ArticlePDF Available

Composition and physicochemical properties of locust bean gum extracted from whole seeds by acid or water dehulling pre-treatment

Authors:

Abstract and Figures

The purpose of this study was to extract locust bean gum (LBG) from whole seeds by two different dehulling pre-treatments. The first process consisted in separating the endosperm (gum) from the hull and the germ after seeds’ pre-treatment with boiling water. The second one used acidic pre-treatment. Then the composition and the physicochemical characteristics of the isolated gum were studied in order to evaluate the effect of extraction process. Comparisons to commercial samples and temperature influence on solubility and rheological properties are included.The yield and quality of Locust bean gum from whole seeds depended on the separation method used. The separation of the seed components by boiling water pre-treatment furnished a higher yield of yellowish endosperm (51–61% w/w), whereas acid dehulling pre-treatment gave an off-white gum yield (37–48% w/w). However, the mannose and galactose content, the solubility, the molecular size and the dynamic viscosity, were higher for LBG from acid dehulling pre-treatment. In addition, a considerable influence of solubilization temperature on macromolecular characteristics and on viscosity properties was noticed.
Content may be subject to copyright.
This article was published in an Elsevier journal. The attached copy
is furnished to the author for non-commercial research and
education use, including for instruction at the author’s institution,
sharing with colleagues and providing to institution administration.
Other uses, including reproduction and distribution, or selling or
licensing copies, or posting to personal, institutional or third party
websites are prohibited.
In most cases authors are permitted to post their version of the
article (e.g. in Word or Tex form) to their personal website or
institutional repository. Authors requiring further information
regarding Elsevier’s archiving and manuscript policies are
encouraged to visit:
http://www.elsevier.com/copyright
Author's personal copy
FOOD
HYDROCOLLOIDS
Food Hydrocolloids 22 (2008) 807–818
Composition and physicochemical properties of locust bean gum
extracted from whole seeds by acid or water dehulling pre-treatment
Patrick Aubin Dakia
a,c,
, Christophe Blecker
b
, Christelle Robert
a
,
Bernard Wathelet
a
, Michel Paquot
a
a
Department of Industrial Biological Chemistry, Gembloux Agricultural University, Passage des de
´porte
´s, 2, B-5030 Gembloux, Belgium
b
Department of Food Technology, Gembloux Agricultural University, Passage des de
´porte
´s, 2, B-5030 Gembloux, Belgium
c
Department of Food Science and Technology, Abobo-Adjame
´University, 02 BP 801 Abidjan 02, Co
ˆte d’Ivoire
Received 14 July 2006; accepted 20 March 2007
Abstract
The purpose of this study was to extract locust bean gum (LBG) from whole seeds by two different dehulling pre-treatments. The first
process consisted in separating the endosperm (gum) from the hull and the germ after seeds’ pre-treatment with boiling water. The second
one used acidic pre-treatment. Then the composition and the physicochemical characteristics of the isolated gum were studied in order to
evaluate the effect of extraction process. Comparisons to commercial samples and temperature influence on solubility and rheological
properties are included.
The yield and quality of Locust bean gum from whole seeds depended on the separation method used. The separation of the seed
components by boiling water pre-treatment furnished a higher yield of yellowish endosperm (51–61% w/w), whereas acid dehulling pre-
treatment gave an off-white gum yield (37–48% w/w). However, the mannose and galactose content, the solubility, the molecular size and
the dynamic viscosity, were higher for LBG from acid dehulling pre-treatment. In addition, a considerable influence of solubilization
temperature on macromolecular characteristics and on viscosity properties was noticed.
r2007 Elsevier Ltd. All rights reserved.
Keywords: Locust bean gum; Galactomannans; Seed dehulling; Sugar composition; Solubility; Macromolecular characteristics; Rheological properties
1. Introduction
The carob gum (locust bean gum (LBG), E410) is a white
to yellowish white powder obtained by crushing the
endosperm of the seeds from the fruit pod of the carob
tree (Ceratonia siliqua L.) found in Mediterranean regions.
From farmer to co-operative, the carob tree fruit passes to
the kibblers (the firms that crush the fruit to extract the
seeds), whom will then largely sell the seeds to the locust
bean gum producer.
The seed is composed of the husk (30–33%), the
endosperm (42–46%) and the germ (23–25%) (Neukom,
1988). Current annual production in the world is estimated
to be 415,000 tons and current prices are 12 to 22 euros/kg
or more depending on grade and supplier.
The carob seeds are covered with a tight-fitting brown
coat and the first stage of the gum extraction involves
removal of the seed hull (Fig. 1). This is achieved either by
thermo-mechanical or by chemical treatment (Ensminger,
Ensminger, Konlande, & Robson, 1994;Hefty, 1953).
Then the seeds are split lengthwise and the germ is
separated from the endosperm. After germ isolation,
endosperms are ground, sifted, graded, packaged and
marketed as LBG or carob gum. Other process combining
extraction and purification (rarely used for LBG) involves
milling of the carob whole seeds, extraction by water
dissolution and precipitation with an alcohol (ethanol or
ARTICLE IN PRESS
www.elsevier.com/locate/foodhyd
0268-005X/$ - see front matter r2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.foodhyd.2007.03.007
Corresponding author. Department of Industrial Biological Chemis-
try, Gembloux Agricultural University, Passage des de
´porte
´s, 2, B-5030
Gembloux, Belgium. Tel.: +32 8162 2232; fax: +32 8162 2231.
E-mail addresses: dakia.patrick@gmail.com,dakia.p@fsagx.ac.be
(P.A. Dakia),blecker.c@fsagx.ac.be (C. Blecker),robert.c@fsagx.ac.be
(C. Robert),wathelet.b@fsagx.ac.be (B. Wathelet),
paquot.m@fsagx.ac.be (M. Paquot).
Author's personal copy
isopropanol) (da Silva & Gonc-alves, 1990;Lazaridou,
Biliaderis, & Izydorczyk, 2000).
In all procedures, the technical and economical difficul-
ties which have to be met in order to obtain sufficient pure
carob mucilage consist mainly in preventing the presence of
impurities from husk and embryo fractions. The process
must avoid, as far as possible, the alteration of the natural
chemical
:
and physical characteristics of the carob gum.
LBG was the first galactomannan used both industrially
(paper, textile, pharmaceutical, cosmetic and other indus-
tries) and in food products (ice cream and other prepara-
tions). An important application of this biopolymer is its
ability to form very viscous solution at relatively low
concentration, to stabilize dispersion and emulsion and to
replace fat in many dairy products. Carob gum properties
are generally unaffected by pH, salts, or heat processing
because it is non-ionic. It is also compatible with other
gums and thickening agents (carraghenan, agar, xanthan)
to form a more elastic and stronger gel (Goycoolea,
Morris, & Gidley, 1995).
Galactomannans are linear polysaccharides based on a
b-(l-4)-mannane backbone to which single D-galactopyr-
anosyl residues are attached via a-(l-6) linkages (da Silva
&Gonc-alves, 1990). In LBG the side branches are not
spaced uniformly. There are also segments of the chain
composed of unsubstituted b-D-mannopyranosyl units,
alternating with chain segments in witch a-D-galactopyr-
anosyl side branches are linked to each of the main chain
units (Daas Piet, Schols Henk, & De Jongh Harmen, 2000).
Among the major commercially available galactoman-
nans (carob, guar and tara gums), carob galactomannan
has the lowest galactose content (20%) (Richarsdson,
Willmer, & Foster, 1998). The average mannose to
galactose ratio (M/G) in LBG is approximately 3.5
compared with guar gum (GG) with an average ratio of
about 1.8 and tara gum (TG) with a ratio of 3.0 (Batlle &
Tous, 1997;Bourriot, Garnier, & Doublier, 1999;Dea &
Morrison, 1975;Fox, 1992;Morris, 1998).
The degree of galactose substitution affects water
solubility. Guar gum is cold water soluble whereas LBG
shows low solubility at ambient temperature and heat
treatment is required for maximum solubilization, to
achieve the best water binding capacity (Gainsford,
Harding, Mitchell, & Bradley, 1986;Hui & Neukom,
1964;Maier, Anderson, Karl, Magnuson, & Whistler,
1993).
The molecular size and the fine structure (M/G ratio,
galactose distribution in the mannose linear chain)
influence solubility mechanism and ability to self-associate
(intrachain and interchain interactions), and also controls
the rheological properties of LBG; in particular, a higher
mannose to galactose ratio (M/G) leads to higher thicken-
ing (Lazaridou et al., 2000).
Different techniques are used to characterize polysac-
charide structure. The molecular weight distributions can
be determined by size exclusion chromatography (SEC),
and the monomeric sugars content and M/G ratio are
generally determined by gas chromatography (GC) or by
high pressure anion exchange chromatography (HPAEC)
after partial and total hydrolysis catalyzed by acid. The
galactose repartition along the mannane chain can be
characterized by
13
C NMR spectroscopy, or by enzymatic
method with b-D-mannanase which degrade specifically the
nonsubstituted regions of galactomannans (Daas Piet et
al., 2000).
Carob seed galactomannans differ in their M/G ratio,
depending on the origin, the variety and age of the plant
(tree), the growth conditions (climate, soil) (Bargallo, Di
Lorenzo, Meli, & Crescimanno, 1997;Deuel & Neukom,
1954) and the method used for extraction of the
polysaccharide in term of purification of crude gum (Dea
& Morrison, 1975). However, very little was published
about carob seeds dehulling procedures or crude gum
separation from whole seeds and particularly their effects
on composition and physicochemical properties of the
carob gum.
So, the objective of the present study was to compare
two dehusking pre-treatments. One treatment uses boiling
water and the other acidic conditions in order to facilitate
the seeds dehulling. The aim is to obtain carob mucilage
with low husk and germ contamination but also to evaluate
the effects of the pre-treatment on the gum properties
(yield, chemical composition, mannose to galactose ratio,
solubility, macromolecular characteristics and rheological
properties).
2. Material and methods
2.1. Raw material and extraction procedures
The carob seeds (commercial seeds obtained after
kibbling) used in this study were provided by Tropical
Agriculture S.A. (Malaga, Spain) and gauged beforehand
according to their morphology; their length ranging
between 5.5 and 6 mm and their thickness ranging between
3.5 and 4 mm.
Two different dehulling pre-treatments of the carob
seeds, with water or acid, were tested after preliminary
experiments.
ARTICLE IN PRESS
Fig. 1. Carob seed constituents.
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818808
Author's personal copy
Procedure A: LBGw (locust bean gum, from water
extraction) was obtained in the following conditions:
Whole carob seeds (100 gE780 seeds) were immersed in
800 ml of boiling water at 100 1C for 1 h. During this pre-
treatment the seeds swell, without tegument disruption.
Seeds were removed from the water; washed and the
tegument broken and separated manually from the
endosperm. Then the germ was separated from the
endosperms which were dried in an oven at 100 1C for
1–2 h, until constant weight. The endosperms were then
milled (MF 10, IKA, Staufen, Germany) and sifted with a
0.125 mm sieve to obtain LBGw flour.
Procedure B: LBGa (locust bean gum, from acid
extraction) was obtained under the following conditions:
Whole seeds (100 gE780 seeds) were macerated in 60 ml of
H
2
SO
4
/H
2
O 60/40 v/v solution at 60 1C for a 1h. This
treatment with acid at an elevated temperature carbonized
the hull which is removed by an extensive washing and
rubbing operation in water and through a metallic sieve of
2 mm. The dehusked seeds were dried at 100 1C for 30 min
and then briefly crushed (10 seeds dehusked/3 s) with a
laboratory mill (model MF 10, IKA, Staufen, Germany) to
separate the two endosperms (albumen) and to release the
germ (Fig. 1) which is detached in pieces because of being
more friable. The germ fractions were then sifted off from
the unbroken endosperm halves with a 2 mm sieve. The
pieces of endosperm are then ground and sifted with a
0.125 mm sieve to furnish LBGa flour, from acid dehulling
pre-treatment.
Two commercial samples of locust bean gum are used as
standard controls:
LBG FG (food grade high quality, from BF GUM
Morocco) and LBG AG (GRINSTED LBG 047, extra
high analytical grade, Viscosity X2800 mPa s (Brookfield
RVT, Spindle No 3, 20 rpm, 1% sol. 25 1C), lot number
3121659 from DANISCO Denmark).
2.2. Chemical analysis
The moisture content of the carob gum was determined
gravimetrically after heating the material (500 mg) in an
oven at 105 1C for 24 h.
The ash content of the carob gum (3 g) was determined
gravimetrically after dry mineralization at 600 1C for 12 h.
The lipid content of the carob gum (3 g) was determined
by extraction with chloroform/methanol (2/1 v/v) as
described by Folch, Lees, and Stanley (1957). The
solvent was removed by rotatory evaporation at 35–40 1C
under reduced pressure. The extracted lipids were
dried in a desiccator to constant weight and determined
gravimetrically.
The protein content of the carob gum (150 mg) was
determined by the Kjeldahl procedure, after mineralization
(with a 1000 KJELTABS MQ tablet and a Digestion
System 20, 1015 Digester, Tecator AB, Ho
¨gana
¨s, Sweden)
and distillation (by a Kjeltec Auto 1030 Analyser, Tecator
AB, Ho
¨gana
¨s, Sweden) with a conversion factor of 5.87
according to Anderson (1986).
The nitrogen free extract (as carbohydrate content) was
estimated by difference.
2.3. Sugar composition and mannose to galactose ratio by
GC
The neutral sugars in carob gum were determined as
their alditol-acetate derivatives by gas–liquid chromato-
graphy (GLC) analysis after hydrolysis with 1 M HCl
hydrochloric acid for 2 h at 110 1C according to the slightly
modified method described previously by Albersheim,
Nevins, English, and Karr (1967) and Blakeney, Harris,
Henry, and Stone (1983). Optimum hydrolysis time is
dependent on a balance between the rate of release of
hydrolysable polysaccharides and the degradation of
monosaccharides that occurs during prolonged treatment
under experimental conditions. The hydrolysate was
centrifuged (at 2000 rpm, 5 min in a Centrifuge MSE
Mistral 4L) and the sugars (0.4 ml of supernatant) were
reduced to their corresponding alditols by adding 2 ml of
DMSO containing 2% NaBH
4
. Reduction was performed
for 90 min at 40 1C. The excess of sodium borohydride was
then destroyed by adding 0.6 ml glacial acetic acid.
Acetylation was then performed with acetic anhydride
(4 ml, 10 min at room temperature) in the presence of
1-methylimidazole (0.4 ml) as a catalyst. Acetylation was
stopped with 10 ml deionized water and the acetylated
alditols were partitioned between dichloromethane (4.0 ml)
and water. After the phase had separated, the lower one
was removed with a pasteur pipette and putted (1 ml) in a
septum-cap vial.
2-deoxy-D-glucose was employed as internal standard
and standards of different carbohydrates (L(+)-rhamnose,
D(–)-arabinose, D(+)-xylose, D(+)-mannose, D(+)-glucose
and D(+)-galactose from Fluka Chemie (Buchs, Switzer-
land)) were used.
The analyses were accomplished using a Hewlett-
Packard Agilent 6890 series gas chromatograph equipped
with a HP1 column (30 m 0.32 mm, film thickness
0.25 mm). Derivatized extracts (1.0 ml) in dichloromethane
were injected on-column. Helium was used as the carrier
gas with a flow of 1.6 ml/min. The injection temperature
was 290 1C and the temperature program was: 1 min at
120 1C, linear increase in 4 min to 220 1C and finally in
35 min to 290 1C and this temperature was then maintained
for 4 min. Compounds were detected using a flame
ionization detector at 320 1C.
2.4. Solubility measurements
Samples (4) were prepared 0.1% w/w concentration on a
dry weight basis (i.e. solids content is constant) at ambient
temperature (23–25 1C) for 0.5, 1, 2 and 3 h, under
mechanical stirring.
ARTICLE IN PRESS
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818 809
Author's personal copy
Others preparations were made in the same conditions
but at 80 1C for 5, 10, 30 and 60 min.
Then, the corresponding solution was taken and
centrifuged (6000g, 30 min, at 20 1C) to remove the
insoluble material. The supernatent recovered and the final
polymer concentrations were determined as total solids
dried at 105 1C for 24 h in an air-circulated oven.
solubility ð%Þ
¼supernatent concentration ðmg=mlÞ
initial preparation concentration ðmg=mlÞ100. ð1Þ
2.5. Molecular weight by size exclusion chromatography
(SEC)
The gums were solubilized (0.1% w/v on a dry weight
basis) in deionized water at 80 1C for 30 min under
mechanical stirring. Insoluble material was removed by
centrifugation at 9400g(14000 rpm in a Centrifuge
BECKMAN J-21C, rotor JA14) for 30 min at 20 1C and
filtration through a 0.45 mm membrane filter prior to the
injection onto the column and final polymer concentration
determination.
The weight-average molecular weight (M
w
) and intrinsic
viscosity [Z] of carob gums were determined using high
performance size exclusion chromatography (HPLC
Waters 2690 ALLIANCE) equipped with a TSKGMPW
XL
column (TosoHaas Co. Ltd., Tokyo, Japan) and coupled
with refractive index (RI, Model 2410, Waters Corpora-
tion, Milford, USA), viscosity and right angle laser light-
scattering (Dual Detector, Model 270, Viscotek, Houston,
USA) detectors.
The columns was thermostated at 30 1C, the flow rate
was of 0.7 ml/min, the mobile phase was 0.05 M NaNO
3
with 0.05% NaN
3
as conservator and the injection volume
was of 100 m1.
2.6. Rheological properties
2.6.1. Solution preparation
Rheological properties of carob gum were characterized
at 25 1C on carob gum solutions preparated as follows: 1%
on a dry weigh basis was prepared with distilled water at
ambient temperature (23–25 1C), under mechanical stirring
for 1 h. Other gum solutions were prepared at the same
concentration but at 80 1C for 30 min and cooled at
ambient temperature before measurements.
2.6.2. Rotational rheological analysis
Rheological measurements were performed in a Roto-
visco Haake RV20 (Germany) rotational viscometer fitted
with a thermostatic bath for temperature control. A Haake
CV20 controller was used to program the tests and the
sensor System ME30 utilizing a cone/cylinder configura-
tion was used for measurement. Each sample (3 ml) was
placed in the sensor system for measurement at 25 1C.
Curves of shear stress (t) as a function of the shear rate (D),
were obtained with the following program: 5 min from 0 to
300 s
1
(the maximum shear rate).
Experimental data were fitted to Ostwald–de Waele
model or power low model ðt¼kDnÞusing Excel 2000
software. The parameters kand n, which are related to
consistency and flow index, respectively, were determined.
For n¼1, the power-law model reduces to a Newtonian
fluid model (A fluid which exhibits a viscosity that is
independent of the current shear conditions). For no1 the
fluid behaves as a pseudoplastic and for n41 the fluid
behaves as a dilatant (less common).
2.6.3. Oscillatory dynamic tests
Oscillatory tests were performed at 25 1C using a stress
controlled rheometer (Bohlin Instruments In., NJ) fitted
with a cone and plate geometry (41cone angle, 40 mm plate
diameter, 150 mm gap). Variations in G0(dynamic elastic
modulus), G00 (dynamic viscous modulus) and Z(complex
viscosity) were recorded as a function of frequency, thus
obtaining the characteristic mechanical spectra. Before
performing these frequency spectra, the linear viscoelastic
region was determined and an appropriate strain was
selected, by means of strain sweeps conducted at a constant
frequency (1 Hz) and variable strain (g) ranging from 0 to
50 Pa. This type of test determines the maximum deforma-
tion attainable for a system without structural failure.
Frequency sweeps from 0.01 to 10 Hz were performed
at constant strain within the linear viscoelastic range
(g¼1 Pa).
Descriptive statistics were calculated and results were
expressed as means7SD. All the measurements were
performed at least in duplicate.
3. Results and discussion
3.1. Extraction yield
Table 1 shows the results of the separation of carob seeds
in their three components (husk, endosperm and germ)
after water or acid pre-treatments.
In both extraction procedures, the cuticle was easily
broken by manual shear of the seeds.
In boiling water extraction procedure to produce LBGw
flour, the volume of seeds had greatly increased after the
boiling period. So, the cuticle was easily broken and
the germ easily separated (manually) from the endosperm.
On the other hand, the endosperms were swollen. So, the
boiling water has perhaps achieved the water binding
capacity of the gum (endosperm). The final LBGw
contained low remains of husk and germs and was
yellowish. It may be due to the passage of pigment or
tannic substances (Avallone, Plessi, Baraldi, & Monzani,
1997) from the brown tegument or from the yellow germ
to the endosperm. Yield (dried endosperm) obtained
by this procedure represents 56% of the total weight of
the entire seeds.
ARTICLE IN PRESS
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818810
Author's personal copy
In the acid pre-treatment for LBGa flour, the carob seeds
were not swelled. Skin was burnt and the disintegrated
(carbonized) husks were easily eliminated by washing and
manual shear. After dehusked seeds drying, the germ and
endosperm were separated by a brief milling. In the case of
acid pre-treatment, fragments of hull remained attached to
the dehusked seed. In particular, a thin skin layer around
the dehusked seed, at the joint of the two endosperms
(Fig. 1), was more resistant at the acidic attack. These
resistant coats contaminated the endosperm flours during
the milling operation. The acid pre-treatment rendered an
off white mucilage (LBGa flour) containing low remains of
the husk and germ fractions. If the acid pre-treatment,
which appeared as a progressive hydrolysis from external
to internal component of carob seed, was prolonged after
husk carbonization, the acid may nibble importantly the
endosperm (gum source). So, it is important to follow
the acidic attack cautiously. The endosperm (LBGa)
yield by this procedure represents 43% of the total weight
of the seeds.
The endosperm (which is the most important fraction in
carob seed) yields from acid (43%) and water (56%)
procedures were significantly different. It may be due to the
partial hydrolysis of the endosperm in acid dehulling
procedure. In addition, the husk (37%), calculated by
difference to 100% in acid pre-treatment, contained
certainly some hydrolyzed gum (in comparison with the
husk (23%) obtained by the aqueous pre-treatment). These
results are close to those reported (42–46% of gum) by
Herald (1986), and Neukom (1988). The extraction yield
depends on gum separation method from the whole seed, in
addition to the origin and the culture conditions of the
carob tree (Bargallo et al., 1997;Lazaridou et al., 2000).
Boiling water method could be selected for its higher
yield, but for gum whiteness acid pre-treatment could be
preferred.
3.2. Chemical composition
The chemical composition of the two isolated flours of
carob seeds gum (LBGw and LBGa) is presented in Table
2. Values of commercial gums (LBG FG and LBG AG) of
carob seeds are included in the table, for comparison. In
general results were quite similar each other and closer to
those of literature (da Silva & Gonc-alves, 1990;Herald,
1986). However, high protein content observed in LBGw
(7.4%) compared to LBGa (5.2%) may be due to a greater
contamination by carob germ which contains a high
(54–67%) protein content (Dakia, Wathelet & Paquot,
2007).
According to da Silva and Gonc-alves (1990) the protein
content (5%) of the crude gum reflects the natural
presence of structural proteins and enzymes, but also a
possible contamination with seed germ.
3.3. Sugars composition
Results obtained from gas chromatography (Table 3)
revealed the presence of mannose and galactose as major
sugars, with a level of 64.9% and 17.9% in LBGa (and in
commercial gums), whereas a lesser quantity was found in
LBGw (51.9% and 14.6%). Rizzo, Tomaselli, Gentile, La
ARTICLE IN PRESS
Table 1
Portions (% w/w) of husk, endosperm and germ of carob whole seeds
isolated by acid and boiling water procedures. The whole seed of carob
contains 9.5% of moisture
Boiling water pre-treatment Acid pre-treatment
Husk 237237
a
73
Endosperm (LBG) 56754376
Germ 21742073
Data are the results of minimum three determinations7SD.
a
By difference.
Table 2
Composition (%) of carob seed gum
Extracted gums Commercial gums
LBGw LBGa LBG FG LBG AG
Moisture 6.570.6 5.970.1 14.570.5 9.870.3
Ashes 1.570.1 0.770.2 0.870.1 1.070.3
Total proteins
(N 5.87)
7.470.7 5.270.4 5.770.4 6.070.5
Lipids (neutral
and polar)
1.570.1 1.370.1 0.870.2 1.070.2
Nitrogen free
extract (by
difference)
89.6 92.8 92.8 91.9
Data are the means of triplicate analysis7SD. All measurements are on a
dry weight basis (except for moisture).
With LBGw (gum from Water dehusking pre-treatment), LBGa (gum
from Acid dehusking pre-treatment), LBG FG (Food grade commercial
gum), LBG AG (Analytical grade commercial gum).
Table 3
Monosaccharide composition (% w/w) of the LBG samples
Extracted gums Commercial gums
LBGw LBGa LBG FG LBG AG
Rhamnose 0.270.1 0.170.0 0.270.1 0.170.0
Arabinose 1.970.1 1.270.1 1.370.2 1.370.1
Xylose 0.670.1 0.770.1 0.670.1 0.470.1
Mannose (M) 51.970.5 64.970.3 62.870.4 67.270.6
Glucose 4.170.1 2.570.2 1.770.1 1.770.2
Galactose (G) 14.670.2 17.970.5 18.570.2 18.070.6
Galactomannan (M+G) 66.5 82.8 81.3 85.2
Total sugars 73.3 87.3 85.1 88.7
M/G Ratio 3.5 3.6 3.4 3.7
Data are the means of triplicate analysis7SD. All measurements are on a
dry weight basis.
With LBGw (gum from Water dehusking pre-treatment), LBGa (gum
from Acid dehusking pre-treatment), LBG FG (Food grade commercial
gum), LBG AG (Analytical grade commercial gum).
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818 811
Author's personal copy
Malfa, and Maccarone (2004) have previously published a
less amount of mannose and galactose (40% and 10%)
for carob gums also extracted by boiling water treatment.
The total galactomannan (mannose+galactose) content
(67% LBGw compared to 81–85% in the other LBG
samples) showed evident difference (Table 3). In addition,
the nitrogen free extract (89.6% LBGw and 92.8% for
LBGa, calculated by difference in Table 2) compared to the
total amount of sugars (73.3% LBGw and 87.3% of total
weight of LBGa sample, in Table 3) showed a difference of
16.3% for LBGw and 5.5% for LBGa.
These differences could be attributed to an incomplete
hydrolysis (due to contaminants or samples particles size)
or a degradation of part of released sugars during acid
hydrolysis. It can be hypothesized that LBGw sample
became more sensitive to acid hydrolysis (i.e. boiling pre-
treatment increased the rate of polymer degradation as
cooked starches, Sveinbjo
¨rnsson, Murphy, & Ude
´n, 2007).
The rate of polymer degradation may also be increased by
the possible presence of small molecules in LBGw. In
addition, the remainder (difference between nitrogen free
extract and total sugars) may consist of volatile compo-
nents, residual water or unidentified sugars.
Further work might be carried out to determine the exact
content of total carbohydrates in LBG flour (e.g. photo-
metrically using the anthrone reaction).
The Mannose/Galactose (M/G) ratios for LBGw (3.5),
LBGa (3.6) and commercial gums (LBG FG (3.4), LBG
AG (3.7)) are in good agreement with those (43:1)
generally reported for carob gums by others researchers
(Ramirez., 2002;Richarsdon et al., 1998).
According to da Silva and Gonc-alves (1990) the presence
of minor amount of rhamnose, arabinose, xylose and
glucose could be attributed to a more complex poly-
saccharide composition or probably to contaminants
proceeding from the seed coat. Therefore the relatively
high content of glucose in LBGw (4.1% compared to
2% for the other gums) may reflect a relative greater
contamination by husk fractions.
3.4. Solubility measurements
An overview of the curves of solubility measurement
(Fig. 2 compared to Fig. 3) shows that the carob gum
is partially (50% at 25 1C/1 h) cold water-soluble
and needs to be heated to reach maximum (70–85% at
80 1C/30 min) solubility. This is perfectly in agreement with
the literature (Gainsford et al., 1986;Garcia-Ochoa &
Casas, 1992;Hui & Neukom, 1964;Ko
¨k, Hill, & Mitchell,
1999b;Maier et al., 1993;Richarsdon et al., 1998). This
difference in solubilization may be due to the fact that at
high temperature some molecules (i.e. high molecular
weight components and galactomannan with low level
of galactoses residues) are dissolved which are not at
low temperature, showing that locust bean gum is not
a very homogeneous galactomannan (Garcia-Ochoa &
Casas, 1992).
From Fig. 2 (solubility at room temperature); LBGw
and LBGa curves are almost superimposed. However, the
slight difference observed (e.g. 53% LBGw and 48% LBGa
at 25 1C/1 h) could be attributed to the possible presence of
a great number of small molecules in LBGw than in LBGa
and a possible contamination by protein from germ (as
described in Section 3.2). According to Del Re-Jime
´nez and
Amado
`(1989), more than 50% of the proteins of carob
germ are water soluble at room temperature.
At 80 1C(Fig. 3), it seems evident that LBGa (82%
at 80 1C/30 min) is more soluble than LBGw (70% at
80 1C/30 min). Difference in solubility at 80 1C may be
due to the difference in gums purity. It can be hypothesized
that LBGa may be purer in galactomannan (66.5%
LBGw and 82.8% LBGa, as described in Section 3.3,
Table 3) and may contain a great number of high molecules
than LBGw. In addition, structural change may be
occurred in LBGw during boiling water dehulling
process making this sample probably less soluble at high
temperature.
In general, the solubility of carob gum samples does not
exceed 90%, which is related to some variable such as
granulation (particle size) (Herald, 1986;Pollard et al.,
2007) and impurities (i.e. husk, germs fractions) in the gum
flours.
ARTICLE IN PRESS
Fig. 2. Solubility kinetic at 25 1C of carob gum extracted by water (LBGw
m) and by acid (LBGa &) dehulling pre-treatments.
Fig. 3. Solubility kinetic at 80 1C of carob gums extracted by water
(LBGw m) and by acid (LBGa &) dehulling pre-treatments.
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818812
Author's personal copy
3.5. Macromolecular characteristics
3.5.1. Chromatographic profiles, weight-average molecular
weights and intrinsic viscosities
The polysaccharide distribution of the extracted gums
(LBGw and LBGa) and for comparison the commercial
gums (LBG FG and LBG AG) was analyzed by gel
permeation chromatography (GPC). Fig. 4 shows the
superimposed chromatograms of the four LBG flours,
whereas Table 4 reports other informative chromato-
graphic data.
Large variations in molecular size distributions of LBG
samples were evident regarding their chromatographic
profiles. Such difference in e1ution profiles reflects differ-
ences in molecular size, structure of these extracted
polysaccharides and certainly has implications for the
rheological properties of carob gum solutions. In addition,
it should be mentioned that the chromatogram presented in
Fig. 4 is connected to the refractive index signal, so the
peak areas depend on the concentration.
The macromolecular property measurements, calculated
using the signals from the tree detectors (as described in
Section 2.5), were shown in Table 4. The result shows that
the weight-average molecular weight (M
w
) values for LBGw
(1.024 10
6
Da) compared to LBGa (0.900 10
6
Da) seem
quite similar. However, the intrinsic viscosity [Z]and
the radius of gyration (Rg) (a type of molecular size
measurement) values determined for LBGw (7.1 dl/g and
61.0 nm) were substantially lower than those of LBGa
(13.0 dl/g and 73.2 nm) and commercial gums (LBG FG and
LBG AG).
These results (LBGw compared to LBGa) indicated a
reduction in hydrodynamic volume, since the intrinsic
viscosity and the radius of gyration depend on the
dimensions and the extension of the polymer chain (Azero
& Andrade, 2002). The intrinsic viscosity (a volumetric
measurement, expressed in dl/g) is related to the reverse of
the density of the polymer in solution. A polymer rolled up
on itself (a random coil) in a very compact way will have a
strong density in solution, and thus a low intrinsic
viscosity. Therefore, the most likely explanation for the
ARTICLE IN PRESS
Fig. 4. High performance size exclusion chromatogram (profil) of extracted carob gum (LBGw and LBGa) and commercial gums (LBG FG and LBG
AG).
Table 4
Measurements of macromolecular characteristics of LBG samples by
HPSEC
Prepared at Extracted samples Commercial samples
LBGw LBGa LBG FG LBG AG
80 1C/30 min 80 1C/30 min 80 1C/30 min 80 1C/30 min
M
n
(Daltons) 0.587 10
6
0.675 10
6
0.633 10
6
1.092 10
6
M
w
(Daltons) 1.024 10
6
0.900 10
6
0.856 10
6
1.196 10
6
Pi ¼M
w
/M
n
1.74 1.33 1.35 1.09
[Z] (dl/g) 7.1 13.0 11.5 13.3
Rg (nm) 61.0 73.2 71.8 79.5
With LBGw (gum from Water dehusking pre-treatment), LBGa (gum
from Acid dehusking pre-treatment), LBG FG (Food grade commercial
gum), LBG AG (Analytical grade commercial gum).
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818 813
Author's personal copy
small [Z] and the high M
w
value for LBGw may reflect the
presence of compacted (through intramolecular associa-
tion) molecules.
In addition, the low number-average molecular weight
(M
n
) (which tends to overemphasize the importance of low
molecular weight species) and high polydispersity index
(Pi ¼M
w
/M
n
related to unhomogeneity of polysacchar-
ides) values may arise from samples whose macromolecules
had been (partially) broken (i.e. by thermal or mechanical
degradation according to Ko
¨k, Hill, & Mitchell, 1999a)
during gum extraction and/or solution preparation under
stirring (for M
w
measurement). These results suggest a
presence of great number of small molecules in LBGw and
may explain its relatively high solubility at ambient
temperature (as described in Section 3.4, Fig. 2).
According to these results (M
n
,[Z], Rg), LBGa seems to
contain a great number of high and expanded molecules
than LBGw and this could promote interchain associations
and increase its rheological properties.
In general, all values are consistent to those reported by
others researchers (Brummer, Cui, & Wang, 2003;da Silva &
Gonc-alves, 1990;Dea & Morrison, 1975;Mao & Chen, 2005;
Richarsdon et al., 1998) excepted for LBGw with [Z]¼7.1 dl/
g. These observations suggest that galactomannan macro-
molecular properties measurements can be complicated by
self-association (Bradley, Ball, Harding & Mitchell, 1989).
3.5.2. Temperature fractionation and M
w
measurement of
extracted carob gums
In order to know the characteristics of the main
molecules which influence the solubility and the rheological
properties of the gum in cold or hot water, LBGw and
LBGa were fractionated simply by stirring in cold
water (25 1C/1 h), centrifuging, stirring the residue with
hot water (80 1C/30 min) and re-centrifuging. The
macromolecular characteristics of the two fractions
(supernatents), namely, cold water-soluble and hot
water-soluble were analyzed (Table 5). In general, in the
two fractions analyzed, the macromolecular values (M
n
,
M
w
,[Z], Rg) seem to increase with the temperature
of solubilization. It could be noticed that at low
temperature low molecular weight molecules were dis-
solved whereas high molecular weight components were
dissolved at high temperature. As expected, there is a good
correlation between the solubilization temperature and the
molecular size and rheological properties of galactoman-
nan samples.
These results may also indicate that macromolecular
characteristics of LBG can differ based on gum separation
or solution preparation technique.
3.6. Rheological characterization
3.6.1. Rotational rheological properties
Typical flow curves, defined as the plot of shear stress (t)
versus shear rate (D) and the effect of shear rate on
dynamic viscosity (calculated as the ratio of shear stress to
shear rate) for LBGw and LBGa solution prepared at
ambient and high temperature, are shown in Figs. 5 and 6.
It should be mentioned, particularly because the term
‘‘LBG solution’’ is employed, that part of the material
prepared could be indeed a dispersion because solubilization
ARTICLE IN PRESS
Table 5
Temperature fractionation and M
w
measurement of extracted carob gum
Fractionation condition LBGw LBGa
25 1C/1 h fraction 80 1C/30 min fraction 25 1C/1 h fraction 80 1C/30 min fraction
M
n
(Daltons) 0.525 10
6
0.996 10
6
0.770 10
6
0.977 10
6
M
w
(Daltons) 0.980 10
6
1.100 10
6
1.000 10
6
1.300 10
6
Pi ¼M
w
/M
n
1.82 1.16 1.34 1.35
[Z] (dl/g) 6.24 9.14 7.13 16.42
Rg (nm) 57.43 71.30 61.40 90.04
Fig. 5. Flow curves and viscosity curves rheograms of the extracted LBG solutions (LBGw mand LBGa &) prepared at 25 1C/1 h and measured at 25 1C
for 1% polymer concentration.
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818814
Author's personal copy
was not complete for all the samples even at high
temperature (as described in Section 3.4).
The results (Figs. 5 and 6) show that the shear stress and
the viscosity of locust bean gum solutions were shear rate
dependent and in all cases the behavior was shear-thinning
(or pseudoplastic).
In order to know the extent of deviation of each flow
curve from the Newtonian behavior, the power-law model
(t¼kD
n
) was applied, where: n¼flow behavior index
(dimensionless), and k¼consistency index (Pa s
n
). The
calculated constants of the power law are compiled in
Table 6.
Viscosity measurement values of all gums prepared at
ambient and high temperature, measured at 25 1C, at 1%
concentration, and at shear rate of 10 and 300 s
1
, were
shown in Table 6. The values of viscosity at the weak shear
rate could permit to appreciate the consistency in mouth of
the product (Morris & Taylor, 1982), while the values of
viscosity at the high shear rate permit to appreciate the
viscosity of the product during some processing operation
(when it is pumped in a machine, for instance). The values
of nwere less than 1 at the solubilization temperatures
investigated, confirming that all samples present pseudo-
plastic characteristic. It can be observed also that values of
kincreased (for LBGw or LBGa), with higher solubiliza-
tion temperature.
The shear-thinning behavior of LBG may be regarded as
arising from modifications in macromolecular organization
in the solution as the shear rate changes. The disruption of
entanglements by the imposed shear made that molecules
align in the direction of flow and the dynamic viscosity
decreases (Figs. 5 and 6) with increasing shear rate (Mao &
Chen, 2006;Sittikijyothin, Torres, & Gonc-alves, 2005).
In general, the viscosity values (Table 6) of LBG
prepared at 80 1C are higher than those solubilized at
25 1C, showing that viscosity evolves with the temperature.
This seems to be supported by the solubility measurements
(as described in Section 3.4, Fig. 2 compared to Fig. 3) and
by macromolecular data (as shown in Table 5). LBG
showed maximum viscosity at higher temperatures due
(i) to additional material being solubilized (increased
solubilization), and (ii) to increasing macromolecule
motion with increasing in aggregate and entanglement
(Ko
¨k et al., 1999b).
For similar concentration (1%), LBGw solutions were
less viscous than LBGa solutions at low and at high
temperature (although LBGw and LBGa solubility seemed
quite similar in cold water, as described in Section 3.4,
Fig. 2). It can be hypothesized that this difference in
viscosity (Table 6) is not only related to the solubility
(Figs. 2, 3) but to the weakness of the intermolecular
entanglements in LBGw solutions, due to the great
ARTICLE IN PRESS
Fig. 6. Flow curves and viscosity curves rheograms of the extracted LBG solutions (LBGw mand LBGa &) prepared at 80 1C/30 min and measured at
25 1C for 1.0% polymer concentration.
Table 6
Rheological parameters of the viscosity measured at 25 1C for LBG samples
Dissolution condition Extracted gums Commercial gums
LBGw (from Water pre-
treatment)
LBGa (from Acid pre-
treatment)
LBG FG (Food grade) LBG AG (Analytical grade)
25 1C/1 h 80 1C/30 min 25 1C/1 h 80 1C/30 min 80 1C/30 min 80 1C/30 min
Dynamic viscosity (mPa s) at 10 s
1
26075 28375 59575 1832750 1676725 3015750
Dynamic viscosity (mPa s) at 300 s
1
387357734975 280715 24475 367710
K(consistency index) (Pa s
n
) 1.89 2.20 5.26 9.79 7.88 18.78
n(flow behavior index) 0.82 0.80 0.71 0.64 0.65 0.32
LBGw and LBGa solutions (1.0% polymer concentration) were prepared at 251C/1 h or at 80 1C/30 min and compared with best grade of commercial
gums.
With LBGw (gum from Water dehusking pre-treatment), LBGa (gum from Acid dehusking pre-treatment), LBG FG (Food grade commercial gum), LBG
AG (Analytical grade commercial gum).
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818 815
Author's personal copy
presence of very compacted and small molecules (as
described in Section 3.5). According to Cheng, Brown
and Prud’homme (2002), aggregation is an intrinsic
property of native galactomannan. Thus, boiling water
dehulling pre-treatment (for sample LBGw) had a strongly
negative influence on the viscosity and therefore, on the
thickening capacity of the gum.
In addition, higher galactomannan content in LBGa
(Table 3) with higher molecular size according to [Z] and
Rg values (as described in Section 3.5, Tables 4, 5), notably
contributes to a higher solubility (Fig. 3), a strength
polymer–polymer association and a higher viscosity
(Table 6). With a viscosity of 1832 centipoises, LBGa can
be regarded as a commercial gum, i.e. that its physico-
chemical characteristics were closer to food grade gum
(LBG FG).
3.6.2. Rheological behavior under oscillatory dynamic shear
The viscoelastic behavior of the gum solutions (1% w/w)
was analyzed and the mechanical spectra (the frequency
sweeps) obtained at a constant strain (g) of 1 Pa, are shown
in Fig. 7. As it can be observed, the viscous modulus G00,
related to the viscous response of the system, keeps higher
than the elastic modulus G0, related to the elastic response,
until a crossover frequency (the system shows a liquid-like
behavior when G004G0). After this point, the behavior is
reversed and the elastic response prevails (the system
behave like a solid when G004G0). Complex viscosity (Z),
related to the global viscoelastic response depends on both
frequency and G0G00 values. The nature of this phenom-
enon is still controversial and not at all clear. However, this
type of mechanical spectra, typical of viscoelastic fluids or
material, and previously described by Iban
˜ez and Ferrero
(2003) and Brummer et al. (2003),corresponds to a
solution of entangled macromolecules since gels would
show values of G0higher than G00 throughout the frequency
range (Steffe, 1996).
The mechanical spectra of LBGa have a greater
magnitude than LBGw, reflective of the greater network
development in LBGa solution owing to the presence of
high and expanded molecules of galactomannan (with
unsubstituted regions of the mannose backbone) that
permit greater polymer–polymer associations.
4. Conclusions
This study provides evidence that the yield and the
quality of locust bean gum (LBG) flours, depends on the
ARTICLE IN PRESS
Fig. 7. Mechanical spectra (at g¼1 Pa) of LBG solutions, prepared at 80 1C/30 min and measured at 25 1C for 1% polymer concentration. &dynamic
viscous modulus G00,dynamic elastic modulus G0,mcomplex viscosity Z. LBGw ¼carob gums extracted by boiling water procedure, LBGa ¼gum
extracted by acid procedure, LBG FG ¼food grade commercial gum and LBG AG ¼analytical grade commercial gum.
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818816
Author's personal copy
seed dehulling process or on the gum separation method
from the entire seeds. Large variations in the yield,
whiteness, chemical composition and molecular character-
istics were observed, as well as in rheological properties.
The best thickening properties are measured for locust
bean gum from acid dehulling pre-treatment compared to
LBG from boiling water dehulling pre-treatment, accord-
ing to its higher values of galactomannan content,
solubility at high temperature, molecular size and intrinsic
viscosity.
The results of investigation were also shown, that the
carob gum is partially cold water-soluble and needs to be
heated to reach its maximum solubility and maximum
viscosity. A considerable influence of solubilization tem-
perature on macromolecular properties was also observed.
Acknowledgements
We thank Jean Re
´mont from T.A.S.A. (Malaga, Spain)
for the supply of raw materials. Patrick A. Dakia thanks
the ‘Ministe
`re de l’Enseignement Supe
´rieur et de la
recherche Scientifique de Coˆ te d’Ivoire’ for the scholarship.
References
Albersheim, P., Nevins, D. J., English, P. D., & Karr, A. (1967). A method
for the analysis of sugars in plant cell-wall polysaccharides by gas-
liquid chromatography. Carbohydrate Research,5, 340–345.
Anderson, D. M. W. (1986). Nitrogen conversion factors for the
proteinaceous content of gums permitted as food additives. Food
Additives and Contaminants,3, 225–230.
Avallone, R., Plessi, M., Baraldi, M., & Monzani, A. (1997). Determina-
tion of chemical composition of carob (Ceratonia siliqua): Protein, Fat,
Carbohydrates, and Tannins. Journal of Food Composition and
Analysis,10(2), 166–172.
Azero, E. G., & Andrade, C. T. (2002). Testing procedures for
galactomannan purification. Polymer Testing,2(5), 551–556.
Bargallo, M. G., Di Lorenzo, R., Meli, R., & Crescimanno, F. G. (1997).
Characterization of carob gerplasm (Ceratonia siliqua L.) in Sicily.
Journal of Horticultural Science,72(4), 537–543.
Batlle, I., & Tous, J. (1997). Properties. Agronomy: Processing. In
Carob tree,Ceratonia siliqua L. (pp. 24–29, 61–62). Rome. Italy:
IPGRI.CGIAR.
Blakeney, A. B., Harris, P. J., Henry, R. J., & Stone, B. A. (1983).
A simple and rapide preparation of alditol acetates for monosacchar-
ide analysis. Carbohydrate Research,113, 291–299.
Bourriot, S., Garnier, C., & Doublier, J. L. (1999). Phase separation,
rheology and microstructure of micellar casein-guar mixtures. Food
Hydrocolloids,13, 43–49.
Bradley, T. D., Ball, A., Harding, S. E., & Mitchell, J. R. (1989). Thermal
degradation of guar gum. Carbohydrate Polymers,10(3), 205–214.
Brummer, Y., Cui, W., & Wang, Q. (2003). Extraction, purification and
physicochemical characterization of fenugreek gum. Food Hydrocol-
loids,17, 229–236.
Cheng, Y., Brown, K. M., & Prud’homme, R. K. (2002). Preparation and
characterization of molecular weight fractions of guar galactomannans
using acid and enzymatic hydrolysis. International Journal of Biological
Macromolecules,31(1–3), 29–35.
da Silva, J. A. L., & Gonc-alves, M. P. (1990). Studies on a purification
method for locust bean gum by precipitation with isopropanol. Food
Hydrocolloids,4, 277–287.
Daas Piet, J. H., Schols Henk, A., & De Jongh Harmen, H. J. (2000). On
the galactosyl distribution of commercial galactomannans. Carbohy-
drate Research,329(3), 609–619.
Dakia, P. A., Wathelet, B., & Paquot, M. (2007). Isolation and chemical
evaluation of the carob (Ceratonia siliqua L.) seeds germ. Food
Chemistry,102(4), 1368–1374.
Dea, I. C. M., & Morrison, A. (1975). Chemistry and interactions of seed
galactomannans. Advances in Carbohydrate Chemistry and Biochem-
istry,31, 241–242.
Deuel, H., & Neukom, H. (1954). Some properties of locust bean gum. In
Natural plant hydrocolloids (Advanced Chemistry Series No. 11)
(pp. 51–61).
Ensminger, A. H., Ensminger, M. E., Konlande, J. E., & Robson, J. R. K.
(1994). Carob Ceratonia siliqua. In Food and Nutrition Encyclopedia.
(2nd ed., Vol. 1, pp. 346–348). Boca Raton, FL: CRC Press, Inc,.
Folch, Lees, L. M., & Stanley, S. G. H. (1957). A simple method for the
isolation and purification of total lipids from animal tissues. Journal of
Biological Chemistry,226, 497–509.
Fox, J. E. (1992). Seed gums. In A. Imeson (Ed.), Thickening and gelling
agents for food. London: Blackie Academic and Professional.
Gainsford, S. E., Harding, S. E., Mitchell, J. R., & Bradley, T. D. (1986).
A comparison between the hot and cold water-soluble fractions of two
locust bean gum samples. Carbohydrate Polymers,6, 423–442.
Garcia-Ochoa, F., & Casas, J. A. (1992). Viscosity of locust bean
(Ceratonia siliqua) gum solutions. Journal of the Science of Food and
Agriculture,59, 97–100.
Goycoolea, F. M., Morris, E. R., & Gidley, M. J. (1995). Viscosity of
galactomannans at alkaline and neutral pH: Evidence of ‘hyperentan-
glement’ in solution. Carbohydrate Polymers,27, 69–71.
Hefty (1953). U.K. Patent No 14813/53.
Herald, C. T. (1986). Locust/carob bean gum. In M. Glicksman (Ed.),
Food hydrocolloids (Vol. 3(5), pp. 161–170). Boca Raton, FL: CRC
Press.
Hui, P. A., & Neukom, H. (1964). Properties of galactomannans. Tappi,
47, 39–42.
Iban
˜ez, M. C., & Ferrero, C. (2003). Extraction and characterization of
the hydrocolloid from Prosopis flexuosa DC seeds. Food Research
International,36(5), 455–460.
Ko
¨k, M. S., Hill, S. E., & Mitchell, J. R. (1999a). A comparison of the
rheological behaviour of crude and refined locust bean gum prepara-
tion during thermal processing. Carbohydrate Polymers,38(3),
261–265.
Ko
¨k, M. S., Hill, S. E., & Mitchell, J. R. (1999b). Viscosity of
galactomannanes during high temperature processing: Influence of
degradation and solubilisation. Foods Hydrocolloids,13(6), 535–542.
Lazaridou, A., Biliaderis, C. G., & Izydorczyk, M. S. (2000). Structural
characteristics and rheological properties of locust bean galactoman-
nans: A comparison of samples from different carob tree populations.
Journal of the Science of Food and Agriculture,81, 68–75.
Maier, H., Anderson, M., Karl, C., Magnuson, K., & Whistler, R. L.
(1993). Guar, locust bean, tara and fenugreek gums. In R. L. Whistler,
& J. N. BeMiller (Eds.), Industrial gums, polysaccharides and their
derivates (pp. 205–215). San Diego: Academic Press.
Mao, C.-F., & Chen, J.-C. (2006). Interchain association of locust bean
gum in sucrose solutions: An interpretation based on thixotropic
behavior. Food Hydrocolloids,20(5), 730–739.
Morris, E. R., & Taylor, L. J. (1982). Oral perception of fluid viscosity.
Progress in Food and Nutrition Science,6, 285–296.
Morris, V. J. (1998). Gelation of polysaccharides. In S. E. Hill, D. A.
Ledward, & J. R. Mitchell (Eds.), Functional properties of food
macromolecules (pp. 143–226). Gaithesburg, MD: Aspen Publishers,
Inc.
Neukom, H. (1988). Carob bean gum: properties and applications. In
P. Fito, & A. Mulet (Eds.), Proceedings of the II international carob
symposium (pp. 551–555). Valencia, Spain.
Pollard, M. A., Kelly, R., Wahl, C., Windhab, E., Eder, B., & Amado,
R. (2007). Investigation of equilibrium solubility of a carob
galactomannan. Food Hydrocolloids,21(5–6), 683–692.
ARTICLE IN PRESS
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818 817
Author's personal copy
Ramirez, J. A. (2002). Effect of xanthan and locust bean gums on the
gelling properties of myofrillar protein. Food Hydrocolloids,16, 11–16.
Richarsdon, P. H., Willmer, J., & Foster, T. J. (1998). Dilute properties of
guar and locust bean gum in sucrose solutions. Food Hydrocolloids,12,
339–348.
Rizzo, V., Tomaselli, F., Gentile, A., La Malfa, S., & Maccarone, E.
(2004). Rheological properties and sugar composition of locust bean
gum from different carob varieties (Ceratonia siliqua L.). Journal of
Agricultural and Food Chemistry,52(26), 7925–7930.
Sittikijyothin, W., Torres, D., & Gonc-alves, M. P. (2005). Modelling the
rheological behaviour of galactomannan aqueous solutions. Carbohy-
drate Polymers,59(3), 339–350.
Steffe, J. (1996). Rheological methods in food process engineering (2nd ed).
East Lansing, MI, USA: Freeman Press [Chapter 5].
Sveinbjo
¨rnsson, J., Murphy, M., & Ude
´n, P. (2007). In vitro evaluation
of starch degradation from feeds with or without various
heat treatments. Animal Feed Science and Technology,132(3–4),
171–185.
ARTICLE IN PRESS
P.A. Dakia et al. / Food Hydrocolloids 22 (2008) 807–818818
... First, the carob pods were crushed, and the seeds were collected and sorted (Dakia et al., 2008). Next, 100 g of carob seeds (780 seeds) were immersed in 800 mL of distilled water, and heated to 100°C for 1 h in a water bath. ...
... Galactomannan polysaccharides can be obtained from carob beans by aqueous or aqueous alkaline extraction. Their content in the seeds can reach 85% (Dakia et al., 2008). In the present work, the ratio of protein, crude fibre, fat, and galactomannan in carob bean gum powder was 4.8%:1.17%:0.43%:84.7%, ...
Article
For the first time, this study presented the use of raw locust bean gum (LBG) as a prebiotic, with one probiotic strain in synbiotic fermented milk or combined with Na-alginate as a biopolymer, for a targeted release of bacteria under colon-like conditions. For this purpose, the fermentative characteristics (biomass, pH), bacterial survival, and developed viscosities of the stored fermented milks were determined. The survival rates of microencapsulated bacteria using the emulsion technique under simulated gastrointestinal conditions (stomach: pH 2 + 0.3% pepsin; colon: pH 6.5 + 1% pancreatin + 0.3% bile) were also evaluated. Results showed that all the tested bacteria maintained better biomass and acidifying activities in the presence of LBG, especially at 2%. During cold storage, the viscosities of the LBG-fermented milks were regulated and better appreciated, especially at 2%. Lactobacillus rhamnosus LbRE-LSAS and Bifidobacterium animalis subsp. lactis Bb12 microencapsulated separately in Ca-alginate-raw carob gum maintained good survival rates (51 - 66%) as compared to free cells (21 - 59%) under simulated digestive conditions, and were released under colon-like conditions. Therefore, the formulation of LBG-enriched fermented milks containing probiotic bacteria could represent a very good candidate for industrial application. Ca-alginate-raw LBG beads for the specific release of probiotics in the colon could benefit consumers with celiac disease or other digestive disorders because LBG is naturally gluten-free.
... First, the carob pods were crushed, and the seeds were collected and sorted (Dakia et al., 2008). Next, 100 g of carob seeds (780 seeds) were immersed in 800 mL of distilled water, and heated to 100°C for 1 h in a water bath. ...
... Galactomannan polysaccharides can be obtained from carob beans by aqueous or aqueous alkaline extraction. Their content in the seeds can reach 85% (Dakia et al., 2008). In the present work, the ratio of protein, crude fibre, fat, and galactomannan in carob bean gum powder was 4.8%:1.17%:0.43%:84.7%, ...
Article
Full-text available
For the first time, this study presents the use of raw locust bean gum (LBG) as a prebiotic with one probiotic strain in synbiotic fermented milk or combined with Na-alginate as a biopolymer for a targeted release of bacteria under colon-like conditions. For this purpose, the fermentative characteristics (biomass, pH), bacterial survival, and developed viscosities of the stored fermented milks were determined. The survival rates of microencapsulated bacteria using the emulsion technique under simulated gastrointestinal conditions (stomach: pH 2 + 0.3% pepsin; colon: pH 6.5 + 1% pancreatin + 0.3% bile) were also evaluated. The results obtained show that all the bacteria analyzed maintain better biomass and acidifying activities in the presence of LBG, especially at 2%. During cold storage, the viscosities of the LBG-fermented milks were regulated and better appreciated, especially at 2%. Lactobacillus rhamnosus LbRE-LSAS, and Bifidobacterium animalis subsp. lactis Bb12 microencapsulated separately in Ca-alginate-raw carob gum, maintained good survival rates (51-66%) compared to free cells (21-59%) under simulated digestive conditions, and were released under colon-like conditions. Therefore, the formulation of LBG-enriched fermented milks containing probiotic bacteria could represent a very good candidate for industrial application. Ca-alginate-raw LBG beads for the specific release of probiotics in the colon could benefit consumers with celiac disease or other digestive disorders because LBG is naturally gluten-free.
... This exceptional quality may be clarified by the presence of acids, esters, and aldehydes/ketones produced from carob fruit and powder, which are biogenic volatile organic composites that promote plant growth, breeding, protection [13,14] and nutrition benefits [15]. In addition, it has been confirmed to possess remarkable bioactivity and is considered dietary fiber in the food industry [16,17], wherein it is used for the preparation of soft drinks, confectionery products, and baked goods and as a substitute for cocoa or chocolate [18]. Furthermore, a variety of bioactive compounds were found in all parts of Ceratonia siliqua L., (leaves, pods, and seeds), such as phenolic acids, flavonoids, tannins, and alkaloids, as well as nutritional compounds, such as vitamins, protein, lipids, and minerals. ...
Article
Full-text available
The present work was designed to investigate the effects of different extraction processes, namely ultrasonic-assisted, supercritical fluid, microwave-assisted and Soxhlet applied to carob pods. The total phenolic quantification and the antioxidant activity were assessed by the means of rapid in vitro spectrophotometric assays; the phenolic profile was identified using ultra-high performance liquid chromatography coupled to mass spectrometry. The results revealed that the phenolic compounds and the antioxidant capacity varied significantly with the nature of the extraction process. The content of total phenolic compounds ranged from 11.55 to 34.38 mg GAE/g DW; the content of total flavonoids varied from 3.50 to 10.53 mg QE/g DW, and the content of condensed tannins fluctuated from 3.30 to 6.55 mg CE/ g DW. All extracts performed differently on antioxidant activity when determined by the DPPH assay producing a dose-dependent response, with IC50 extended from 11.33 to 6.07 µg/mL. HPLC analysis enabled the identification of nine compounds. As a function of the studied extraction methods, the phenolic compound contents were positively correlated with antioxidant activity.
... Locust bean gum (LBG), as a biological macromolecule is a natural polysaccharide extracted from the endosperm part of carob tree seeds (Ceratonia siliqua) (Barak and Mudgil, 2014;Prajapati, Jani, Moradiya, Randeria, & Nagar, 2013;Dakia, Blecker, Robert, Wathelet, & Paquot, 2008;Samil Kök, 2007). The physicochemical properties of LBG including outstanding bio-compatibility, appropriate bio-degradability, and low-cost extraction make it suitable for food and pharmaceutical applications (Barak and Mudgil, 2014;Prajapati et al., 2013;Li, Lei, Liao, & Zhang, 2021). ...
Article
The goal of this work was to introduce an eco-friendly pH-sensitive indicator for monitoring food freshness. In this regard, pH-sensitive locust bean gum (LBG) film containing 5 wt % of the extracted anthocyanin from Viola (VE) was fabricated. Subsequently, synthesized graphene oxide (GO) at the optimum concentration (0.5 wt %) was added to the film’s formulation. It was revealed that incorporating GO into the neat LBG and LBG/VE films significantly enhanced the mechanical properties and thermal stability of the film (p<0.05). The LBG/VE/GO film showed a superior moisture content, water solubility, surface hydrophilicity and biosafety than LBG/VE film. The release study demonstrated a controlled release of VE from LBG/VE and LBG/VE/GO films over a period of 48 h. The antioxidant activity of LBG film significantly improved with the incorporation of VE (p<0.05). Overall, LBG/VE/GO film can be introduced as a smart packaging system to monitor the freshness of meat in real-time.
... The extraction was carried out according to the protocol described by Dakia et al. (2008) which consists of weighing 100 g of carob seeds (about 780 seeds) and heating them for one hour to boiling in 800 mL of bi-distilled water. The integuments and the germ were manually separated from the endosperms. ...
Book
The assurance of the bacteria survival is the key of the protective technique aiming to alleviate the bacteria resistance under digestive hostilities. Among the methods of protection, microencapsulation of cells in various biomaterials has given convincing results. We tried to exploit for the first time the emulsifying properties of carob galactomannans reinforced herein by the sodium alginate gel in the microencapsulation of beneficial bacteria. On the other hand, we explored the benefits of this protective technique upon the expression of the bacterial ability to uptake cholesterol, in complement to our previously published results. The present study aimed to develop a new mixed gel containing calcium alginate and galactomannans extracted from the Algerian carob seeds endospermes, for the microencapsulation of the human strain of Lactobacillus rhamnosus LbRE-LSAS; compared with the probiotic strain of Bifidobacterium animalis subsp. lactis Bb12. Influence of microencapsulationwas tested under simulated digestive environment to verify if both bacteria preserve their viability and their cholesterol assimilation ability. High viable loads of encapsulated LbRE-LSAS and Bb12 were registered (6.97 and 8.66 of 10 Log CFU g−1, respectively). Conversely, the free cell levels strongly (P < 0.05) decreased during exposure to the digestive simulated conditions. According to our results, the new formed gel permits to improve 1.8-fold on average the cholesterol assimilation ability of probiotic bacteria. We underlined the possible use of carob galactomannans-Ca-alginate beads as alternative healthy solution in protecting beneficial bacteria under gastro-intestinal conditions, and by the way, lowering the serum cholesterol level in the host.
... The germ from endosperms was dried at 100 °C for 1-2 h to obtain a constant weight. The endosperms were then crushed and sifted with a 0.125 mm sieve to obtain LBG flour [52]. ...
Article
Full-text available
Indigofera linifolia is a medicinally important plant, and by virtue of its rich phytochemical composition, this plant is widely used as essential component in traditional medication systems. Due to its wide range of medicinal applications, the extract-loaded chitosan (Ext+Ch), extract-loaded PEG (Ext+PEG), and extract-loaded locust bean gum (Ext+LGB) nanoparticles (NPs) were prepared in the present study. The prepared NPs were then evaluated for their antibacterial, anti-oxidant, and antidiabetic potentials. Antibacterial activities of the crude extract and the synthesized NPs were performed following standard procedures reported in the literature. The antioxidant capabilities of extract and NPs were evaluated using DPPH free radical scavenging assay. The antidi-abetic potential of the samples was evaluated against α-amylase and α-glucosidase. Ext+PEG NPs showed more potent antibacterial activity against the selected strains of bacteria with the highest activity against Escherichia coli. The lowest antibacterial potential was observed for Ext+LGB NPs. The Ext+LGB NPs IC50 value of 39 μg/mL was found to be the most potent inhibitor of DPPH free radicals. Ext+LGB NPs showed a greater extent of inhibition against α-glucosidase and α-amylase with an IC50 of 83 and 78 μg/mL, whereas for the standard acarbose the IC50 values recorded against the mentioned enzymes were 69 and 74 μg/mL, respectively. A high concentration of phenolics and flavonoids in the crude extract was confirmed through TPC and TFC tests, HPLC profiling, and GC-MS analysis. It was considered that the observed antibacterial, antidiabetic, and antioxidant potential might be due the presence of these phenolics and flavonoids detected. The plant could thus be considered as a potential candidate to be used as a remedy of the mentioned health compli-Citation: Talha, M.; Islam, N.U.; Zahoor, M.; Sadiq, A.; Nawaz, A.; Khan, F.A.; Gulfam, N.; Alshamrani, S.A.; Nahari, M.H.; Alshahrani, M.A.; et al. Biological Evaluation, Phytochemical Screening, and
... Carob gum, also called Locust Bean Gum (LBG), is the ground endosperm of the seeds. It is widely used as food additive (E410) to improve the texture of foods [2][3][4][5]. Carob molasses, also called carob syrup, is a juice concentrate (60-80°Brix) prepared by water extraction from the pod or the pulp and then concentration. It is widely consumed especially during the cold periods of the year as an energetic food rich in sugars [6][7][8][9][10][11][12][13]. ...
Article
Full-text available
The by-product generated from carob molasses processing is considered as an excellent source of dietary fiber and may be used as a functional ingredient in food industry. However, it presents a high value of water activity (~ 0.98) which facilitates its microbiological contamination and rapid deterioration. So that, this study provides a solution for the valorization of this by-product and suggests the incorporation of the dried carob by-product into Halva to produce an added value product (Halva with carob powder). Thus, the present work focused on the characterization of carob powder and the optimisation of incorporation percentage of carob powder into Halva formulation. The characterization showed the absence of caffein in carob powder compared to cocoa’s one. Besides, carob and cocoa powders had both a brown color. The former had lower fat and higher sugar contents compared to the latter. The optimization promoted the addition of 5% carob powder into Halva formulation according to the evaluation of hardness, sensory quality and exudative stability. Therefore, the new confectionary product could be considered as a promising nutritious and healthy foodstuff to consumers.
Article
Background: Okra is a vegetable that is widely grown around the world. Okra mucilage contains a high mucus concentration that can be useful for supporting the swallowing process. Although the extensional rheology of okra mucilage is essential to its flow, its extensional viscosity has not received much attention. Objective: Using a filament stretching rheometer, the extensional viscosity of the mucilage in okra was examined. The Giesekus model is also used to predict this parameter. Methods: The okra mucilage with different concentrations was extracted from fresh okra. The extensional viscosity was measured using a filament breakup apparatus. The diameter of the liquid bridge was measured by a laser micrometer and it was also observed by a high-speed camera. A rotational rheometer was used to measure the shear viscosity. In addition, the master curves for the shear viscosity were plotted to eliminate the influence of solvent and shear rate and evaluate the influence of concentration on the elasticity of okra mucilage. The okra mucilage shear and extensional viscosity were predicted using the Giesekus model. Results: Every sample of okra mucilage exhibits shear thinning behavior. Additionally to having a high extensional viscosity that is hundreds of times higher than its shear viscosity, okra mucilage also exhibits stretching phenomena. The master curves demonstrated that the pseudoplasticity of the okra mucilage increased along with the concentration. The rheological behavior of the mucilage in okra can be explained by the Giesekus model. Conclusions: Okra mucilage's shear viscosity exhibited shear thinning behavior and a strong extensional viscosity that was significantly higher than its shear viscosity. The shear and extensional viscosity of okra mucilage can be described and predicted using the Giesekus model.
Chapter
Locust bean gum (LBG) is a galactomannan-based natural biopolymer. LBG is extensively used commercially in food and other industries. Besides being a high value additive that brings about desired functional attributes upon usage, it is reported to have several health benefits as well. Processing of seed coat is required to separate the gum from germ and hull so as to access the gum portion of carob (locust) seeds. To obtain high-quality gum from seed, it is crucial to minimize impurities. Upon hydration, LBG forms a gel-like structure, being soluble in warm water. This and other changes associated with the solubility of LBG result in high demand for such products. This chapter is created to provide a basic intuitive overview of locust bean gum and various aspects related to it.
Article
Background: Mucilage is an important polysaccharide with a broad range of physicochemical properties and antioxidant activity that is widely used for various applications in the medicine and food industries. Objectives: This study aims to evaluate the effect of the extraction method on the physicochemical properties of mucilage extracted from yellow and brown flaxseeds. Methods: Mucilage was extracted by different methods: heating, sonotrode, and bath sonication. The extracted mucilage was evaluated for mucilage extraction efficiency (MEE%), solubility, water-binding capacity (WBC%), antioxidant activity, and foam stability. Results: In all extraction methods, the MEE% of yellow flaxseed was significantly higher than that of brown flaxseed. The antioxidant activity of mucilage extracted from brown and yellow flaxseed was 43.65 ± 1.86% and 12.65 ± 1.23%, respectively (P < 0.001). In all extraction methods, the solubility of mucilage was increased by enhancing the temperature. Significantly, higher solubility (P < 0.01) and stronger foam stability (P < 0.001) was obtained for mucilage extracted from brown flaxseed. The highest foam stability was obtained by the sonotrode method. Mucilage extracted by sonotrode and bath sonication methods showed significantly stronger (P < 0.01) water-binding capacity (WBC%) compared to that of the heating method. Conclusions: Our results showed that the ultrasonic methods, especially sonotrode, due to their positive effects on physicochemical properties of mucilage, could be more appropriate methods for extraction of mucilage.
Article
Sixteen carob cultivars were studied to evaluate pulp and seed yield with regard to endosperm percentage, to determine the overall degree of polymorphism of the characters and to detect similarities among cultivars. Bean size and numbers of normal and aborted seeds were characters with a certain degree of polymorphism. The low between-year variability observed suggests that differences in the variables could be attributed to genetic factors. A high year-to-year variation was observed only for the number of aborted seeds. Seed characteristics showed small changes both between years and among cultivars. Out of all the variables, PCA identified four principal components that explained more than 80% of the total variance. The first two principal components were related to qualitative characters and were useful in ranking cultivars. Plots of the principal components scores separated some cultivars for particular characteristics for industrial purposes.
Chapter
Publisher Summary This chapter discusses the manufacturing, properties, and applications of guar, locust bean, tara, and fenugreek gums. Guar gum is obtained from the seed of the legume Cyamopsis tetragonolobus. Guar is grown principally as a food crop for animals and an ingredient in human foods. The germ portion of its seed is predominantly protein, and the endosperm is predominantly guar galactomannan. Guar gum can be produced from endosperm splits, simply by grinding in attrition mills, hammer mills, or other size-reduction equipment. Guar gum and its hydroxypropyl and carboxymethyl ethers are used in the petroleum industry as additives for aqueous and water/methanol-based fracturing fluids. Locust bean gum and its derivatives are used in a variety of industrial applications. Tara gum—sometimes called huarango, guaranga, or Peruvian carob—is a galactomannan with a galactosyl: mannosyl ratio between those of locust bean gum and guar gum. Fenugreek seed contains about 25% protein high in both lysine and tryptophan although lower in methionine and cystine than other legumes.