Comparative evaluation of physical properties and volatiles profile of cabbages subjected to hot air and freeze drying

- Freeze dried cabbage has less shrinkage than the hot air dried cabbage.
- Freeze drying yields dried cabbage with almost no change in its original color.
- Character impact volatile compounds retained better in freeze dried cabbage.
- Some new volatile compounds having pungent odor detected in cabbages.

The aim of the present study was to evaluate the physical parameters, volatiles profile and sensory quality of the cabbage pieces subjected to hot air drying and freeze drying processes. Physical properties such as water activity, shrinkage, hardness, springiness, cohesiveness, chewiness, rehydration ratio and color measurements were measured using standard procedures while the volatile compounds were determined by the SPME-GC-MS method. The results showed that convective drying of cabbages lead to major adverse changes in physical and volatile compounds characteristics. Hot air and freeze drying of cabbages display different volatiles profile containing aldehydes, alcohols, terpenes, ketones and furans. Better retention of character impact cabbage green and pungent aroma compounds viz. allyl isothiocyanate, dimethyl sulfide, dimethyl disulfide, 1-octen-3-ol and (Z)-2-penten-1-ol was found in freeze dried cabbage. The presence of 3-(methylthio)-propyl isothiocyanate, methyl benzene isothiocyante and phenyl ethyl isothiocyanate is reported here for the first time in fresh cabbages. The flavor components of fresh cabbage were largely retained in the freeze dried product. Freeze drying also leads to positive sensory effects and better overall acceptability by consumers compared to the hot air dried product.