crop purees and pomaces.