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•Insect cuticles showed a lower mineral content (1.9%) compared to shrimp shells (21.73%).•High purity insect chitin (89.7%) was obtained in only 1 step of extraction compared to the ...2-steps shrimp chitin (<65%).•Untreated chitins extracted from Bombyx eri larva, exhibit a better enzymatic digestibility in comparison to the commercially available chitin from shrimp shells.•After C2mimOAc-pretreatment, a very competitive yields of GlcNAc can be achieved by chitinase-catalyzed hydrolysis (899.2 mg/g of chitin).•Fermentescibility of chitin hydrolysates with a natural wild-type yeast strain was demonstrated.•Better enzymatic digestibility was observed with untreated insect chitin compared to commercially shrimp chitin
Chitins of different purity grades (45%, 89.7% and 93.3%) were efficiently extracted from Bombyx eri larva and fully physico-chemically characterized. Compared to commercially available and extracted α-chitin from shrimp shell, the collected data showed that insect chitins had similar characteristics in terms of crystallographic structures (α-chitin), thermal stability and degree of acetylation (>87%). The major differences lay in the crystallinity indexes (66% vs 75% for shrimp chitin) and in the morphological structures. Furthermore, low ash contents were determined for the insect chitins (1.90% vs 21.73% for shrimp chitin), making this chitin extraction and purification easier, which is highly valuable for an industrial application. Indeed, after only one step (deproteinization), the obtained chitin from Bombyx eri showed higher purity grade than the one extracted from shrimp shells under the same conditions. Insect chitins were then subjected to room temperature ionic liquid (RTIL) pretreatment prior to enzymatic degradation and presented a higher enzymatic digestibility compared to commercial one whatever their purity grade and would be thus a more relevant source for the selective production of N-acetyl-D-glucosamine (899.2 mg/g of chitin-2 stepsvs 760 mg/g of chitin com). Moreover, for the first time, the fermentescibility of chitin hydrolysates was demonstrated with Scheffersomyces stipitis used as ethanologenic microorganism.
The impact of cryogenic pretreatments on drying performance was studied in blueberries, seabuckthorn fruits and green grapes. The fruits were immersed in liquid nitrogen in 2 min freezing/thawing ...cycles (one to five). Untreated samples were used as the control. Drying experiments were carried out on treated and non-treated berries at 50 °C and 1 m/s (hot-air-drying), 50 °C and 25″ Hg vacuum (vacuum-drying), 30 mTorr total pressure and 25 °C shelf temperature (freeze-drying). The weight loss evolution of the foodstuffs was measured as a function of time. Microscopic (SEM and optical) determinations of the epicarp were performed. A visual inspection was performed and color changes and volume reductions were assessed before and after dehydration. The thickness of the berries' epicarp decreased between 20 and 50% (depending on the fruit) after 3-5 immersions in liquid N2. The drying kinetics was accelerated significantly for the three tested drying processes (i.e., drying time decreased from 48 to 16 h for blueberry freeze-drying). The best quality of dried berries was observed for pretreated blueberries after freeze-drying, keeping their volume, shape and color after the process. This work shows that "tailor-made" dried berry products with desired properties can be achieved and drying performance can be improved by the application of ultra-low temperature pretreatments.
During electrodialysis (ED) treatment of solutions with different Mg/Ca ratios (
R
=
0, 1/20, 1/10, 1/5 and 2/5) and in different pH conditions (acid, neutral and basic), foulings on ion-exchange ...membranes were previously characterized and identified, by the way of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. A mineral fouling was observed in neutral and basic conditions (for
R
=
1/5 and 2/5) on the anion-exchange membrane (AEM) concentrate side and in basic conditions on the cation-exchange membrane (CEM) concentrate side as well as on the diluate side for
R
=
1/5 and 2/5. The objectives of this present work were to link the morphological characterization and identification of membrane fouling to electrodialytic parameters and cation migration kinetics. It appeared that the CEM permselectivity was severely affected in basic conditions for
R
≥
1/5. The consequence of this alteration was the migration of OH
− through the CEM, a pH increase in the diluate compartment and different treatment durations. The calcite observed on AEM concentrate side for Mg/Ca
≥
1/5 would be due first to the particular operating conditions such as the recirculation of the concentrate solution, and also to the supersaturated conditions reached or not at the AEM interface and favourable pH conditions.
Osmotic dehydration of whole seabuckthorn berries, followed by convective or vacuum drying, was investigated. First, different pretreatments were applied to the fruits in order to accelerate the rate ...of osmotic dehydration: immersion in liquid nitrogen, steam blanching, or freeze cycles. Immersion in liquid nitrogen was found to be the best pretreatment to maximize dehydration rate and to increase sugar gain during osmotic dehydration. An evaluation of moisture loss and sugar gain kinetics during osmotic dehydration of seabuckthorn fruits pretreated with liquid nitrogen, followed by vacuum or hot-air drying, was then performed. Loss of nutritional compounds due to processing was also measured. Sugar intake and partial dehydration of seabuckthorn samples increased with osmosis time and reached an equilibrium value after 4 h treatment. The finish drying methods (vacuum or convective) applied after OD showed a marked impact on the remaining moisture content of seabuckthorn samples. Concentration of some nutritional compounds was, however, dramatically reduced after the combined osmotic dehydration/drying processes.
An effective and rapid HPLC-MS method for the simultaneous separation of the eight most abundant tea catechins, gallic acid, and caffeine was developed. These compounds were rapidly separated within ...9 min by a linear gradient elution using a Zorbax SB-C18 packed with sub 2 μm particles. This methodology did not require preparative and semipreparative HPLC steps. In fact, diluted tea samples can be easily analyzed using HPLC-MS as described in this study. The use of mass spectrometry detection for quantification of catechins ensured a higher specificity of the method. The percent relative standard deviation was generally lower than 4 and 7% for most of the compounds tested in tea drinks and tea extracts, respectively. Furthermore, the method provided excellent resolution for folate determination alone or in combination with catechins. To date, no HPLC method able to discriminate catechins and folates in a quick analysis has been reported in the literature.
Determination of proteins and peptides is among the main challenges of today's bioanalytical chemistry. The application of microchip technology in this field is an exhaustively developed concept that ...aims to create integrated and fully automated analytical devices able to quantify or detect one or several proteins from a complex matrix. Selective extraction and preconcentration of targeted proteins and peptides especially from biological fluids is of the highest importance for a successful realization of these microsystems. Incorporation of solid structures or supports is a convenient solution employed to face these demands. This review presents a critical view on the latest achievements in sample processing techniques for protein determination using solid supports in microfluidics. The study covers the period from 2006 to 2015 and focuses mainly on the strategies based on microbeads, monolithic materials and membranes. Less common approaches are also briefly discussed. The reviewed literature suggests future trends which are discussed in the concluding remarks.
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•Miniaturization offers unique opportunities for extraction and preconcentration.•Solid supports include microbeads, monoliths and membranes.•High performances are achieved via the synergy of microfluidics and solid supports.•Integrated microsystems enable analysis of complex samples.
A microdevice combining online preconcentration and separation of phosphopeptides was developed in a glass microchip. An ethylene glycol methacrylate phosphate (EGMP), acrylamide (AM) and ...bisacrylamide (BAA) based monolith was synthesized within microchannels through a photo-driven process. Morphological investigations revealed a homogeneous monolithic structure composed of uniform nodules (∼0.8 μm), with a large pore volume (0.62 cm
g
) and sufficiently high specific surface area (34.1 m
g
). These features make the monolith particularly interesting for preconcentration purposes. Immobilization of Zr
ions on the phosphate groups present at the poly(EGMP-co-AM-co-BAA) monolith surface leads to immobilized metal affinity chromatography support. This monolith-Zr
showed a great capacity to capture phosphopeptides. Successful preconcentration and separation of a mixture of ERK2 derived peptides differing only by their phosphorylation degree and sites could be achieved with signal enhancement factors between 340 and 910 after only 7 min of preconcentration. This integrated microdevice represents a novel approach for phosphoproteomic applications.
Liquid biopsy, in particular circulating tumor DNA (ctDNA) analysis, has paved the way for a new noninvasive approach to cancer diagnosis, treatment selection and follow-up. As a crucial step in the ...analysis, the extraction of the genetic material from a complex matrix needs to meet specific requirements such as high specificity and low loss of target. Here, we developed a new generation of microfluidic fluidized beds (FBs) that enable the efficient extraction and preconcentration of specific ctDNA sequences from human serum with flow rates up to 15 µL/min. We first demonstrated that implementation of a vibration system inducing flow rate fluctuations combined with a mixture of different bead sizes significantly enhanced bead homogeneity, thereby increasing capture efficiency. Taking advantage of this new generation of high-throughput magnetic FBs, we then developed a new method to selectively capture a double-stranded (dsDNA) BRAF mutated DNA sequence in complex matrices such as patient serum. Finally, as proof of concept, ligation chain reaction (LCR) assays were performed to specifically amplify a mutated BRAF sequence, allowing the detection of concentrations as low as 6 × 104 copies/µL of the mutated DNA sequence in serum.
We report here a one-pot approach to achieve, for the first time, the simultaneous synthesis/anchorage of polymer monoliths in native PDMS channels. Monoliths consisting of ethylene glycol ...methacrylate phosphate (EGMP) and N,N′-methylene-bis-acrylamide (BAA) were synthesized within PDMS microchips through a photo-driven process. The EGMP monomer has never been employed for this purpose. To achieve this method, both the chemical nature of the photoinitiator and irradiation conditions were investigated. The main result was that the use of 2-methyl-4′-(methylthio)-2-morpholino-propiophenone, as photoinitiator, allowed simultaneous polymerization and anchorage of the resulting monolithic structure onto the PDMS channel. Morphology of the monolith revealed a compact structure composed of uniform nodules (135 ± 30 nm) and small pores (10–200 nm). The high specific surface area (66 m2/g) and the sufficient permeability (14.35 × 10−14 m2) obtained make the monolith particularly interesting for preconcentration. Such free radical-mediated method open new perspectives for preconcentration and electrophoretic separation in PDMS microsystems.
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•Efficient one-pot/one-step method for simultaneous synthesis and wall-anchoring of polymer monoliths in/to PDMS microchannel.•Polymer monoliths can be prepared in PDMS microchips without pre-treatment of the PDMS channel surface.•Dual role of 2-methyl-4′-(methylthio)-2-morpholino-propiophenone as H2 abstractor and free radical polymerization initiator.•Monolith morphology combined specific surface area and permeability optimized for separation and concentration purposes.
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