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ORIGINAL ARTICLE
Sugar composition and yield of syrup production from
the pulp of Moroccan carob pods (Ceratonia siliqua L.)
H. El Batal
a
, A. Hasib
a,
*, A. Ouatmane
a
, F. Dehbi
a
, A. Jaouad
b
, A. Boulli
a
a
Laboratory of Environment and Valorisation of Agro-resources, Faculty of Science and Technology of Beni-Mellal,
University of Sultan Moulay Slimane, Morocco
b
Laboratory of Applied Organic Chemistry, Faculty of Science Semlalia, University of Cadi Ayyad Marrakesh, Morocco
Received 8 February 2011; accepted 10 October 2011
KEYWORDS
Carob pods;
Provenance of carob;
Pulp yield;
Total sugars;
Reducing sugars;
Syrup yield
Abstract The aim of this work is to provide a process for obtaining natural carob syrup of
Morocco carob pods and their total and reducing sugar. Samples were collected from different
regions in the agro-forestry system of Morocco. The total sugar and reducing sugar in pods
obtained from different regions were 31.5–50.1 and 10.2–14.6 g/100 g ‘‘%w/w’’, respectively. The
yield of syrup from the different regions varies between 28.76 and 37.22 g/100 g ‘‘%w/w’’. Popula-
tions from Essaouira and Beni-mellal have higher levels of sugar and yield of syrup. The values
obtained vary according to the origin of the samples.
ª2011 King Saud University. Production and hosting by Elsevier B.V. All rights reserved.
1. Introduction
The carob tree (Ceratonia siliqua L.), belonging to the family
Cesalpiniaceae sub-family of the family Leguminoseae, is
widely used in the Mediterranean regions (Battle and Tous,
1997; Yousif and Alghzawi, 2000), cultivated for ornamental
and industrial purposes (Girolamo and Laura, 2002).
World production is estimated at about 315 000 ton per
year, and the main producers for pulp, seeds, respectively,
are Spain (36%, 28%), Morocco (24%, 38%), Italy (10%,
8%), Portugal (10%, 8%), Greece (8%, 6%), Turkey (4%,
6%) and Cyprus (3%, 2%) of the world production (Chitt
et al., 2007).
The total area is approximately 200 000 ha and the yield
depends on crop, region and cultural practices (Makris and
Kefalas, 2004).
The carob distribution in Morocco is in the north selvage of
the Atlas chain, the Rif Mountain and in some valleys of the
south-west of the Anti-Atlas confined to arid and semi-arid
bioclimates with an extension to sub-humid bioclimate in some
stands (Sidina et al., 2009).
Chemical composition of the carob pod depends on varie-
ties, origin and harvesting time (Albanell et al., 1991). The
two main carob pod constituents are (by weight): pulp
(90%) and seed (10%) (Tous et al., 1995).
The seeds, covered with a tight-fitting brown coat, contain a
white and translucent endosperm (containing galagtomannans),
*Corresponding author.
E-mail address: azhasib@yahoo.fr (A. Hasib).
1878-5352 ª2011 King Saud University. Production and hosting by
Elsevier B.V. All rights reserved.
Peer review under responsibility of King Saud University.
doi:10.1016/j.arabjc.2011.10.012
Production and hosting by Elsevier
Arabian Journal of Chemistry (2011) xxx, xxx–xxx
King Saud University
Arabian Journal of Chemistry
www.ksu.edu.sa
www.sciencedirect.com
Please cite this article in press as: El Batal, H. et al., Sugar composition and yield of syrup production from the pulp of Moroccan
carob pods (Ceratonia siliqua L.). Arabian Journal of Chemistry (2011), doi:10.1016/j.arabjc.2011.10.012
also called carob gum, locust bean gum (LBG) or E411. Locust
bean gum is utilized in food and non-food industries for its abil-
ity to form a very viscous solution at relatively low concentra-
tion. It is also exploited for its synergy property with
carrageenan, agar and xanthan to form stronger and more elas-
tic gels (Hoichman et al., 2007).
Nowadays, the main application of the pulp is as an animal
feed (Manso et al., 2010). In human the carob pulp has been
used mainly as a cocoa substitute (Kumazawa et al., 2002; Ben-
goechea et al., 2008), in pharmaceutical products (Calixto and
Canellas, 1982) and ethanol production (Turhan et al., 2010).
The pulp of carob pods (fruit of Ceratonia siliqua L.) con-
tains high contents of sugar (sucrose, fructose and glucose) and
can be employed as a raw material for the production of syrups
(Petit and Pinilla, 1995) and crystallized sucrose (Lafuente,
1961) for the food industry.
The aim of the present work is to identify rich sugar carob
provenance to be used for industrial carob syrup extraction.
Figure 1 Repartition map of Moroccan carob population.
Table 1 Geographic and meteorological conditions of provenance of carob (Ceratonia siliqua L.) used in the study.
Provenance Geographic region Latitude N Longitude W Altitude (m) Rainfall (mm)
Taroudant High atlas (south-west) 303708200200–400 250
Agadir West coastal 304109330150–350 300
Essaouira –312009400100–200 300
Marrakech High atlas mountain 312907430700–1000 500
Beni-Mellal Middle atlas mountain 323006030500–800 550
Taza –340804080500–600 700
El Houceima North coastal 35110357050–250 327
2 H. El Batal et al.
Please cite this article in press as: El Batal, H. et al., Sugar composition and yield of syrup production from the pulp of Moroccan
carob pods (Ceratonia siliqua L.). Arabian Journal of Chemistry (2011), doi:10.1016/j.arabjc.2011.10.012
2. Materials and methods
2.1. Selection and preparation of samples
The material collection was carried out during summer. For
each provenance (Fig. 1) 30 trees were randomly chosen for
collection of composite samples. These later were characterized
according to the following morphological parameters: pod
weight, seed yield and pulp yield.
2.2. Determination of total and reducing sugars
Analyses of sugar in various food products are based on the
determination of total sugar, sucrose and reducing sugars, with
little emphasis on the other individual sugars. Precise, easy to
use and cost effective, the Bertrand’s method (Browne and
Zerban, 1955) of analysis remains a widely used industrial
method to estimate the total sugar and reducing sugar content
of syrups and other sugar solutions.
In this work, we used this method for the analysis of sugars in
the extracts of carob pulp. The assay itself involves collecting the
precipitate of cuprous oxide formed by reduction of the copper-
alkaline liquor in the presence of reducing sugars and assayed by
the manganimetric method. Bertrand tables give a direct corre-
spondence between the volume of potassium permanganate
(0.1 N) used and the reducing sugar content of the sample.
2.3. Production of syrup
For the production of syrup from the carob, the samples were
separated from the seeds and dried at 40 C for 1 day. In the
extraction process a sample weight of 100 g of pulp, with a
mean particle size between 0.5 and 1.0 cm, was suspended in
water in a ratio (pulp/water) (1:2) and stirred under optimum
conditions (T=43C, t= 160 min). The sugar extract and
solid phase were separated by centrifugation.
The juice obtained in the previous stage has to be concen-
trated using a rotary evaporator to the commercial levels of
66.5 Brix. The concentration of sugar must approach but not
quite reach the super-saturation point: The sugar concentra-
tion should be between 65% and 67% in weight. A lower per-
centage of sugar makes the syrup an excellent nutriment for
yeast and other microorganisms. A sugar saturated syrup leads
to crystallization of a part of the sugar under conditions of
changing temperature.
2.4. Statistical analysis
Each analysis was done at least in triplicate and the results are
expressed as mean and standard deviation (SD). The student’s
t-test was used to evaluate the differences between the means
of each group. P< 0.05 was considered to be statistically
significant.
3. Results and discussion
This work was carried out on different geographic regions of
carob trees in agro-forestry systems. Based on previous study
(Wahid et al., 2006) in which climatic data were analysed all
over Morocco, a stratified sampling method was used in which
topography, vegetation homogeneity and altitude were re-
grouped in seven geographic entities (Fig. 1). Each entity
(provenance) is here defined as a region characterized by sim-
ilar topographic and climatic conditions with a homogeneous
flora. Geographic characteristics, such as altitude slice, central
Figure 2 Yield of pulp and seeds of carob pods from different
provenances.
Table 2 Measurement average of carob in this study and from other studies.
Country Seed yield
(g/100 g ‘‘w/w%’’ of carob pods)
Pulp yield
(g/100 g ‘‘w/w%’’ of carob pods)
Morocco (present work) 17.47–29.44 71.30–82.30
Portuguese (Barracosa et al., 2007) 12.00–14.00 86.00–88.00
Tunisia (Naghmouchi et al., 2009) 13.00–18.00 82.00–87.00
Spanish (Haselberg, 1988) 7.00–16.00 84.00–93.00
Turkey (Biner et al., 2007) 10.02–17.77 82.23–89.98
Figure 3 The overall mean values for the total sugar, reducing
sugar and syrup yield of carob pulp.
Sugar composition and yield of syrup production from the pulp of Moroccan carob pods (Ceratonia siliqua L.) 3
Please cite this article in press as: El Batal, H. et al., Sugar composition and yield of syrup production from the pulp of Moroccan
carob pods (Ceratonia siliqua L.). Arabian Journal of Chemistry (2011), doi:10.1016/j.arabjc.2011.10.012
latitude and longitude as well as the mean precipitation of
these provenances are summarized in Table 1.
3.1. Measurement of carob pods
Results of carob pod measurements are shown in (Fig. 2). The
overall mean values for all parameters measured and their
standard deviations are presented. High levels of variation
were found considering the seven provenances studied. The
data from this study showed that there were no significant dif-
ferences (P> 0.05) among the seven crops as far as the yield
of pulp and seeds is concerned (Fig. 2).
Data obtained from other studies (Table 2) showed a
high diversity in the yield of pulp and seeds of carob.
Moroccan crops are largely characterized by high seed yields
average [17.47–29.44 g/100 g ‘‘w/w%’’] content and medium
pulp yields average [71.30–82.30 g/100 g ‘‘w/w%’’]. Spanish,
Tunisian, Portuguese and Turkey crops produce low to
medium seed yields and medium to high pulp yields (Hasel-
berg, 1988; Barracosa et al., 2007; Biner et al., 2007; Nagh-
mouchi et al., 2009). The results obtained in this study,
however, were in agreement with the literature.
3.2. Total and reducing sugar values from pods
The overall mean values for the total sugar and reducing sugar
and their standard deviations were presented in (Fig. 3). The
total sugar content varied between 31.5 and 50.1 g/100 g ‘‘w/
w%’’ of dry pulp in populations of Agadir and Essaouira,
respectively. There was only one carob for Essaouira, which
values were the highest averages. In this study it was found
that no significant (P> 0.05) difference was observed between
Taroudannt,Marrakech,Beni-Mellal,Taza and El houceima.
Essaouira had a significantly (P< 0.05) higher total sugar
content than all the other crops (Fig. 3).
The levels of reducing sugars varied between 11.3 and 14.6 g/
100 g ‘‘w/w%’’ of dry pulp, respectively, in the regions of Agadir,
Marrakech and Essaouira. There was a relatively high average
value (14.6 g/100 g ‘‘w/w%’’ of dry pulp) among the native pop-
ulation of the West Coast (Essaouira). Taroudannt, Agadir,
Marrakech,Beni-Mellal and Taza did not differ (P> 0.05),
but significantly differed (P< 0.05) from El Houceima and
Essaouira.
These results are comparable to those reported by Albanell
et al. (1991) in Spanish crops of about 46.95 and 12.75 g/100 g
‘‘w/w%’’ of dry pulp for total and reducing sugars,
respectively.
3.3. Syrup yield
The results of syrup (66.5 Brix) yield obtained in experimental
conditions are presented in Fig. 3. The obtained average values
vary between 28.7 and 37.2 g/100 g ‘‘w/w%’’ of dry pulp. The
samples with the higher yield were from Essaouira and
Beni-Mellal, with averages of 37.21 and 36.61 g/100 g ‘‘w/
w%’’ of dry pulp, respectively. The regions with the lower yield
were Agadir and Taroudannt with averages of 28.76 and
29.27 g/100 g ‘‘w/w%’’ of dry pulp, respectively. No significant
(P> 0.05) differences were observed between the syrup yield
of Taroudannt, Agadir, Taza and El Houceima. The Essaouira
and the Marrakech differed from one another and from the
Taroudannt,Agadir and Taza. The Taroudannt was
significantly (P< 0.05) lower in syrup yield than the other
crops. These results are less than with those reported by Petit
and Pinilla (1995) in Spanish crops of about 54.24 g/100 g
‘‘w/w%’’ of dry pulp for the syrup yield.
4. Conclusion
The proportions of carob pulp and seeds and the contents of
total and reducing sugars in pulp show a great diversity be-
tween the populations of the Moroccan carob tree. This
diversity seems to take place according to the geographical
origin of the population. The obtained results are comparable
with those reported in other studies for cultivars of various
origins.
The obtained carob syrup yields ranging between 28 and
39 g/100 g ‘‘w/w%’’ of dry pulp are very interesting for indus-
trial exploitation. According to this study, the most interesting
samples for the production of high syrup yield are those col-
lected in the regions of Essaouira and Beni-Mellal.
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Please cite this article in press as: El Batal, H. et al., Sugar composition and yield of syrup production from the pulp of Moroccan
carob pods (Ceratonia siliqua L.). Arabian Journal of Chemistry (2011), doi:10.1016/j.arabjc.2011.10.012
