2.3. Quality evaluation
Colour: Colour of the samples was measured using a Minolta colour reader (CR-10, Japan). The colour readings were expressed by ICI coordinates (L*a*b*) system. L*, a* and b* indicates whiteness/darkness, redness/greenness, blueness/yellowness values, respectively. A standard white colour was used as a reference. Eight replicate readings were carried out.
Rehydration ratio: Rehydration ratio was determined by using the method of Maskan (2001). The rehydration capacity of dried carrot slices was evaluated by immersing 10 g of dried samples in water at 50 °C for 50 min. In every 10 min, sample was taken out, blotted with paper towel to eliminate surface water and then reweighed. The rehydration ratio described as percentage water gain was calculated from sample weight difference before and after rehydration using Eq. (1):
equation(1)
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where Wt is the weight of rehydrated sample (g) at any time and Wd is the weight of the dried sample.
2.4. Statistical analysis
Analysis of variance (ANOVA) was performed to determine significant differences between different drying methods (p⩽0.05). Variable means were compared by Duncan's Multiple Range test. Standard errors were calculated and added to the bar graphs. Drying experiments were repeated twice.