Flavour changes in asian white radish (Raphanus sativus) produced by different methods of drying and salting

Asian white radish pieces were dried to <10% moisture using a hot air drier, a heat pump drier and a freeze drier, and whole roots were partially dried by salting under pressure with sodium chloride. The level of the primary flavor compound, 4-methylthio-3-trans-butenyl isothiocyanate (MTBITC), decreased in all treatments. Freeze-dried white radish showed the lowest loss of about 15% MTBITC. Radish dried with hot air and heat pump driers showed increasing MTBITC loss with increasing drier temperature with a lower loss in the heat pump drier at equivalent temperatures with the rate of drying also faster with the heat pump drier. Osmotic dehydration with salt caused a substantial loss of MTBITC with the loss increasing with increasing salt concentration. Use of 5% salt resulted in the lowest loss of MTBITC while achieving an acceptable rate of water loss.