Houcine Mhemdi - Academia.edu (original) (raw)

Papers by Houcine Mhemdi

The seeds of coriander (Coriandrum sativum) are rich in vegetal oil (VO) and in essential oil (EO... more The seeds of coriander (Coriandrum sativum) are rich in vegetal oil (VO) and in essential oil (EO), which have both an interesting potential for the food, pharmaceutical and cosmetic industries. The review of the literature shows that most of the research works related to the extraction of coriander seeds are aimed at extracting either the VO or the EO. The aim of this work is to develop a process that can extract selectively the VO and EO in a consecutive way by tuning experimental conditions. A 4-step process has been set up: (i) seeds preparation by grinding and sieving, (ii) extraction by supercritical CO 2 (SC CO 2) and (iii; iv) selective separation in two separators with different pressure level. The first part of this study consisted in studying the effects of the operating conditions (T, P, CO 2 density, flow rate and particle size distribution of ground seeds) on the yield of extraction. The results showed that the global performance of the process depended mainly on the p...

The vegetable oil extraction process from seeds and nuts depends on mechanical and solvent (usual... more The vegetable oil extraction process from seeds and nuts depends on mechanical and solvent (usually n-hexane) extractions. Despite the efficiency of n-hexane, its use is nowadays questioned due to health, environmental, and technological issues. As an alternative to hexane extraction, several greener solvents and extraction techniques have been developed and tested during the last decades. Among these alternatives, the Surfactant-Aqueous Extraction Process (SAEP) appears as a promising method. Initially developed for the petroleum sector, this method was then tested and optimized for vegetable oil extraction. Successful implementations at the laboratory scale led to slightly more than 90% oil yield, mainly by using so-called “extended surfactants”. Compare to conventional surfactants, these surfactants can efficiently solubilize a large amount of vegetable oil in water, despite the structural diversity and the bulkiness of vegetable oil molecules. The present review is devoted to ex...

Separation and Purification Technology, 2017

This work investigates the purification of juices obtained with innovative pulsed electric field ... more This work investigates the purification of juices obtained with innovative pulsed electric field treatment and alkaline pressing of sugar beet tissue. Sugar beets were first sliced into cossettes and treated by pulsed electric field (PEF) at ambient temperature with a strength of E = 600 V/cm and an effective duration of t PEF = 10 ms to electroporate cell membranes. Electroporated cossettes were then subjected to a double pressing with intermediate preliming using 0.6 g CaO/100 g fresh cossettes to produce mixed prelimed juice (MPJ). Alternatively, electroporated cossettes were pressed without preliming to produce non-limed raw juice (RJ). MPJ and RJ were then purified by liming-carbonation and alternatively by stirred ultrafiltration. Preliming of electroporated cossettes improves filtration and sedimentation characteristics of juices. Moreover, the overall lime quantity required for the liming-carbonation was lower for MPJ (6 kg/m 3 ) than for RJ (10 kg/m 3 ). Purified MPJ had ...

Pulsed Electric Fields to Obtain Healthier and Sustainable Food for Tomorrow

Proceedings of the Virtual 2021 AOCS Annual Meeting & Expo

Food and Bioproducts Processing

Industrial Crops and Products

The Journal of Supercritical Fluids

Food industry is increasingly interested in replacing conventional processes of plant extraction,... more Food industry is increasingly interested in replacing conventional processes of plant extraction, as well as microbial inactivation, by alternative, greener and cheaper techniques. In many cases, chemical extraction processes are hindered by several drawbacks such as the use of chemical solvents, which is associated with many health and environmental issues. Furthermore, the use of high temperatures to improve and/or accelerate the processes, which may affect and degrade the thermolabile compounds, is usually required. Among the most promising techniques that could be competitive to the current extraction methods of molecules from plant matrices and microbial inactivation of food products, ultrasound assisted supercritical fluid extraction has taken great interest. This non-exhaustive review, covering the last 20 years, gives a critical commentary on the main published results using this emerging technology. Promising prospects opened up by new applications are described, without omitting the main limitations still to be overcome for a harmonious industrial development of these technologies.

Industrial Crops and Products

Innovative Food Science & Emerging Technologies

Journal of Cleaner Production

Food and Bioproducts Processing, 2017

Industrial Crops and Products, 2016

Innovative Food Science & Emerging Technologies, 2016

ABSTRACT Impact de la température d'extraction sur la purification du jus sucré de la bet... more ABSTRACT Impact de la température d'extraction sur la purification du jus sucré de la betterave Mots-clés: Betterave à sucre, purification, qualité, champs électriques pulsés, échaudage Le jus de la betterave à sucre est industriellement extrait par diffusion à haute température (70-75 °C). Ce procédé d'extraction thermique induit une dilution importante du jus, consomme beaucoup d'énergie et favorise la co-extraction de certaines molécules indésirables (pectines, protéines, colorants…). Ces molécules diminuent la pureté du jus et risquent de compliquer l'étape de purification calco-carbonique en aval. Par analogie avec le procédé d'extraction utilisé pour la canne à sucre, le pressage de la betterave a été proposé comme une technique d'extraction alternative très économe. Pour améliorer les rendements d'extraction par pressage, différentes approches ont été proposées. Certains auteurs ont proposé de réaliser un préchauffage des cossettes à haute température (80-85 °C) pendant une courte durée (5-10 min) [1]. Ce prétraitement thermique (échaudage) présente pour certains aspects les mêmes inconvénients que le procédé traditionnel (consommation énergétique et solubilisation des macromolécules). Récemment, d'autres études ont soulignés l'intérêt de l'application d'un prétraitement par champs électriques pulsés modéré (0.4-0.8 kV.cm -1) pour l'extraction du jus sucré par pressage à froid. Ce prétraitement, de faible consommation énergétique, induit la perméabilisation des membranes cellulaires à froid et permet ainsi d'extraire un jus plus pur et moins coloré [2]. La présente étude porte sur la comparaison de l'impact de ces deux prétraitements (échaudage et CEP à froid) sur l'étape de purification du jus. Le jus d'échaudage est obtenu par pressage des cosettes préalablement chauffées à 80 °C pendant 10 min. Le jus CEP a été obtenu par pressage de cossettes prétraitées à froid (20 °C) par champs électriques pulsés (0.6 kV.cm -1 pendant 10 ms). Les analyses physico-chimiques des jus bruts ont montré que la qualité du jus extrait à froid est meilleure que celle du jus obtenu par traitement thermique. Les jus obtenus ont été ensuite purifiés par épuration calco-carbonique en variant la quantité de chaux utilisée de 0 à 15 kg CaO/m 3 de jus. Le coefficient de filtrabilité F k et la résistance spécifique du gâteau α ont été calculés. La qualité des jus épurés ainsi obtenus a été caractérisée par des analyses physico-chimiques (pureté, coloration, turbidité, colloïdes et protéines). Les résultats obtenus ont montré que l'extraction à froid permet de réduire d'environ 50 % la quantité de chaux nécessaire pour l'étape d'épuration par rapport au jus issu du procédé thermique (jus d'échaudage). Il a été également démontré que pour la même quantité de chaux (10 kg CaO/m 3), le coefficient de filtrabilité F k du jus extrait à froid (jus CEP) est 80 % plus faible par rapport au jus thermique (jus d'échaudage). Il en résulte une cinétique de filtration plus rapide et donc une économie d'équipement et de tissu filtrant. D'autre part, la qualité du jus CEP épuré est toujours meilleure par rapport à celle du jus d'échaudage. Il s'agit d'une coloration et d'une turbidité plus faibles et d'une concentration moins élevée en substances colloïdales. La pureté est ainsi plus élevée (96.2 vs. 94.5 %). Le rendement d'épuration du jus CEP à 10 kg CaO/m 3 est supérieur à celui du jus d'échaudage à 15 kg CaO/m 3 (43 % vs. 41,5 %).

Innovative Food Science & Emerging Technologies, 2016

Food Research International, 2016

Efficiency is a key point to ensure the profitability in the production of vegetable oils fromoil... more Efficiency is a key point to ensure the profitability in the production of vegetable oils fromoilseeds. To maximize the recovery yields of seed oils, the traditional process involves mechanical expression followed by subsequent chemical extraction using organic solvents (e.g. hexane). Besides health, environmental, and economic related issues to the use of organic solvents, thermal treatment of seeds during conventional oil extraction process inevitably leads to chemical changes (e.g. changes in macronutrients such as protein denaturation/degradation in the meal, oil oxidation, and changes in minor constituents such as fatty acids, sterols, phenolic compounds and tocols). Thus, at this stage of development there is a need for new efficient processes that can improve oil yield and its quality from an economical and environmental point of view. Several research groups have investigated the potential of ultrasounds (US) and microwaves (MW) as additional seed treatments to enhance oil yields and to reduce temperature and extraction times with promising results. The present review is devoted to critically discuss the main findings reported in the literature regarding the feasibility of using US and MW as potential tools to improve oil recovery yields as well as its nutritional, sensorial and physicochemical properties.

Journal of the Science of Food and Agriculture, 2016

Investigating Opuntia species for their seed oil contents is of high importance due to its potent... more Investigating Opuntia species for their seed oil contents is of high importance due to its potential use for food and cosmetic applications. These oils have an important content in unsaturated fatty acids as well as antioxidant compounds (e.g. polyphenols, vitamin E), which have been associated with the prevention of some chronic diseases. Moreover, Opuntia stricta oils possess important antimicrobial activities. For instance, the main focus of this study was to compare the effectiveness of conventional (hexane extraction) and novel (supercritical CO2 ) extraction methods for oil and phenolic compounds recovery from O. stricta seeds. The oil yield of both extracts was then compared and the polyphenol content and composition of both extracts was determined by liquid chromatography-high resolution mass spectrometry. Additionally, the antioxidant (DPPH assay) and antimicrobial activities (disc diffusion's method) of O. stricta seed oils were determined. The oil yield (based on Soxhlet's method) of O.stricta seeds was determined using SC-CO2 (49.9 ± 2.2%), and hexane (49.0 ± 1.5%). Although obtaining similar oil extraction yields using the two methods, the extracted oil using SC-CO2 was more enriched in polyphenols (172.2 ± 11.9 µg GAE g(-1) of oil) than that extracted using hexane (76.0 ± 6.9 µg GAE g(-1) of oil). Polyphenol profiles showed that SC-CO2 process led to yield more compounds (45) than that using hexane extraction (11). Moreover, the antioxidant and antimicrobial activities of SC-CO2 extract showed high percentage of inhibitions. SC-CO2 extraction of Opuntia stricta seed oil lead to extract oil with similar yield than that with hexane extraction, but with higher polyphenol content. The extract containing polyphenols exhibited high antioxidant and antibacterial properties demonstrating their great potential as feedstock for high oil quality.

Journal of Food Engineering, 2016

Food and Bioprocess Technology, 2015

The seeds of coriander (Coriandrum sativum) are rich in vegetal oil (VO) and in essential oil (EO... more The seeds of coriander (Coriandrum sativum) are rich in vegetal oil (VO) and in essential oil (EO), which have both an interesting potential for the food, pharmaceutical and cosmetic industries. The review of the literature shows that most of the research works related to the extraction of coriander seeds are aimed at extracting either the VO or the EO. The aim of this work is to develop a process that can extract selectively the VO and EO in a consecutive way by tuning experimental conditions. A 4-step process has been set up: (i) seeds preparation by grinding and sieving, (ii) extraction by supercritical CO 2 (SC CO 2) and (iii; iv) selective separation in two separators with different pressure level. The first part of this study consisted in studying the effects of the operating conditions (T, P, CO 2 density, flow rate and particle size distribution of ground seeds) on the yield of extraction. The results showed that the global performance of the process depended mainly on the p...

The vegetable oil extraction process from seeds and nuts depends on mechanical and solvent (usual... more The vegetable oil extraction process from seeds and nuts depends on mechanical and solvent (usually n-hexane) extractions. Despite the efficiency of n-hexane, its use is nowadays questioned due to health, environmental, and technological issues. As an alternative to hexane extraction, several greener solvents and extraction techniques have been developed and tested during the last decades. Among these alternatives, the Surfactant-Aqueous Extraction Process (SAEP) appears as a promising method. Initially developed for the petroleum sector, this method was then tested and optimized for vegetable oil extraction. Successful implementations at the laboratory scale led to slightly more than 90% oil yield, mainly by using so-called “extended surfactants”. Compare to conventional surfactants, these surfactants can efficiently solubilize a large amount of vegetable oil in water, despite the structural diversity and the bulkiness of vegetable oil molecules. The present review is devoted to ex...

Separation and Purification Technology, 2017

This work investigates the purification of juices obtained with innovative pulsed electric field ... more This work investigates the purification of juices obtained with innovative pulsed electric field treatment and alkaline pressing of sugar beet tissue. Sugar beets were first sliced into cossettes and treated by pulsed electric field (PEF) at ambient temperature with a strength of E = 600 V/cm and an effective duration of t PEF = 10 ms to electroporate cell membranes. Electroporated cossettes were then subjected to a double pressing with intermediate preliming using 0.6 g CaO/100 g fresh cossettes to produce mixed prelimed juice (MPJ). Alternatively, electroporated cossettes were pressed without preliming to produce non-limed raw juice (RJ). MPJ and RJ were then purified by liming-carbonation and alternatively by stirred ultrafiltration. Preliming of electroporated cossettes improves filtration and sedimentation characteristics of juices. Moreover, the overall lime quantity required for the liming-carbonation was lower for MPJ (6 kg/m 3 ) than for RJ (10 kg/m 3 ). Purified MPJ had ...

Pulsed Electric Fields to Obtain Healthier and Sustainable Food for Tomorrow

Proceedings of the Virtual 2021 AOCS Annual Meeting & Expo

Food and Bioproducts Processing

Industrial Crops and Products

The Journal of Supercritical Fluids

Food industry is increasingly interested in replacing conventional processes of plant extraction,... more Food industry is increasingly interested in replacing conventional processes of plant extraction, as well as microbial inactivation, by alternative, greener and cheaper techniques. In many cases, chemical extraction processes are hindered by several drawbacks such as the use of chemical solvents, which is associated with many health and environmental issues. Furthermore, the use of high temperatures to improve and/or accelerate the processes, which may affect and degrade the thermolabile compounds, is usually required. Among the most promising techniques that could be competitive to the current extraction methods of molecules from plant matrices and microbial inactivation of food products, ultrasound assisted supercritical fluid extraction has taken great interest. This non-exhaustive review, covering the last 20 years, gives a critical commentary on the main published results using this emerging technology. Promising prospects opened up by new applications are described, without omitting the main limitations still to be overcome for a harmonious industrial development of these technologies.

Industrial Crops and Products

Innovative Food Science & Emerging Technologies

Journal of Cleaner Production

Food and Bioproducts Processing, 2017

Industrial Crops and Products, 2016

Innovative Food Science & Emerging Technologies, 2016

ABSTRACT Impact de la température d'extraction sur la purification du jus sucré de la bet... more ABSTRACT Impact de la température d'extraction sur la purification du jus sucré de la betterave Mots-clés: Betterave à sucre, purification, qualité, champs électriques pulsés, échaudage Le jus de la betterave à sucre est industriellement extrait par diffusion à haute température (70-75 °C). Ce procédé d'extraction thermique induit une dilution importante du jus, consomme beaucoup d'énergie et favorise la co-extraction de certaines molécules indésirables (pectines, protéines, colorants…). Ces molécules diminuent la pureté du jus et risquent de compliquer l'étape de purification calco-carbonique en aval. Par analogie avec le procédé d'extraction utilisé pour la canne à sucre, le pressage de la betterave a été proposé comme une technique d'extraction alternative très économe. Pour améliorer les rendements d'extraction par pressage, différentes approches ont été proposées. Certains auteurs ont proposé de réaliser un préchauffage des cossettes à haute température (80-85 °C) pendant une courte durée (5-10 min) [1]. Ce prétraitement thermique (échaudage) présente pour certains aspects les mêmes inconvénients que le procédé traditionnel (consommation énergétique et solubilisation des macromolécules). Récemment, d'autres études ont soulignés l'intérêt de l'application d'un prétraitement par champs électriques pulsés modéré (0.4-0.8 kV.cm -1) pour l'extraction du jus sucré par pressage à froid. Ce prétraitement, de faible consommation énergétique, induit la perméabilisation des membranes cellulaires à froid et permet ainsi d'extraire un jus plus pur et moins coloré [2]. La présente étude porte sur la comparaison de l'impact de ces deux prétraitements (échaudage et CEP à froid) sur l'étape de purification du jus. Le jus d'échaudage est obtenu par pressage des cosettes préalablement chauffées à 80 °C pendant 10 min. Le jus CEP a été obtenu par pressage de cossettes prétraitées à froid (20 °C) par champs électriques pulsés (0.6 kV.cm -1 pendant 10 ms). Les analyses physico-chimiques des jus bruts ont montré que la qualité du jus extrait à froid est meilleure que celle du jus obtenu par traitement thermique. Les jus obtenus ont été ensuite purifiés par épuration calco-carbonique en variant la quantité de chaux utilisée de 0 à 15 kg CaO/m 3 de jus. Le coefficient de filtrabilité F k et la résistance spécifique du gâteau α ont été calculés. La qualité des jus épurés ainsi obtenus a été caractérisée par des analyses physico-chimiques (pureté, coloration, turbidité, colloïdes et protéines). Les résultats obtenus ont montré que l'extraction à froid permet de réduire d'environ 50 % la quantité de chaux nécessaire pour l'étape d'épuration par rapport au jus issu du procédé thermique (jus d'échaudage). Il a été également démontré que pour la même quantité de chaux (10 kg CaO/m 3), le coefficient de filtrabilité F k du jus extrait à froid (jus CEP) est 80 % plus faible par rapport au jus thermique (jus d'échaudage). Il en résulte une cinétique de filtration plus rapide et donc une économie d'équipement et de tissu filtrant. D'autre part, la qualité du jus CEP épuré est toujours meilleure par rapport à celle du jus d'échaudage. Il s'agit d'une coloration et d'une turbidité plus faibles et d'une concentration moins élevée en substances colloïdales. La pureté est ainsi plus élevée (96.2 vs. 94.5 %). Le rendement d'épuration du jus CEP à 10 kg CaO/m 3 est supérieur à celui du jus d'échaudage à 15 kg CaO/m 3 (43 % vs. 41,5 %).

Innovative Food Science & Emerging Technologies, 2016

Food Research International, 2016

Efficiency is a key point to ensure the profitability in the production of vegetable oils fromoil... more Efficiency is a key point to ensure the profitability in the production of vegetable oils fromoilseeds. To maximize the recovery yields of seed oils, the traditional process involves mechanical expression followed by subsequent chemical extraction using organic solvents (e.g. hexane). Besides health, environmental, and economic related issues to the use of organic solvents, thermal treatment of seeds during conventional oil extraction process inevitably leads to chemical changes (e.g. changes in macronutrients such as protein denaturation/degradation in the meal, oil oxidation, and changes in minor constituents such as fatty acids, sterols, phenolic compounds and tocols). Thus, at this stage of development there is a need for new efficient processes that can improve oil yield and its quality from an economical and environmental point of view. Several research groups have investigated the potential of ultrasounds (US) and microwaves (MW) as additional seed treatments to enhance oil yields and to reduce temperature and extraction times with promising results. The present review is devoted to critically discuss the main findings reported in the literature regarding the feasibility of using US and MW as potential tools to improve oil recovery yields as well as its nutritional, sensorial and physicochemical properties.

Journal of the Science of Food and Agriculture, 2016

Investigating Opuntia species for their seed oil contents is of high importance due to its potent... more Investigating Opuntia species for their seed oil contents is of high importance due to its potential use for food and cosmetic applications. These oils have an important content in unsaturated fatty acids as well as antioxidant compounds (e.g. polyphenols, vitamin E), which have been associated with the prevention of some chronic diseases. Moreover, Opuntia stricta oils possess important antimicrobial activities. For instance, the main focus of this study was to compare the effectiveness of conventional (hexane extraction) and novel (supercritical CO2 ) extraction methods for oil and phenolic compounds recovery from O. stricta seeds. The oil yield of both extracts was then compared and the polyphenol content and composition of both extracts was determined by liquid chromatography-high resolution mass spectrometry. Additionally, the antioxidant (DPPH assay) and antimicrobial activities (disc diffusion's method) of O. stricta seed oils were determined. The oil yield (based on Soxhlet's method) of O.stricta seeds was determined using SC-CO2 (49.9 ± 2.2%), and hexane (49.0 ± 1.5%). Although obtaining similar oil extraction yields using the two methods, the extracted oil using SC-CO2 was more enriched in polyphenols (172.2 ± 11.9 µg GAE g(-1) of oil) than that extracted using hexane (76.0 ± 6.9 µg GAE g(-1) of oil). Polyphenol profiles showed that SC-CO2 process led to yield more compounds (45) than that using hexane extraction (11). Moreover, the antioxidant and antimicrobial activities of SC-CO2 extract showed high percentage of inhibitions. SC-CO2 extraction of Opuntia stricta seed oil lead to extract oil with similar yield than that with hexane extraction, but with higher polyphenol content. The extract containing polyphenols exhibited high antioxidant and antibacterial properties demonstrating their great potential as feedstock for high oil quality.

Journal of Food Engineering, 2016

Food and Bioprocess Technology, 2015