AppNote 185: 2-Step Multi-Volatile Method (2-Step MVM) for Characterization of Aroma Compounds in Bread
App Note 185/2016
A full evaporation DHS (FEDHS) method, based on a classical full evaporation technique (FET)  was demonstrated for uniform enrichment of aroma compounds in several sample types [2, 3]. FEDHS of 10-100 μL of samples at 80ºC enables near-complete vaporization and uniform recovery of aroma compounds with hydrophilic and/or low vapor pressure characteristics while leaving most of the low volatile matrix behind. In 2014, a multi-volatile method (MVM) with sequential DHS sampling using different individual trapping conditions on the same sample was developed for uniform extraction and enrichment of a wide range of aroma compounds in aqueous samples . The feasibility and benefits of using the MVM approach have been demonstrated by the determination of key aroma compounds (spanning the range from highly volatile acetaldehyde to much less volatile vanillin) in brewed coffee. There are several important aspects to consider when developing an MVM procedure: (1) Proper water management for successful GC/MS analysis, (2) choice of adsorbent trap to enable targeting of specific compound ranges, (3) an appreciation of the risk of breakthrough of (very) volatile compounds, (4) thermal desorption efficiency for polar and/or low vapor pressure compounds, (5) recovery of hydrophilic and/or low vapor pressure compounds from aqueous sample. In order to satisfy these considerations, the MVM procedure consists of three different DHS sampling steps performed at increasing temperatures, including a final full evaporation DHS (FEDHS) method.