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Supercritical fluid extraction (SFE) was used to obtain brewed coffee extracts with an aroma as similar as possible to the original brewed coffee. The optimization of the process operating variables was performed by means of a sequential simplex method whose response was based on the sensorial evaluation of the aroma extracts. Subsequently, the composition of the extracts obtained at the optimal SFE conditions was determined by using a purge-and-trap device coupled to a GC-MS. For comparison, extracts obtained by using liquid−liquid extraction and headspace-solid-phase microextraction were also obtained and analyzed by GC-MS. Keywords: Supercritical fluid extraction; brewed coffee; aroma; simplex method

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SummaryTwo methods based in dynamic headspace sampling have been compared for GC/MS analysis of volatile components in hard cheeses (Manchego and other ewe's milkvarieties). In the first approach, a purge & trap concentrator allowed volatile on-line determination with reduced sample handling. The second method consisted of a manual device for trapping dynamically purged volatiles, which were then analysed by using an automatic thermal desorption system, coupled on-line with a GC-MS. The influence of the most significant operating parameters (desorption times, flows and temperatures) on recovery and repeatabilily was studied for both methods. Automatic purge & trap gave the best sensitivily and repeatabihly for high volatilily components, probably because its on-line operation mode, while the second procedure allowed the determination of a greater number of volatile components, and gave better yields for fatly acids and other medium volatilily components.

SummaryAutomatic thermal desorption (ATD) has been evaluated for the analysis of volatile components from dairy products. It has resulted in a fast and reproducible method which needs only a low amount of sample. Volatile components from milk are collected by off-line purging and trapped on cartridges packed which a suitable adsorbent. Cheese samples are submitted to the same process or directly introduced into the cartridges. The desorption step that follows is carried out automatically and on-line with the chromatographic analysis. Repeatability and sensitivity were satisfactory for both types of products.

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