Pierre-yves Pontalier | Institut National Polytechnique de Toulouse (original) (raw)

Papers by Pierre-yves Pontalier

Ultrafiltration is a very efficient concentration method prior to the atomization of biopolymers ... more Ultrafiltration is a very efficient concentration method prior to the atomization of biopolymers extracted from plants. Trials for the concentration of rhamnogalacturonan solutions were realized with PES membrane cassettes with a molecular weight cut-off (MWCO) ranging from 1kDa to 50 kDa. The higher rejection rates were obtained by the two membranes with the highest MWCO. These results can partially be explained by the differences in the membranes' structure. As a consequence of the biopolymers gel forming properties, the gel layer created in the feed channel may also modify the permeation properties of the membranes. Two parameters seem to act on gel layer properties : the shear-thinning properties of the polymer solution and the screen in the feed channel which both change the flow pattern.

DESCRIPTION Biorefinery for Food, Fuels and Materials 2015 symposium - BFFM 2015, 15 June 2015 - ... more DESCRIPTION Biorefinery for Food, Fuels and Materials 2015 symposium - BFFM 2015, 15 June 2015 - 17 June 2015 (Montpellier, France)

Fractionation of sunflower whole plant is carried out with water in a twin-screw extruder. An ext... more Fractionation of sunflower whole plant is carried out with water in a twin-screw extruder. An extract and a raffinate are produced in a single step. Oil extraction yield is 55%. Lipids are extracted in the form of two oil-in-water emulsions: the higher hydrophobic phase and the lower one. Stability of both hydrophobic phases is ensured by the presence at interface of surface-active agents co-extracted: phospholipids and proteins. Pectins and non pectic sugars complete the dry matter of the lower hydrophobic phase. Hydrophobic phases may have applications for non food uses: biolubricants market, transport of active principles (odours, colours, bactericides, antifungals), and treatment of hydrophilic surfaces. They can be also used for oil production because their demulsification with ethanol is efficient. Oil recovery produces also a precipitate containing proteins with tensioactive properties. The extract contains also a hydrophilic phase (aqueous phase). This largest phase is an ex...

Aqueous extraction of sunflower oil is a reasonable environment-friendly alternative to the solve... more Aqueous extraction of sunflower oil is a reasonable environment-friendly alternative to the solvent extraction. It can even be realized directly from the whole plant using the twin-screw extrusion technology. Co-rotating twin-screw extruder behaves like a chemo-thermo-mechanical reactor. Equipped with a filtration module, it allows to separate extract and raffinate in a continuous mode and in a single step. This only apparatus carries out three essential unit operations: conditioning and grinding of sunflower seeds, liquid/solid extraction and liquid/solid separation. Starting from whole plant is a promising new way of extraction. Thanks to the fibers of the stalk, wringing out the mixing is favoured. The process can also be considered as an original and powerful solution for fractionating and value-adding to sunflower since obtained fractions may have direct applications in industrial products.

Twin-screw extrusion is a powerful solution for biorefinery of sunflower whole plant. Thermomecha... more Twin-screw extrusion is a powerful solution for biorefinery of sunflower whole plant. Thermomechanical fractionation and aqueous extraction are conducted simultaneously. A filter is outfitted along the barrel to collect a filtrate and a cake meal. Best oil yield is 57%. Proteins are also partly extracted, just as pectins. The cake meal is relatively moist (63%), and it is first dried. It is largely composed of fibers (58%). Oil content is 14% (40% of oil in whole plant). Protein content is 7% (51% of proteins in whole plant). As a mixture of fibers and proteins, this natural composite is successfully processed into biodegradable agromaterials by thermo-pressing. During moulding, macromolecular structure of proteins is transformed. Effects of pressure and temperature result in their glass transition. Proteins ensure the agromaterial cohesion. Fibers entanglement also acts like reinforcement. Stress at break and elastic modulus increase with temperature, pressure and time chosen for t...

The objective of this study was to evaluate the feasibility of an aqueous process for the biorefi... more The objective of this study was to evaluate the feasibility of an aqueous process for the biorefinery of sunflower whole plant using a twin-screw extruder. Aqueous extraction of oil was chosen as an environment-friendly alternative to the solvent extraction. The extruder was used to carry out three essential unit operations: grinding, liquid/solid extraction, and liquid/solid separation. Wringing out the mixing was effective. However, drying of the cake meal was not optimal. Lixiviation of cotyledon cells was also incomplete. Extraction efficiency depended on operating conditions: screw rotation speed, and input flow rates of whole plant and water. In the best conditions, oil yield was 57%. Residual oil content in the cake meal was 14%. These conditions leaded to the co-extraction of proteins, pectins, and hemicelluloses. The corresponding protein yield was 44%. Oil was extracted in the form of two oil-in-water emulsions. These hydrophobic phases were stabilized by phospholipids and...

Sunflower (Helianthus annuus L.) is cultivated for its seeds' high oil content. Water is an inter... more Sunflower (Helianthus annuus L.) is cultivated for its seeds' high oil content. Water is an interesting alternative medium for sunflower oil extraction. Aqueous extraction of oil can be conducted in a twinscrew extruder using the whole seeds (Evon et al., Ind. Crops Prod. 26:351, 2007) or using a press cake (Evon et al., Ind. Crops Prod. 29:455, 2009). When it is conducted using the whole plant, wringing out the resulting mix is favored because of the natural abundance of fibers in stalk (Evon et al., Ol. Corps gras Li. 17:404, 2010). A filtrate and a cake are produced simultaneously, and twin-screw extrusion appears to be a powerful tool for the biorefinery of sunflower whole plant. Oil extraction yield is 57% in the best operating conditions, and residual oil content in cake is 14.3% dry matter. As cake is a mixture of fibers and proteins, it can be considered as a natural composite that is processed successfully into biodegradable agromaterials by thermo-pressing (Evon et al., Ol. Corps gras Li. 17:404, 2010; Evon et al., Adv. Mater. Res. 112:63, 2010). Thermo-pressing is not only a molding operation to manufacture cohesive fiberboards. It also consists in increasing the oil extraction efficiency (Evon et al., Ol.

L'invention concerne un procédé de fabrication d'un matériau solide à partir d'une co... more L'invention concerne un procédé de fabrication d'un matériau solide à partir d'une composition de plante oléagineuse, dans lequel : - on soumet d'abord ladite composition de plante oléagineuse à un traitement, dit traitement thermo-mécano-chimique, dans lequel on réalise une trituration de ladite composition de plante oléagineuse dans l'eau de façon à former : o une composition liquide comprenant une émulsion stable d'au moins un corps gras de la composition de plante oléagineuse dans l'eau, et ; o un solide, dit tourteau de plante oléagineuse, présentant une teneur en corps gras inférieure à celle de la composition de plante oléagineuse, puis ; - on soumet le tourteau de plante oléagineuse à une étape de thermo-compression à une température et à une pression prédéterminées ; caractérisé en ce qu'on maintient la pression prédéterminée et la température prédéterminée pendant une durée supérieure à 1 min et inférieure à 10 min de façon à former le matér...

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Biorefinery of sunflower whole plant can be conducted with water by thermo-mechanochemical fracti... more Biorefinery of sunflower whole plant can be conducted with water by thermo-mechanochemical fractionation in a Clextral BC 45 (France) co-penetrating and co-rotating twin-screw extruder. An extract and a raffinate are produced separately and in a single continuous step. The arrangement of screw profile makes possible to define three successive zones along the barrel, in which the three unit operations of the aqueous extraction process are taking place. (I) The grinding zone consists of a succession of 10 monolobes paddles, and 5 bilobe paddles. It ensures the conditioning and the grinding of solid matter. (II) The extracting zone begins with water injection. It is composed of a second series of 5 bilobe paddles to mix liquid and solid. (III) The pressing zone is the place where liquid/solid separation is realized. Screw configuration is then arranged with reversed pitch screws used to place pressure on the liquid/solid mixture, and positioned immediately downstream from a filter section. Representation of liquid/solid transport inside the barrel is performed thanks to (i) the measuring of the filling of each screw element after visual observation, (ii) the characteristics of the corresponding solid, and (iii) the modelling of the contribution of each screw element to the residence time distribution of solid and liquid phases. Consequently, twin-screw extruder can be represented as the association of a grinder, a liquid/solid extractor, and a liquid/solid separator, in which material exchanges are intensified. Thus, it is possible to predict the evolution of mean residence times of liquid and solid in the three zones of twin-screw extruder with the main operating variables: screw rotation speed, and inlet flow rates of whole plant and water. The decrease of both screw rotation speed and inlet flow rate of whole plant, simultaneously with the increase of inlet flow rate of water, causes the increase of liquid to solid ratio in the extracting zone, and the increase of residence time of solid in the pressing zone. These operating conditions (60 rpm for screw rotation speed, 5.0 kg/h and 20.3 kg/h for inlet flow rates of whole plant and water, respectively) are favourable to an efficient contact between liquid and solid (8.2 for liquid to solid ratio), and to the liquid/solid separation (156 sec for residence time of solid inside the separator). Oil yield is then around 55%, and residual oil content of the cake meal is only 13% of dry weight. The oil is extracted in the form of oil-in-water emulsions. The emulsion stability is ensured at interface by surface-active agents: phospholipids, proteins, and pectins. Extracts are also made up of a hydrophilic phase. This major fraction contains water-soluble components: proteins, and pectins. Raffinates are rich in fibres, and they have also a significant content of proteins with thermoplastic properties. They can be manufactured into biodegradable agromaterials by compression moulding.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Filtration & Separation, 2003

Diester plants produce large quantities of glycerin solutions, whose commercial exploitation requ... more Diester plants produce large quantities of glycerin solutions, whose commercial exploitation requires sodium sulphate elimination. Bipolar electrodialysis (BED) has been investigated for its capability to both demineralize solutions and to produce alkali and acid solutions. Demineralization rates above 80% were achieved with glycerin loss below 2%. Alkali and acid solutions were obtained with a final concentration of about 2 N

Desalination, 2004

Diester manufacturing plants produce large quantities of glycerol solutions. Their economic devel... more Diester manufacturing plants produce large quantities of glycerol solutions. Their economic development requires sodium sulfate elimination to obtain glycerol rates over 80% of the initial content. Conventional electrodialysis (ED) and bipolar electrodialysis (BED) were investigated for their performances in the demineralisation of effluents. Results indicate that both ED and BED achieve the demineralisation objective with a global loss below 2.5% of the initial glycerol. Salt fluxes are twice as high with a bipolar membrane, bipolar membranes having however a lower efficiency. Hence energetic consumption is higher for BED. This technique also leads to the production of alkali and acid solutions which are useful to the diester process. The glycerol content of the solutions acts, via its viscosity, on the energetic cost of fluid pumping and on energetic efficiency. Therefore, ED or BED has to be used before the preconcentration of the solution.

Advances in Structural Analysis of Advanced Materials, 2010

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Algal Research, 2014

In order to release proteins in the aqueous phase, high-pressure homogenization and alkaline trea... more In order to release proteins in the aqueous phase, high-pressure homogenization and alkaline treatments were applied to rupture the cell walls of five intensively grown microalgae. Protein characterisation was carried out by analysing the amino acid profiles of both the crude microalgae and the protein extracts, obtained after both types of treatment. The results showed that the proportion of proteins released from microalgae following both treatments was, in descending order: Porphyridium cruentum N Arthrospira platensis N Chlorella vulgaris N Nannochloropsis oculata N Haematococcus pluvialis, reflecting the increasingly protective, cell walls. Nonetheless, mechanical treatment released more proteins from all the microalgae compared to chemical treatment. The highest yield was for the fragile cell walled P. cruentum with 88% hydro-soluble proteins from total proteins, and the lowest from the rigid cell walled H. pluvialis with 41%. The proportion of essential and non-essential amino acids in the extract was assessed and compared to the crude microalgae profile. It was higher after alkaline treatment and much higher after high-pressure homogenization. These results suggest that non-essential amino acids are more concentrated actually inside the cells and that different types of proteins are being released by these two treatments.

Algal Research, 2014

The microalgal structure has been investigated to evaluate the release of proteins in aqueous med... more The microalgal structure has been investigated to evaluate the release of proteins in aqueous media from five microalgae after conducting different cell disruption techniques: manual grinding, ultrasonication, alkaline treatment, and high-pressure treatment. After conducting cell disruption, the protein concentration in water was determined for all the microalgae and the results are discussed within the context of their cell wall structure. It was found that the aqueous media containing most protein concentration followed the order: high-pressure cell disruption N chemical treatment N ultrasonication N manual grinding. Fragile cell-walled microalgae were mostly attacked according to the following order: Haematococcus pluvialis b Nannochloropsis oculata b Chlorella vulgaris b Porphyridium cruentum ≤ Arthrospira platensis.

Separation and Purification Technology, 1997

Two tight nanofiltration membranes of 100 and 400 Da were tested at different operating condition... more Two tight nanofiltration membranes of 100 and 400 Da were tested at different operating conditions. The results show that the selective properties of nanofiltration membranes come from a combination of several physicochemical mechanisms. Mass transport is mainly ...

Ultrafiltration is a very efficient concentration method prior to the atomization of biopolymers ... more Ultrafiltration is a very efficient concentration method prior to the atomization of biopolymers extracted from plants. Trials for the concentration of rhamnogalacturonan solutions were realized with PES membrane cassettes with a molecular weight cut-off (MWCO) ranging from 1kDa to 50 kDa. The higher rejection rates were obtained by the two membranes with the highest MWCO. These results can partially be explained by the differences in the membranes' structure. As a consequence of the biopolymers gel forming properties, the gel layer created in the feed channel may also modify the permeation properties of the membranes. Two parameters seem to act on gel layer properties : the shear-thinning properties of the polymer solution and the screen in the feed channel which both change the flow pattern.

DESCRIPTION Biorefinery for Food, Fuels and Materials 2015 symposium - BFFM 2015, 15 June 2015 - ... more DESCRIPTION Biorefinery for Food, Fuels and Materials 2015 symposium - BFFM 2015, 15 June 2015 - 17 June 2015 (Montpellier, France)

Fractionation of sunflower whole plant is carried out with water in a twin-screw extruder. An ext... more Fractionation of sunflower whole plant is carried out with water in a twin-screw extruder. An extract and a raffinate are produced in a single step. Oil extraction yield is 55%. Lipids are extracted in the form of two oil-in-water emulsions: the higher hydrophobic phase and the lower one. Stability of both hydrophobic phases is ensured by the presence at interface of surface-active agents co-extracted: phospholipids and proteins. Pectins and non pectic sugars complete the dry matter of the lower hydrophobic phase. Hydrophobic phases may have applications for non food uses: biolubricants market, transport of active principles (odours, colours, bactericides, antifungals), and treatment of hydrophilic surfaces. They can be also used for oil production because their demulsification with ethanol is efficient. Oil recovery produces also a precipitate containing proteins with tensioactive properties. The extract contains also a hydrophilic phase (aqueous phase). This largest phase is an ex...

Aqueous extraction of sunflower oil is a reasonable environment-friendly alternative to the solve... more Aqueous extraction of sunflower oil is a reasonable environment-friendly alternative to the solvent extraction. It can even be realized directly from the whole plant using the twin-screw extrusion technology. Co-rotating twin-screw extruder behaves like a chemo-thermo-mechanical reactor. Equipped with a filtration module, it allows to separate extract and raffinate in a continuous mode and in a single step. This only apparatus carries out three essential unit operations: conditioning and grinding of sunflower seeds, liquid/solid extraction and liquid/solid separation. Starting from whole plant is a promising new way of extraction. Thanks to the fibers of the stalk, wringing out the mixing is favoured. The process can also be considered as an original and powerful solution for fractionating and value-adding to sunflower since obtained fractions may have direct applications in industrial products.

Twin-screw extrusion is a powerful solution for biorefinery of sunflower whole plant. Thermomecha... more Twin-screw extrusion is a powerful solution for biorefinery of sunflower whole plant. Thermomechanical fractionation and aqueous extraction are conducted simultaneously. A filter is outfitted along the barrel to collect a filtrate and a cake meal. Best oil yield is 57%. Proteins are also partly extracted, just as pectins. The cake meal is relatively moist (63%), and it is first dried. It is largely composed of fibers (58%). Oil content is 14% (40% of oil in whole plant). Protein content is 7% (51% of proteins in whole plant). As a mixture of fibers and proteins, this natural composite is successfully processed into biodegradable agromaterials by thermo-pressing. During moulding, macromolecular structure of proteins is transformed. Effects of pressure and temperature result in their glass transition. Proteins ensure the agromaterial cohesion. Fibers entanglement also acts like reinforcement. Stress at break and elastic modulus increase with temperature, pressure and time chosen for t...

The objective of this study was to evaluate the feasibility of an aqueous process for the biorefi... more The objective of this study was to evaluate the feasibility of an aqueous process for the biorefinery of sunflower whole plant using a twin-screw extruder. Aqueous extraction of oil was chosen as an environment-friendly alternative to the solvent extraction. The extruder was used to carry out three essential unit operations: grinding, liquid/solid extraction, and liquid/solid separation. Wringing out the mixing was effective. However, drying of the cake meal was not optimal. Lixiviation of cotyledon cells was also incomplete. Extraction efficiency depended on operating conditions: screw rotation speed, and input flow rates of whole plant and water. In the best conditions, oil yield was 57%. Residual oil content in the cake meal was 14%. These conditions leaded to the co-extraction of proteins, pectins, and hemicelluloses. The corresponding protein yield was 44%. Oil was extracted in the form of two oil-in-water emulsions. These hydrophobic phases were stabilized by phospholipids and...

Sunflower (Helianthus annuus L.) is cultivated for its seeds' high oil content. Water is an inter... more Sunflower (Helianthus annuus L.) is cultivated for its seeds' high oil content. Water is an interesting alternative medium for sunflower oil extraction. Aqueous extraction of oil can be conducted in a twinscrew extruder using the whole seeds (Evon et al., Ind. Crops Prod. 26:351, 2007) or using a press cake (Evon et al., Ind. Crops Prod. 29:455, 2009). When it is conducted using the whole plant, wringing out the resulting mix is favored because of the natural abundance of fibers in stalk (Evon et al., Ol. Corps gras Li. 17:404, 2010). A filtrate and a cake are produced simultaneously, and twin-screw extrusion appears to be a powerful tool for the biorefinery of sunflower whole plant. Oil extraction yield is 57% in the best operating conditions, and residual oil content in cake is 14.3% dry matter. As cake is a mixture of fibers and proteins, it can be considered as a natural composite that is processed successfully into biodegradable agromaterials by thermo-pressing (Evon et al., Ol. Corps gras Li. 17:404, 2010; Evon et al., Adv. Mater. Res. 112:63, 2010). Thermo-pressing is not only a molding operation to manufacture cohesive fiberboards. It also consists in increasing the oil extraction efficiency (Evon et al., Ol.

L'invention concerne un procédé de fabrication d'un matériau solide à partir d'une co... more L'invention concerne un procédé de fabrication d'un matériau solide à partir d'une composition de plante oléagineuse, dans lequel : - on soumet d'abord ladite composition de plante oléagineuse à un traitement, dit traitement thermo-mécano-chimique, dans lequel on réalise une trituration de ladite composition de plante oléagineuse dans l'eau de façon à former : o une composition liquide comprenant une émulsion stable d'au moins un corps gras de la composition de plante oléagineuse dans l'eau, et ; o un solide, dit tourteau de plante oléagineuse, présentant une teneur en corps gras inférieure à celle de la composition de plante oléagineuse, puis ; - on soumet le tourteau de plante oléagineuse à une étape de thermo-compression à une température et à une pression prédéterminées ; caractérisé en ce qu'on maintient la pression prédéterminée et la température prédéterminée pendant une durée supérieure à 1 min et inférieure à 10 min de façon à former le matér...

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Biorefinery of sunflower whole plant can be conducted with water by thermo-mechanochemical fracti... more Biorefinery of sunflower whole plant can be conducted with water by thermo-mechanochemical fractionation in a Clextral BC 45 (France) co-penetrating and co-rotating twin-screw extruder. An extract and a raffinate are produced separately and in a single continuous step. The arrangement of screw profile makes possible to define three successive zones along the barrel, in which the three unit operations of the aqueous extraction process are taking place. (I) The grinding zone consists of a succession of 10 monolobes paddles, and 5 bilobe paddles. It ensures the conditioning and the grinding of solid matter. (II) The extracting zone begins with water injection. It is composed of a second series of 5 bilobe paddles to mix liquid and solid. (III) The pressing zone is the place where liquid/solid separation is realized. Screw configuration is then arranged with reversed pitch screws used to place pressure on the liquid/solid mixture, and positioned immediately downstream from a filter section. Representation of liquid/solid transport inside the barrel is performed thanks to (i) the measuring of the filling of each screw element after visual observation, (ii) the characteristics of the corresponding solid, and (iii) the modelling of the contribution of each screw element to the residence time distribution of solid and liquid phases. Consequently, twin-screw extruder can be represented as the association of a grinder, a liquid/solid extractor, and a liquid/solid separator, in which material exchanges are intensified. Thus, it is possible to predict the evolution of mean residence times of liquid and solid in the three zones of twin-screw extruder with the main operating variables: screw rotation speed, and inlet flow rates of whole plant and water. The decrease of both screw rotation speed and inlet flow rate of whole plant, simultaneously with the increase of inlet flow rate of water, causes the increase of liquid to solid ratio in the extracting zone, and the increase of residence time of solid in the pressing zone. These operating conditions (60 rpm for screw rotation speed, 5.0 kg/h and 20.3 kg/h for inlet flow rates of whole plant and water, respectively) are favourable to an efficient contact between liquid and solid (8.2 for liquid to solid ratio), and to the liquid/solid separation (156 sec for residence time of solid inside the separator). Oil yield is then around 55%, and residual oil content of the cake meal is only 13% of dry weight. The oil is extracted in the form of oil-in-water emulsions. The emulsion stability is ensured at interface by surface-active agents: phospholipids, proteins, and pectins. Extracts are also made up of a hydrophilic phase. This major fraction contains water-soluble components: proteins, and pectins. Raffinates are rich in fibres, and they have also a significant content of proteins with thermoplastic properties. They can be manufactured into biodegradable agromaterials by compression moulding.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Filtration & Separation, 2003

Diester plants produce large quantities of glycerin solutions, whose commercial exploitation requ... more Diester plants produce large quantities of glycerin solutions, whose commercial exploitation requires sodium sulphate elimination. Bipolar electrodialysis (BED) has been investigated for its capability to both demineralize solutions and to produce alkali and acid solutions. Demineralization rates above 80% were achieved with glycerin loss below 2%. Alkali and acid solutions were obtained with a final concentration of about 2 N

Desalination, 2004

Diester manufacturing plants produce large quantities of glycerol solutions. Their economic devel... more Diester manufacturing plants produce large quantities of glycerol solutions. Their economic development requires sodium sulfate elimination to obtain glycerol rates over 80% of the initial content. Conventional electrodialysis (ED) and bipolar electrodialysis (BED) were investigated for their performances in the demineralisation of effluents. Results indicate that both ED and BED achieve the demineralisation objective with a global loss below 2.5% of the initial glycerol. Salt fluxes are twice as high with a bipolar membrane, bipolar membranes having however a lower efficiency. Hence energetic consumption is higher for BED. This technique also leads to the production of alkali and acid solutions which are useful to the diester process. The glycerol content of the solutions acts, via its viscosity, on the energetic cost of fluid pumping and on energetic efficiency. Therefore, ED or BED has to be used before the preconcentration of the solution.

Advances in Structural Analysis of Advanced Materials, 2010

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Algal Research, 2014

In order to release proteins in the aqueous phase, high-pressure homogenization and alkaline trea... more In order to release proteins in the aqueous phase, high-pressure homogenization and alkaline treatments were applied to rupture the cell walls of five intensively grown microalgae. Protein characterisation was carried out by analysing the amino acid profiles of both the crude microalgae and the protein extracts, obtained after both types of treatment. The results showed that the proportion of proteins released from microalgae following both treatments was, in descending order: Porphyridium cruentum N Arthrospira platensis N Chlorella vulgaris N Nannochloropsis oculata N Haematococcus pluvialis, reflecting the increasingly protective, cell walls. Nonetheless, mechanical treatment released more proteins from all the microalgae compared to chemical treatment. The highest yield was for the fragile cell walled P. cruentum with 88% hydro-soluble proteins from total proteins, and the lowest from the rigid cell walled H. pluvialis with 41%. The proportion of essential and non-essential amino acids in the extract was assessed and compared to the crude microalgae profile. It was higher after alkaline treatment and much higher after high-pressure homogenization. These results suggest that non-essential amino acids are more concentrated actually inside the cells and that different types of proteins are being released by these two treatments.

Algal Research, 2014

The microalgal structure has been investigated to evaluate the release of proteins in aqueous med... more The microalgal structure has been investigated to evaluate the release of proteins in aqueous media from five microalgae after conducting different cell disruption techniques: manual grinding, ultrasonication, alkaline treatment, and high-pressure treatment. After conducting cell disruption, the protein concentration in water was determined for all the microalgae and the results are discussed within the context of their cell wall structure. It was found that the aqueous media containing most protein concentration followed the order: high-pressure cell disruption N chemical treatment N ultrasonication N manual grinding. Fragile cell-walled microalgae were mostly attacked according to the following order: Haematococcus pluvialis b Nannochloropsis oculata b Chlorella vulgaris b Porphyridium cruentum ≤ Arthrospira platensis.

Separation and Purification Technology, 1997

Two tight nanofiltration membranes of 100 and 400 Da were tested at different operating condition... more Two tight nanofiltration membranes of 100 and 400 Da were tested at different operating conditions. The results show that the selective properties of nanofiltration membranes come from a combination of several physicochemical mechanisms. Mass transport is mainly ...