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Sugar composition and yield of syrup production from the pulp of Moroccan carob pods (Ceratonia siliqua L.)
⁎Corresponding author. azhasib@yahoo.fr (A. Hasib)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
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”. Populations 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.
Keywords
Carob pods
Provenance of carob
Pulp yield
Total sugars
Reducing sugars
Syrup yield
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 varieties, 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), also called carob gum, locust bean gum (LBG) or E411. Locust bean gum is utilized in food and non-food industries for its ability to form a very viscous solution at relatively low concentration. It is also exploited for its synergy property with carrageenan, agar and xanthan to form stronger and more elastic 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; Bengoechea 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.) contains 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.
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.
Repartition map of Moroccan carob population.
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 correspondence 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 = 43 °C, t = 160 min). The sugar extract and solid phase were separated by centrifugation.
The juice obtained in the previous stage has to be concentrated 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 concentration should be between 65% and 67% in weight. A lower percentage 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 regrouped in seven geographic entities (Fig. 1). Each entity (provenance) is here defined as a region characterized by similar topographic and climatic conditions with a homogeneous flora. Geographic characteristics, such as altitude slice, central latitude and longitude as well as the mean precipitation of these provenances are summarized in Table 1.
| Provenance | Geographic region | Latitude N | Longitude W | Altitude (m) | Rainfall (mm) |
|---|---|---|---|---|---|
| Taroudant | High atlas (south-west) | 30°37′ | 8°20′ | 200–400 | 250 |
| Agadir | West coastal | 30°41′ | 9°33′ | 150–350 | 300 |
| Essaouira | – | 31°20′ | 9°40′ | 100–200 | 300 |
| Marrakech | High atlas mountain | 31°29′ | 7°43′ | 700–1000 | 500 |
| Beni-Mellal | Middle atlas mountain | 32°30′ | 6°03′ | 500–800 | 550 |
| Taza | – | 34°08′ | 4°08′ | 500–600 | 700 |
| El Houceima | North coastal | 35°11′ | 3°57′ | 50–250 | 327 |
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 differences (P > 0.05) among the seven crops as far as the yield of pulp and seeds is concerned (Fig. 2).
Yield of pulp and seeds of carob pods from different provenances.
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 (Haselberg, 1988; Barracosa et al., 2007; Biner et al., 2007; Naghmouchi et al., 2009). The results obtained in this study, however, were in agreement with the literature.
| 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 |
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 overall mean values for the total sugar, reducing sugar and syrup yield of carob pulp.
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 population 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 between 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 industrial exploitation. According to this study, the most interesting samples for the production of high syrup yield are those collected in the regions of Essaouira and Beni-Mellal.
References
- Bulletin mensuel d’information et de liaison du PNTTA MAPM/DERD. 2007;153:1-4.
- Characteristics of Spanish carob pods and nutritive value of carob kibbles. Cahiers Options Mediterranean. 1991;16:135-136.
- [Google Scholar]
- Evaluation of fruit and seed diversity and characterization of carob (Ceratonia siliqua L) cultivars in Algarve region. Scientia Horticulturae. 2007;114:250-257.
- [Google Scholar]
- Battle, I., Tous, J., 1997. Carob tree. Ceratonia siliqua L. promoting the conservation and use of underutilized and neglected crops. 17. Institute of Plant Genetics and Crop Plant Research. Gatersleben/International Plant Genetic Resources Institute, Rome.
- Composition and structure of carob (Ceratonia siliqua L) germ proteins. Food Chemistry. 2008;107:675-683.
- [Google Scholar]
- Sugar profiles of the pods of cultivated and wild types of carobbean (Ceratonia siliqua L.) in Turkey. Food Chemistry. 2007;100:1453-1455.
- [Google Scholar]
- Physical and Chemical Methods of Sugar Analysis (third ed). John Wiley and Sons; 1955. pp. 497–512
- Components of nutritional interest in carob pods Ceratonia siliqua. Journal of the Science of Food and Agriculture. 1982;33:1319-1323.
- [Google Scholar]
- Evaluation and preservation of genetic resources of carob (Ceratonia siliqua L.) in southern of Italy for pharmaceutical use. Breeding Research on Aromatic and Medicinal Plants. 2002;9:367-372.
- [Google Scholar]
- von Haselberg, C., 1988. A contribution to the classification and characterisation of female and male varieties of Ceratonia siliqua L. In: Fito, P., Mulet, A. (Eds.), Proceedings of the II International Carob Symposium, Valencia, Spain, pp. 137–151.
- Synergistic gel formation in aqueous solutions of guar–gellan composition. Pharmaceutical Chemistry Journal. 2007;41:42-45.
- [Google Scholar]
- Antioxidant activity of polyphenols in carob pods. Journal of Agricultural and Food Chemistry. 2002;50:373-377.
- [Google Scholar]
- Azticares de la algarroba I. La fermentaci6n selectiva de las hexosas en la obtenci6n de sacarosa. Revista de Agricultura y Technologia de Alimentos. 1961;1:1-7.
- [Google Scholar]
- Carob pods (Ceratonia siliqua L.) as a source of polyphenolic antioxidants. Food Technology and Biotechnology. 2004;42:105-108.
- [Google Scholar]
- Carob pulp as raw material for production of the biocontrol agent P. agglomerans PBC-1. Journal of Industrial Microbiology & Biotechnology 2010:1367-5435.
- [Google Scholar]
- Tunisian carob (Ceratonia siliqua L.) populations: morphological variability of pods and kernel. Scientia Horticulturae. 2009;121:125-130.
- [Google Scholar]
- Production and purification of a sugar pods syrup from carob. Lebensmittel-Wissenschaft und-Technologie. 1995;28:145-152.
- [Google Scholar]
- Fruit and seed diversity of domesticated carob (Ceratonia siliqua L.) in Morocco. Scientia Horticulturae. 2009;123:110-116.
- [Google Scholar]
- Prospección de variedades de algarrobo en Andalucía. Información Técnica Económica Agraria. 1995;3:164-174.
- [Google Scholar]
- Ethanol production from carob extract by using Saccharomyces cerevisiae. Bioresource Technology. 2010;101:5290-5296.
- [Google Scholar]
- Variation of morphological traits in natural populations of maritime pine (Pinus pinaster Ait) in Morocco. Annals of Forest Science. 2006;63:83-92.
- [Google Scholar]