Enhanced flavour extraction in continuous liquid-liquid extractors

Abstract

Continuous liquid-liquid extraction is a versatile, reliable and robust sample preparation technique, but there is a tendency for the solvent to make channels through the sample, causing uneven and incomplete extraction. A simple, cheap magnetic stirrer that prevents channelling improves extraction efficiency by between 2.8 and 17.6 times. Use of the stir bar extends the application of CLLE to samples that are not free-running liquids, thereby reducing sample manipulations with their associated artefacts. The stir bar can be sealed inside the glass tube, but this has the disadvantage that the end of the glass tube then tends to scratch the bottom of the extractor. Adding fins or other projections to the sides of the bar increases its stirring action. A polyethylene disc encircling the stir bar about half way up was a fast and simple modification that helped if samples contain suspended solids