Quality Changes of Red Pitaya (Hylocereus undatus) Slices Dried in Hot Air, Microwave-Hot Air and Microwave-Vacuum Dryers

Quality changes of red pitaya (Hylocereus undatus) slices dried in hot air, microwave-hot air andmicrowave-vacuum dryers were investigated. The quality parameters were colour, water activity, shrinkage,rehydration ratio, ascorbic acid content and visual market quality. Microwave-vacuum produced pitaya withthe best quality compared to hot air and microwave-hot air. Pitaya dried in microwave-vacuum had the highestrehydration ratio while the other methods presented similar rehydration ratios. Ascorbic acid in dried pitaya wasalso better retained when drying by microwave-vacuum. Apart from that, the drying time of pitaya dried inmicrowave-vacuum could be reduced by 83% compared to hot air.

Keywords:

Dragon fruit , Drying kinetics , Microwave convective drying , Microwave vacuum drying , Product quality