MODELING PRE-TREATMENTS EFFECT ON DRYING KINETICS OF GARLIC (ALLIUM SATIVUM L ) SLICES IN A CONVECTIVE HOT AIR DRYER

摘要

The study investigated the effect of three pre-treatments of citric-acid (CA), potassium-metabisulphite (KMS), and ethylenediamine-Tetraacetic acid (EDTA) on the drying kinetics and quality of garlic slices in a convective hot-air dryer at temperatures of 45, 50 and 55 ℃. The allicin content of the dried garlic slices compared with the fresh increased non-linearly with increase in temperature from 8.6 to 23.5 μg/mL, 13.3 to 22.4 μg/mL, 11.9 to 23.4 μg/mL, and 12.3 to 24.1 μg/mL for the control, CA, KMS, and EDTA samples respectively. The drying characteristics were evaluated against three mathematical models. The control dried garlic slices were best described by the Midilli et al model whilst the pretreated samples followed the Henderson and Pabis model. The KMS pretreated samples showed greatest brightness and least redness in colour at 50℃ and 45 respectively compared with the fresh, whereas the EDTA pretreated samples were yellower at 45 ℃.