Impact of Traditional Process on Hygienic Quality of Soumbala a Fermented Cooked Condiment in...

Marius K. Somda, Aly Savadogo, François Tapsoba, Nicolas Ouédraogo, Cheikna Zongo, AlfredS. Traoré

  Open Access OPEN ACCESS  Peer Reviewed PEER-REVIEWED

Impact of Traditional Process on Hygienic Quality of Soumbala a Fermented Cooked Condiment in Burkina Faso

Marius K. Somda1,, Aly Savadogo2, François Tapsoba1, Nicolas Ouédraogo1, Cheikna Zongo3, AlfredS. Traoré1, 2, 3

1Laboratory of Microbiology and Biotechnology, Research Center in Biological Food and Nutrition Sciences (CRSBAN), Department of Biochemistry and Microbiology University of Ouagadougou, Burkina Faso

2Laboratory of Food Technology, Department of Biochemistry and Microbiology University of Ouagadougou, Burkina Faso

3Laboratory of Clinical Biochemistry and pharmacology, Department of Biochemistry and Microbiology University of Ouagadougou, Burkina Faso

Abstract

Soumbala is an African fermented locust beans used as a food condiment in Burkina that it quality could be affected due to hygienic practices. The present study aimed to show the implication of traditional process on hygienic quality of soumbala. Soumbala a fermented condiment was collected in six ethnical groups of Burkina Faso. A total of 120 samples were analysed using standards methods of microbiology. The microbial analysis showed a significant difference (p < 0.05) among microorganism groups following to the synthetized diagrams (A and B). Significant difference (p < 0.05) was established among microorganisms targeted in diagram A versus diagram B comparing separately the amount of Bacillus sp. (18.77 ± 0.29% VS 37.22 ± 0.076%), Micrococcus sp. (17.52 ± 0.65% VS 10.68 ± 0.38%) and Staphylococcus sp. (19.63 ± 0.35% VS 14.49 ± 0.2%), Yeasts and Molds (34.74 ± 0.098% VS 37.6 ± 0.26%), Total coliform (9.1 ± 0.16% VS 0). The results indicated that samples of soumbala contain various microorganisms due the impact of processing.

At a glance: Figures

Cite this article:

  • Somda, Marius K., et al. "Impact of Traditional Process on Hygienic Quality of Soumbala a Fermented Cooked Condiment in Burkina Faso." Journal of Food Security 2.2 (2014): 59-64.
  • Somda, M. K. , Savadogo, A. , Tapsoba, F. , Ouédraogo, N. , Zongo, C. , & Traoré, A. (2014). Impact of Traditional Process on Hygienic Quality of Soumbala a Fermented Cooked Condiment in Burkina Faso. Journal of Food Security, 2(2), 59-64.
  • Somda, Marius K., Aly Savadogo, François Tapsoba, Nicolas Ouédraogo, Cheikna Zongo, and AlfredS. Traoré. "Impact of Traditional Process on Hygienic Quality of Soumbala a Fermented Cooked Condiment in Burkina Faso." Journal of Food Security 2, no. 2 (2014): 59-64.

Import into BibTeX Import into EndNote Import into RefMan Import into RefWorks

1. Introduction

The need for additional protein supplies to promote sustainable livestock in most tropical area has increased the search for indigenous wild legumes or condiments basis seeds for least cost formulation and production. Two such legumes or condiments are soumbala and bikalga, commonly known as African locust bean, of tropical trees (Parkia biglobosa and Hibiscus sabdariffa ) which are native to Africa and widely distributed in the savanna region (Adewusi et al. 1992). Bikalga and Soumbala are condiments of traditional uncontrolled alkaline fermentation of Hibiscus sabdariffa and Parkii biglobosa seeds respectivelly. These food condiments are used and produced as major condiment in many African countries including Burkina Faso, Mali, Niger, Nigeria, Cameroon and Sudan among others. Bikalga is also call as Dawadawa botso in Niger, Datou in Mali, Furundu in Soudan, Mbuja in Cameroon (Odunfa 1985; Yagoub et al. 2004). Bikalga and Soumbala are produced by women and create economical source (Ouoba et al. 2003). The seeds serve as source of useful ingredients for consumption as Iru in Yoruba, have some anti-nutritional factors (ANFs) such tannins, oxalate and hydrogen cyanide. ANFs were eliminated or reduced by application of heat and sprouting (Alabi et al. 2005). So fermentation has been reported to destroy some natural toxins which may occur in beans, improve the nutritive value, increase digestibility and enhance growth (Alabi et al. 2005; Bridget et al. 2004). The strains of Bacillus and Staphylococcus are implied fluently in the soumbala fermentation. Bacillus genus is involved to the initial fermentation of seeds characterized by the excretion of exopolysaccharides and lipopeptides (Savadogo et al. 2011). The Staphylococcus strains are responsible to the genesis of specific aromas. The excretion of lipopeptides can explain the use of these condiments as disinfectant in traditional medicine.

The Bacillus subilis and Bacillus pumilus are implied in the deterioration of the indigestibles polysaccharides and oligosaccharides (arabinogalactan, stachyose) content in Parkia biglobosa seeds (Ouoba et al. 2003; Ouoba et al. 2007). Kim and Park (2009) showed that Bacillus cereus isolated in a fermented cooked that showed have a high anticancer effects against AGS Human Gastric Adenocarcinoma cells. The final product from the fermentation of seeds, can present itself in several aspects according to the preferences: flour, curds or wads. This product is used in the human food as condiment in sauces and can replace industrial soups.

The soumbala is a condiment very consumed by some ethnic groups of Burkina Faso. An investigation permitted to target ethnic groups where its consumption is current. It is about the Bissa, Dagara, Dafing, Mossi and Samos. They are also consumed by Peulh, Bwaba, bobo, Sambla, Sénoufo (Ouoba et al. 2003).

This condiment is used preferentially in sauces and also in the preparation of the sauces of rice, couscous and other dishes basis of cereals. Several literature have been developed about fermented seed and related the extent of their physico-chemical properties and microbial aspect (Mohamadou et al. 2007; Ouoba et al. 2007; Parkouda et al. 2008; Oguntoyinbo et al. 2010; Parkouda et al. 2011).

The major problem of the set of the traditional process is located to the fluctuating quality of the different foods obtained. The processing and quality of soumbala is variable according Mossi, Fulani, Bobo, Dagara, Samo, Bissa groups. Indeed, the fermentation process which takes place spontaneously through the microflora development, can conduct to an organoleptic, microbiological or toxicological undesirable products (Rainbaul 1995).

The recipes and preparations of fermented condiments are unfit while the packaging and presentations are traditional; of course they still lack safety and quality controls. The physical conditions and infrastructure in the site of soumbala production are generally poor, with most seeds material displayed in the open. Under these conditions, the material is exposed to microbial and insect attack as well as the effects of moisture, dust, and temperature (De Souza et al. 2011).

Producers often collect seeds material on tree or market and prepare soumbala without any preliminary treatment to eliminate indigenous microbes. Sometimes, seeds processing is carried out in their homes in nonadequate hygienic conditions, and prepared condiments are stored in inappropriate conditions. Overall, the final product proposed to the consumers is sometimes of poor hygienic quality (Djikpo-Tchibozo et al. 2011).

This study was designed to value the impact of traditional process on hygienic quality of Soumbala a fermented cooked condiment in Burkina Faso. It will be able to prevent pathogens contamination and improve the hygienic and safety quality.

2. Material and Methods

The experiment was conducted in the Laboratory of Microbiology and Biotechnology at CRSBAN (University of Ouagadougou/Burkina Faso). The six processing kind of soumbala has been followed in the sites of production among ethnical groups as Mossi, Fulani, Bobo, Dagara, Samo, Bissa in Burkina Faso.

2.1. Diagrams of Production of soumbala

Table 1. Different process steps and their role in the production of soumbala

2.2. Sample Collection

Different samples of fermented condiments (soumbala) were taken to check the process effect on the microbial quality of these foods. Six (06) process of soumbala production were studied. A total 120 samples of soumbala were collected on six (06) sites of production with seller women according to the ethnical groups mentioned in table I. In each site, 20 samples of soumbala were collected and maintained at + 4°C in isothermal box then sent to the laboratory for analysis.

2.3. Microbiological Analysis

The levels of total mesophilic flora, total coliform, Escherichia coli, Staphylococcus sp, Micrococcus, Salmonella, Yeast and Molds were determined by standards microbiology system using the methods of Zinnah et al (2007) and De Souza et al (2011). The prevalence rates and levels of presumptive were determined in 120 samples.


2.3.1. Preparation of Sample

Each sample of soumbala was properly mixed to ensure homogenisation of the microorganisms present in the fermented product. 10 g of each of soumbala was introduced aseptically into 90 ml (1:10 dilution) of buffered Peptone water (0.85% (wv-1) Biomerieux, France) into stomacher blister and stored at ambient temperature for 30min. The mixture introduce in a McCartney bottle was mixed with a vortex (Gemmy Industrial Corporation, Italy) for 5 min. A serial dilution of 10-1 to 10-6 was made and 1 ml of each of dilution was pipetted in duplicate into appropriately marked Petri dishes.


2.3.2. Microbial Numeration

All media used in this study were purchased from Biomerieux (France). The total number of microorganisms expressed as Colony Forming Unit (cfu) per gram of sample was determined by standard plate count. The important approach in numeration was to detect the phenotypic aspect of microorganisms targeted.

-The total aerobic mesophilic flora (FAMT) was counted in Plate Count Agar (PCA), after 24 hours of incubation at 30°C under aerobic conditions.

-Eosin Methylen Blue medium (EMB) was carried out, to enumerate total coliforms and E. coli, after 48 hours of incubation, at 37°C and 44°C ±0.5°C respectively, under aerobic conditions.

-Yeasts and molds were counted in a Sabouraud after 3 - 5 days of incubation at 30°C, under aerobic conditions.

-Salmonella and Shigella sp was researched in a SS medium after 3 - 5 days of incubation at 37°C, under aerobic conditions.

-Suspected pathogenic Staphylococcus sp, were counted in the Chapman positive coagulase after 24 hours of incubation at 37°C, under aerobic conditions.

-Micrococcus sp, were counted in the Chapman medium after 24 hours of incubation at 37°C, under aerobic conditions.

-Bacillus sp, were counted in the Man Rogosa and Sharpe medium after 24 hours of incubation at 37°C, under aerobic conditions.

-Sulphite Reducing Bacteria (SRB) were screened with tryptone-sulfite neomycin broth after 20 hours incubation at 44°C ± 0.5°C.

Standard identification methods included Gram stain morphology, colony morphology, production of catalase or oxidase, lactose fermentation were used for microorganisms phenotypical identification. Coagulase production, pigment production, anaerobic production of acid from glucose of have been used confirm Staphylococcus sp. Mannitol salt agar (MSA) selective both was used to differentiate Staphylococcus sp. (Salt tolerance) and Micrococcus sp. (Salt intolerance). Bacillus sp. was identified by Voges-Proskauer (VP) test which reveal acetoin produced from glucose.

2.4. Statistical Analysis

Data obtained were expressed as means ± standard deviation (SD). Statistical analysis was done using Stata/IC 10.0 from StataCrop LP. All enumeration values analysed were transformed to log10 values due to the abnormal nature of the data. Frequency of microbial groups was calculated using Microsoft excel. A one way analysis of variance (ANOVA) was performed on enumeration values (duplicate means) obtained for each sample per medium. Comparison between mean values for the parameters considered was performed using the least significant difference test at 0.05 significance level.

3. Results

3.1. Diagrams of Production of soumbala

Production of soumbala is a traditional process and involves many steps, including cleaning, boiling in alkaline conditions, pounding, fermentation steaming, drying and roasting. The different steps of process used for soumbala production have been regrouped in two diagrams.

Figure 1. Diagram A relating to different steps of soumbala production in Mossi, Bissa, Fulani
Figure 2. Diagram B relating to different steps of soumbala production in Dagara, Bobo, Samo ethnicals groups

The Figure 1 showed the similar steps process used by ethnicals groups as Mossi, Bissa, Fulani while the Figure 2 denoted same steps in Dagara, Bobo, Samo ethnical groups. The two diagrams A and B showed that the main difference of process between ethnic groups reside in the method fermentation. Even the ingredients used and major route is similar among the groups, the particular difference reside to the safety of finished product intended to the human consumption. The taste, flavour, smell, color, stiffness of soumbala from diagram B were clearly appreciated by the consumers than one of diagram A. These characteristics of fermented products are the major difference between the samples of soumbala obtained.

During the fermentation, proteolysis followed by the degradation of carbohydrates seems to be the main biochemical and smell of seeds. This hypothesis is supported by the found of Ouoba, Parkouda, Diawara, Scotti and Varnam (2007).

They showed that proteolytic, lipolytic and amylolytic activities during the fermentation involve the change of fermented product.

3.2. Numeration of Isolates Microorganisms

The microbial numeration on different samples of soumbala was studied and is presented in Figure 3.

The results in Figure 3 present the phenotypic microorganisms identified and show that neither Salmonella nor Sulphite Reducing Bacteria were found in the soumbala. Total coliform were detected in Diagram A and empty in Diagram B. The samples were much contaminated by total aerobic microorganisms. It was observed that the number of total mesophilic microorganisms from diagram A were most represented (log10 (UFC.g-1): 9.42±0.03) was highest than diagram B (log10 (UFC.g-1): 8.50±0.02) with a significant degree p<0.05. Yeast and molds were count were significantly different ( log10 (UFC.g-1): 7.86±0.02 in diagram A versus log10 (UFC.g-1): 6.63±0.06) in diagram B) with p<0.05). A significant difference (p<0.05) is noted concerning the presence of Bacillus sp, the diagram A (log10 (UFC.g-1): 4.38±0.12) contain a less count than diagram B (log10 (UFC.g-1): 6.46±0.02). And yet the notable remark was the presence of total coliform (log10 (UFC.g-1): 2.13±0.06) in the soumbala provide from diagram A. The count of Staphylococcus sp and Micrococcus sp is higher from diagram A (log10 (UFC.g-1): 4.58±0.15 and 4.09±0.02) than diagram B (log10 (UFC.g-1): 2.51±0.05 at 1.85±0.11) with p<0.05.

In accordance with the AFNOR limits (Association Française de Normalisation [AFNOR], 2009), all of samples investigate were acceptable in hygienic sight according to all enumerated microorganisms.

3.3. Microbial Assessment

The distribution microbial following the diagram production of soumbala is presented in the Table 2.

Figure 3. Number of isolates microorganisms following two diagrams of condiments production

Table 2. Percentage distribution of various microbial genera in soumbala

Results in Table 2 showed a significant difference (p<0.05) between microbial communities presence in soumbala resulting of diagrams A and B of production. Significant difference (p<0.05) was established among microorganisms targeted in diagram A versus diagram B comparing separately the amount of Bacillus sp. (18.77±0.29% VS 37.22± 0.076%), Micrococcus sp. (17.52±0.65% VS 10.68± 0.38%) and Staphylococcus sp. (19.63±0.35% VS 14.49± 0.2%), Yeasts and Molds (34.74± 0.098% VS 37.6± 0.26%), Total coliform (9.1±0.16% VS 0).

4. Discussion

The soumbala collected on the sites of production in hot season are varied and undergo inopportune manipulations including the process of fermentation. These practices can reduce their quality. The soumbala is kept to an elevated ambient temperature. Temperature coupled an absence of cold chain causes a strong contamination (Gonfa et al. 2001). In the present work the microbiological quality of the soumbala examined is relatively acceptable. The rationale determining microbiological quality of the fermented products is to prevent deterioration due to the presence of foodborne pathogens and food intoxication risk.

Any sample was kept to limit to the quality of the international norms. It means unrespect of hygiene condition. The samples most contaminated are especially those of the diagram A due probably to the quality of water used during the production.

The detection of S. aureus and Sulphite Reducing Bacteria (SRB) is for their toxicological properties. So S. aureus is the leading species of the genus Staphylococcus implicated in food poisoning infection while SRB are a group anaerobic sporulating bacteria including Clostridium, their spores resist after heat treatment and may cause damages after contaminated product consumption (De Souza et al. 2011). The contamination of samples pathogen may occur in soumbala processing or during the handling water and implement used also during the storage.

Similar shapes of contamination have been described on fermented products in several countries of Africa by some authors as Godefay and Molla (2000); Gonfa, Foster and Holzapfel (2001).

A number superior to 4.0 log (ufc/g) of Mesophilic total indicates deficiency condition of hygiene in the production or storage about Yamani, Al Kurdi, Haddadin and Robinson (1999). The microbiological quality of the condiment remained important for its conservation (Guinot-Thomas et al. 1995). The strong rate of yeasts and molds in soumbala samples could be explained as well as by the state of containers cleanliness used and the methods of transformation (Gadaga et al. 2000; Beukes et al. 2001).

The massive presence of yeasts and molds is also the expression of a strong outside contamination and a bad hygiene of the implement. The importance of Staphylococcus aureus and Total coliform in the fermented product could result to a lack of hygiene or a strong contamination of the raw material allowing germs to escape the bacteriocin produced by the Bacillus kind. Staphylococcus aureus and Total coliform are responsible to the food damage. The proliferation of the microorganisms on the soumbala could be explained by the necessary mineral and nitrogenous elements found in abundance on the raw material and used by these microorganisms (Somda et al. 2011).

5. Conclusion

The results showed that soumbala contain various microorganismes. The presence of the indicator germs of hygiene lack shows that the soumbala consumed by an important part of the population can especially contribute to reduce the quality and time conservation then create economical impact.

Acknowledgement

We need to thank Pr Alfred S. Traoré responsible of Research Center in Biological Food and Nutrition Sciences (CRSBAN) and also producer women of soumbala for their collaboration.

References

[1]  Adewusi, S. R.A., Orisadare, B.A. & Oke, O. L. 1992. Studies on weaning diets in Nigeria. Two protein sources. Plant Food Human Nutrition. 42: 183-192.
In article      CrossRef
 
[2]  Alabi, D.A, Akinsulire, O.R. & Sanyaolu, M.A. 2005. Qualitative determination of chemical and nutritional composition of Parkia biglobosa. African Journal of Biotechnology 4: 812-815.
In article      
 
[3]  Association Française de Normalisation (AFNOR). 2009. Normes Agroalimentaires. http://www.afnor.org/secteurs/activite/agroalimentaire/normes/liste-desnormes.(accessed January 15, 2014).
In article      
 
[4]  Beukes, E.M., Bester, B. H. & Mostert, J. F. 2001. The microbiology of South African traditional fermented milks. International Journal of Food Microbiology 63: 189-197.
In article      CrossRef
 
[5]  Bridget, O.O, Olumuyiwa, S.F., Bolanie, O.A. & Adewusi, S.A.A. 2004. Biochemical changes in Africa locust beans (Parkia biglobasa) and melon (Citrullus vulgaris) seeds during fermentation to condiment. Pakistan Journal of Nutrition 3: 140-145.
In article      CrossRef
 
[6]  De Souza, C., Ameyapoh, Y., Karou, S.D., Anani, K.T., Kpodar, M.L. & Gbeassor M. 2011. Assessing Market-Sold Remedies in Lomé (Togo) for Hygienic Quality. Biotechnology. Research International. pp: 1-5.
In article      CrossRef
 
[7]  Djikpo-Tchibozo, A. M., Anani, K., Ameyapoh, Y. 2001. Evaluation of hygienic quality of six medicinal plants and traditional phytomedecine. Pharmaceutica Medicine Traditional of Africa. 11: 83-92.
In article      
 
[8]  Gadaga, T.H, Mutukumira, A.N. & Narvhus, J.A. 2000. Enumeration and identification of yeasts from Zimbabwean traditional fermented milk. International Dairy Journal. 10: 459-466.
In article      CrossRef
 
[9]  Godefay, B. & Molla B. 2000. Bacteriological quality of raw cow's milk from four dairy farms and a milk collection centre in and around Addis Ababa. Berlin. Munchener Tierar. Wochen. 113: 276-278.
In article      
 
[10]  Gonfa, A., Foster, H.A. & Holzapfel WH. 2001. Field survey and literature review on traditional fermented milk products of Ethiopia. International Journal of Food Microbiology. 68: 173-186.
In article      CrossRef
 
[11]  Guinot-Thomas, P., Al-Ammoury, M. & Laurent F. 1995. Effects of Storage Conditions on the composition of Raw Milk. International Dairy Journal 5: 211-223.
In article      CrossRef
 
[12]  Mohamadou, B.A., Mbofung, C.M.F. & Thouvenot D. 2007. Functional potential of a product from traditional biotechnology: antioxidant and probiotic potential of Mbuja, produced by fermentation of Hibiscus sabdariffa seeds in Cameroon. Journal of Food Technology. 5: 164-168.
In article      
 
[13]  Odunfa, S.A. 1985. Biochemical changes during “iru”fermentation. Journal of Food Technology 20: 295-303.
In article      CrossRef
 
[14]  Oguntoyinbo, F.A., Huch, M., Cho, G.S., Schillinger, U., Holzapfel, W.H., Sanni, A.I. & Franz, C.M. 2010. Diversity of Bacillus species isolated from okpehe, a traditional fermented soup condiment from Nigeria. Journal of Food Protection. 73: 870-878.
In article      
 
[15]  Ouoba, L.I.I., Parkouda, C., Diawara, B., Scotti, C. & Varnam, A.H. 2007. Identification of Bacillus spp from Bikalga, fermented seeds of Hibiscus sabdariffa: phenotypic and genotypic characterization. Journal of Applied Microbiology 104: 122-131.
In article      
 
[16]  Ouoba, L.I.I., Cantor, M.D., Diawara, B., Traore, A.S. & Jakobsen, M. 2003. Degradation of African locust bean oil by Bacillus subtilis and Bacillus pumilus isolated from soumbala, a fermented African locust bean condiment. Journal of Applied Microbiology 95 (4): 868-873.
In article      CrossRef
 
[17]  Parkouda, C., Diawara, B., Lowor, S., Diako, C., Kwesi-Saalia, F., Annan, N.T., Jensen, J.S., Tano-Debrah, K. & Jakobsen M. 2011.Volatile compounds of maari, a fermented product from baobab (Adansonia digitata L.) seeds. African Journal of Biotechnology 10 (20): 4197-4206.
In article      
 
[18]  Parkouda, C., Diawara, B. & Ouoba, L.I.I. 2008. Technology and physico-chemical characteristics of Bikalga, alkaline fermented seeds of Hibiscus sabdariffa. African Journal of Biotechnolgy.7: 916-922.
In article      
 
[19]  Rainbaul A. 1995. Bactéries lactiques et fermentation du manioc. In: Transformation alimentaire du manioc. Eds T. Agbor Egbe, A. Brauman, D. Griffon and S. Trèche. Paris, ORSTOM. pp. 258-275.
In article      
 
[20]  Savadogo, A., Tapi, A., Chollet, M., Wathelet, B., Traoré, A.S. & Jacques P.H. 2011. Identification of surfactin producing strains in Soumbala and Bikalga fermented condiments using Polymerase Chain Reaction and Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry methods. International Journal Food of Microbiology 151:299-306.
In article      CrossRef
 
[21]  Seo, H.R., Kim, J.Y., Kim, J.H. & Park, K.Y. 2009. Identification of Bacillus cereus in a Chungkukjang that Showed High Anticancer Effects Against AGS Human Gastric Adenocarcinoma Cells. Journal of Medicinal Food. 31: 1274-1280.
In article      CrossRef
 
[22]  Somda, K.M., Savadogo, A., Barro, N., Thonart, P. & Traoré, A.S. 2011. Effect of mineral salts in fermentation process using mango residues as carbon source for bioethanol production. Asian Journal of Industrial Engineering. 3(1): 29-38.
In article      CrossRef
 
[23]  Yagoub, A.E.G.A., Mohamed, B.E., Ahmed, A.H.R. & El-Tinay, A.H. 2004. Study on Furundu, a traditional sudanese fermented roselle (Hibiscus sabdariffa) seed: effect on in vitro protein digestibility, chemical composition and functional properties of the total proteins. Journal of Agricultural Food Chemistry. 52: 6143-6150.
In article      CrossRef
 
[24]  Yamani, M.I., Al-Kurdi, L.M.A., Haddadin, M.S.Y. & Robinson RK. 1999. A simple test for the detection of antibiotics and other chemical residues in ex-farm milk. Food Control. 10: 35-36.
In article      CrossRef
 
[25]  Zinnah, M.A., Bari, M.R., Islam, M.T., Hossain, M.T., Rahman, M.T., Haque, M.H., Babu, S.A.M., Ruma, R.P. & Islam, M.A. 2007. Characterization of Escherichia coli isolated from samples of different biological and environmental sources. Bangladesh Journal of Veterinary Medicine. 5 (2): 25-32.
In article      
 
comments powered by Disqus
  • CiteULikeCiteULike
  • MendeleyMendeley
  • StumbleUponStumbleUpon
  • Add to DeliciousDelicious
  • FacebookFacebook
  • TwitterTwitter
  • LinkedInLinkedIn