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See detailEffect of steam explosion pre-treatment on enzymatic saccharification of lignocellulosic material
Meyer, Laurence ULg; Jacquet, Nicolas ULg; Vanderghem, Caroline ULg et al

Poster (2011, September 08)

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to ... [more ▼]

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to produce biofuels. The “first generation” biofuels are highly controversial because of the use of food plant material. The aim of the “second generation” biofuels is to take lignocellulosic non-food plant material as raw material. Lignocellulosic biomass has a very complex structure made of linkages between lignins, cellulose and hemicelluloses. The saccharification of these lignocellulosic materials requires the fractionation of its constituents. Research has lead to many lignocellulosic biomass fractionation pre-treatments. This study particularly focuses on the steam explosion pretreatment followed by an enzymatic saccharification. Steam explosion is a thermomechanical process which allows the breakdown of the lignocellulosic material structure by the combined action of steam heating, hydrolysis induced by the organic acids formed during the process and shear stress resulting from the pressure rough drop. This treatment leads to modification of the physical parameters such as water retention capacity, cristallinity rate of the cellulosic fraction, hydrolysis of the hemicellulosic fraction and rearrangement in the lignin structure. Such modifications are supposed to make cellulose enzymatic hydrolysis from complex lignocellulosic material easier. In order to verify this hypothesis, different lignocellulosic raw materials have been pre-treated by steam explosion. These materials were sugar beet pulp, corn straw and miscanthus. In order to check the effect of steam explosion pre-treatment on cellulose, a microcrystalline cellulose was also treated. Steam explosion was performed at a vapor pressure of 18 bars and with a retention time of 2 minutes. The steam exploded lignocellulosic materials and the untreated one were submitted to a hydrolysis with a mixture of enzymes composed of cellulases and cellobiase activities during 24 hours. The quantification of glucose in the hydrolysates at different times was performed by HPAEC-PAD. Rate of cellulose converted into glucose were better with steam exploded raw material showing that steam explosion allows improvement of lignocellulosic material for enzymatic saccharification. [less ▲]

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See detailEnzymatic Interesterificationof Palm oil and Fractions: A Calorimetric Study
Danthine, Sabine ULg; De Clercq, Nathalie; Lefebure, Emilie ULg et al

Poster (2011, September)

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See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

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See detailEFFECT OF DATE FLESH FIBER CONCENTRATE ADDITION ON DOUGH PERFORMANCE AND BREAD QUALITY
Borchani,, Chema; Masmoudi, Manel; Besbes, Souhail et al

in JOURNAL OF TEXTURE STUDIES (2011), 42(4), 300-308

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality ... [more ▼]

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality, resistance to deformation increased with the amount of added fiber, whereas degree of softening and extensibility decreased in all levels of fiber. Bread evaluation revealed that DFFC addition caused an increase of bread yield especially for the highest levels, a change of crumb color and an insignificant decrease of bread volume. Breads are subjected to sensory evaluation for odor, taste, crumb color, crumb smoothness and overall acceptability. Significant differences were not found (P > 0.05) between scores for all sensory parameters. [less ▲]

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See detailMonolayer Properties of Uronic Acid Bicatenary Derivatives at the Air-Water Interface: Effect of Hydroxyl Group Stereochemistry Evidenced by Experimental and Computational Approaches
Razafindralambo, Hary ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13(33), 1529115298

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water ... [more ▼]

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirfilmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both films are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA). [less ▲]

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See detailEnzymatic synthesis and surface active properties of novel hemifluorinated mannose esters
Favrelle, Audrey ULg; Boyère, Cédric ULg; Laurent, Pascal ULg et al

in Carbohydrate Research (2011), 346(9), 1161-1164

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length ... [more ▼]

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length have been prepared accordingly in moderate yield. A preliminary evaluation of the surface active properties of these hemifluorinated mannose esters revealed their ability to reduce the surface tension of water much more efficiently than their aliphatic counterparts. [less ▲]

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See detailAn Overview Of Methodology For Predicting Activities And Functionalities Of A Wide Range Of Carbohydrate- Based Surfactants From Their Fundamental Properties
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Paquot, Michel ULg

in 8th World surfactant congress and business convention (2011, June 06)

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main ... [more ▼]

Introduction and Background: Carbohydrate-based surfactants (CBS) are, today, among the most attractive amphiphilic compounds owing to their high potentiality for a large product concept. The main fundamental reasons are the abundance of their precursors from renewable resources, the excellent environmental compatibility, and the quasi-unlimited availability of their molecular structure and geometry. Based on the latter aspect, CBS would be expected to generate a wide range of functionalities and activities for food and non-food applications. All kinds of amphiphilic compounds including small surfactants, bolaforms, geminis, oligomeric, and polymeric molecules with a single or a multiple hydrophobic tails can be designed by synthetic routes thanks to a large number of reactive chemical groups in their basic structure. Consequently, various methodologies are required, and could be used in complementary for identifying all of their potentiality for further development. Methodology: The methodology is based on the characterization in the laboratory scale, i.e. using only small amounts of sample, of CBS properties at fluid and solid interfaces, in bulk liquid phases, and at the solid state with simplified models. Results and Discussion: In this communication, an overview of functionality and activity-predicting methods for a wide range of CBS structures varying in head polar groups, hydrophobic tail and number, and linkers will be presented and discussed. Performances and complementarities of different approaches, methodologies, and techniques will be emphasized. These include sample preparation and analysis procedures, interfacial-characterizing instruments, mainly tensiometers and Langmuir balances used both in dynamic and (quasi)-static modes, particle size and electrical charge analyser, and (micro)calorimeters using differential scanning, isothermal titration, and thermogravimetry methods. Conclusion: The knowledge of these basic properties is helpful for predicting their main activities and functionalities like their aptitude for forming and stabilizing colloidal systems, and for developing biological activities. This is also necessary for the rational design of CBS amphiphilic structure regarding to specific properties. The same approach can also be applied for other required features as the compound stability, toxicity, and biodegradability. [less ▲]

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See detailStructure-Surface Activity Relationships Of Uronic Acid-Derivative Surfactants From Renewable Resources Applications
Razafindralambo, Hary ULg; Richel, Aurore ULg; Richard, Gaetan ULg et al

Poster (2011, June)

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate ... [more ▼]

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate-based surfactants can be easily prepared from renewable raw materials in a wide range of structure by modular synthesis thanks to the presence of one carboxylic and numerous hydroxyl groups. The polar head group configurations according to the stereochemistry of OH groups, and geometry (cyclic or not), the hydrophobic tail (number and length of alkyl chain), and the type of linker (ester, acetal and amide, etc) are among the main variables in their structural entities. Therefore, the investigation of their structure-surface activity relationships appears valuable for increasing backgrounds, and achieving a rational design for selecting the best structures to be used in different industrial fields [2]. Methodology: A few analogous of glucuronic acid-derivative surfactants have been synthesized by chemical or enzymatic routes. After purification, their structure has been confirmed by various spectroscopic techniques (RMN, MS, IR). Surface tensions of true aqueous solution have been then measured in dynamic and static modes using a series of complementary techniques. Critical micelle concentrations, minimum molecular areas, and maximum surface excesses have also been determined. Results and Discussion: Glucuronic acid derivative surfactants under investigation vary in the polar head group configuration including cyclic or non-cyclic structure and α or β anomeric form, in the hydrophobic tail regarding to the chain length (C8 to C14), the presence of a double bond, as well as an OH group at the terminal carbon, and in the type of linker, ester in C6 or acetal in C1. Results showed that all of these structural attributes affect both dynamic and equilibrium surface properties of glucuronic acid -based surfactants. Conclusion: A set of synthetic glucuronic acid-based surfactants varying in the polar head group, hydrophobic tail, and linker allow us to generate various surface-active properties at the air-water interface, and to increase the knowledge on relationships between their structure and surface-active properties. [1] Laurent, P.; Razafindralambo, H.; Wathelet, B.; Blecker, C.; Wathelet, J.-P.; Paquot, M., Synthesis and Surface-Active Properties of Uronic Amide Derivatives, Surfactants from Renewable Organic Raw Materials. Journal of Surfactants and Detergents 2010, in press. [2] Razafindralambo, H.; Blecker, C.; Mezdour, S.; Deroanne, C.; Crowet, J.; Brasseur, R.; Lins, L.; Paquot, M., Impacts of the Carbonyl Group Location of Ester Bond on Interfacial Properties of Sugar-Based Surfactants: Experimental and Computational Evidences. The Journal of Physical Chemistry B 2009, 113 (26), 8872-8877. Acknowledgment: This work was supported by Belgian Walloon Region within DGTRE research project of excellence (TECHNOSE). [less ▲]

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See detailFermentation of date palm juice by curdlan gum production from Rhizobium radiobacter ATCC 6466 (TM): Purification, rheological and physico-chemical characterization
Ben Salah, Riadh; Jaouadi, Bassem; Bouaziz, Amin et al

in Lwt-Food Science And Technology (2011), 44(4), 1026-1034

The present study was undertaken to investigate the possibility of using date palm juice byproducts for curdlan production by Rhizobium radiobacter ATCC 6466(TM) in batch experiments. A number of ... [more ▼]

The present study was undertaken to investigate the possibility of using date palm juice byproducts for curdlan production by Rhizobium radiobacter ATCC 6466(TM) in batch experiments. A number of operational parameters, namely pH value, temperature range, inoculum ratio, agitation speed, carbon concentration, nitrogen source, and fermentation time, were investigated in terms of their optimal values for as well as individual and synergistic effects on curdlan production. The findings indicated that the strain exhibited a high ability to use the natural substrate under investigation. A curdlan production yield of 22.83 g/l was obtained in 500-ml agitated flasks (50 ml) when the strain was cultivated in the optimal medium (pH, 7; ammonium sulphate concentration, 2 g/l; date glucose juice concentration, 120 g/l) operating at 30 degrees C with an inoculum ratio of 5 ml/100 ml, an agitation speed of 180 rpm, and a fermentation period of 51 h. The purified date byproducts-curdlan (DBP-curdlan) had a molecular weight of 180 kDa, a linear structure composed exclusively of beta-(1,3)-glucosidic linkages, a melting temperature (T(m)) and glass transition temperature (T(g)) of 1.24 and -3.55 degrees C. respectively. The average measured heights of its molecules were noted to fluctuate between 14.1 +/- 0.07 and 211.73 +/- 0.6 mu m. (C) 2010 Elsevier Ltd. All rights reserved. [less ▲]

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See detailStudy on the susceptibility of the bovine milk fat globule membrane proteins to enzymatic hydrolysis and organization of some of the proteins
Vanderghem, Caroline ULg; Francis, Frédéric ULg; Danthine, Sabine ULg et al

in International Dairy Journal (2011), 21(5), 312-318

Isolated milk fat globules were subjected to enzyme hydrolysis by a specific protease (trypsin) and a nonspecific protease (pronase E) to study the asymmetric arrangement of milk fat globule membrane ... [more ▼]

Isolated milk fat globules were subjected to enzyme hydrolysis by a specific protease (trypsin) and a nonspecific protease (pronase E) to study the asymmetric arrangement of milk fat globule membrane (MFGM) proteins. The remaining proteins on the globules after proteolysis were resolved by two-dimensional gel electrophoresis and identified by mass spectrometry. By this proteomic approach, the results confirmed different susceptibility of the MFGM proteins to proteolysis by enzymes. Butyrophilin and adipophilin were completely digested by trypsin and by pronase E, whereas lactadherin and xanthine dehydrogenase/oxidase were almost resistant to hydrolysis by trypsin and partially attacked by pronase E. Based on our results and recent bibliographic data, an up-dated model of the organization of some MFGM proteins is proposed and discussed. (c) 2011 Elsevier Ltd. All rights reserved. [less ▲]

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See detailHPLC profile and dynamic surface properties of the proteose-peptone fraction from bovine milk and from whey protein concentrate
Innocente, Nadia; Biasutti, Marialuisa; Blecker, Christophe ULg

in International Dairy Journal (2011), 21(4), 222-228

Extraction of proteose-peptones (PPs) was carried out from fresh milk, from milk after prolonged incubation (12 days at 37 degrees C) and from two different whey protein concentrates (WPCs). The high ... [more ▼]

Extraction of proteose-peptones (PPs) was carried out from fresh milk, from milk after prolonged incubation (12 days at 37 degrees C) and from two different whey protein concentrates (WPCs). The high performance liquid chromatography profiles of these extracts were compared. PPs eluted as three chromatographic peaks, which increased during milk incubation. The PP extracts from WPCs showed a number of peaks that are attributable to small peptides belonging to the proteose-peptone fraction and probably derive from proteolysis during storage of WPC. The dynamic properties at the air-water interface of the PP extracts were investigated by the drop-volume method. The PPs extracted from fresh milk showed the lowest values and a more rapid reduction in surface tension. PPs from WPCs were found to be effective as surfactants, even though a less marked reduction in surface tension compared with PPs from milk samples was shown. (C) 2011 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPRODUCTION OF XANTHAN GUM FROM XANTHOMONAS CAMPESTRIS NRRL B-1459 BY FERMENTATION OF DATE JUICE PALM BY-PRODUCTS (PHOENIX DACTYLIFERA L.)
Ben Salah, Riadh; Chaari, Kacem; Besbes, Souhail et al

in Journal of Food Process Engineering (2011), 34(2), 457-474

In this work, we studied the possibility to use date juice for xanthan gum production by Xanthomonas campestris NRRL B-1459. The results showed that this strain has a high ability to metabolize date juice ... [more ▼]

In this work, we studied the possibility to use date juice for xanthan gum production by Xanthomonas campestris NRRL B-1459. The results showed that this strain has a high ability to metabolize date juice. The data on optimization of physiological conditions of fermentation, pH, temperature, inoculum's size, glucose and nitrogen concentration showed that the maximum xanthan yield of 24.5 g/L was obtained from 60 g/L glucose, 3 g/L ammonium sulphate when batch fermentation was carried with 5% inoculum's size at pH 7, 28C, 48 h, on a rotary orbital shaker at 180 rpm. The polysaccharide purified by high performance liquid chromatography and analyzed by thin layer chromatography contained glucose, glucoronic acid and mannose. PRACTICAL APPLICATIONS Agri-food by-products rich in sugars may be used to produce high added value food ingredients such as xanthan gum. No work has studied the production of this polysaccharide from date. This study is focused on given value addition to date by-product (hard texture) by production of xanthan gum. The effect of several parameters (pH, temperature, inoculum's size, agitation speed, nitrogen source and carbon concentration) on production yield was investigated. [less ▲]

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See detailDate syrup: Effect of hydrolytic enzymes (pectinase/cellulase) on physico-chemical characteristics, sensory and functional properties
Abbes, Fatma; Bouaziz, Mohamed Ali; Blecker, Christophe ULg et al

in Lwt-Food Science And Technology (2011), 44(8), 1827-1834

This work is a contribution to give value addition to second grade dates (with hard texture) by the production of enzymatically treated syrup with high commercial value. It was observed that the pulp ... [more ▼]

This work is a contribution to give value addition to second grade dates (with hard texture) by the production of enzymatically treated syrup with high commercial value. It was observed that the pulp:water at ratio 1:3 treated with 50 U of pectinase and 5 U of cellulase during 120 min at 50 degrees C gave the highest recovery of total soluble solids (72.37 g of total soluble solids/100 g fresh basis) and the lower turbidity (186.45 NTU) compared with control without enzyme addition (Total soluble solids yields: 66.34 g of total soluble solids/100 g fresh basis and turbidity: 1513 NTU). physico-chemical measurements indicated that carbohydrates were predominant in all date varieties as well as their syrups (similar to 69.59-83.76 g/100 g dry matter in dates and similar to 62.14-74.68 g/100 g fresh weight in syrup). Allig variety was characterised by a high content of reducing sugars content (similar to 77.91 g/100 g dry matter), contrary to Deglet Nour (similar to 23.17 g/100 g dry matter) and Kentichi (similar to 21.3 g/100 g dry matter). The CIE L* a* b* colour values of the enzyme-treated date syrup of Deglet Nour, Allig and Kentichi variety showed lighter colours (L* values ranging from 24.16 to 44) than the control without enzyme (L* values ranging from 0.545 to 17.2). Hedonic evaluation showed that enzyme-treated date syrup was more appreciated by consumers. Microbiological study showed that date syrups were free from aerobes, moulds, coliforms and enterobacteriaceae and were microbiologically stable during five months storage. Results suggested that enzymatic treatment could be used for production of date syrup with high commercial value (C) 2011 Elsevier Ltd. All rights reserved. [less ▲]

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See detailInfluence of oven-drying temperature on physico-chemical and functional properties of date fibre concentrates
Borchani, C.; Besbes, S.; Masmoudi, M. et al

in Food and Bioprocess Technology (2011)

Agri-food by-products rich in dietary fibres may be used as feeds and health foods. Owing to its high fibre content, date flesh could be useful in human nutrition. It is interesting to study the influence ... [more ▼]

Agri-food by-products rich in dietary fibres may be used as feeds and health foods. Owing to its high fibre content, date flesh could be useful in human nutrition. It is interesting to study the influence of oven-drying temperatures of date fibre concentrates (DFC) on their physicochemical and functional properties for possible use as a potential fibre source in the enrichment of food. DFC from 11 Tunisian date cultivars were dried at different temperatures (40, 50 and 60 °C) and analysed regarding proximate composition (moisture, ash, protein and lipids), physicochemical (water activity (aw), pH) and functional properties (water holding capacity (WHC), swelling capacity (SC), oil holding capacity (OHC) and emulsifying capacity (EC)). DFC dried at different temperatures showed interesting functional characteristics such as hydration properties, high OHC (2.73–4.60 g oil/g dry fibre) and EC (5.93–12.87%) values. Although drying temperatures promoted little modifications affecting the physicochemical properties of DFC, significant decreases in WHC, SC and EC of DFC were noticed at the highest temperature (60 °C) for most of the date varieties. The observed influence of drying temperature on functional DFC properties calls for the use of low temperature in order to obtain DFC as suitable food ingredient. [less ▲]

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