Colette Besombes

Extraction of essential oils from Algerian myrtle leaves using instant controlled pressure drop technology

In the present work, the new extraction process of Détente Instantanée Contrôlée DIC (French, for instant controlled pressure drop) was studied, developed, quantitatively and qualitatively compared to the conventional hydrodistillation method for the extraction of essential oils from Algerian myrtle leaves. DIC was used as a thermomechanical treatment, DIC subjecting the product to a high-pressure saturated steam. The DIC cycle ends with an abrupt pressure drop towards vacuum, and this instantly leads to an autovaporization of myrtle volatile compounds. An immediate condensation in the vacuum tank produced a micro-emulsion of water and essential oils. Thus, an ultra-rapid cooling of residual leaves occurred, precluding any thermal degradation. An experimental protocol was designed with 3 independent variables: saturated steam pressure between 0.1 and 0.6 MPa, resulting in a temperature between 100 and 160°C, a total thermal processing time between 19 and 221 s, and between 2 and 6 DIC cycles. The essential oils yield was defined as the main dependent variable. This direct extraction gave high yields and high quality essential oil, as revealed by composition and antioxidant activity (results not shown). After this treatment, the myrtle leaves were recovered and hydrodistilled in order to quantify the essential oil content in residual DIC-treated samples. Scanning electron microscope (SEM) showed some modification of the structure with a slight destruction of cell walls after DIC treatment.

Instant controlled pressure drop extraction of lavandin essential oils: Fundamentals and experimental studies

Détente Instantanée contrôlée (DIC), French for Instant Controlled Pressure Drop, was performed on laboratory apparatus as well as on a pilot plant for proving its feasibility, and identifying the optimized processing conditions and recognizing the energy consumption and the quantity of water used for such an operation. GC-MS and SPME analysis of the extracts and residue material were carried out to assess the extracts and solid residues. The lavandin essential oils obtained by using the new DIC extraction process was studied, modeled and quantitatively and qualitatively compared to the conventional hydrodistillation method. The most important differences between the two essential oils were reflected in the yields, with 4.25 as against 2.3 g EO/100 g of raw matter, and in the extraction time, with 480 s as against some hours for respectively the DIC and the hydrodistillation operations. These differences have been previewed through the fundamental analysis. They can normally explain the great decreasing of energy consumption to be 662 kWh/t of raw material. The amount of water to be added was about 42 kg water/t of raw material.

Study of Instant Controlled Pressure Drop DIC Treatment in Manufacturing Snack and Expanded Granule Powder of Apple and Onion

While the use of “puffing” process is mainly limited to products like cereals or carrot, the instant controlled pressure drop (DIC) can treat and expand the large domain of heat sensitive food products. In the present article, this operation is applied on partially dried apple and onion, to produce snack or, by shadow grinding, expanded granule powder. DIC is a high-steam pressure treatment (up to 0.6 MPa in this article), where steam is applied constantly during a short treatment time t (5–55 s) and instantaneously dropping the pressure toward vacuum 5 kPa with a rate higher than 0.5 MPa s−1. The expanded structure allows the product to achieve better functional properties linked with a greater specific surface area. Thus, the time of final hot air drying (with air flow at 40°C, 1 m s−1, and 267 Pa partially pressure humidity) is reduced by about 55% through greater effective diffusivity and initial starting accessibility. The products nutritional value is partially preserved (vitamins) or even improved through more available flavonoids. DIC can perfectly decontaminate the products, and end quality attributes are higher than normally dried or as good as freeze-dried fruits.

Extraction of Essential Oils and Volatile Molecules

Fundamental studies of the transfer processes in steam extraction (steam distillation) have identified a paradoxical situation in which gradients of temperature and essential oil vapor pressure are both directed towards the core, resulting in a flow in the opposite direction to that required for an extraction operation. Steam distillation is thus a front progression operation. In order to intensify essential oil (EO) extraction and improve the quality of both extract and residue, instant controlled pressure drop (DIC) treatment was defined and used as a direct extraction–texturing treatment. With DIC treatment, volatile molecules can be removed by autovaporization, followed by a total pressure gradient (Darcy-type law) which substantially reduces extraction time. Thus, the processing time of DIC-EO extraction is about 4 min compared to several hours (or even days) with hydro- or steam distillation. This is obviously linked to low heat energy consumption. The final essential oil that is extracted meets the various quality requirements in terms of the absence of thermal degradation. In addition, DIC treatment can also be used to expand the compact plant and to enhance its technological aptitude for a second operation such as drying, solvent extraction, and press extraction.

One-step processes for in situ transesterification to biodiesel and lutein extraction from microalgae Phaeodactylum using instant controlled pressure drop (DIC)

Abstract A one-step biodiesel fabrication in situ transesterification (ISTE) process and a value adding to residual material through lutein extraction were defined in the case of microalgae Phaeodactylum. This work aims at intensifying these two processes, thus reducing energy consumption and manufacturing cost, using the well-known instant controlled pressure drop (DIC) as a thermomechanical pretreatment. A two factor central composite design (12 samples) was used to optimize DIC processing parameters, which were the saturated steam pressure and heating time. The responses (dependent variables) were defined from the lipid extraction, the ISTE and the lutein extraction. Lipids and biodiesel, the mono-alkyl fatty acid methyl esters (FAMEs) were isolated and analyzed using an Iatroscan Thin-layer chromatography (TLC)-flame ionization detector (FID) instrument. Lutein extraction utilized an alcoholic mixture. The isolated lutein was identified by high performance liquid chromatography (HPLC). The overall results confirmed the importance of these DIC parameters and that the saturated steam pressure was the most significant parameter. Under optimized conditions, it led to an increase of about 27% in total lipids and more than 75% in FAMEs yield, as well as twice more lutein extractability, both compared with the untreated raw material.

Coupling DIC and Ultrasound in Solvent Extraction Processes

Solvent extraction can be achieved in two steps: the first stage of solute dissolution in the solvent is carried out at the surface of the product (illustrated by the starting accessibility) and a second stage of diffusion phenomena, of the both, solvent towards the core of the solid matrix and the solute within the filled-with-solvent pores.