Drying kinetics of osmotically pretreated carrot shreds to be used for preparation of sweet meat

Abstract

The carrot shreds having 2 mm and 4 mm thickness were osmotically pre-treated with different proportions of powdered sucrose and were convectively dehydrated at different temperatures (50, 60 and 70 °C) up to a final moisture content of 4-5% (dry basis).  The convective dehydration mechanism was well represented by Approximate Diffusion Model.  During convective dehydration, the effective moisture diffusivity varied from 1.827 × 10^-9 m²/sec to 4.587 × 10^-9 m²/sec for shred size 2 mm and 1.832 ×10^-9 m²/sec to 4.157 × 10^-9 m²/sec for shred size 4 mm for the temperature range of 50 to 70 °C.  The activation energy values ranged from 12.71 to 21.85 KJ/mole for shreds having 2 mm size; and 7.433 to 8.391 KJ/mole for shreds having 4 mm size.  The dehydrated carrot shreds were packaged in aluminium laminates of thickness 42 micron and stored at ambient temperatures.  The dehydrated shreds were utilized for the preparation of dairy based product named ‘gajrella’ or sweet meat.  The gajrella prepared with carrot shreds treated with 35 g sucrose per 100 g carrot shreds dried at 70 °C has scored highest during sensory analysis.

Keywords: carrot shreds, convective dehydration, drying kinetics, effective moisture diffusivity, activation energy