In the present paper, explosion puffing drying kinetics of sliced apples affected by four different pretreatments,
including freezing, maltose syrup, calcium chloride and standard pasteurized milk immersion
at atmospheric pressure were investigated. Four thin-layer drying models were applied to describe
the drying kinetics. The results indicated that a parabolic model was the best model to characterize the
drying kinetics of apple slices. The average values of determination coefficient (r2) varied between 0.9803
and 0.9933. The parabolic model had the lowest root mean square error (RMSE), mean bias error (MBE)
and chi-square (c2), the highest modeling efficiency and regression coincident. The values of effective
moisture diffusivity were ranged from 154.0650 1012m2 s1 to 397.6886 1012m2s1. Freezing
pretreatment had the highest effective moisture diffusivity value and maltose syrup immersion treatment
exhibited the lowest one.
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1. Introduction
Apple is regarded as one of the most important raw material in
the food industry, and is cultivated all over the world. China has the
largest cultivated area and yield in the world producing 31.6 million
tons in 2011. Most apples were supplied for fresh consumption,
juice and jam processing. Unsuitable preservation and storage
methods can induce loss of fresh fruits. During the past decades,
dehydration has proven to be a good method to preserve fruits and
vegetables by not only maintaining nutrients but also avoiding
quality deterioration.
Drying is a complicated process which involves simultaneous
heat and