M. Gabriela Bernardo-Gil

Supercritical fluid extraction and characterisation of oil from hazelnut

Hazelnut (Corylus avellana L.) oil was extracted with compressed carbon dioxide in the temperature range of 308—321 K and in the pressure range of 18—23.4 MPa. In addition the influence of the superficial velocity, within a tubular extractor was studied. Physical and chemical characteristics of the oil were obtained. The results including contents of free fatty acids, sterols, triacylglycerols and tocopherols were compared with those obtained when n-hexane was used as solvent. No significant differences were found when the oils extracted by both methods were analysed. The main fatty acid was the oleic acid (83—85%), followed by linoleic acid (6—8%) and palmitic acid (5—6%). The main triglyceride found in hazelnut oils was the trioleylglycerol (OOO) (63.4—69.6%), followed by the linoleyl-dioleylglycerol (LOO) (11.6—15.5%) and palmitoyl-dioleylglycerol (POO) (9.9—10.4%). In terms of sterols, the main component was β-sitos-terol (∼83%) followed by campesterol (∼6%). The amount of cholesterol was very low (∼0.2%). The CO2 extracted oil contained about 17% more tocopherols (458.7 μg/g oil) than the oil extracted by n-hexane (382.8 μg/g). Oxidative stability was studied by using the induction time determined by the Rancimat method. The oil obtained by supercritical fluid extraction (SFE) was slightly more protected against oxidation (8.7 h for SFE extracted oil and 6.7 h for the hazelnut oil extracted with n-hexane). Both oils presented high stability index values (7.81 for the oil extracted by n-hexane and 8.7 for the oil extracted with supercritical CO2). Oil extracted by supercritical CO2 was clearer than the one extracted by n-hexane, showing some refining. Besides, the acidity index was 1.6 for the n-hexane extracted oil and 0.9 for the oil extracted with supercritical carbon dioxide. The central composite non-factorial design was used to optimise the extraction conditions, using the Statistica, version 5 software (Statsoft). The best results, in terms of recoveries of hazelnut oil by SFE, were found at 22.5 MPa, 308 K and superficial velocity of 6.0 × 10—4 ms—1.

Supercritical fluid extraction of organochlorines from fish muscle with different sample preparation

Abstract Supercritical carbon dioxide was used to extract PCBs, p , p ′-DDE, p , p ′-DDD, p , p ′-DDT and dieldrin from fillets of black scabbardfish ( Aphanopus carbo ). Using standards, the optimal extraction conditions of pressure and temperature were determined using the statistical method of central composite surface design. The studied temperatures ranged from 309 to 337 K and pressure from 10 to 24 MPa. It was observed that temperature do not affect significantly the extraction and, on the contrary, a significant effect was recorded for pressure. The best extraction efficiencies were obtained at pressures near 14 MPa, for all the studied compounds. To study the matrix effect on the yields, three types of raw materials were selected: fresh fillet, fresh fillet with anhydrous sodium sulphate and freeze-dried fillet. It was observed that supercritical carbon dioxide can extract efficiently the organochlorine compounds from freeze-dried fillets, but very low recoveries were obtained from fresh fillets. The pressure effect on extraction was studied for the freeze-dried samples. Three pressures were tested: 18, 22 and 26 MPa, maintaining the temperature at 328 K. Analysing the initial extraction velocities it was observed that 22 MPa was the optimal extraction pressure. The concentration of organochlorine compounds obtained by supercritical fluid extraction was, in some cases, higher than those obtained by Soxhlet extraction, using n -hexane.

Relations between Oxidative Stability and Antioxidant Content in Vegetable Oils Using an Accelerated Oxidation Test - Rancimat

In vegetable oils, particularly virgin olive oil and sunflower oil and in lard, the effects of temperature and antioxidant extracts concentration on the induction time were investigated using a sequence of simple factorial designs.The antioxidant extracts were obtained from aromatic plants by hydrodistillation followed by liquid-liquid extraction using diisopropyl ether as a solvent. Vegetable oils and lard were spiked with those extracts in a range of concentrations from 250 to 2500 ppm and then subjected to oxidation in a 679 Rancimat apparatus.In the sequence of factorial designs, two blocks of 23 design were run. In the first block only peppermint extract was used in two different matrices (virgin olive oil and sunflower oil). In the second block the antioxidant extract was introduced as a new variable but keeping the same matrix (sunflower oil). A simple equation was derived trying to relate the induction time (TI) with the extract concentration (C). The model was validated with data obtained from rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), lemon balm (Melissa officinalis) and marjoram (Origanum majorana) in virgin olive oil and sunflower oil at temperatures of 100, 110, 120, 130, 140 and 150 °C. To confirm the results, supplementary experiments were done with peppermint in lard at 120 and 130 °C.

Mathematical models for supercritical extraction of oregano “Origanum virens L.”*

The extraction of essential oil from oregano-Origanum virens L.- using liquid carbon dioxide (7 MPa and 298 K) and supercritical carbon dioxide (10 and 15 MPa and 313 K) was investigated. Experimental results were obtained in a laboratory scale plant equipped with a 100 mL tubular extractor. During the extraction an unsteady process prevails. The present paper presents an unsteady state mathematical model for a fixed bed extractor (model I). The overall mass transfer coefficients were calculated by matching the calculated and experimental values of oil loading in CO2. The results are compared with those obtained by the model developed by Catchpole et al, 1994 (model II). Good agreement between both models results and our experimental measurements were obtained, although the model II allows the best fit over the entire extraction curve.

Extraction of alkaloids from Lupinus albus sp. using compressed carbon dioxide

The extraction of lupanine from lupine (Lupinus albus sp.) flour using liquid carbon dioxide (8 MPa, 313 K) and supercritical carbon dioxide (10 MPa, 15 MPa and 20 MPa at 298 K and 313 K) was investigated. Small quantities of lupanine were obtained at the studied conditions, being the percentages of lupanine related to the total mass of extract between 0.02 % and 1.13 % at 10 MPa and 298 K, and 20 MPa and 313 K, respectively.