Energy requirements for drying of sliced agricultural products: A review

Abstract

This work presented a review of energy requirement for drying sliced agricultural crops in order to produce high quality and shelf-stable products.  Work on the estimation of energy requirement for drying different sliced crops such as potato, carrot, garlic, onions, mango, banana, apple, tomato etc. and factors affecting their energy requirement were reported.  From the review, programming models for drying sliced fruits, as well as different empirical equations adopted by some researchers for estimating the energy requirements of different sliced crops at specific drying parameters were reported. Obtained results showed that crop functional characteristics, initial and desired moisture contents, slice thickness, air temperatures, specific heat capacity, relative humidity, and air velocity are the major parameters affecting sliced crop drying energy requirement.  Generally, the minimum energy requirement for drying moisture-laden sliced crops like tomatoes, apples, carrot, mango, cucumber etc. were found to be between 4.22 and 24.99 MJ/kg water removed. Field test results by other researchers for different drying systems and crops were also presented. Prospects for future work were suggested.