Journal of the American Oil Chemists' Society, 2007
Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as bo... more Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as both the wax composition in sunflower oils obtained from washed seeds and the wax composition in the solvent extracts. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and on wax distribution was observed by scanning-electron microscopy. Washing preferentially removed the crystallized fraction, hexane being the most effective solvent. Short contact times (20 s) at 25-40°C were sufficient to extract the insoluble waxes by hexane washing. The extracted material consisted of C40-C54 waxes with higher percentages of extracted C44, C46 and C48. These are superficially in the hull of sunflower seed presenting a non-uniform distribution as observed by microscopy. Solvent washing with pre-heating of the seeds caused a decrease in sample moisture content, which reduced dehulling ability. Ethanol-washed seeds were the easiest to dehull, but higher production of fines was also observed. Solvent washing improves both the dehullingseed ability increment and the recovery of sunflower waxes as a by-product for commercial use.
ABSTRACT: Phospholipids from sunflower oil samples were enriched by using solid-phase extraction ... more ABSTRACT: Phospholipids from sunflower oil samples were enriched by using solid-phase extraction (SPE) cartridges and subsequently separated and analyzed by high-performance liq-uid chromatography (HPLC) with an ultraviolet detector. The recovery of individual phospholipids at different ...
In this work, a modified International Olive Council (IOC) method for wax determination involving... more In this work, a modified International Olive Council (IOC) method for wax determination involving a double-adsorbent layer of silica gel and silver nitrate-impregnated silica gel is presented (SN method). Column chromatography by the SN method did not show retention of wax esters standards with an even number of carbon atoms (C34–C44), observing recovery percentages higher than 90% even for unsaturated wax esters. All wax fractions were lower by the SN method than by the IOC method, resulting in a percentage decrease in the total wax content (olive oils: 20–50%, crude sunflower oil: 38%, crude soybean oil: 58% and crude grape seed oil: 13%). Olive oils analysed by the SN method showed increases of up to 27% in C40 relative percentage with respect to the IOC method. Additionally, decreases were observed by the SN method in the relative percentages for odd-carbon atom waxes for the seed oils in comparison to the IOC method (crude sunflower oil: 27%, crude soybean oil: 28% and crude grape seed oil: 13%). The main advantages of the proposed modification consist in its easy implementation and a better determination of wax esters (C34–C60) by controlling their complete recovery and removing interfering substances. The method is suitable for quality control and for authentication of olive oil and seed oils as well as in processing monitoring. Practical applications: The proposed method is useful in the quality, authentication and processing control of fruit and seed oils. Moreover, it can be an important tool for vegetable oil industries to control the efficiency of the wax separation process to prevent turbidity in the refined oil.
Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as bo... more Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as both the wax composition in sunflower oils obtained from washed seeds and the wax composition in the solvent extracts. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and on wax distribution was observed by scanning-electron microscopy. Washing preferentially removed the crystallized fraction, hexane being the most effective solvent. Short contact times (20 s) at 25–40 °C were sufficient to extract the insoluble waxes by hexane washing. The extracted material consisted of C40–C54 waxes with higher percentages of extracted C44, C46 and C48. These are superficially in the hull of sunflower seed presenting a non-uniform distribution as observed by microscopy. Solvent washing with pre-heating of the seeds caused a decrease in sample moisture content, which reduced dehulling ability. Ethanol-washed seeds were the easiest to dehull, but higher production of fines was also observed. Solvent washing improves both the dehulling-seed ability increment and the recovery of sunflower waxes as a by-product for commercial use.
Oil extraction from confectionery, oilseed and wild sunflower seeds with n-hexane was investigate... more Oil extraction from confectionery, oilseed and wild sunflower seeds with n-hexane was investigated by laboratory tests carried out in a stirred batch extractor at several temperatures (40, 50 and 60°C). The rates of extraction were determined from ground sunflower seeds (particle sizes between 0.420 and 1.000 mm). The oil yield in the extract increased with higher contact time and extraction temperature in all the cases. Equilibrium constants at 50°C for different solvent-ground seed ratios are reported. A mathematical model of oil extraction from seeds of sunflowers, based on a modified diffusive process in spherical geometry of particles, was proposed. The analysis of significance of the coefficient of fitting regression models showed significant differences between temperatures for each genotype and between genotypes at each temperature. The resulting diffusion coefficient ranged from 1.34 Â 10 À12 to 1.87 Â 10 À12 m 2 /s for confectionery, 2.06 Â 10 À12 to 5.03 Â 10 À12 m 2 /s for oilseed, and 9.06 Â 10 À13 to 1.18 Â 10 À12 m 2 /s for wild sunflower. The temperature dependence of the diffusion coefficient was represented by an Arrhenius-type equation for each sunflower seed studied. Activation energy values of 13.74, 33.95 and 11.32 kJ/mol were obtained for confectionery, oilseed and wild sunflower, respectively.
Journal of the American Oil Chemists' Society, 2007
Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as bo... more Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as both the wax composition in sunflower oils obtained from washed seeds and the wax composition in the solvent extracts. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and on wax distribution was observed by scanning-electron microscopy. Washing preferentially removed the crystallized fraction, hexane being the most effective solvent. Short contact times (20 s) at 25-40°C were sufficient to extract the insoluble waxes by hexane washing. The extracted material consisted of C40-C54 waxes with higher percentages of extracted C44, C46 and C48. These are superficially in the hull of sunflower seed presenting a non-uniform distribution as observed by microscopy. Solvent washing with pre-heating of the seeds caused a decrease in sample moisture content, which reduced dehulling ability. Ethanol-washed seeds were the easiest to dehull, but higher production of fines was also observed. Solvent washing improves both the dehullingseed ability increment and the recovery of sunflower waxes as a by-product for commercial use.
ABSTRACT: Phospholipids from sunflower oil samples were enriched by using solid-phase extraction ... more ABSTRACT: Phospholipids from sunflower oil samples were enriched by using solid-phase extraction (SPE) cartridges and subsequently separated and analyzed by high-performance liq-uid chromatography (HPLC) with an ultraviolet detector. The recovery of individual phospholipids at different ...
In this work, a modified International Olive Council (IOC) method for wax determination involving... more In this work, a modified International Olive Council (IOC) method for wax determination involving a double-adsorbent layer of silica gel and silver nitrate-impregnated silica gel is presented (SN method). Column chromatography by the SN method did not show retention of wax esters standards with an even number of carbon atoms (C34–C44), observing recovery percentages higher than 90% even for unsaturated wax esters. All wax fractions were lower by the SN method than by the IOC method, resulting in a percentage decrease in the total wax content (olive oils: 20–50%, crude sunflower oil: 38%, crude soybean oil: 58% and crude grape seed oil: 13%). Olive oils analysed by the SN method showed increases of up to 27% in C40 relative percentage with respect to the IOC method. Additionally, decreases were observed by the SN method in the relative percentages for odd-carbon atom waxes for the seed oils in comparison to the IOC method (crude sunflower oil: 27%, crude soybean oil: 28% and crude grape seed oil: 13%). The main advantages of the proposed modification consist in its easy implementation and a better determination of wax esters (C34–C60) by controlling their complete recovery and removing interfering substances. The method is suitable for quality control and for authentication of olive oil and seed oils as well as in processing monitoring. Practical applications: The proposed method is useful in the quality, authentication and processing control of fruit and seed oils. Moreover, it can be an important tool for vegetable oil industries to control the efficiency of the wax separation process to prevent turbidity in the refined oil.
Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as bo... more Wax distribution in sunflower seeds was determined by capillary-gas chromatography, as well as both the wax composition in sunflower oils obtained from washed seeds and the wax composition in the solvent extracts. The dehulling efficiency was evaluated by using a laboratory centrifugal process. The washing effect on hull morphology and on wax distribution was observed by scanning-electron microscopy. Washing preferentially removed the crystallized fraction, hexane being the most effective solvent. Short contact times (20 s) at 25–40 °C were sufficient to extract the insoluble waxes by hexane washing. The extracted material consisted of C40–C54 waxes with higher percentages of extracted C44, C46 and C48. These are superficially in the hull of sunflower seed presenting a non-uniform distribution as observed by microscopy. Solvent washing with pre-heating of the seeds caused a decrease in sample moisture content, which reduced dehulling ability. Ethanol-washed seeds were the easiest to dehull, but higher production of fines was also observed. Solvent washing improves both the dehulling-seed ability increment and the recovery of sunflower waxes as a by-product for commercial use.
Oil extraction from confectionery, oilseed and wild sunflower seeds with n-hexane was investigate... more Oil extraction from confectionery, oilseed and wild sunflower seeds with n-hexane was investigated by laboratory tests carried out in a stirred batch extractor at several temperatures (40, 50 and 60°C). The rates of extraction were determined from ground sunflower seeds (particle sizes between 0.420 and 1.000 mm). The oil yield in the extract increased with higher contact time and extraction temperature in all the cases. Equilibrium constants at 50°C for different solvent-ground seed ratios are reported. A mathematical model of oil extraction from seeds of sunflowers, based on a modified diffusive process in spherical geometry of particles, was proposed. The analysis of significance of the coefficient of fitting regression models showed significant differences between temperatures for each genotype and between genotypes at each temperature. The resulting diffusion coefficient ranged from 1.34 Â 10 À12 to 1.87 Â 10 À12 m 2 /s for confectionery, 2.06 Â 10 À12 to 5.03 Â 10 À12 m 2 /s for oilseed, and 9.06 Â 10 À13 to 1.18 Â 10 À12 m 2 /s for wild sunflower. The temperature dependence of the diffusion coefficient was represented by an Arrhenius-type equation for each sunflower seed studied. Activation energy values of 13.74, 33.95 and 11.32 kJ/mol were obtained for confectionery, oilseed and wild sunflower, respectively.
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