The effectiveness of combined infrared and hot-air drying strategies for sweet potato

Onwude, Daniel I. and Hashim, Norhashila and Abdan, Khalina and Janius, Rimfiel and Chen, Guangnan (2019) The effectiveness of combined infrared and hot-air drying strategies for sweet potato. Journal of Food Engineering, 241. pp. 75-87. ISSN 0260-8774


This study examined the performance of different combined infrared (IR) and hot-air drying (HAD) strategies for
sweet potato. Experiments were conducted for simultaneous infrared and hot-air drying, two-stage sequential
hot-air and infrared drying, two-stage sequential infrared and hot-air drying, and intermittent infrared and hotair
drying in a laboratory scale combined infrared and hot-air dryer. The drying air temperature varied between
50 and 70 °C, the infrared intensity was 1100 W/m2, the air-velocity was 1.5 m/s, and the pulse ratio (PR) ranged
from 1 to 3. Results indicated that the drying rate, drying time, effective moisture diffusivity, shrinkage, specific
energy consumption (SEC), colour attributes and phytochemical compounds of sweet potato were affected by the
different drying combination strategies. The drying kinetics, product shrinkage, and sample temperature were
also influenced by drying time and air temperature. The two-term exponential model adequately explained the
drying behaviour of sweet potato for all the different combination strategies. The intermittent IR and HAD
combination strategy proved to be the most suitable based on the combined effect of total drying time
(113–120 min), SEC (27.67–41.44 kWh/kg), total colour change (17.15–26.48) and bioactive compounds.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Date Deposited: 30 Aug 2018 02:05
Last Modified: 05 Apr 2019 02:08
Uncontrolled Keywords: drying, combined infrared and hot-air drying, combination strategy, energy consumption, product quality, sweet potato
Fields of Research : 09 Engineering > 0999 Other Engineering > 099901 Agricultural Engineering
Socio-Economic Objective: B Economic Development > 82 Plant Production and Plant Primary Products > 8203 Industrial Crops > 820399 Industrial Crops not elsewhere classified
Identification Number or DOI: 10.1016/j.jfoodeng.2018.08.008

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