Effect of air-drying conditions on physical and nutritional properties of osmotically pre-treated pomegranate seeds

Poster (2012, June 01)

Design of sugar-based surface active agents for emulsion polymerization in supercritical carbon dioxide

Conference (2012, May 10)

The use of aqueous dispersed media, such as emulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of ... [more ▼]

The use of aqueous dispersed media, such as emulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of products recovery and increased reaction rate. Emulsions are usually implemented from a water/organic solvent mixture in the presence of a surfactant. However, supercritical carbon dioxide (scCO2) (Pc =74 bars; Tc = 31°C) constitutes an interesting alternative to the traditional organic solvents in these heterogeneous systems because it is inexpensive, non-toxic, non-inflammable and environmentally friendlier. In this context, we developed a novel class of surfactants for the stabilization of H2O/scCO2 emulsions, i.e. fluorinated modified carbohydrates. The hydrophilic head of the surfactant consists in a sugar moiety whereas a fluorinated tail is specifically located in the scCO2 phase. The strategies for the synthesis of these carbohydrates esters rely on selective lipase-catalyzed modifications of sugars and on the versatile thiol-Michael addition reaction. The ability of these molecules to decrease the H2O/scCO2 interfacial tension and to stabilize such emulsions will be presented. Finally, high internal phase scCO2-in-water emulsion (HIPE) were prepared with these new surfactants and used as template for the acrylamide polymerization. The monomer is polymerized in the continuous aqueous phase before removing the CO2 droplets (at least 70 % of the total volume). The resulting permeable porous polymers, called polyHIPEs, exhibit highly interconnected voids (cfr SEM picture) and should be valuable in many applications including support for catalyst, filtration process, immobilization of proteins, etc. [less ▲]

Use of ionic liquids for biocatalytic synthesis of sugar derivatives

in Journal of Chemical Technology & Biotechnology (2012), 87(4), 451-471

Sugar-based compounds are widely used in pharmaceuticals, cosmetics, detergents and food. They are mainly produced by chemical methods, but the use of enzymes as ‘a greener alternative’ to organic ... [more ▼]

Sugar-based compounds are widely used in pharmaceuticals, cosmetics, detergents and food. They are mainly produced by chemical methods, but the use of enzymes as ‘a greener alternative’ to organic synthesis has been investigated for more than 20 years. Due to the low polar substrate solubility in organic solvents compatible with enzymes, research has focused on the application of substitutes for biocatalysis, especially ionic liquids (ILs). After introducing the main properties of ILs and especially their ability to solubilize sugars, this review focuses on one of their applications, the biocatalytic synthesis of carbohydrate derivatives. In this context, they can be used in pure IL systems, in IL/IL systems or in IL/organic solvent systems. Finally, this review provides an update on the environmental fate of ILs. Their exploitation in ‘green’ processes is still limited due to their low degradability but research is currently under way to design new more ‘eco-friendly’ ILs. [less ▲]

Steam explosion, application en tant que prétraitement de la matière ligno-cellulosique en vue de l’obtention de sucres fermentescibles, valorisables dans les unités de production de biocarburants de deuxième génération ou de molécules à haute valeur ajoutée.

Scientific conference (2012, March 23)

INFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER INFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER INFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER

Poster (2012, March 01)

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct ... [more ▼]

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct stages: vapocracking and explosive decompression. The treatment intensities is determined by a severity factor, established by a correlation between temperature process and retention time. The results show that steam explosion treatment has an impact on the crystallinity properties of pure cellulose fiber. When the severity factor is below 5.2, an increase of the overall crystallinity of the samples is observed with the treatment intensities. For higher intensities, a significant thermal degradation of cellulose lead to an important change in substrate composition, which lead to a further decrease of cellulose crystallinity [less ▲]

Carbohydrate-based surfactants: structure-activity relationships

in Nawaz, Zeeshan; Naveed, Shahid (Eds.) Advances in Chemical Engineering (2012)

The aim of the present contribution is: (1) to review CBS in terms of structural classification based on their molecular size (mono-, oligo-, polymeric surfactants), geometry (standard, bipolar or ... [more ▼]

The aim of the present contribution is: (1) to review CBS in terms of structural classification based on their molecular size (mono-, oligo-, polymeric surfactants), geometry (standard, bipolar or bolaform, and gemini surfactants), and the nature of the polar headgroup (charged or not, cyclic or not), the apolar tail (number and length of alkyl chain), and the linker (amide, ester, ...) and/or the spacer; (2) to present systematically results on structure- activity relationships of uronic acid derivatives (UADs), a particular class of carbohydrate-based surfactants. These concern the impact of each structural entity including the polar headgroup (stereochemistry), apolar tail (chain length, number, and unsaturation), and linkage/spacer, on the performance of UADs to change surface properties, and possibly, to form and stabilize colloidal systems. [less ▲]

La chimie des saccharides

Learning material (2012)

Synthèse de chimie des sucres

Characterization of by-products from cooked fruit processing and potential use in food products

in Journal of Food Composition and Analysis (2012), 27

The process that produces Lie`ge syrup (apple butter-like) results in high amounts of residues from cooked apples, pears and sun-dried dates. These unusual fruit by-products were studied for their ... [more ▼]

The process that produces Lie`ge syrup (apple butter-like) results in high amounts of residues from cooked apples, pears and sun-dried dates. These unusual fruit by-products were studied for their composition in total proteins and fats, dietary fiber (DF) and their content in total and free monosaccharides. All three by-products contained around 20% of total non-cellulosic monosaccharides and around 10% of free monosaccharides. According to two different methods, DF accounted for 70% of the dry weight (DW) with an insignificant soluble fraction; pectin represented 2–3% of DW. Apple and pear residues were composed mainly of cellulose, whereas lignin was the main fraction for dried date. The polyphenolic content and the antioxidant activity of the three products were also assessed and the values showed that their antioxidant characteristics were comparable to that of various raw fruits. No phenolic acids were detected, indicating that the cooking process resulted in their extraction. The lyophilized and ground residues exhibited high water holding capacities (between 5.2 g water per g DW for pear and 8.6 for apple) and average oil holding capacities (around 2.5 g oil per g DW), whereas their color was light brownish as shown by the L*, a*, b* coordinates determined. These data open the possibility to contemplate new specific and niche applications for such by-products. Besides, it provides information about the effects of a cooking process on apple and pear pomaces, as well as on an unusual residue from a dried fruit (date). [less ▲]

Conversion of carbohydrates under microwave heating

in Chang, C.F. (Ed.) Carbohydrates - Comprehensive Studies on Glycobiology and Glycotechnology (2012)

The non-energetic valorisation of renewable resources using efficient and eco-friendly methodologies is the central axis of the "green chemistry" concept. In particular, the chemical and chemo-enzymatical ... [more ▼]

The non-energetic valorisation of renewable resources using efficient and eco-friendly methodologies is the central axis of the "green chemistry" concept. In particular, the chemical and chemo-enzymatical transformations of carbohydrates arising from the hydrolysis of non-edible vegetal feedstock (i.e., lignocellulosic biomass) are a widely explored thematic for the production of new high-added value materials, synthons, and platform chemicals. Since the seminal works of Gedye and Giguere in 1986, the use of microwaves as a non-conventional heating source has gained large attention in organic chemistry. Due to commonly observed acceleration in reactions rates and improved selectvities and yields, microwave heating has progressively emerged as a green chemistry technology. Minimizing both energy consumption (via the reduction of temperature and reaction times) and wastes (by improvement of selectivity), microwaves has enjoyed significant adoption by the research community. This chapter describes the use of microwave processes to mediate key reactions in the field of carbohydrates chemistry. Some examples of typical carbohydrates reactions (glycosylations, hydroxyl groups’ protection, etc.) under microwave conditions are displayed and highlight the benefits of this microwave approach in terms of yields, atom efficiency, environmental factor, and carbon efficiency. [less ▲]

Kinetics of the hydrolysis of polysaccharide galacturonic acid and neutral sugars chains from flaxseed mucilage

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(2), 139-147