Disruption of glandular trichomes with compressed CO2: alternative matrix pre-treatment for CO2 extraction of essential oils

The disruption of essential oils glandular trichomes by contact with compre ssed carbon dioxide followed by rapid decompression was studied at isotherm al condition (310 K). The pre- and post-expansion pressures, the exposure t ime to the pre-expansion pressure and the rate of decompression were all fo und to have a significant effect on the efficiency of the disruption proces s. The efficiency of the disruption process (percentage of glands disrupted during the fast decompression) was deduced from the results of subsequent extraction tests using compressed CO2 under standard conditions. The damage to the glands was observed by SEM microscopy. The efficiency of the disrup tion process seems to be closely related to the amount of gas dissolved wit hin the glands, the rate of decompression of the bed and the permeability o f the glands. The experimental results revealed that for an exposure time o f 60 min and a rate of decompression of 2 kg m(-3) s(-1), the decompression from 70 barg to atmosphere led to a maximum efficiency of the disruption p rocess. At these conditions, the improvement in the extractability of essen tial oils by compressed CO was similar to that obtained by cryogenic commin ution of the matrix and better than that obtained by ambient comminution. O ne advantage of the fast decompression treatment method is that it virtuall y eliminates the losses of essential oils observed in mechanical treatments . A further advantage is that it selectively liberates the essential oils w ith respect to higher molecular weight material. This results in a final ex tract with a higher content of essential oils. (C) 2001 Elsevier Science B. V. All rights reserved.