Retention of aroma compounds in basil dried with low pressure superheated steam

Abstract

Basil leaves were dried using either conventional hot air (50, 60 and 70 °C) and low pressure superheated steam (LPSS) dryers. The effect of the drying method on the retention of some volatile compounds was evaluated. The extraction from the fresh and dried products was performed by the simultaneous distillation–extraction technique. Identification and quantification was performed by capillary gas chromatography–mass spectrometry (GC–MS) and gas chromatography (GC) respectively. The identified compounds were 23, with 61% of monoterpenes, 26% of aromatic and 13% of aliphatic compounds, out of which those characteristic of this spice were detected (1,8-cineole, methyl chavicol, methyl cinnamate and linalool). Results show that in the LPSS dried product, the original aroma profile of the fresh vegetable is kept almost constant, while air-dried product shows a significant variation in the relative proportions of aroma compounds. The conclusion is that the LPSS drying technique renders a better product in terms of the aroma compounds content, than the conventional air-drying, with the advantage of being cheaper.