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See detailImpact of extraction procedures on the chemical, rheological and textural properties of ulvan from Ulva lactuca of Tunisia coast
Yaich, Hela; Garna, Haikel; Besbes, Souhail et al

in Food Hydrocolloids (2014), (40), 53-63

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained ... [more ▼]

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained after combining enzymatic and chemical extraction but the lowest yield results at the drastic conditions (pH 1.5 and 90 C). Besides, solvent acidity was an important parameter controlling the ulvan extraction efficiency. The different extraction processes affected chemical composition of ulvan extracts and in particular, sulphate, ash and sugar contents. Low proportions of galactose, glucose and protein were also found in sulphated polysaccharides. The extract, which is resulted from combined enzymatic and chemical extraction, was mainly composed of high peak molecular weight polysaccharides. Ulvan hy-drocolloids demonstrated a pseudoplastic behavior. Viscoelastic behavior was carried out at a concen-tration of 1.6% (w/v) in the presence of 7 mM sodium tetraborate and at pH 7.5. However, polysaccharides formed a gel. It was not the case for the extract at pH 1.5 and 90 C under the same conditions. The results showed that a significant effect of the conditions of extraction on the textural characteristic (firmness, springiness and adhesiveness) of ulvan gels. [less ▲]

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See detailEffect of extraction conditions on the yied and purity of ulvan extracted from Ulva lactuca
Yaich, Hela; Garna, Haikel; Besbes, Souhail et al

in Food Hydrocolloids (2013)

A study of the influence of extraction conditions (pH: 1.5 and 2; temperature: 80 °C and 90 °C; extraction time: 1-3 h), on the yield, chemical composition and purity of the sulphated cell wall ... [more ▼]

A study of the influence of extraction conditions (pH: 1.5 and 2; temperature: 80 °C and 90 °C; extraction time: 1-3 h), on the yield, chemical composition and purity of the sulphated cell wall polysaccharides ulvan, extracted from the green seaweed Ulva lactuca and precipitated by alcohol is carried out. The alcohol precipitate yields varied from 21.68% to 32.67% (%dw/dw) depending on the pH. At pH 2, the alcohol precipitate yields and the uronic acid recovery from extract juice are higher than those obtained at pH 1.5. Other compounds than ulvan such as cellulose, hemicellulose, proteins and ash are solubilized from the cell walls of Ulva lactuca at both pH, and they are precipitated with alcohol. The alcohol precipitate obtained from different extraction conditions has high uronic acid (20.37%-23.60%) and neutral sugar content (20.09%-29.12%), especially when the conditions (pH, temperature) are drastic. It contains rhamnose (13.35%-15.59%), glucose (2.90%-10.97%), and xylose (2.36%-2.73%). A decrease in the molecular weight of ulvan was observed at acid pH, and for long extraction times. The presence of proteins (1.94%-2.32%) and inorganic material (33.36%-47.15%) in alcohol precipitate prove the lower purity of ulvan extracted and shows that ulvan precipitation with ethanol is not specific. © 2012 Elsevier Ltd. [less ▲]

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See detailPurification of pectin from apple pomace juice by using sodium caseinate and characterisation of their binding by isothermal titration calorimetry
Happi Emaga, Thomas; Garna, Haikel; Paquot, Michel ULg et al

in Food Hydrocolloids (2012), 29

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See detailNew method for the purification of electrically charged polysaccharides
Garna, Haikel; Emaga, Thomas Happi; Robert, Christelle et al

in Food Hydrocolloids (2011), 25(5), 1219-1226

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See detailDevelopment of gelling properties of inulin by microfluidization
Ronkart, Sebastien N; Paquot, Michel ULg; Deroanne, Claude et al

in Food Hydrocolloids (2010), 24(4), 318-324

In this paper, we report the impact of a microfluidic device (Microfluidizer (R)) on the development of gelling properties of inulin-water systems. Inulin dispersions at a concentration of 2, 7 and 15%, w ... [more ▼]

In this paper, we report the impact of a microfluidic device (Microfluidizer (R)) on the development of gelling properties of inulin-water systems. Inulin dispersions at a concentration of 2, 7 and 15%, w/w, were subjected to microfluidization treatments at 30 MPa with various numbers of circulations in the apparatus (1, 2 or 5 passes). The high shear stress treatment did not induce a chemical composition change of inulin. However, it allowed an increase of the gel-like behavior of the system as well as the viscosity of the inulin dispersion, transforming a visual aspect of the product similar to milk, to a system similar to yogurt or margarine depending on the concentration and the number of passes in the Microfluidizer (R). The viscosity increased with both the number of passes and the inulin concentration. Granulometry as well as optical and electronic microscopy ascertained the reduction of the particle size and the formation of a network composed of agglomerates which interacted with the solution and thus led to textural modifications. (C) 2009 Elsevier Ltd. All rights reserved. [less ▲]

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See detailEffect of water uptake on amorphous inulin properties
Ronkart, Sebastien N; Paquot, Michel ULg; Fougnies, Christian et al

in Food Hydrocolloids (2009), 23(3), 922-927

Physical property changes of amorphous spray-dried inulin were investigated during water uptake at 20 degrees C. Modulated Differential Scanning Calorimetry (MDSC) and Wide Angle X-ray Scattering (WAXS ... [more ▼]

Physical property changes of amorphous spray-dried inulin were investigated during water uptake at 20 degrees C. Modulated Differential Scanning Calorimetry (MDSC) and Wide Angle X-ray Scattering (WAXS) were used to investigate the evolution of the glass transition temperature (T-g) and the crystallinity index, respectively. The water content, crystallization and thermal properties relationship enabled the identification of three zones in the T-g-water content state diagram. Zone I delimited inulin in a glassy amorphous state, while zone II characterized inulin in a liquid amorphous state. Inulin crystallized and caked when T-g was below the storage temperature of 20 degrees C, but crystallization (zone III) was not spontaneous and was delayed by the defined zone II. The crystallization led to thermograms with an endotherm close to T-g. Temperature-Resolved WAXS allowed to correctly ascertain the MDSC endothermic peak as a melting peak because the crystallinity index was maximal at onset temperature of the transition, and dropped to zero at the endset temperature. (C) 2008 Elsevier Ltd. All rights reserved. [less ▲]

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See detailComposition And Physicochemical Extracted From Whole Seeds By Acid Properties Of Locust Bean Gum Or Water Dehulling Pre-Treatment
Dakia, Patrick; Blecker, Christophe ULg; Robert, Chiristelle et al

in Food Hydrocolloids (2008), 22(5),

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See detailInteractions between bacterial surfaces and milk proteins, impact on food emulsions stability
Ly, M. H.; Aguedo, Mario ULg; Goudot, S. et al

in Food Hydrocolloids (2008), 22(5), 742-751

Bacteria possess physicochemical surface properties such as hydrophobicity, Lewis acid/base and charge which are involved in physicochemical interactions between cells and interfaces. Moreover, food ... [more ▼]

Bacteria possess physicochemical surface properties such as hydrophobicity, Lewis acid/base and charge which are involved in physicochemical interactions between cells and interfaces. Moreover, food matrices are complex and heterogeneous media, with a microstructure depending on interactions between the components in media (van der Waals, electrostatic or structural forces, etc.). Despite the presence of bacteria in fermented products, few works have investigated how bacteria interact with other food components. The objective of the present study was to determine the effects of the surface properties of lactic acid bacteria on the stability of model food emulsions. The bacteria were added to oil/water emulsions stabilized by milk proteins (sodium caseinate, whey proteins concentrate or whey proteins isolate) at different pH (from 3 to 7.5). The effect of bacteria on the emulsions stability depended on the surface properties of strains and also on the characteristics of emulsions. Flocculation and aggregation phenomena were observed in emulsion at pHs for which the bacterial surface charge was opposed to the one of the proteins. The effects of bacteria on the stability of emulsion depended also on the concentration of cations present in media such as Ca2+. These results show that the bacteria through their surface properties could interact with other compounds in matrices, consequently affecting the stability of emulsions. The knowledge and choice of bacteria depending on their surface properties could be one of the important factors to control the stability of matrices such as fermentation media or fermented products. © 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailComparison of alcohol precipitation and membrane filtration effects on sugar beet pulp pectin chemical features and surface properties
Yapo, B. M.; Wathelet, Bernard ULg; Paquot, Michel ULg

in Food Hydrocolloids (2007), 21(2), 245-255

Two different procedures, alcohol precipitation with washing (APW) and a 10 kD MWCO membrane ultrafiltration with diafiltration (UF-DF), for pectin recovering and purification from crude aqueous extracts ... [more ▼]

Two different procedures, alcohol precipitation with washing (APW) and a 10 kD MWCO membrane ultrafiltration with diafiltration (UF-DF), for pectin recovering and purification from crude aqueous extracts were investigated. The results showed that the yield, purity, chemical, and physicochemical features of isolated pectins depended upon the type of procedure used. The APW technique gave a higher pectin yield, and the isolated pectin contained more neutral sugars, more proteins, and more ash but less galacturonic acids than the 10 kD membrane UF-DF one. The weight-average molar mass of the APP was lower and its emulsifying properties slightly better than those of the UFPR10. Molar mass distribution of APP or UFPR10 showed two distinct pectin fractions peaks, which were separated in high-MW and low-MW pectin fractions using a 50kD MWCO membrane. The high-MW fractions exhibited poor emulsifying and emulsion stabilizing abilities whereas the low-MW fractions displayed a much higher emulsifying ability than the initial pectin fractions. Therefore, it was inferred that the ability of beet pectin to be an effective emulsifier and/or emulsion stabilizer was greatly dependent on its weight-average molar mass. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

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See detailFoaming properties of a natural cyclic lipoheptapeptide belonging to a special class of amphiphilic molecules
Razafindralambo, Hary ULg; Paquot, Michel ULg; Baniel, A. et al

in Food Hydrocolloids (1997), 11(1), 59-62

The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus ... [more ▼]

The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus combining bubbling, optical and conductimetric methods was used to study continuously foam formation and stability in terms of the quantity and density of foam. The increase in surfactin concentration from 0.05 to 0.2 mg/ml had little effect on its foaming capacity, measured by the bubbling time to produce the required foam volume, but improved the foam maximum density significantly. Surfactin produced foam with higher maximum density and stability, and forms more regular and smaller bubbles than BSA. In addition, a synergistic effect was observed on the stability of liquid in foam prepared with a mixture of 50:50 surfactin/BSA. The liquid half-life of BSA foam was enhanced up to 40% when surfactin was added to the solution. [less ▲]

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