Water-soluble polysaccharides from Opuntia stricta Haw. fruit peels: Recovery, identification and evaluation of their antioxidant activities

Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical composition revealed the presence of rhamnose, arabinose, glucose, mannose, galactose and galacturonic acid. The infra-red spectroscopic analysis showed a similar structure to that of Opuntia ficus-indica polysaccharide peels. Additionally, the extracted polysaccharides exhibited high antioxidant activities. In fact, the free radical scavenging activity (half inhibition concentration = 6.5 mg ml-1 with 94.9% inhibition at 50 mg ml-1), the total antioxidant activity (100 μg ascorbic acid equivalent at 50 mg polysaccharides) and the reducing power capacity (absorbance 700 nm = 0.7 at 50 mg ml-1), appeared to be interesting compared to natural and synthetic antioxidants. Therefore, water-soluble polysaccharides from Opuntia stricta Haw. fruit peels could be a natural alternative to replace synthetic antioxidants

Residence time distribution and flow pattern modeling of oilseeds in a pilot screw press

Mechanical expression is widely applied for oil recovery from oilseeds using continuous screw presses. Despite significant recent advances in the field of press design and automation, it remains difficult to predict the press performances based on the theoretical approaches, and more experimental investigations are needed to clarify and characterize the seeds flow and expression behavior in the press. Residence Time Distribution (RTD) is a frequently used tool in chemical engineering to characterize the material flow by simple tracer tests. In this paper, we explore the feasibility of using RTD for the screw presses, in order to check the flow patterns homogeneity and identify the possible deviations depending on the press geometry and the operating conditions. Both theoretical modeling and experimental investigation are conducted for two different screw press designs (Reinartz and Olexa), and at the different rotation speeds. An original and reliable experimental methodology was developed by using erucic acid as tracer in the form of pulse injection and gas chromatography as detection method. Experimental results coupled with statistical calculations showed the influence of the screw geometry and the rotation speed on the seeds flow inside the press. The matter displacement was much faster and the experimental residence time was very close to the theoretical one indicating more homogeneity and less dispersion in the Olexa arrangement in comparison to the Reinartz arrangement. The higher variance observed at lower rotation speed (2.4 rpm) suggested the presence of flow defects like mixing and axial dispersion in the press. To complete the experimental work, axial dispersion model was applied, and allowed obtaining the valuable information, such as axial dispersion degree and distribution functions. Obtained results can be very useful to predict the performance of existing screw presses and design more efficient industrial equipments

Isolation and Purification of Mustard Glucosinolates by Macroporous Anion-Exchange Resin: Process Optimization and Kinetics’ Modelling

Glucosinolates (GSL) (β-thioglucoside-N-hydroxy sulfates) are rich-sulfur secondary metabolites raising potential biofumigation interest due to their biological properties. Sinigrin and gluconapin are the main glucosinolates present in brown mustard seeds (Brassica juncea). These glucosinolates are very suitable for the development of phytosanitary products due to their fungicidal, bactericidal and insecticidal effects. In this work, the purification of sinigrin and gluconapin extracted from defatted mustard seeds was studied using macroporous anion exchange resins. A strongly and a weakly anionic resin were first tested according to the nature of their functional group and through their selectivity towards glucosinolates. Anion-exchange resin purification was first studied in static (batch) mode in order to determine the optimal operating conditions; it was then tested in a dynamic (continuous) mode (column) to validate the process. In static mode, the adsorption behavior and characteristics of both resins were compared. The results showed that the strongly basic resin PA312LOH ensures better adsorption of glucosinolates and that the experimental data fit well with the Freundlich isotherm. Moreover, analysis showed that PA312LOH resin was selective for glucosinolates purification towards the proteins. The desorption of glucosinolates was then investigated. Firstly, the operating conditions were optimized by studying the effects of salt concentration and the eluate-resin ratio. This preliminary optimization allowed recovering 72.9% of intact sinigrin and the juice purity was increased from 43.05% to 79.63%. Secondly, dynamic (continuous mode) experiments allowed the recovery of 64.5% of sinigrin and 28% of gluconapin by varying the eluent ionic strength and the flow rate. Resin was finally successfully regenerated using NaOH

Novel One-Step Process for the Production of Bioplastic from Rapeseed Press Cake

Crude rapeseed cake was employed as the starting material for the preparation of protein-based bioplastic films through a wet process. A simple exposure of the agricultural waste to formic acid realized at 40 °C for 15 min could afford a slurry ready for producing robust bioplastic films by casting without another plasticizer addition. After determining the optimal process conditions, all films and membranes were successively characterized by DSC and FT-IR spectroscopy. They were also tested for their water absorption capacity, tensile strength, and elongation at break performance. The respective surface morphology and elementary composition of the products were determined by FE-SEM/EDX. Some attempts to improve their intrinsic properties were performed by loading graphene oxide inside the biopolymer three-dimensional matrix

A one-pot process for the extraction of fats and essential oil from coriander seeds by supercritical CO2

International audienceThe 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 pressure level, on the CO 2 flow rate and on the size of ground seeds. An optimization of the parameters gave an extraction efficiency of 90 %. The second part of this study dealt with the effects of operating conditions on the quality of extracts, and more precisely on their composition in VO and EO. It was observed that the supercritical extraction had no major effect on the fatty acid composition of the VO compared to classical extraction procedures, while EO is enriched in components such as linalol and that a previous drying of the seeds is deleterious. Finally, we proposed a protocol in order to extract separately VO and EO by tuning CO 2 density and separation conditions

Extended surfactants and their tailored applications for vegetable oils extraction: An overview

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 extended surfactant applications to SAEP. This review summarizes and discusses the main findings related to the extended surfactant structures and properties, as well as the main experimental results on the SAEP, and the advantages and the current limitations towards a scaling-up of this promising process

Gas assisted mechanical expression (GAME) as a promising technology for oil and phenolic compound recovery from tiger nuts

International audienceThe aim of this work was to investigate the potential of gas assisted mechanical expression (GAME) process as an innovative technology for oil extraction and polyphenol recovery from tiger nuts. GAME process was first studied by varying the supercritical carbon dioxide (SC-CO2) and the mechanical expression (ME) pressures (10–30 MPa), then was compared to separate processes applied alone, using either SC-CO2 or ME. The results showed that the better conditions for GAME were found using 20 MPa for SC-CO2 and 30 MPa for ME. Under these conditions, 50% of oil was released from tiger nuts after 10 min extraction, compared to only 10% and 20% when using SC-CO2 and ME separately at 20 and 30 MPa pressures, respectively. In addition to the faster extraction of oil using GAME process, the obtained results showed that this oil contains higher amount of polyphenols than that obtained using either SC-CO2 or ME. These molecules were extracted and identified using ultra performance liquid chromatography–high resolution mass spectrometry (UPLC–HRMS). Polyphenol profiles showed that GAME process led to the maximum polyphenol's recovery with 57 compounds, followed by SC-CO2 with 48 compounds, and ME process with only 27 compounds, concurring with the trends observed for total phenolic compounds. Although non-significant differences were observed in oil recovery after applying GAME or SC-CO2 alone, scanning electron microscopy (SEM) images revealed that GAME had a higher impact on cell structure, which can facilitate the release of important valuable compounds. All of these results pave the way towards the industrialization of GAME process as an innovative and alternative technology for enhanced oil extraction, thus replacing the conventional processes

Impact of pulsed electric field treatment on the viability of Tenebrio molitor insect biomass, and on the following pressing and drying processes

International audienc