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See detailInterfacial behavior of colored protein fractions from Spirulina platensis
Barka, Abakoura ULiege

Doctoral thesis (2018)

ABSTRACT This study is carried out to evaluate the interfacial activity of different fractions of Spirulina soluble proteins. Before the experimental steps, a broad literature review is highlighted to ... [more ▼]

ABSTRACT This study is carried out to evaluate the interfacial activity of different fractions of Spirulina soluble proteins. Before the experimental steps, a broad literature review is highlighted to point out the global microalgae potential, with particular emphasis on Spirulina sp. The protein content of different microalgae species is presented, together with the nutritional quality of these proteins. Out of this investigation, it clearly appeared that micro algae present a higher productivity per unit area when compared to high plants. They are able to thrive and survive in drastic climatic conditions. Spirulina platensis particularly presents high protein content with good nutritional characteristics. The first experimental assessment is the extraction of the colored Spirulina soluble protein fractions from dry Spirulina powder and evaluation of their physicochemical properties. Three fractions, including the blue soluble (BSSP), the green soluble (GSSP), and the total soluble (TSSP) Spirulina protein fractions are obtained. Investigations on their behavior at air/water interface are carried out, using dynamic methods of drop volume (TVT1), automated drop (tracker), and bubble pressure (BP100) tensiometers. Evaluation of their monolayer films mechanical behavior is done via compression isotherms using Langmuir film balance. The protein contents of the fractions are 82.76%; 82.29%; 74.53% for the blue, the green and the total fractions, respectively. Surface tension decay increases with increasing concentration for all the fractions. The tension decay is less important at pH 3 for all the fractions. The total fraction and the blue fraction appeared to form more elastic films than the green fraction. The blue soluble fraction also presented the highest collapse pressure and initial area. The second experimental evaluation is focused on the performances of colored Spirulina soluble protein fractions as surfactants at water/n-dodecane interface. Evaluation of their interfacial activities is carried out using different methods as for the air/water interface. Different concentrations (0.1%; 0.3% and 0.5% (w/w)) and pH levels (3, 5, and native pH) are tested. Results show that, the interfacial tension decay increased with increased protein concentration. At 0.3% (weight/weight) colored protein concentration in the aqueous phase, the surface tension decay is greater at pH 5 compared to pH 3 and native pH. The interfacial elastic moduli of the fractions suspensions decrease with concentration unlike viscosity moduli. Investigations on the emulsifying and foaming properties make the third experimental task. Emulsions at pH 3 are very susceptible to destabilization phenomena such as coalescence, and creaming. The emulsifying properties of the three fractions follow the same trends. However, the BSSP fraction shows a better emulsifying effect. Fractions present higher foaming capacities at their native pH, but foams are more stable at pH 3. The foaming behavior at pH 5 is close to that at the native pH. Despite the undoubted link between Spirulina protein surface activity and foaming and emulsifying properties, it should be beard in mind that the best properties are not always only obtained by the conditions of greater ability of the protein to reduce surface or interfacial tension but also to its solubility. Nevertheless the surface activity of the proteins remains the prerequisite to foaming or emulsifying properties. It should also be emphasized that the fractionation method developped in this work, unlike the methods so far available in the literature, is industrially feasible and could allow for large production of the Spirulina protein fractions. One of the obtained fractions (BSSP) presents better emulsifying ptoperties. All the three fractions present interfacial activities, and can provide foaming and emulsifying properties that would allow for their industrial use as emulsifiers in lieu and place of conventional proteins. Their color may be an asset for their use in some specific applications. [less ▲]

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See detailPhysicochemical characterization of colored soluble protein fractions extracted from Spirulina (Spirulina platensis)
Barka, Abakoura ULiege

in Food Science and Technology International (2018)

The aim of this study was to evaluate the physicochemical properties of Spirulina colored soluble protein fractions extracted from spray-dried Spirulina powder. Three fractions, including the blue soluble ... [more ▼]

The aim of this study was to evaluate the physicochemical properties of Spirulina colored soluble protein fractions extracted from spray-dried Spirulina powder. Three fractions, including the blue soluble Spirulina protein, the green soluble Spirulina protein, and the total soluble Spirulina protein fractions were obtained. Investigations on their behavior at air/water interface were carried out using dynamic methods of drop volume and bubble pressure surface tension measurements. Evaluation of their monolayer films’ mechanical behavior was done via compression isotherms using Langmuir film balance. The protein contents of the fractions were 82.76, 82.29, and 74.53% for the blue, the green, and the total fractions, respectively. Surface tension decay increased with increasing concentration for all the fractions. No significant difference in surface tension decay was observed between the samples at 0.3% (w/w). Surface tension decay was less important at pH 3 for all the fractions. The total fraction and the blue fraction appeared to form more elastic films than the green fraction. The blue soluble fraction also presented the highest collapse pressure and initial expansion area. [less ▲]

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See detailPerformances of Colored Spirulina (Spirulina platensis) Soluble Protein Fractions as Surfactants at Liquid-Liquid Interface
Barka, Abakoura ULiege; Blecker, Christophe ULiege

Poster (2017, September 09)

Abstract: A study was carried out to evaluate the performances of colored spirulina (Spirulina platensis) soluble proteins fractions as surfactants at water/n-dodecane interface using a drop volume ... [more ▼]

Abstract: A study was carried out to evaluate the performances of colored spirulina (Spirulina platensis) soluble proteins fractions as surfactants at water/n-dodecane interface using a drop volume tensiometer. Also the mechanical behavior at this interface were studied via an automated drop tensiometer. Various concentrations (0.1%; 0.3% and 0.5% (w/w)) and pH levels (native, 3 and 5) were tested. Results showed that the interfacial tension decay increased with increased protein concentration. Also, at 0.3% (w/w) colored protein in the aqueous phase there were no significant difference in interfacial tension decay between the native pH and the pH3 levels while at pH5 the surface tension decay was greater. The viscoelastic moduli and the equilibrium interfacial tension of the fractions suspensions also decreased with concentration. [less ▲]

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See detailPerformances of Colored Spirulina (Spirulina platensis) Soluble Protein Fractions as Surfactants at Liquid-Liquid Interface
Barka, Abakoura ULiege; Blecker, Christophe ULiege

in Prof. Dr Bulent, Topcuoglu (Ed.) Sept 2017 International Conferences (2017, September)

A study was carried out to evaluate the performances of colored spirulina (Spirulina platensis) soluble proteins fractions as surfactants at water/n-dodecane interface using a drop volume tensiometer ... [more ▼]

A study was carried out to evaluate the performances of colored spirulina (Spirulina platensis) soluble proteins fractions as surfactants at water/n-dodecane interface using a drop volume tensiometer. Also the mechanical behavior at this interface were studied via an automated drop tensiometer. Various concentrations (0.1%; 0.3% and 0.5% (w/w)) and pH levels (native, 3 and 5) were tested. Results showed that the interfacial tension decay increased with increased protein concentration. Also, at 0.3% (w/w) colored protein in the aqueous phase there were no significant difference in interfacial tension decay between the native pH and the pH3 levels while at pH5 the surface tension decay was greater. The viscoelastic moduli and the equilibrium interfacial tension of the fractions suspensions also decreased with concentration [less ▲]

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See detailMicroalgae as a potential source of single-cell proteins. A review
Barka, Abakoura ULiege; Blecker, Christophe ULiege

in Biotechnologie, Agronomie, Société et Environnement (2016), 20(3), 427-436

Detailed reference viewed: 72 (15 ULiège)