Gabriela Bernardo-Gil | Universidade de Lisboa (original) (raw)

Papers by Gabriela Bernardo-Gil

Journal of the American …, Jan 1, 2002

Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO 2 ) in the tempera... more Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO 2 ) in the temperature range of 308 to 321 K and in the pressure range of 18 to 23.4 MPa. The influence of particle size was also studied at a superficial velocity of 0.068 cm/s, within a tubular extractor of 0.2 L capacity (cross-sectional area of 16.4 cm 2 ). FFA, sterol, TAG, and tocopherol compositions were not different from those of oil obtained with n-hexane. The main FA was linoleic acid (56.5%), followed by oleic acid (21.2%) and linolenic acid (13.2%). The main TAG was LLL (linoleic, linoleic, linoleic) (24.4%), followed by OLL (oleic, linoleic, linoleic) (19.6%) and LLLn (linoleic, linoleic, linolenic) (18.4%). The main component of sterols was β-sitosterol (85.16%), followed by campesterol (5.06%). The amount of cholesterol was low (0.31 and 0.16% for oils extracted by n-hexane and supercritical fluid extraction, respectively. The CO 2 -extracted oil presented a larger amount of tocopherols (405.7 µg/g oil) when compared with 303.2 µg/g oil obtained with n-hexane. Oxidative stability determined by PV and the Rancimat method revealed that walnut oil was readily oxidized. Oil extracted by supercritical CO 2 was clearer than that extracted by n-hexane, showing some refining. A central composite, nonfactorial design was used to optimize the extraction conditions using the software Statistica, Version 5. The best results were found at 22 MPa, 308 K, and particle diameter (Dp) = 0.1 mm.

… Food Research and …, Jan 1, 2001

Cherry seeds (Prunus avium L.) were extracted with compressed carbon dioxide at 313 K and 333 K i... more Cherry seeds (Prunus avium L.) were extracted with compressed carbon dioxide at 313 K and 333 K in the pressure range 18-22 MPa. The influence of superficial velocity was also analysed using values of 0.02, 0.06 and 0.08 cm/s. The extraction yield was increased by a reduction in particle size. The physical and chemical characteristics of the oil were determined. The results, in terms of free fatty acids and sterol compositions, were compared with those obtained when hexane was used as solvent. Other physical and chemical characteristics were also compared with refined hexane-extracted oil.

European Journal of …, Jan 1, 2002

Lipids are important in all cells as structural components. To date, the nutritional interest in ... more Lipids are important in all cells as structural components. To date, the nutritional interest in the lipid composition of vegetable oils is increasing. Hazelnuts, walnuts, almonds, peanuts, pumpkin seeds and other kernels are a source of energy in the Mediterranean diet due to their ...

The Journal of …, Jan 1, 2004

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.

The Journal of Supercritical Fluids, Jan 1, 1993

$Research paper thumbnail of Densities and refractive indices of components of pine resin$

Journal of Chemical and Engineering …, Jan 1, 1990

... Densities were determined with a 10-mL Brand pycnometer that was calibrated with redistilled ... more ... Densities were determined with a 10-mL Brand pycnometer that was calibrated with redistilled water at all the temperatures. ... Albertina Ribeiro and Gabrieia Bernardo-Gil * Departamento Engenharia Quimica, Znstituto Superior Tgcnico, ...

The Journal of supercritical fluids, Jan 1, 2003

Supercritical carbon dioxide was used to extract PCBs, p,p′-DDE, p,p′-DDD, p,p′-DDT and dieldrin ... more 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 ...

Journal of AOAC …, Jan 1, 2001

Ultrasound and microwave techniques were used to extract tobacco alkaloids, and response surface ... more Ultrasound and microwave techniques were used to extract tobacco alkaloids, and response surface methodology was used to optimize extraction conditions. Ultrasonic technique factors were temperature, 30-85°C; time, 3-45 min; solvent volume, 8-80 mL. Microwave extraction factors were pressure, 15-75 psi; time, 3-40 min; power, 30-90% of the maximum magnetron power of 650 W. Soxhlet and solvent AOAC-modified extraction methods were also applied after some improvements. Nicotine, nornicotine, anabasine, and anatabine were quantified by gas chromatography. A steam distillation International Standards Organization method for total alkaloid evaluation was used as reference. The results obtained by the different methods were compared using a least squares deviation test. The ultrasonic and the proposed modified-AOAC extraction method were the more convenient with regard to practicability and precision. The relative deviations (n = 5) were as follows: For the ultrasonic method in low-level alkaloid tobaccos, 0.7% nicotine and 1.4-14% minor alkaloids; in high-level alkaloid tobaccos, 2.4% nicotine and 4.5-5.1% minor alkaloids. For the modified AOAC method in low-level alkaloid tobaccos, 0.9% nicotine and 2.4-11.6% minor alkaloids; and in high-level alkaloid tobaccos, 1.7% nicotine and 2.0-2.4% minor alkaloids.

European journal of lipid …, Jan 1, 2005

Page 1. Isabel MG Lopes M. Gabriela Bernardo-Gil Centre for Biological and Chemical Engineering, ... more Page 1. Isabel MG Lopes M. Gabriela Bernardo-Gil Centre for Biological and Chemical Engineering, DEQ, Instituto Superior Técnico, Lisboa, Portugal Characterisation of acorn oils extracted by hexane and by supercritical carbon dioxide ...

European Food Research and …, Jan 1, 2004

Pumpkin, Cucurbita ficifolia, seed oil was extracted with supercritical carbon dioxide (SC-CO 2 )... more Pumpkin, Cucurbita ficifolia, seed oil was extracted with supercritical carbon dioxide (SC-CO 2 ) in the temperature range of 308-318 K and in the pressure range of 18-20 MPa. In addition, the influence of the superficial velocity within a tubular extractor was studied. The oil content determined by a Soxhlet apparatus was 43.5%. Physical and chemical characteristics of the oil were obtained. The results in terms of free fatty acids contents were compared with those obtained when n-hexane was used as the solvent, and no significant differences between the oils extracted by both methods were found. The main fatty acid was w6-linoleic acid (about 60%), followed by palmitic acid (about 15%) and oleic acid (about 14%). Oxidative stability was studied by using the induction time determined by the Rancimat method. The oil obtained by supercritical fluid extraction (SFE) was less protected against oxidation (4.2 h for SFE-extracted oil and 8.3 h for the pumpkin seed oil extracted with nhexane). The oil extracted by SC-CO 2 was clearer than that extracted by n-hexane, showing some refining. The acidity index was 5.5 for the n-hexane extracted oil. For the oils extracted by SC-CO 2 , two analyses were made: for the oils obtained at 15 min of extraction time, for which the acidity indices varied from about 15 to 20, and for the remaining oils (extracted until 150 min), for which the acidity indices varied from about 2 to 2.6. The central composite nonfactorial design was used to optimise the extraction conditions, using the Statistica, version 5, software (Statsoft). The best results, in terms of oil recovered by SC-CO 2 , were found at 19 MPa, 308 K and a superficial velocity of 6.010 4 ms 1 .