Comparison of Two Monitoring Methods for Almond Oil Extraction with Supercritical Co2

Nuts provide an interesting nutritional supply. However, their high fatty content makes them unattractive for new consumers demanding “light”, low-fatty foods. Among nuts, almonds have a significant economical importance for the whole Mediterranean area. In the last years, high production and competition among productive zones have hardened the commercialisation of this product. On the other hand, almond oil is very appreciated for alternative medicine, cosmetics, etc. Thus, obtaining the almond oil may be an option for expanding the almond market. In this way, using clean process such as supercritical fluid extraction for almond oil extraction may also lead to an almond revalorisation as a “light” product (partially defatted almonds). In this work, several experiments have been carried out at different conditions, modifying pressure, temperature or flow rate of SC-CO2. Extraction pressures have been chosen in the 20–28 MPa range. Extraction temperatures have ranged between 30 and 50oC. Flow rate of supercritical carbon dioxide varies from 2 up to 4 kg/h. All the experiments have been carried out with the same almond variety (Marcona) in the same extractor (0.5 L). For each experiment, the supercritical extraction process has been applied to approximately the same amount of raw, entire, non-peeled almonds. Extraction processes have been monitored by two different methods. By the first method, the cumulated amount of extract obtained at different moments is registered and by the second one, mass loss of the partially deffated almond is determined at different moments. This last monitoring method implies stopping the extraction process, depressurising, and opening the extractor to weight the content of the basket. Extraction curves are obtained by joining several points coming from extractions carried out under the same operating conditions but that have been stopped at different moments. Only slight differences have been observed between results given by the two applied monitoring methods.