A Study on Infrared - Convective Drying of Onion
Loading...
Date
2003
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
MPUAT, Udaipur
Abstract
India ranks first in the world with 21% of the world area planted under onion. Presently,
35 - 40 % of onion is lost during post harvest, due to lack of proper processing and storage
facilities. Therefore in order to overcome these losses, the dehydration of onion is to be employed
as one major processing operation, which reduces the weight and volume, thereby, reduces
transportation cost and increase in shelf life.
Hot air drying is mostly used for the dehydration of onion but there are losses of thermal
energy, quality and involvement of the higher drying time. Keeping the above views in mind, the
research work on dehydration of onion using infrared radiations was undertaken. A laboratory
scale infrared-convective dryer was developed. For the experiment locally available onion was
used. The effects of process variables such as infrared power (300, 400 and 500 W), drying air
temperature (35, 40 and 450C) and drying air velocity (1.0, 1.25 and 1.5 m/s) on drying time,
moisture diffusivity and rehydration characteristics were studied.
It was inferred from the results that the drying time was reduced by as much as 2.25 times
in infrared power range of 300 to 500 W, air temperature 35 to 450C at velocity 1.0 to 1.5 m/s.
However, the drying rates were lower at higher air velocity. Effective moisture diffusivity
increased with decrease in moisture content. A third order polynomial equation predicted the
variation in effective moisture diffusivity with moisture content. The rehydration ratio of
dehydrated onion slices was found to be in the range of 4.5 and 5.3.
Description
A Study on Infrared - Convective Drying of Onion
Keywords
null
Citation
Baburao and Sharma, 2003