ORIGINAL ARTICLE
Bromatological characterization of cocoa shell (Theobroma cacao), from seven cantons of the Amazonia, Ecuador
Caracterización bromatológica de la cáscara de cacao (Theobroma cacao), procedente de siete cantones de la Amazonia, Ecuador
Ana L. Chafla,I Zoraya Rodríguez,II R. Boucourt,II Verena Torres,II
]]> IUniversidad Estatal Amazónica, km. 2½, vía Puyo - Tena (Paso Lateral), Ecuador.
ABSTRACT
In order to determine the variability of the bromatological composition of cocoa shells between Amazonia cantons, seven cantons were selected and, from each of them, three farms, according to their production and edaphoclimatic characteristics. For sampling, the "five points" method for plots lower than ten hectares was applied. Statistical relations by analysis of principal components and cluster were analyzed. The total variance indicated that with three principal components which was possible to explain 85.03% of the total variability. The principal component 1 (crude fiber, ether extract and nitrogen-free extract) was identified with the "energetic component", and explained 39.35% of the system variance. The principal component 2 (dry matter and ash) corresponded to the mineral component, and explained 26.2%. The principal component 3 was identified with the crude protein and explained 19.05%. The cut made in the dendrogram to interrupt the forming groups process, ranged 2.52, allowed to join four groups:1) comprising three cantons, characterized by a slight increase of dry matter and ash (90.30 and 9.09%); 2) a canton, with increase of ether extract, nitrogen-free extract and lower crude fiber content (3.61, 57.41, 21.95%); 3) two cantons, with crude protein increase of 8.97% and 4) two cantons with higher crude fiber content (24.93%). It is concluded that the bromatological composition of cocoa shells, from the seven cantons of the Amazonia, can be mainly differentiated by the contents of ether extract, nitrogen-free extract and crude fiber, but remains in the range described in the literature, so they would be good alternatives as substrates in the solid state fermentation processes.
Key words: cocoa shell, energetic component, dendrogram.
RESUMEN
Para determinar la variabilidad de la composición bromatológica de las cáscaras de cacao entre cantones de la Amazonia se seleccionaron siete cantones y, de cada uno, tres fincas, de acuerdo a su producción y características edafoclimáticas. Para la toma de muestras se aplicó el método “cinco de oro” para parcelas menores de diez hectáreas. Se analizaron relaciones estadísticas mediante análisis de componentes principales y conglomerados. La varianza total indicó que con tres componentes principales fue posible explicar 85.03 % de la variabilidad total. La componente principal 1 (fibra bruta, extracto etéreo y extracto libre de nitrógeno) se identificó con el “componente energético”, y explicó 39.35 % de la varianza del sistema. La componente principal 2 (materia seca y ceniza) correspondió al componente mineral, y explicó 26.2 %. La componente principal 3 se identificó con la proteína bruta y explicó 19.05 %. El corte realizado en el dendrograma para interrumpir el proceso de conformación de los grupos, a distancia de 2.52 permitió aunar cuatro grupos: 1) compuesto por tres cantones, caracterizados por un ligero incremento de la materia seca y ceniza (90.30 y 9.09 %); 2) un cantón, con incremento de extracto etéreo, extracto libre de nitrógeno y menor contenido de fibra cruda (3.,61, 57.41, 21.95 %); 3) dos cantones, con incremento en proteína bruta de 8.97 % y 4) dos cantones con mayor contenido de fibra bruta (24.93 %). Se concluye que la composición bromatológica de las cáscaras de cacao, procedentes de los siete cantones de la Amazonia, se puede diferenciar fundamentalmente por los contenidos de extracto etéreo, extracto libre de nitrógeno y fibra bruta, aunque se mantiene en el rango descrito en la literatura, por lo que serían buenas alternativas para sustratos en los procesos de fermentación en estado sólido.
Palabras clave: cáscara de cacao, componente energético, dendrograma.
INTRODUCTION
Ecuador is a country of biodiversity, thanks to its geographical location and its edaphoclimatic characteristics. Its economy is based on agriculture, mainly in cocoa production, which in 2014 recorded an export of 235,000 metric tons (Moncayo 2016). Of the national surface, 8.86% corresponded to the northern Amazonia region, with 44,300 ha, of these 83% of the surface corresponds to national cocoa or creole and the remaining, 17% to other types of trinitarian cocoa (Cuvi et al. 2013).
Experts in cocoa production determined that in this exploitation only 10% of the fresh fruit weight is used, 90% corresponded to waste products, such as cocoa shell which represents 75% of the total weight of the harvested pods (González and Jaimes 2005, Barazarte et al. 2008).
The large volumes of waste generated in the cocoa industry are translated into environmental problems. Among them we can cite the foul- smelling appearance, lixiviate generation that filter into the ground and contaminate the soil, due to the high ammonia nitrogen concentrations, disposal problems to the environment, since it facilitates the culture medium for the spread of Phytophthora sp. fungus, the main cause of economic losses in the cocoa activity (Hernandez et al. 2014).
This has led to the development of several studies, in order to increase the commercial value and diversify the use of cocoa shells, which are commonly used in soil recovering and as input for animal feeding (Oddoye et al. 2010).
These strategies are of great importance, if are considered as an alternative for livestock production, especially in the Amazon region, specifically in Pastaza and Napo, areas with low production, due to weather conditions which is extremely rainy, with infertile soils, susceptible to nutrient leaching and erosion (Bravo et al. 2015). Therefore, the objective of this study was to determine the variability of the bromatological composition of cocoa shells between Amazonia cantons, for later use as a substrate in biotechnological processes that modify their nutritional value.
MATERIALS AND METHODS
]]> Procedure for sampling. Samples of cocoa, Criollo variety, were taken in five cantons of Pastaza province, one from Napo and Morona Santiago, belonging to the Amazon region. This area is characterized by annual average temperature, which range between 24 and 30 ºC, average rainfall of 3000 mm and average relative humidity of 85-90%. Samples were collected from three farms per canton, according to their production and edaphoclimatic characteristics, representing 24 samples in total. In the case of Santa Clara Canton, sampling was conducted in two sectors located in different edaphoclimatic zones, which also differ by their agronomical management. For sampling the fruits, in each farm the five points methodology was applied, proposed by Navarro et al. (2011). Healthy and ripe fruits were taken, with an average weight of 478.94 ± 95 g per pod, to which the seed was extracted. The color table (Korneup and Wonscher 1981) was used. The residual shell was identified and stored in bags for transport to the laboratory.Sample processing. Samples were milled until reached a particle size of 0.5 to 1 cm, in a crusher Jf 10-D. They were dried in oven at 65 °C for 48 h. Then, a spray dried material was performed. From the meals, 100 g by applying the quartering method were taken. To the dehydrated wastes, there was determined the content of dry matter (DM), ash (As), crude protein (CP), crude fiber (CF), ether extract (EE) and nitrogen-free extract (NFE) by standard methods (Latimer 2012).
Statistical methods. A principal components analysis (PCA) was conducted to evaluate bromatological variables. From the correlation matrix of the original indicators and with the application of eigenvalues criteria higher or equal to the unit, the principal components were selected which higher variability explained, those with preponderance values close to 0.70, for being value of the accumulated variance of those who reach the first assumption.
Cluster analysis (CA). To identify the groups according to their characteristics, the clustering method was used from the Euclidean distance. To define the groups, the cut was made at 2.5. The statistical procedures were performed in the SPSS software, version 22.0 (IBM Corporation 2013).
RESULTS AND DISCUSSION
The principal components analysis (table 1) explains 85.03% of the total variability of the evaluated indicators in the seven cantons.
The variables of higher contribution to the variance with 39.35%, expressed by the first principal component, were the CF percentage, with negative value, and the rest of variables with positive values, EE and NFE. These results can be interpreted as a component, whose percentages are associated with the energy characteristics of cocoa residual, and which have high values in these variables. The negative values in the CF percentage, associating component variables, indicate that a higher percentage of this indicator, reduces the energy content of the residual (Cruz and Sánchez 2000).
The variability in these indicators could be related to the climatic conditions of the areas under study, such as solar radiation, which leads to energy processes. Gomez (2002), when determing the effect of different light intensities (20-60%) in gas exchange and criole cacao development, obtained statistical differences in the leaves size, internodes length and DM. According to INAMHI (2013), cocoa crops require light percentages between 55 and 70%, heliophany 4 h/d, 800-1000 h/d per year.
Temperature, another factor which affects the crop variability, when it increases, modifies the phenological phases of the plant. The short cycles of high or low temperatures may affect flower buds, flowering, number of grains, grain weight and, thereby, yields (Chmielewski et al. 2004, Jarma et al. 2012). The optimum temperature for cocoa sowing is between 18 and 32 °C (24 °C). When it is lower than 15 °C, it provides few flowers and higher unsaturated salts concentration and if it is higher to 32 °C, its fruits are smaller (INAMHI 2013). This factor could influence on the composition of the sampled cocoa shells. Table 2 shows the temperature differences in each canton. The lower value corresponds to Pomona canton and the highest, to Canelos canton. However, temperature ranges are among the requirements for this plant species.
]]> The relative humidity (RH) also plays an important function in the carbon assimilation: to higher RH, higher will be the assimilation (Pimienta et al. 2011). Between the different values of luminosity, RH and temperature, determined in each canton, the highest corresponded to Canelos and Tena cantons (table 2).In component two (table 1), which explains 26.62% of the variability, the variables of higher contribution were the percentage of DM and As. The As are considered the mineral component which, from the nutritional point of view, it shows a little documented potential, in general sense, of the agricultural wastes for animal feeding. The variability in these indicators is related to rainfall and soil quality, which is a comprehensive indicator of sustainable agricultural ecosystems (Harrier and Watson 2003). In Pastaza province, are different soil types (table 2), characterized by low fertility and mineral deficiency, in addition to physical problems, not structure defined and high humidity saturation, although they have high level of organic matter, due to the higher rainfall of this region (Martin and Pérez 2009).
The third component (table 1), which was identified with the protein (19.05%) influence on the CP percentage. The indicator variability might be affected by the crop fertilization, as Carvajal (1984) pointed out, when determining that the potassium absorption in the plant increases under nitrogen and, therefore, increases the protein and the adenosine triphosphate (ATP).
The adequate nitrogen supply determines, largely, the plant growth, which is manifested by leaf area increase and net photosynthesis (Flores et al. 2012).
The cut made in the dendrogram to interrupt the groups formation process, at 2.52 of distance (figure 1), allowed to combine four groups. Group 1 consisted of three cantons (Arajuno, Santa Clara A and Triunfo), characterized by slight increase in DM and As with respect to others, except group 2, which was very similar in DM content (table 3). In this, a canton (Santa Clara B) differed by the slight increase in the percentage of EE, NFE and lower CF content. This sampling area presented edaphoclimatic characteristics different to Santa Clara A. In addition, 67% of sampled crops belonged to experimental areas with advanced crop management. In group 3, two cantons (Pomona and Macas) showed slight increase in the CP percentage. In group 4, two cantons (Canelos and Tena) had higher CF content.
Although there were no higher variations in the bromatological composition from the biological point of view, the Santa Clara (B) canton had higher energy content, an important characteristic for a substrate destined to biotechnological processes as the solid state fermentation (SSF) (Saval 2012). The cantons from group 1 had an intermediate performance. The groups 3 and 4 showed the most modest results. However, all can be used as a supplementary source of minerals and proteins, mainly for SSF processes. According to Rivas et al. (2011), the energy content in wastes is important, when it is used as a substrate for fermentation processes, because they must provide the nutrients and energy necessary to support microbial growth. It is important especially carbon-nitrogen relation, which should be between 20 and 30 parts of the first element per each of the second one, because it affects the efficiency of energy conversion.
When comparing the results with those reported by Abarca et al. (2010), Aguilar (2011), Ovaco and Pineda (2011), who analyzed cocoa shells belonging to Cone and Taura cantons, the obtained values were lower in CP, EE and NFE, and higher in DM, As and CF. However, it is not correct to attribute the variations of the bromatological composition to the edaphoclimatic conditions which prevail in the study areas, as these were not controlled. There are necessary other studies which deal in these aspects in an integral way. In both cases, it was worked with the same cocoa variety and similar analytical methods were used, but it would be necessary to know other factors inherent to the plant, aspect that in most of cases is the main source in the results variation.
It is known that the maturity degree of the plant, samples collection method, type of drying and the analytical standards used have marked influence on determining the chemical composition of the plant material (Crescente et al. 1999, Angulo et al. 2001, Ardila and Carreño 2011, Sanchez 2013), aspects that were monitored during this study.
]]> The PCA was a useful statistical tool to group the cantons, which was to maximize homogeneity in the groups and heterogeneity between them. However, according to Cabrera et al. (2004), the higher degree of heterogeneity that often exists between the samples that form a population, difficult decision.It is concluded that the bromatological composition of cocoa shells from the seven cantons of the Amazonia can be differentiated mainly by the contents of EE, NFE and CB. However, all of them are in the ranges recognized in the literature for this residual, so that could be used as substrates in the SSF processes.
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Received: 7/10/2015
Accepted: 13/6/2016
Ana L. Chafla, Universidad Estatal Amazónica, km. 2½, vía Puyo - Tena (Paso Lateral), Ecuador. Email: achafla@uea.edu.ec
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