Influence of pretreatment and slice thickness on drying behavior and quality attributes of orange carrots

Abstract

The research tackles the significant problem associated with inefficient drying methods in drying carrots, giving rise to longer drying times, high drying energy, and poor color and rehydration properties. To mitigate this problem, this research examines the drying parameters in relation to pretreatments based on their impact on drying rate, color retention, and rehydration ability. The drying times for untreated slices, 3, 6, and 9 mm, started from 255, 570, and 675 min, respectively, at 55 degrees C. The experiment also involved a comparative study on 6 mm slices pretreated with steam blanching (SB), water blanching (WB), citric acid solution (CA), showing substantial reductions in drying times to 435 min in SB, 465 min in WB, and 525 min in CA, relative to 570 min in untreated slices. Diffusivity measurements indicated improved moisture diffusivity for all pretreated samples, specifically in SB samples, which reached 5.78 x 10-10 m2/s, an increase by 35.7% from that in untreated samples (4.26 x 10-10 m2/s). The quality appraisal results revealed that CA had a superior color retention with a minute total color difference (Delta E value of 13.56), while SB had the highest ratio for rehydration (2.85). The Midilli and Kucuk model, followed by the Aghbashlo et al. model, were found to be the most accurate models. The conclusion drawn from this research is that SB is the most efficient pre-drying treatment, as it helps improve the efficiency of drying by altering microstructures that promote dehydration while retaining tissue integrity.