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Physicochemical characterization and ionic studies of sodium alginate from Sargassum terrarium (brown algae)

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Physical and chemical analysis of the polysaccharides isolated from Sargassum terrarium (brown algae) of Karachi coast showed characteristics of sodium alginate. The optical rotation and sulphated ash content were found to be −113° and 30.6% respectively. FTIR spectra showed a sharp and strong absorption band at 1600 cm−1 representing carboxylate ion, which confirms high uronic acid content of the product. Viscosity measurements revealed a linear relationship with increases in concentration and decreased with the rise in temperature of aqueous solution of sodium alginate. Thermodynamic parameters were determined by the change in viscosity data as a function of temperature and concentration. The free energy change of activation (ΔGη) increased regularly as the concentration of sodium alginate increased, as well as rises in temperature. Higher values of free energy change of activation, showed the higher association of sodium alginate with water at a given temperature. The values of entropy change of activation (ΔSη) of viscous flow also increased with the increase in concentration and temperature of sodium alginate solution. The high negative values of entropy change of activation (ΔSη) showed that the solution of sodium alginate was more ordered in initial state than the activated one.
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Physicochemical characterization and ionic studies of sodium alginate
from <i>Sargassum terrarium</i> (brown algae)
Fatima Bia; S. Junaid Mahmooda; Muhammad Armana; Noor Taja; Seema Iqbala
a PCSIR Laboratories Complex, Karachi - 75280, Pakistan
To cite this Article Bi, Fatima , Mahmood, S. Junaid , Arman, Muhammad , Taj, Noor and Iqbal, Seema(2007)
'Physicochemical characterization and ionic studies of sodium alginate from <i>Sargassum terrarium</i> (brown algae)',
Physics and Chemistry of Liquids, 45: 4, 453 — 461
To link to this Article: DOI: 10.1080/00319100600745198
URL: http://dx.doi.org/10.1080/00319100600745198
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Physics and Chemistry of Liquids
Vol. 45, No. 4, August 2007, 453–461
Physicochemical characterization and ionic studies of sodium
alginate from Sargassum terrarium (brown algae)
FATIMA BI*, S. JUNAID MAHMOOD, MUHAMMAD ARMAN,
NOOR TAJ and SEEMA IQBAL
PCSIR Laboratories Complex, Karachi – 75280, Pakistan
(Received 1 March 2006; in final form 7 April 2006)
Physical and chemical analysis of the polysaccharides isolated from Sargassum terrarium
(brown algae) of Karachi coast showed characteristics of sodium alginate. The optical rotation
and sulphated ash content were found to be 113and 30.6% respectively. FTIR spectra
showed a sharp and strong absorption band at 1600 cm
1
representing carboxylate ion, which
confirms high uronic acid content of the product. Viscosity measurements revealed a linear
relationship with increases in concentration and decreased with the rise in temperature of
aqueous solution of sodium alginate. Thermodynamic parameters were determined by the
change in viscosity data as a function of temperature and concentration. The free energy
change of activation (G) increased regularly as the concentration of sodium alginate
increased, as well as rises in temperature. Higher values of free energy change of activation,
showed the higher association of sodium alginate with water at a given temperature. The values
of entropy change of activation (S) of viscous flow also increased with the increase in
concentration and temperature of sodium alginate solution. The high negative values of
entropy change of activation (S) showed that the solution of sodium alginate was more
ordered in initial state than the activated one.
Keywords:Sargassum terrarium; Sodium alginate; Energy of activation; Latent heat of
vaporization; Entropy of activation
1. Introduction
Alginates are the polysaccharides generally extracted from brown algal plants and
are the copolymers of L-guluronic and D-mannuronic acids [1,2]. The high viscosity and
polyelectrolyte character of alginate solutions and their capacity for gel formation
make their widespread industrial use in many pharmaceuticals, textile, food and dairy
products [3,4]. Compared with other food gels, sodium alginate (algin) gels have many
advantages i.e. form low calorie food, quickly and easily melt in mouth, non-toxic
nature and low in cost.
Sodium alginate also forms thick and stable gel when it comes in contact with calcium
ions in solution by cross-linking between the carboxylate ions of alginate guluronate
*Corresponding author. Email: fatima_bi220@hotmail.com
Physics and Chemistry of Liquids
ISSN 0031-9104 print/ISSN 1029-0451 online ß2007 Taylor & Francis
DOI: 10.1080/00319100600745198
Downloaded By: [PERI Pakistan] At: 10:57 17 August 2010
units and the calcium ions [5]. The viscosity method is employed for the determination
and confirmation of compounds and their behaviour in different solvents. Viscosity is
affected by a number of parameters such as molecular mass, shape and size of
molecules, concentration, temperature and intermolecular attractions i.e. ion–ion and
ion–solvent interactions [6]. Ample data are available in literature on rheological
studies of alginates [7,8]. However, little attention has been paid on physicochemical
characterization of the alginates obtained from brown algae of Karachi coast.
The present investigation deals with chemical characterization, spectral and
thermodynamic study of the sodium alginate isolated from brown algae of Karachi
coast. Various thermodynamic parameters such as energy of activation (E
), free energy
change of activation (G
), latent heat of vaporization (L
) and entropy change of
activation (S
), for the viscous flow of aqueous sodium alginate solutions were studied
as a function of temperature and concentration. The activation energy of flow gave
information about the behaviour of sodium alginate in water and FTIR spectral
analysis helped to study the structure of sodium alginate.
2. Materials and methods
2.1. Isolation of sodium alginate
Sargassum terrarium (S. terrarium) of class pheophyceae (brown algae) was collected
from paradise point of Karachi coastal area in March 2004. The plant material was
cleaned from epiphytes, washed with tap and distilled water, dried and ground to a fine
powder in a domestic model mixer. Algal powder (50 g) was de-pigmented and extracted
by the method described previously [9]. The gel (sodium alginate) obtained after alcohol
treatment (1 : 2 v/v) was dried at low temperature at 45–50C.
2.2. Chemical methods
Moisture content was determined as described earlier [10]. The analysis of sulphated ash
was carried out by the conventional method of ashing in the presence of concentrated
sulphuric acid. pH of 0.1% algin solution was recorded by a digital pH meter. Total
sugar content was determined by the phenol sulphuric acid [11]. Assay for sulphate
group was done by modified method [12]. Total acidic sugar was determined by uronic
acid carbazole method [13]. Reactions with calcium chloride, sodium hydroxide and
mineral acids were performed [14]. Optical rotation of aqueous solution of algin of
known concentration (1%) was determined with Digital Polarimeter (Jas. Co. Dip. 360)
using 50 mm tubes and sodium D line at 589 cm wavelength. FTIR analysis was
performed on Nicolet Avatar 370 DTGS Fourier Transform Infrared Spectrometer.
2.3. Viscosity measurement
All glass wares used were of Pyrex A grade quality. A 0.5% stock solution was prepared
in 100 mL volumetric flask by dissolving the 0.5 g of isolated sodium alginate in
deionized water having conductivity less than 1 mScm
1
with constant stirring till clear
solution formed, then volume was made to the mark. This stock solution was used
454 F. Bi et al.
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to prepare further dilutions ranging from 0.05 to 0.25%. Relative viscosities were
measured with Ubbehlode Viscometer type techniconominal constant 0.1 cSt capillary
ASTM D 445. The viscometer was placed inside a glass tube connected with
thermostatic water bath (type VWP Scientific, model 1120, Ser 9143791) having a
constant circulation of water throughout the course of the experiment. The temperature
of the water bath was kept constant with the help of temperature control device type
Haake Delab Instrument (Electro Laboratoriet, Copenhagen) with 0.1C. A known
volume of solvent (water) and solution was placed in the viscometer for at least 15 min
to attain the required temperature and the time of flow was recorded.
Densities of solvents and solutions were measured with the help of a relative density
bottle (10 mL) at different temperatures. The reproducibility of results was checked
by repeating the measurements three times. The uncertainty in the experimental data
was found to be 0.001 g mL
1
and 0.002 cP respectively.
3. Results and Discussion
Yield of Algin (sodium alginate) isolated from brown algae, S. terrarium was
about 30% (w/w) of the dry plant. The yield was much higher than that reported
earlier i.e. 23.7% [15]. Physicochemical properties of isolated algin and a commercial
sample purchased from the local market were compared, significant differences were
observed in the optical rotations and in the sulphated ash contents (table 1). Isolated
product showed a rotation of 113and was present in the range as described earlier
[16]. However, optical rotation cannot be taken as a criterion of quality or a reliable
index of purity. Chemical analysis revealed that isolated sample exhibited 20% sugar
and low sulphate content (0.12%). Uronic acid content was 8%, which is in good
agreement with that reported by Johnson et al. [17]. Sometimes variables used during
extraction procedures like type of solvents, concentration of solvents and also the
seasonal variations influence and affect the yield, apparent viscosity, colour and
chemical composition of the product [18]. Infra red (IR) spectroscopy is a simple and
Table 1. Physicochemical properties of commercial and isolated samples of sodium alginate (algin).
Tests Isolated algin Commercial algin
Colour Light brown Light brown
Moisture (% w/w) 12.4 15.1
Sulphated ash (% w/w) 30.6 41.9
pH (0.1% solution) 6.6 6.6
Aqueous gel strength (2% w/v) Yellow transparent gelling
solution at 4C
Pale yellow turbid
solution at 4C
Optical rotation ½25
D11368
Total sugar content (% w/w) 20 16
Uronic acid content (% w/w) 8 9.2
Sulphate content (% w/w) 0.12 0.73
Reactions with
Calcium chloride (2.5%) Gelatinous precipitate formed Same
Sodium hydroxide (3N) Clear yellow solution on heating Same
Mineral acids Gelatinous precipitate formed Same
Characterization and ionic studies of sodium alginate in S. terrarium 455
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faster technique used for the characterization of alginates [19,20]. IR spectra of the
product showed a sharp and strong absorption band at 1600 cm
1
and represented
the carboxylate antisymmetric stretching which is in accordance with the high uronic
acid content of the sample, (figure 1, table 1). The spectra is identical and resemble
the finger print region of the typical spectrum of sodium alginate [21].
In this article we describe the viscosity measurements of aqueous solution of sodium
alginate from 30 to 50C at the rate of 5C increments at various dilutions ranging from
0.05 to 0.25 g dL
1
. Solution properties of chemical substances in the region of extreme
dilution are of great importance, both theoretically and experimentally. Viscosities of
various aqueous solutions of isolated algin at five temperatures are recorded in table 2.
The results showed a regular increment in viscosity with the increase of concentration of
solutes at each temperature i.e. 303, 308, 313, 318 and 323 K respectively. The viscosity
of the solutions seems to decrease with the rise of temperature as reported earlier [8,22].
The increase in viscosity on addition of sodium alginate to water is understood,
to be due to increase in the degree of solvation. Representative plot of
sp
/C
(reduced viscosity) versus concentration of aqueous sodium alginate solution at 323K
is shown in figure 2. The values of reduced viscosity (
sp
/C) of each sample of aqueous
sodium alginate solution were studied systematically.
Viscosity measurement is one of the most appropriate techniques used to study
various types of interaction occurring in solutions. The viscosity data are computed
Figure 1. Infrared spectra of isolated algin (sodium alginate).
456 F. Bi et al.
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by using Jones–Dole equation [23]. A representative plot of
sp
/C
1/2
versus C
1/2
at 308 K
is shown in figure 3.
sp
C1=2¼AþBC1=2ð1Þ
where
sp
is the specific viscosity, Aand Bare coefficients which represents ion–ion and
ion–solvent interactions respectively, Cis the concentration of algin solution in g dL
1
.
The values of Aand Bcoefficients were determined from the intercept and slope of the
linear plots of
sp
/C
1/2
versus C
1/2
. The regression method was applied for this purpose
and the resulting Aand Bcoefficients are summarized in table 3. The negative values of
coefficient Ado not have any significance. In this case, Avalues have been found to
decrease with the rise of temperature, which is due to dielectric constant of the medium
and decrease in the ion–ion interactions. The values of coefficient Bcalculated are
found to increase with the increase of sodium alginate content at all the temperatures.
A solute with a positive Bcoefficient is expected to have a structure-making effect.
Our data show the regular variation of B-values with the rise of temperature, this may
be due to the different degrees of hydrolysis in the given solvents. In this case as our
solutes are of high molecular weights, high B-values show that the ion–solvent
interactions are strong i.e. structure maker.
24
26
28
30
0.03 0.08 0.13 0.18 0.23 0.28
C
hsp/C
Figure 2. Plot of
sp
/Cvs. concentration for aqueous sodium alginate solution at 323 K.
Table 2. Viscosity (cP) of sodium alginate aqueous solution at various concentrations and temperatures.
Temperatures (K)
Concentration (g dL
1
) 303 308 313 318 323
0.05 1.9964 1.6990 1.4450 1.2750 1.2080
0.10 2.9655 2.7780 2.4240 2.0990 1.9930
0.15 4.4668 3.9070 3.4470 2.9440 2.8960
0.20 5.2109 4.9100 4.2640 3.5470 3.5220
0.25 6.3400 5.6800 5.0870 4.4840 4.4020
Characterization and ionic studies of sodium alginate in S. terrarium 457
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3.1. Energy of activation
The relationship between viscosity and energy of activation is given by the following
equation.
¼Aexp E
RT
 ð2Þ
where is the viscosity of the algin solution. E
is the energy of activation, Ris the
universal gas constant and Tis the absolute temperature. The activation energy (E
)
was evaluated from the Arrhenius relation [24] and the representative plot of log
versus 1/Tas a function of sodium alginate concentrations is shown in figure 4.
The latent heat of vaporization (L
) was evaluated from following relation,
E¼0:4L:ð3Þ
The values of energy of activation and latent heat of vaporization are tabulated
in table 4. Decrease in energy of activation and latent heat of vaporization, as
temperature rises is due to weakening of the inter molecular forces between the
molecules of sodium alginate by uncoiling aggregated molecules there by reducing
entanglement between them. The energy of activation is related to the work required to
3
5
7
9
11
13
15
0.15 0.2 0.25 0.30 0.35 0.4 0.45 0.50 0.55
C½
hsp/C1/2
Figure 3. Plot of
sp
/C
1/2
vs. square root of concentration of aqueous sodium alginate solution at 308 K.
Table 3. Values of ionic interactions of aqueous sodium alginate solution in terms of Jones–Dole
coefficients Aand Bat various temperatures.
Aand Bcoefficients of Jones–Dole equation
Temperatures (K)A(mol
1/2
dm
3/2
)B(mol
1
dm
3
)
303 þ0.7124 0.003 26.624 0.004
308 0.0732 0.002 28.697 0.003
313 0.9452 0.001 29.713 0.001
318 0.9881 0.002 29.886 0.003
323 1.4432 0.003 31.108 0.002
458 F. Bi et al.
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form a hole in the liquid. The holes are necessary for a liquid to flow. Hence, it is
concluded that the values of activation energy are found high in pure water.
3.2. Free energy and entropy of activation
The free energy change of activation for viscous flow (G
) is given by the following
expression.
G
¼2:303RT log =103ð4Þ
where Ris the universal gas constant, Tis the absolute temperature and is the
viscosity. The values of G
, control the rate of flow in fluid process. The flow process
is governed by the activity of the molecule to move into the prepared hole and
the readiness with which the holes are prepared in the liquid. The values of free energy
change of activation are calculated and tabulated in table 5.
The entropy change of activation is given by
S¼HG
T:ð5Þ
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
0.7
2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35
log h
1/T × 10
3
(K
1
)
Figure 4. Plot of log vs.1/Tfor sodium alginate in water at 0.15 g dl
1
.
Table 4. Energy of activation (E
) and latent heat of vaporization (L
)
of aqueous sodium alginate solution.
Composition of
algin (g dL
1
)
Energy of activation
(E
) (J mol
1
)
Latent heat of vaporization
(L
) (J mol
1
)
0.05 14.1970 35.4920
0.10 12.5010 31.2520
0.15 12.0300 30.0750
0.20 11.7810 29.4520
0.25 11.2700 28.1750
Characterization and ionic studies of sodium alginate in S. terrarium 459
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Energy of activation (E
) does not differ appreciably from enthalpy change of
activation (H
)
S¼EG
T:ð6Þ
The values of entropy change of activation are summarized in table 6. The data show
that in some cases the values of E
and S
are found lesser than that of the pure
solvent indicating that the solvent structure is broken by the presence of solutes.
In some cases, these values are found to be higher, which are attributed to the excess of
energy necessary to break the hydrogen bonds in solution. When these values are found
equal to that of the solvent, the hydrogen bond breaking of the solvent is not
significantly affected by the solutes.
The Mark–Houwink equation is used for estimation of average molecular weight
of alginic acid of sodium salt in water at 323 K.
½¼1:60 102M0:748:ð7Þ
The average molecular weight is found approximately 4100,000, whereas commercially
available alginate has molecular weight between 32,000 and 200,000 and the degree
of polymerization of alginate is 180–930 [25].
Chemical analysis and other physical data such as optical rotation, FTIR spectral
studies etc. revealed that isolated algin is a representative of sodium alginate.
Viscometric study confirms that associative interaction between the isolated product
and water exists at specific temperature. Rheological studies described algin as a gelling,
thickening and viscosity increasing agent for the given solvent i.e. water.
Table 6. Entropy change of activation (S
) of aqueous sodium alginate solution at various
concentrations and temperatures.
Entropy of activation (S
) at different concentration of algin (kJ mol
1
)
Temperatures (K) 0.05 (g dL
1
) 0.10 (g dL
1
) 0.15 (g dL
1
) 0.20 (g dL
1
) 0.25 (g dL
1
)
303 63.1410 66.2370 68.2200 70.1260 72.5250
308 63.3920 66.5300 68.3130 70.2940 72.7260
313 63.6300 66.6660 68.7910 70.9850 72.9130
318 63.9010 66.8310 68.9160 70.8690 72.0990
323 64.1840 67.1340 69.1410 70.0700 72.2110
Table 5. Free energy change of activation (G
) of aqueous sodium alginate solution at various
concentrations and temperatures.
Free energy change of activation (G
) at different concentrations of algin (kJ mol
1
)
Temperatures (K) 0.05 (g dL
1
) 0.10 (g dL
1
) 0.15 (g dL
1
) 0.20 (g dL
1
) 0.25 (g dL
1
)
303 19.1460 20.1430 21.2860 21.5630 22.0570
308 19.2310 20.1960 21.2990 21.6010 22.1030
313 19.4610 20.2530 21.3560 21.6980 22.2590
318 19.6990 20.3110 21.3870 21.8170 22.4210
323 19.8090 20.4050 21.4080 21.9340 22.5330
460 F. Bi et al.
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Acknowledgements
The authors are thankful to Mr. Muhammad Sadiq Ali, Junior Technical Officer
and Mr. Muhammad Javed, Senior Technician for their technical assistance in
laboratory work.
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Characterization and ionic studies of sodium alginate in S. terrarium 461
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... Additionally, the thiolation degree has also an influence on the "gel-point". This could occur, because of the decreasing entanglement of the polymer chain with increasing thiolation degree(Bi et al., 2010) (Phys and Grest, 2016). Increasing functionalization of the negative charged carboxyl group leads to a decrease in repulsion of the polymer chains with each other or also within one polymer chain, which could result in an increase in entanglement(Tanaka, Adachi and ...
Thesis
In recent years, hydrogels developed to promising tools for biomedical and industrial applications. For biomedical approaches hydrogels, possess the capacity to immobilize and release cells, they offer the desired 3D environment to induce cell specific behaviour or serves as a drug delivery system. Moreover, they can be used for tissue engineering approaches by mimicking the ECM. In this thesis, a novel hybrid double cross-linked hydrogel is presented and designed based on the bottom-up approach of synthetic biology. It consists of simultaneously formed chemical and physical cross-links and made out of two components: (1) thiol functionalized HA (74 kDa) (HA-DTPH) and (2) ionic crosslinker (Cl+). HA-DTPH provides the chemical cross-link by forming disulphide bonds and the ionic cross-linker forms physical cross-links, such as hydrogen bonds and salt bridges. Three different ionic cross-linker were used: (1) deacetylated disaccharide unit of HA (dHA+) (2) charged glucosamine (GluA+) and (3) ammonium chloride (NH4+). These ionic cross-linker were chosen due to their biocompatibility and ability to form physical cross-links, such as hydrogen bonds and salt bridges. The increasing capacity to form hydrogen bonds from NH4+ to dHA+ enabled us to study the influence of the physical cross-link on the hydrogel properties. I could show that the disulphide bond formation was enhanced, by adding an ionic cross-linker and led to the formation of stable hydrogels. Under the same reaction conditions, HA-DTPH without an ionic cross-linker, needed further oxidation with hydrogen peroxide to result in a stable hydrogel (HA-DTPH-Ox.). By varying the degree of thiolation on HA and additionally by varying the type and concentrations of the used ionic cross-linker, the mechanical stiffness, swelling properties and response to external stimuli were tuneable. Varying the degree of modification and used ionic cross-linker enables a specific adjustment of the hydrogels specifically the hydrogel suitable for cell studies with mechanical range of 0.1 Pa to 8 kPa. Furthermore, swelling ratios of HA-DTPH-Cl+ hydrogels are highly influenced by the ionic strength and pH. Remarkably HA- DTPH- dHA+ hydrogels upon incubation in a solution of pH 7 showed a feedback loop swelling behaviour. At the swollen state of the hydrogel, the ionic cross-linker dHA+, leaked out of the hydrogel network, acidified the solution, which resulted in shrinking of the hydrogel. Biological properties like enzymatic degradability showed that the half-live of HA-DTPH-Cl+ hydrogels are increasing with increasing capacity of the ionic cross-linker to form hydrogen bonds. Moreover, due to the absence of any toxic agent during the hydrogel formation the hydrogel system was used for live cell applications such as cell encapsulation or cell adhesion studies. To conclude, a hybrid double cross-linked hydrogel system could be presented, mimicking the ECM, in a minimal model and a critical influence of physical cross-links is observed from results obtained by characterizing the physical and biochemical properties by investigating the gels’ swelling capability, response to environmental changes and sensitivity to hyaluronidases. Depending on the desired biomedical application, these hydrogel systems can be tuned in regards to their stiffness, swelling behavior and degradability enabling applications in 3D tissue engineering, drug delivery and regenerative medicine.
... Therefore, sodium alginate is the main polysaccharide found in the tested brown seaweeds, despite the small-signal appearing between 1710 cm −1 and 1730 cm −1 , particularly in the spectra of Fucus guiryi, S. muticum, S. polyschides, L. ochroleuca, and F. vesiculosus, corresponding to the carbonyl group as the carboxylic acid ester form (C=O). The abroad bands at 1600-1610 cm −1 were suggested as the O-C-O carboxylate asymmetric stretching [23,24]. The bands located at 1400-1428 cm −1 were assigned to C-OH deformation vibration with the involvement of the symmetric stretching vibration of O-C-O [13,25]. ...
Article
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Alginates are widely used as gelling agents in textile print pastes, medical industries, impression material in dentistry, and anticoagulant material in toothpaste. In the present study, the content and spectroscopic characterization (1H NMR and FT-IR) of the sodium alginates were investigated in the eight brown seaweeds Sargassum muticum, Fucus vesiculosus f. volubilis, Carpodesmia tamariscifolia, Bifurcaria bifurcata, Laminaria ochroleuca, Cystoseira humilis, Saccorhiza polyschides, and Fucus guiryi harvested from the NW Atlantic coast of Morocco. The results proved that the most studied algae depicted alginate yields higher than 18% dry weight. The FT-IR analysis showed that the spectra of the extracted alginates exhibited significant similarities to the commercial alginate from Sigma-Aldrich. The 1H NMR spectroscopy indicated that the extracted alginates have a high content of β-D-mannuronic (M) than α-L-guluronic acid (G) with M/G ratio values ranging from 1.04 to 4.41. The homopolymeric fractions FMM are remarkably high compared to the FGG and heteropolymeric fractions (FGM = FMG) especially for F. guiryi, C humilis, C. tamariscifolia, L. ochroleuca, and S. polyschides. Nevertheless, the heteropolymeric fractions (FGM/FMG) are quite abundant in the alginates of S. muticum, F. vesiculosus f. volubilis, and B. bifurcata accounting for more than 52% of the polymer diads. Based on these results, the investigated algal species (except Fucus guiryi and Bifurcaria bifurcata) could be regarded as potential sources of alginates for industrial uses.
... With the increase of active chlorine concentration, the band reflecting the adsorbed H 2 O shifted to a lower wavenumber further accompanied by an increasingly obvious carboxyl band at about 1600 cm −1 (Fig. S3B). The absorption band at 1600 cm −1 represented the carboxylate assymetric stretching was reported by Bi, Mahmood, Arman, Taj, and Iqbal (2007). In a recent study, Barthold, Kletting, Taffner, Carvalhowodarz, Lepeltier, Loretz, et al. (2016) confirmed that the band occurring at 1600 cm −1 was ascribed to C=O assymetric stretching in the carboxyl anion COONa. ...
Preprint
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Enhanced dispersion stability and heavy metal ion adsorption capability of oxidized starch nanoparticles, Food Chemistry (2017), doi: http://dx. Abstract Starch nanoparticles (SNPs) have attracted much research interest recently due to their biodegradability and biocompatibility. However, practical utilization of SNPs is generally restricted due to their weak colloid stability and reduced functionality. In this work, SNPs were functionally modified by sodium hypochlorite (1-5% active chlorine based on dry SNPs weight). The degree of modification, particle size, stability, and adsorption characteristics of the SNPs were systematically investigated. The results showed that as the active chlorine concentration increased, the carbonyl and carboxyl contents increased to 0.150% and 0.855%, respectively. Compared with SNPs, the zeta potential value of SNPs modified with 5% active chlorine increased significantly (p < 0.05) from-13 to-31 mV and the dispersion stability of modified SNPs was remarkably improved. Moreover, modified SNPs exhibited high adsorption capacities for Pb 2+ and Cu 2+ , suggesting that they could be employed as a novel absorbent for removal of heavy metal ions.
... Alginate beads as such have been studied extensively for their adsorption characteristics due to their high porosity. Adsorption studies of heavy metals like cadmium (Bi et al. 2007), lead (Nińã et al. 2007), and chromium (Pandey et al. 2007;Mahmoud and Mohamed 2015) have reiterated the alginate's capacity for high diffusion of adsorbates. On retrospection, activated carbon and alginate beads proved to be an efficient adsorbent for low molecular weighted dyes like methylene blue-319.85 ...
Article
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The disodium salt of Rose Bengal [4, 5, 6, 7-tetrachloro-2′, 4′, 5′, 7′-tetraiodofluorescein] commonly finds application in medical procedures and its removal from aqueous solution is difficult owing to its high molecular weight of 1017.67 g/mol. Activated carbon was prepared from Prosopis juliflora and immobilized into sodium alginate beads and doped with aniline for enhanced adsorption of Rose Bengal. The effect of initial dye concentration, beads’ dosage, contact time, and the temperature over the adsorption of Rose Bengal dye were studied. The optimum conditions derived for maximum dye uptake capacity were 4 mg/L of initial dye concentration, contact time of 60 min with the adsorbent dosage of 0.2 g, and temperature of 303 K at neutral pH. The equilibrium data were found to be best fitted for Langmuir −1 model, whereas the kinetics were interpreted through Ho-Mckay’s pseudo-second-order equation. The adsorbents were subjected to thermo-gravimetric studies to determine the activation energy under a heating rate of 20 °C/min. The activation energy was computed using Broido’s plot and was found to be 35.21 ± 0.84 kJ/mol for the activated carbon, and 16.77 ± 2.19 kJ/mol for the dye-adsorbed beads. The heat capacity was determined through differential scanning calorimetry and was calculated to be 19.41 J/g °C for activated carbon and 39.43 J/g °C for beads post-adsorption of Rose Bengal dye.
... The absorption band at 1395 cm −1 shows the weaker COO symmetric stretching vibration of the carboxylate group. The characteristic peaks obtained in this study correlates closely with previous studies (Bi, Mahmood, Arman, Taj, & Iqbal, 2007;Fenoradosoa et al., 2010;Fertah, 2017;Latifi, Sadegh Nejad, & Babavalian, 2015;Papageorgiou et al., 2010;Rhein-Knudsen, Ale, Ajalloueian, & Meyer, 2017) giving strong bands at around 1600 and 1400 cm −1 indicative of the asymmetric and symmetric vibrations. The presence of these carboxylate groups further show that the alginate was extracted at alkaline pH in the form of a sodium alginate salt (Rhein-Knudsen et al., 2017b). ...
Article
Sargassum in the Caribbean region has affected the livelihood of several coastal communities due to the influx of large quantities of the seaweed in recent times. This article seeks to explore how waste Sargassum natans can be utilized to produce sodium alginate. The novelty in this research lies in the optimization process, whereby multistage extraction and precipitation were investigated over commonly used single stage processing, in an effort to maximize both yield and purity. The results showed that a maximum yield of 19% was observed after 1 stage, while the purity was 74% after 4 stages. In addition, optimization of the multistage precipitation process using the Global Optimization Toolbox in MATLAB R2017b provided a novel model which indicated that a compromise between the maximum purity and yield can be obtained at 3 stages; 71–74% and 12–16% respectively. Furthermore, characterization was done using FTIR and NMR, with results comparable to a commercial sodium alginate brand, giving absorption bands at 1610 cm⁻¹ and 1395 cm⁻¹ and an M/G ratio of 0.51 respectively.
... Presence of polysaccharides (sugars, uronic acid and sulfates groups), proteins, and polyphenols were determined by selecting the corresponding wavenumbers. (Bi et al., 2007;Prati et al., 2010;Gomez-Ordonez and Ruperez, 2011;Marimuthu et al., 2012;Girija et al., 2013;Kannan, 2014;Sugiono et al., 2014;Rodrigues et al., 2015;Kusumaningsih et al., 2016). ...
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En France et Indonésie, Sargassum est une espèce abondante mais elle algue n’a pas encore été exploitée de façon optimale. Sargassum contient de nombreux métabolites primaires ainsi que des composés bioactifs, dont les phlorotannins, ayant une large gamme de propriétés pharmacologiques intéressantes à valoriser. L’hétérogénéité et la complexité de la paroi cellulaire des algues réduisent fortement l’efficacité d’extraction conventionnelle. Cette étude a eu trois principaux objectifs (1) la caractérisation de la composition biochimique de Sargassum et ses variations saisonnières, (2) l'extraction solide-liquide et (3) l'extraction assistée par enzymes des phlorotannins et l’étude de leurs activités biologiques. Dans cette étude, les minéraux de Sargassum représentent d’une valeur importance avec une teneur qui atteint 33% suivi par les protéines avec 24% de la matière sèche. Les sucres ne représentent que 13% de la matière sèche. La composition biochimique de Sargassum, comme pour la plupart des algues, est fortement affectée par les saisons et est liée au cycle de vie de l’algue. La saisonnalité affecte également la production de phlorotannins. L’étude des différents procédés d’extraction montre que les rendements sont plus faibles pour une extraction solide-liquide traditionnelle (5 à 24% de la matière sèche de l'algue) par rapport à l'extraction assistée par enzyme (21 à 38% de la matière sèche de l'algue). L’extraction assistée par enzymes augmente le rendement d’extraction des polyphénols par rapport à l'extraction solide-liquide. Les extraits obtenus par extraction assistée par enzymes présentent une forte activité antiradicalaire.
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s The behavior and toxicity of nanoparticles could be affected significantly by the ubiquitous natural organic matter (NOM) in aquatic environments. However, the influence of NOM on nanoparticles along the food chain remains largely unknown. This study constructed bacteria Escherichia coli (E. coli) – protozoa Tetrahymena thermophila (T. thermophila) to evaluate the influence of NOM on the bioaccumulation, trophic transfer and toxicity of silver nanoparticles (Ag NPs). Results demonstrated that NOM could reduce the toxicity of Ag NPs to E. coli and T. thermophila by different influence mechanisms (e.g., reduce Ag NPs accumulation or complex with dissolved silver ion (Ag⁺)) which related to the type of NOM and organisms. Moreover, Ag NPs can be transferred and biomagnified to T. thermophila via trophic transfer. Three typical NOM could significantly increase the trophic transfer factors of Ag NPs ranging from 1.16 to 2.49, which may be ascribed to NOM reducing the capacity for T. thermophila to excrete total silver (Ag) as NOM could significantly change the form of Ag. These findings provide a novel insight into the impact of NOM on the ecological risk posed by Ag NPs through the food chain and emphasize the need to understand further the interactions between nanoparticles and NOM in various ecosystems.
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A novel phytic acid-doped sodium alginate aerogel (Alg-PA) was prepared via a simple doping and freeze-drying method and was used as a self-supporting electrode material to remove uranium ions from aqueous solutions. The effects of chemical composition, UO22+ concentration, solution pH, and applied voltage on the adsorption of UO22+ were investigated. Chemical adsorption was found to be the main mechanism of uranium adsorption and the application of voltage can effectively improve the adsorption capacity and adsorption rate in this removal system. The experimental maximum capacity of the Alg-PA electrode was 430.8 mg/g, while the theoretical maximum capacity of Alg-PA was found to be 563.8 mg/g. Moreover, Alg-PA also has a good reusability and selectivity to uranium ions. These advantages make Alg-PA a promising material for extracting of uranium from uranium-containing solutions.
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Accumulation of non-biodegradable plastics has adversely affected the environment. Hence, there is a need of promoting biodegradable polymer packages as substitutes for non-biodegradable plastic packages. Various studies have focused on utilisation of seaweed-derived polysaccharides in the development of coatings and films because of their renewability and sustainability for food packaging. Alginate, agar, and carrageenan are seaweed-derived polysaccharides that are widely used in the development of coatings and films due to their gelling ability. Alginates are mainly extracted from brown algae. Agar and Carrageenan are extracted from certain types of red algae. These developed coatings could be successfully utilized to extend the shelf life and maintain proper quality parameters of food during the shelf life. Films can be used to partially replace non-biodegradable polymer packages found in the market. Thus, the article reviews the basic information and applications of edible coatings and films from seaweed-derived polysaccharides in the food industry.
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The slime material from a revertant nonmucoid variant, derived by serial passage of a heavily mucoid Pseudomonas aeruginosa strain isolated from a patient with bacteremia, was found to contain 16% uronic acids, 48.5% carbohydrates, 11% protein, and 2% lipids. Chromatographic analysis by ion exchange chromatography revealed that this extracellular material consisted of three fractions, one uronic acid fraction with properties similar to those of the alginate fraction of the parental strain and two other fractions consisting of neutral sugars and proteins in approximately a 5:1 ratio. In addition, the slime material from six other clinical macroscopic nonmucoid P. aeruginosa strains was found to contain alginate. These results demonstrate that alginate production in various amounts is a property shared by all P. aeruginosa strains.
Book
The sucess of the first edition of Thickening and Gelling Agents for Food underlined the keen interest in functional food ingredients. In this second edition, the text has been completely revised and updated to reflect the current market trends. New chapters have been included to broaden the scope of materials used by the food technologist. Agar and konjac gum (flour), probably the most traditional gelling and thickening agents, but most widely utilised in the Far East, have been given greater prominence. Microcrystalline cellulose, a relatively new food stabiliser used widely in the USA, has been included. The preparation of traditional products using formulations suited to bulk food processings is described while new areas focus on low fat and low calorie foods where there is an even greater demand for controlling the stability, viscosity, gelation and mouthfeel using a broad range of thickening and gelling agents. Recent legislative changes in the USA and EC impact the use of additives including gellan gum, konjac flour, carrageenan, tara gum and microcrystal­ line cellulose: some changes have increased the number of additives ap­ proved for foods, while others allow a broader range of materials to be used in foods. The detailed information on products, properties and applications given in this second edition will enable these highly functional thickening and gelling agents to be used to full advantage.
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Hypnea musciformis and Botryocladia leptopoda (red algae), collected from Karachi coast were studied for chemical investigation and elicitor activity. Ash content of H. musciformis was bit high (40%). Yields of High Molecular Weight Crude Elicitor Preparations HM.WCEP 'Polysaccharides' of two algal genus were high (14-49%) in NaOH extracts. These HMWCEP were chemically analysed for total sugar protein, SO4 group and uronic acid contents. Simple profile of monosaccharide consisting of galactose, glucose, fucose, mannose and galactoronic acid were detected in acid and aqueous extracts of H. musciformis and B. leptopoda respectively as compared to its alkaline extracts. Elicitor activity of HMWCEP was determined in terms of induced browning in Cicer arietinum (chick pea) tissues. A pronounced browning was produced by the samples treated with various extracts of H. musciformis. The response was low in the samples treated with various preparations of B. leptopoda.
Article
The presence of non newtonian media in food industries is very common. For this reason, it is necessary characterize the fluid properties for process to be more effective. In this paper, we had studied the rheological behaviour of water-polymer dispersions using sodium alginate as the polymer. The alginate is an additive widely used in food industries. We had studied the influence of polymer concentration and temperature on the solutions viscosity. © 2002 Altaga. All rights reserved.ResumenLa frecuente presencia de fluidos de características no newtonianas en las industrias alimentarias hace necesario un conocimiento y caracterización de estas propiedades para que los procesos sean llevados a cabo de manera efectiva. En este caso se ha estudiado el comportamiento reológico de dispersiones agua-polímero (agua-Alginato Sódico). Dicho polímero es empleado en numerosas industrias como aditivo alimenticio. Se ha estudiado el efecto que causa sobre la viscosidad tanto la concentración de polímero presente en la muestra, como la temperatura a la cual se le determina. © 2002 Altaga. Todos los derechos reservados.Palabras clave: alginato, agua, caracterización reológica.ResumoA frecuente presencia de fluidos de características no newtonianas nas industrias alimentarias fai necesario un coñecemento e caracterización destas propiedades para que os procesos sexan levados a cabo de maneira efectiva. Neste caso estudiouse o comportamento reolóxico de dispersións auga—polímero (auga-alxinato sódico). Dicho polímero é empregado en numerosas industrias como aditivo alimenticio. Estudiouse o efecto que causa sobre a viscosidade tanto a concentración de polímero presente na mostra, como a temperatura a cal se lle determina. © 2002 Altaga. Tódolos dereitos reservados.Palabras chave: alxinato, auga, caracterización reolóxica.
Article
Fifteen specimens of sodium alginate from various brown algae, including species of Laminaria, Fucus and Ascophyllum, have been prepared in the laboratory or obtained from commercial sources. Tests on these samples included measurements of optical rotation, ionic mobility, rate of sedimentation, viscosity and content of sulphated ash. Most specimens were homogeneous by electrophoresis and in the ultracentrifuge. The content of alginate of the samples varied from 61.7 to 99.6%. Rate of sedimentation was strongly dependent on concentration. Electrophoretic mobilities varied only slightly. Viscosity varied much more widely than other physical properties and was the best criterion of state of polymerization. Fucoidin was detected as impurity in some preparations.From the best preparations examined the following values were obtained: []d20° = −133°to −140°; μ = 2.9 to 3.1 × 10−4 cm.2 sec.−1 volt−1 at 25°, pH 5.5, I 0.05; s40 = 1.3 to 1.6 S (c = 0.5%); sulphated ash = 34.0 to 35.9%. Viscosity varied from 2 to 20 centistokes at 25°in 0°1n-NaCl (c = 0.25% w/w). Values for [η] varied from 3.6 to 19.2 corresponding to a degree of polymerization of 210 to 1,100 and particle weight of 42,000 to 222,000. The specific refractive increment of sodium alginate was found to be 0.160 g.−1 cm.3.
Article
Glucose oxidase (GOD) was encapsulated within calcium alginate gel capsules. The effects of gelation conditions on capsule characteristics such as thickness, percentage of enzyme leakage and encapsulation efficiency were studied and the optimal conditions for GOD encapsulation obtained. Oxidation of glucose to gluconic acid followed Michaelis–Menten kinetics.
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Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orange-yellow color when treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.
Article
I.r. absorption bands associated with the functional groups of carboxylic acid derivatives are useful for the analysis of alginates and pectins. The ester, amide, and uronate contents of pectins and the uronate content of alginates were determined, respectively, from the ester-carbonyl stretching band (1740 cm- minus 1), the amide I band (1650 cm- minus 1), and the carboxylate antisymmetric stretching band (1607 cm- minus 1) obtained from the spectra of solutions in D2O-phosphate buffer. The results are accurate to within plus or minus 2-4%, are self consistent, and agree well with the few reliable results that are available. The method should be applicable for the determination of carboxylic acid derivatives in other polysaccharides.