Fatty acids are of key importance to the food industry. Especially long chain polyunsaturated fatty acids (LC PUFA) are receiving more and more attention due to their positive infl uence on human health. LC PUFA refined from natural oils are frequently added to food products to gain a positive health effect. Since LC PUFA are rather unstable and prone to oxidation, the quality of oils and fats has to be controlled. Certain aldehydes, ketones and other compounds are markers for oil and fat quality (Figure 1). Some of these have unpleasant odors and/or tastes (e.g. fi shy) which are not acceptable to consumers. The compound 4-heptenal, for example, adds a detectable fishy odor and taste to food products at concentrations as low as 10 ng/g. This and other marker compounds therefore have to be monitored in the ng/g range by the food industry.

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Dynamic Headspace (DHS)

Automated Dynamic Headspace (DHS) is available for the GERSTEL MultiPurpose Sampler (MPS). The DHS station efficiently extracts and concentrates VOCs from liquid or solid sample placed in standard Headspace vials (DHS) or in larger sample containers up to 1 L volume (DHSLarge). The sample is thermostated and agitated while the headspace is purged with a controlled flow of inert gas, providing controlled and efficient extraction conditions. Sample temperatures can be selected from 10oC to 200oC. Lowering the temperature provides a means of reducing the amount of water vapor released and ultimately retrapped. The DHS station additionally holds a replaceable adsorbent- or sorbent filled tube used for analyte concentration. The temperature of the adsorbent tube during the DHS process can be varied from 20oC to 70oC for optimal trapping of the analytes in question.

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