Tesi sul tema "Cocoa"

The interaction between cocoa polyphenols and sugars was investigated in the Caco-2 cell model. Previous investigations have suggested a link between sugar content of a food/meal and epicatechin bioavailability. To investigate this hypothesis further, the effect of sucrose, glucose and fructose on epicatechin absorption across the Caco-2 monolayer was studied, and is presented here. Apical to basolateral transport of epicatechin was enhanced by co-incubation with sucrose, but not glucose or fructose. It is proposed that sucrose-induced cell signalling stimulated activity of the sodium-dependent glucose transporter SGL T1, which lead to widening of tight junction pore size. Consequently paracellular permeability of epicatechin was enhanced. The presence of glucose or fructose, but not sucrose, reduced the total concentration of methylated epicatechin produced by Caco-2 cells. Decreased formation of methylated epicatechin is hypothesised to be a consequence of catechol-O-methyl transferase inhibition (COMT). COMT requires a magnesium cation cofactor, which is also required by some glycolytic enzymes. It is suggested that competition for the magnesium (11) cofactor leads to reduced epicatechin methylation. Flavanol-rich dark chocolate extract also reduced total methylation of epicatechin. It is proposed that flavanols with a degree of polymerisation greater than monomer compete with epicatechin for methylation.

[ES] «Aplicación de nuevas tecnologías a la alcalinización de cacao» es una tesis doctoral centrada, por un lado, en el estudio de los cambios fisicoquímicos y funcionales causados por dos técnicas de alcalinización alternativas a la convencional y, por otro, en la comparación de dichas propiedades con las de muestras comerciales. En el capítulo I, se describe un sistema de alcalinización basado en extrusión. Esta tecnología se ha aplicado a la alcalinización de cacao dada su capacidad de tratar la materia prima de forma rápida y continúa, y su bajo consumo energético. En primer lugar, se estudiaron los efectos de diversas variables de proceso sobre las propiedades fisicoquímicas y funcionales de cacaos en polvo. En general, de todas las variables, el tipo y la concentración de álcali fueron las principales responsables del incremento de pH, del oscurecimiento de las muestras y de la reducción en el contenido de compuestos funcionales. En cuanto a la humedad, fueron la temperatura y el contenido en agua las que mostraron causar los mayores efectos, llegando a producir reducciones de casi un 50%. Además de evaluarse el efecto de las diferentes variables, en este capítulo también se compararon los cacaos producidos mediante extrusión con los alcalinizados por el método convencional. Los resultados mostraron que la extrusión, en menos de cinco minutos, fue capaz de oscurecer y de producir cacaos en polvo con un perfil sensorial, una capacidad antioxidante y un contenido en polifenoles totales relativamente similar al de los productos comerciales. En cuanto al capítulo II, en este se ha estudiado la técnica de calentamiento por microondas como una alternativa al tratamiento de alcalinización tradicional. La tecnología microondas ha demostrado ser rápida, versátil y capaz de preservar las características funcionales y sensoriales, lo que ha hecho interesante su aplicación a la alcalinización de cacao. En los trabajos que forman este segundo capítulo, se estudiaron los efectos de diversas variables de proceso sobre el producto. En general, el tipo y la concentración de álcali fueron las variables principalmente responsables del oscurecimiento del cacao, del incremento del pH y de la reducción de las concentraciones de catequina y epicatequina. Sin embargo, el álcali empleado no redujo la actividad antioxidante ni al contenido en fenoles totales, propiedades que se vieron incrementadas por la presión, la potencia y la duración del tratamiento. Estos incrementos se relacionaron con la capacidad de estas variables para liberar a los polifenoles no extractables y para promover determinadas reacciones químicas. Además, también se estudió el efecto de las diferentes variables sobre la humedad. La potencia y la duración del tratamiento fueron las que se mostraron esenciales para lograr el secado del producto, llegando a producir reducciones de hasta el 70%. Por otro lado, además de estudiarse el impacto de las diferentes variables, también se compararon cacaos producidos por microondas con muestras producidas por el método convencional para evaluar su similitud con los cacaos comerciales. Los resultados mostraron que el microondas, en solo cuatro minutos, fue capaz de oscurecer el cacao y de mantener un perfil sensorial similar al producido por el método tradicional, a la par que conducía a una mejora en sus propiedades funcionales. En resumen, los métodos para la alcalinización de cacao desarrollados en el marco de la presente tesis doctoral han demostrado ser unas alternativas muy prometedoras a la tecnología convencional. Ambas técnicas no solo han sido capaces de oscurecer el cacao tanto como el método comercial en un tiempo mucho menor, sino que también han conseguido el secado parcial de la muestra y unas características sensoriales y funcionales comparables o incluso mejores que las del método convencional.
[CAT] «Aplicació de noves tecnologies a l'alcalinització de cacau» és una tesi doctoral centrada, d'una banda, en l'estudi dels canvis fisicoquímics i funcionals causats per dos tècniques d'alcalinització alternatives a la convencional i, d'altra banda, en la comparació d'aquestes propietats amb les de mostres comercials. En el capítol I, es descriu un sistema d'alcalinització similar al convencional però basat en extrusió. Aquesta tecnologia s'ha aplicat a l'alcalinització de cacau per la seua capacitat de tractar la matèria primera de forma ràpida i continua, i pel seu baix consum energètic. En primer lloc, es van estudiar els efectes de diverses variables de procés sobre les propietats fisicoquímiques i funcionals de cacaus en pols. En general, de totes les variables, el tipus i la concentració d'àlcali van ser les principals responsables de l'increment de pH, de l'enfosquiment de les mostres i de la reducció en el contingut de compostos funcionals. Pel que fa a la humitat, van ser la temperatura i el contingut en aigua les que van causar els majors efectes, arribant a produir reduccions d'un 50%. A més d'avaluar l'efecte de les diferents variables, en aquest capítol també es van comparar els cacaus produïts mitjançant extrusió amb els alcalinizats pel mètode convencional. Els resultats van mostrar que l'extrusió, en menys de cinc minuts, va a ser capaç d'enfosquir i de produir cacaus en pols amb un perfil sensorial, una capacitat antioxidant i un contingut en polifenols totals relativament similar al dels productes comercials. Pel que fa al capítol II, en aquest s'ha estudiat la tècnica de calfament per microones com una alternativa a l'alcalinització tradicional. La tecnologia microones ha demostrat ser ràpida, versàtil i capaç de preservar les característiques funcionals i sensorials, el que ha fet interessant la seua aplicació a l'alcalinització de cacau. En els treballs que formen aquest segon capítol, es van estudiar els efectes de diverses variables de procés sobre el producte. En general, el tipus i la concentració d'àlcali van ser les variables principalment responsables de l'enfosquiment del cacau, de l'increment del pH i de la reducció de les concentracions de catequina i epicatequina. No obstant això, l'àlcali empleat no va reduir l'activitat antioxidant ni al contingut en fenols totals, propietats que es van incrementar per la pressió, la potència i la duració del tractament. Aquests increments es van relacionar amb la capacitat d'aquestes variables per alliberar els polifenols no extractables i per promoure determinades reaccions químiques. A més, també es va estudiar l'efecte de les diferents variables sobre la humitat. La potència i la duració del tractament van ser les que es van mostrar essencials per aconseguir la deshidratació del producte, arribant a produir reduccions de fins al 70%. D'altra banda, a més d'estudiar-se l'impacte de les diferents variables, també es van comparar els cacaus produïts per microones amb mostres produïdes pel mètode convencional per tal d'avaluar la seua similitud amb els cacaus comercials. Els resultats van mostrar que el microones, en només quatre minuts, va ser capaç d'enfosquir el cacau i de mantenir un perfil sensorial similar al produït pel mètode tradicional, al mateix temps que conduïa a una millora en les seues propietats funcionals. En resum, els mètodes per a l'alcalinització de cacau desenvolupats en el marc de la present tesi doctoral han demostrat ser unes alternatives molt prometedores per a substituir la tecnologia convencional. Les dos tècniques no només han estat capaces d'enfosquir el cacau tant com el mètode comercial en un temps molt menor, sinó que també han aconseguit la deshidratació parcial de la mostra i unes característiques sensorials i funcionals comparables a les del mètode convencional.
[EN] "Application of new technologies to cocoa alkalization" is a PhD thesis that aims to study the effects of two alternative techniques on the physicochemical and functional features of alkalized cocoa, and to evaluate their suitability to replace the traditional treatment. In chapter I, the conventional system for alkalization in closed and pressurized vessels has been replaced by extrusion. This technique has been proved to be a fast, continuous and less energy-consuming method, characteristics that the traditional system lacks and that have promoted its application to cocoa alkalization. On the one hand, the effects produced by temperature, water content and alkali type and concentration were evaluated on the physicochemical and functional features of cocoa. In general, alkali type and concentration were the main variables increasing the pH, darkening the sample, but also reducing the functional content, while water content and temperature exerted minor effects. On the other hand, the temperature and the water content were the variables exhibiting the greatest effect on the moisture content, leading to reductions of almost 50%. Moreover, the extrusion alkalization products were compared to traditionally produced cocoa powders based on physicochemical, functional and sensory criteria. The results revealed that extrusion was faster and able to dark cocoa in a greater extent than the conventional treatment and to produce sensory acceptable powders. These results confirm that extrusion is a feasible and promising alternative method able to alkalize cocoa in a fast, continuous and less energy-consuming manner. In chapter II, microwave heating has been studied as a substitute of the traditional alkalization treatment. This heating method has proven to be fast, versatile and able to preserve functional and sensory features of the treated products, which has made interesting its application to cocoa alkalization. The effects of the microwave heating technique on water content, power, duration, pressure application and alkali type and concentration were analyzed. In general, alkali type and concentration were the main variables inducing the darkening of cocoa, increasing its pH and reducing the concentrations of catechin and epicatechin. However, these variables did not affect the antioxidant activity and the total phenol content of the treated cocoas in comparison to the untreated one. Treatment pressure, power and duration exerted positive effects on the antioxidant activity, the total phenol content or both. These changes were related to the capacity of these variables, in combination with the alkali agent, to release non-extractable polyphenols from the matrix and to the induction of different chemical reactions. Additionally, the effects of the different variables were studied on the moisture content. Power and duration of the microwave heating treatment were decisive in the reduction of the water content, which was significantly reduced up to 70%. In terms of the evaluation of the suitability of the developed microwave heating alkalization method, the produced cocoas were compared to the traditionally alkalized ones in their physicochemical, functional and sensory characteristics. The developed fast microwave heating treatment showed to be able to dark cocoa as much as the traditional method, to produce sensory equivalent powders and to lead to the obtaining of cocoas with higher antioxidant activity and phenol content. In conclusion, this PhD thesis has applied extrusion and microwave heating as promising alternatives to cocoa alkalization. These technologies have demonstrated to dark cocoa in a significantly faster fashion than the traditional alkalization treatment, while keeping similar sensory profile and functional features, and substantially drying the product.
The authors would like to acknowledge the financial support of the Spanish Government and European Regional Development Fund (Project RTC-2016-5241- 2)
Valverde García, D. (2020). Application of new technologies to cocoa alkalization [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/140311
TESIS

This thesis elaborates the determinants of cocoa supply in Ghana. It takes a detailed look on the history of cocoa production with a focus on Ghana, the institutional setup in Ghana and analyses changing factors and institution over time. The core of thesis is the analysis of the factors that have an impact on the cocoa suppply. The regression shows that the following determinants are significant in deciding the supply of cocoa beans: area harvested, yield, GDP of high income countries, oil price, the globally available stock of cocoa beans as well as the past cocoa price.

Leading cocoa-consuming countries have declared that in the year 2020, they will permit imports of sustainably sourced cocoa beans only, threatening the sustainability of the cocoa farming business. Certification offers enhanced market access for sustainability of the business of cocoa bean producers in Ghana. The purpose of this case study was to explore the strategies that farm managers used to obtain certification for cocoa bean production. Seven farm managers of a cocoa producer's cooperative located in the eastern region of Ghana who consistently produced certified cocoa beans for at least 5 years participated in the study. Deming's quality management theory served as the conceptual framework for this study. Semistructured interviews constituted the primary technique for data collection. Additional data from UTZ-certified documents and the archives of the cooperative supported the process of achieving data saturation. Data were analyzed using Bengtsson's manifest content analysis framework of decontextualization, recontextualization, categorization, and compilation to arrive at conclusions. Three themes emerged from data analysis: training in farming practices and certification code of conduct, management discipline, and environmental and social sustainability. The implications of this study for social change include the potential that certification might influence a positive change in the farming practices of Ghanaian cocoa farm managers. Social change might be reflected in the adoption of sustainable production practices, improved living conditions of producers, and biodiversity conservation.

Brazil is the world's sixth largest cocoa producer with 270,000 tonnes of cocoa produced per year. In a world with an increasing demand for chocolate, but with agriculture threatened by climate change, the chocolate industry is worried about a possible shortage of cocoa. Furthermore, growing cocoa is a main cause of deforestation. However, in the state of Bahia, Northeast Brazil, cocoa is grown in traditional agroforests called 'cabrucas' which maintain a forest cover. Cocoa, an understorey crop, is planted under the shade of native Atlantic Forest trees and exotic fruit trees introduced by the farmers. These cabrucas have high conservation value but very low cocoa yield. In my thesis I investigate the factors limiting cocoa yield and how to increase yield in cabrucas. I explore the role of shade trees and the nutrient dynamics in litterfall. Finally, I explore the risk that climate change could represent for cocoa production in the future by looking at the effects of an unexpected drought caused by an El Niño Southern Oscillation (ENSO) event between November 2015 and May 2016. My study is based on data collected in permanent transects in 32 randomly chosen cabruca farms in Barro Preto a municipality of Bahia over a period of three years. I also established littertraps in 10 cocoa farms where I intensively studied nutrient dynamics and cocoa yield per tree over 12 months. My results showed that unproductive trees, low cocoa tree density, high shade cover and high cocoa mortality due to drought were the main factors limiting cocoa yield in cabrucas. Surprisingly, adding fertilisers to the cocoa trees did not increase yield. This suggests that there is no nutrient deficiency in cabrucas. In the farms, I found 69 species of shade trees for an average density of 125 ± 32 trees per hectare. Half of the species of shade trees were Atlantic Forest species of conservation value. The litterfall experiment showed the shade tree species and the quantity of litterfall produced, can affect the number of cocoa pods per tree. In cabrucas, a higher number of cocoa pods was found on cocoa trees under shade trees than under no shade. Finally, I showed that the exceptionally severe ENSO-related drought caused 80% loss in yield and 11% cocoa tree mortality in Barro Preto. Climate models predict an increased frequency of strong ENSO events in the future. Farmers in Bahia are not prepared to face regular drought events. The 2015/16 drought affected the dynamics of cocoa production in Brazil: it accelerated the decrease of extensive wildlife-friendly cocoa production in Bahia whereas it increased the development of cocoa production in intensive low shade plantations in the state of Pará. This suggests that climate change could be a threat to traditional cocoa agroforests in Bahia. Developing wildlife-friendly certification schemes and Payment for Ecosystem Services to internalise the value of forest conservation and to encourage farmers to maintain their shade trees could save cabruca systems from going extinct.

La investigación realizada busca dar a conocer los factores que influyeron a las exportaciones de la granilla de cacao a Corea del Sur durante los años 2013-2017. En el primer capítulo se expone los aspectos relacionados con las oportunidades del mercado en cuanto a tendencias y también relacionadas al producto por sus características y beneficios; mencionamos la definición, origen, variedades, especificaciones y proceso de producción de la granilla de cacao para su exportación y conceptos relacionados con los superfoods. Además, se investigó sobre el mercado objetivo Corea del sur, sus características, intercambio comercial, tratados vigentes, estrategias de marketing y comercialización. Hemos incluido el tema de la logística que involucre el traslado a destino con las medidas sanitarias correspondientes, empaques y embalajes solicitados. Todas estas medidas son importantes a tener en cuenta para una correcta exportación. En el segundo capítulo desarrollamos el sustento de la investigación. La metodología de investigación utilizada es la de tipo cualitativa, descriptiva-explicativa y la validamos mediante entrevistas a exportadores, organismos públicos y expertos. Además, se describen en la recolección de datos las experiencias que observamos. En el tercer capítulo, procedemos a utilizar los datos recopilados, llevando los resultados por diferentes categorías y segmentos. En el cuarto capítulo discutimos sobre los resultados de las entrevistas los cuales nos ayudaron a identificar los factores de exportación para la granilla de cacao al mercado Sur Coreano en los años 2013-2017, incluyendo los hallazgos, barreras y brechas de nuestra investigación. Finalmente, detallamos las conclusiones y recomendaciones de este tema.
The research carried out seeks to reveal the factors that influenced the export of cacao beans to South Korea during the years 2013-2017. In the first chapter, the details of the aspects related to market opportunities are exposed in terms of trends and related to the product by its characteristics and benefits. We also mention the definition, origin, varieties, specifications and production process of cocoa beans for publication, as well as the details of their benefits and the nutritional aspect and concepts related to superfoods. In addition, it was investigated on the target market of South Korea, its characteristics, commercial exchange, and marketing strategies. Similarly, we have included the issue of logistics involving the product in the country of destination that indicates the corresponding sanitary measures with the packaging and packaging requested by the final buyer. In the second chapter, we developed the sustenance of the research. The research methodology is based on the kind of qualitative, descriptive-explanatory and validity through interviews with the exporters, public bodies and experts. Additionally, the collection of data of the experiences and processes we observed during the interviews. In the third chapter, we will use the collected data, considering the results of different categories and segments. In the fourth chapter, we discussed the results of the interviews that helped us identify the communication factors for cocoa beans in the South Korean market in the years 2013-2017, including the findings, barriers and gaps of our research.
Tesis

Post-emancipation Grenada poses a unique situation in the agricultural milieu of the Caribbean. Grenada not only defied the norms of a mono-cultural existence, but experienced relative prosperity during a time of general depression. The colony's prosperity between 1870-1917 can be attributed to the agricultural transformation from large-scale sugar production to small-scale peasant cultivation of cocoa in the latter half of the nineteenth century.

Much of the written history concerning post-emancipation society in the Caribbean has tended to underline the collective impoverishment following the decline of sugar production. Furthermore, studies have concentrated on the handicaps and inefficiencies associated with peasant agriculture. This thesis attempts to go beyond these broad generalizations of underdevelopment and examines how Grenada's agricultural transformation to cocoa initiated fundamental change in the countryside. This agricultural transformation to cocoa not only allowed Grenada to escape the disastrous consequences experienced by its neighbors, but gave rise to an independent peasantry. An evaluation of the resulting socioeconomic consequences will focus on how the cultivation of cocoa helped the peasantry improve their situation, provided them with a greater sense of humility and most importantly contributed to the overall welfare of the colony.

Master of Science

The basidiomycete fungus Crinipellis perniciosa (Stahel) Singer is the causative agent of witches' broom disease of cocoa (Theobroma cacao). Witches' broom disease is endemic to large areas of the Americas and is a major constraining factor on cocoa production in such areas. The disease cycle includes a primary monokaryotic biotrophic phase and a secondary dikaryotic saprotrophic phase. In order to study the early stages of infection the possibility of quantifying the relative concentrations of the primary and secondary phases using changes in the ratio of mannan to chitin was investigated. Both chitin and mannan are fungal cell wall polymers. Separate gas chromatographic based mannan and chitin assays were developed. The new chitin estimation procedure was significantly more sensitive than the commonly used colorimetric based methods and was also selective for chitin rather than a range of similar components. The new method required only about 2oo ug of material whilst the previous and colorimetric based procedures required approximately 25 mg. Thus, the new procedure was sufficiently sensitive to detect extremely low levels of infection in clearly defined plant regions, such as meristems. The mannan assay was not significantly more sensitive than the previous assays, but produced cleaner samples, and thus interpretation of results was simplified and mass spectrometer maintenance reduced. To capitalise on the new chitin and mannan assays, the work was extended to encompass neutral and amino sugars. No useful biomarkers or ratios between components were discovered. Ratios between sugars may have been capable of apportioning the relative concentration of primary and secondary phase C. perniciosa in infected cocoa. All extractable lipids were also evaluated as potential biomarkers, and the lipid profiles assessed for potentially useful ratios. No useful lipid ratios were discovered, but ergosterol was found to be a useful biomarker. The newly developed chitin assay was used to study C. perniciosa infection in green and brown brooms. The assay was also used to investigate the distribution of C. perniciosa in sections taken throughout the length of an entire broom. The results indicated C. perniciosa was highly localised at the broom base and at the growing points. The use of random amplified polymorphic DNA polymerase chain reaction as a guide to pathogenicity was also evaluated. The method was adapted for use with C. perniciosa at the Institut Fur Genbiologische Forschung, Berlin. The method indicated the presence of fungal plasmids in the primary phase of C. perniciosa but not in the secondary.

The essential ingredient of chocolate is a product of the cocoa tree and is used world-wide in confectionary as a flavorant and as an ingredient of beverages. The flavour and odour of chocolate varies according to the source of the cocoa but must be free from objectionable or unpleasant characteristics. With the increasing demand for this product, chocolate producing companies have invested heavily in cocoa plantations in a number of areas in the world This has included South East Asia and Papua New Guinea. Cocoa from these sources suffers from high acidity and low chocolate flavour. It is felt that the presence of acids in excessive amounts can effect the flavour not only by imparting their own flavour but also by reacting with the basic flavour components which are formed during roasting. Such a group of compounds is pyrazines which make an essential contribution to chocolate flavour. The objective for the work in this thesis was to investigate the extent of reaction between the carboxylic acids and the methylpyrazines commonly found in different cocoas through the study of model systems in aqueous and non-aqueous environments. This involved the use of static gas chromatographic headspace analysis and 13C NMR :.pectroscopy. Data obtained from these techniques not only allowed observations on the reaction of pyrazines with carboxylic acids but also the calculation of the pKa of the pyrazines. It was shown that the acids which are commonly found in cocoa were present in sufficient concentration to reduce the concentration of free trimethylpyrazine and tetramethylpyrazine. The other methylpyrazines were not sufficiently basic to react with these acids to any extent and little or none of the pyrazine would be bound up in salt formation. The headspace analysis technique gave pKa values for the various methylsubstituted pyrazines which were consistently lower than those determined by other methods and reported in literature. However, when these values were normalised with respect to pyridine the pKa values agreed with the published values which had been determined by other techniques. The use of 13C NMR spectroscopy for the determination of the pKa value of pyrazine has been reported in literature. This technique was extended in this investigation to all other methylpyrazines. The results obtained were reproducible and compared favourably with the reported values. The analysis of Ghana and South East Asian cocoa liquors confirmed the unpublished results of Holm in which the concentration of alkylpyrazine in the latter were significantly higher than in the former. The application of the headspace analysis technique developed was used in a preliminary assessment of the alkylpyrazine concentrations in a number of chocolate tasters which had been prepared from cocoa liquors which originated from a number of South East Asian sources. Insufficient data was obtained to deduce any correlation with the taste panels scores of the samples. However, the method showed potential and warrants further investigation.

An indirectly heated solar drier fitted with a flat plate collector and a directly heated solar drier were compared with open air sun drying of cocoa beans under field conditions in St. Lucia. Sun drying was conducted on two surfaces, perforated steel and non perforated wood. The methods were examined for the ability to adequately dry fermented beans and effect on quality. Loading rates of 13.5, 26.9 and 40.4 kg/m$ sp2$ were examined.
Temperature increases of 15$ sp circ$C and 20$ sp circ$C above ambient were achieved in the indirect and direct drier, respectively. The solar driers were more efficient than sun drying units at removing moisture throughout at loading rates of 26.9 and 40.4 kg/m$ sp2$ but only in the initial stages at 13.5 kg. External mould development was therefore reduced. Open air sun drying on the wooden surface proved more effective in the final stages at 13.5 kg/m$ sp2$.
The dried beans were of similar internal quality despite faster drying in the driers. The various drying methods and loading rates produced beans of similar pH while only loading rates affected titratable acidity differently. The direct solar drier achieved lower final moisture levels at high loads and was the cheaper alternative.

Cacao swollen shoot virus (CSSV) is a major pathogen that has seriously constrained cocoa production in West Africa, particularly Ghana and Nigeria. To date, cordon sanitaire control measures in Ghana have failed to prevent the spread of the condition caused by the virus, Cacao swollen shoot virus disease (CSSVD). The aim of this study was to assess the efficacy of cocoa somatic embryogenesis to produce virus-free clonal propagation material both for replanting and to facilitate the safe international exchange of germplasm. CSSVD detection in the field is hampered by the sometimes slow appearance of visual symptoms and their complete absence in mild strains. Polymerase Chain Reaction (PCR)-based screening, a sensitive tool for microbial pathogen identification, is employed in this study because of its capacity for CSSV detection prior to the appearance of visual symptoms. Degenerate PCR primers were developed in order to improve the CSSV-strain dependence of earlier tests. Accordingly it was found that these primers (comprising a mixture of 48 variable redundant nucleotide bases) were capable of detecting 37 out of a putative 56 CSSV strains maintained at the Cocoa Research Institute of Ghana, four more than the sequence specific primers. For tissue culture studies, cocoa staminodes cultures were established from flowers of CSSV-infected cocoa genotypes CL 19/10 strain 1A and Amelonado Plant 2 to produce callus, primary and secondary somatic embryos, with genotype AMAZ 15 from the Intermediate Cocoa Quarantine Facility used as a virus-free control. In terms of primary somatic embryo production tested across five cocoa genotypes the Nestle protocol proved to be more efficient than the Penn State protocol, although the distinction was less clear with virus-infected donor trees. PCR- based CSSV detection proved that virus could be detected at callus, primary somatic embryos and secondary somatic embryo stages, although the frequency of CSSV was reduced, indicating that the progress of the virus was progressively impeded. Assessment on the presence of plasmodesmata within CSSV-infected cocoa tissues by using transmission electron microscopy was hampered with the presence of artefacts in all sections mounted on Formvar films. Plasmodesmata were not detected may be indicative of a low frequency of plasmodesmata and may also be due to the techniques and methods used. Trials were conducted to assess Nicotiana benthamiana plantlets as alternate CSSV indicators and while they did receive viral DNA this was at too Iowa frequency to make them a viable option for glasshouse- based viral screening. The overall findings of this work do, however, support the use of somatic embryogenesis as a means of improving CSSV-free clonal propagation of cocoa.

The principal objectives of this study are to identify the production factors that influence cocoa productivity at the smallholder's level and to examine resource allocation and technical efficiency in cocoa production. Cross-sectional data collected from 260 cocoa smallholders were used for the study. Both the average production function estimated by the Ordinary Least Squares techniques and the frontier production function estimated by the Linear Programming methodology were employed in the analysis. The results indicated that the input factors which had a significant impact on the production of cocoa were land size, labour, living capital, farm implements and fertilisers. Among the management proxies, only farmer's age, extension contact, farmer's education and the practice of keeping farm records and accounts were important. The data presented in this study 1end support to the hypothesis that the cocoa smallholders were highly inefficient allocatively. Inputs comprising land, fertilisers, and farm implements were underused while labour and living capital were overused. Technical inefficiencies were also present in the study area. The study revealed that a large proportion of the farmers have output levels below their potential. Output could be increased between 18 to 52 per cent if all the least efficient farmers attained those levels of technical efficiency that were achieved by the best farmers in the sample. The variations in technical efficiency in this area were explained by differences in land size, farmer's educational level, their age and the practice of keeping farm records and accounts. This study emphasises the need that increasing efforts must be directed at the least efficient farmers through better and effective management practices and better organization of farm activity without major new investments, at least in the short-run.

Some part of this study was covered by Dr. S.O. Adeyeye. His work published in 1978 concentrated on a general overview of cooperative movement in Nigeria. Since his work, there has been remarkably little or no research into the development of Cocoa Marketing Cooperatives' policies. A review of this study shows that Adeyeye carried out a historical work which did not account for the emergence of cocoa marketing policies during the early years of self government in Nigeria and what effect these policies had on the cooperatives' ability to practice their principle of democratic control. Our study is an attempt to fill in this important part of Marketing Coperatives' history. The theoretical part reviewed the conceptual framework of cooperative ideals and principles which enabled us to examine the operational policies of Cocoa Marketing Cooperatives in Nigeria, against the cooperatives' principle of democratic control. Our finding is that the adoption of cooperatives' principle of democratic control was not encouraged by the Governments who took the responsibility of promoting cooperatives in Nigeria, There was no provision for basic training in democratic procedure which is essential for any cooperative to be an independent viable organisation. The absence of cooperative education culminated in corruption and inefficient administration of the cooperative which was widespread over the period under study. Finally, the study acknowledges the difficulties of applying the cooperative principles in a real world, but recommended that it is of the utmost importance that cooperative organisations as they try to survive in a real world, should find new ways of putting principles into practice because the principles enable any cooperative organisation to fulfil the basis of its formation, that is, the promotion of members interests. The principle of democratic control to some extent indicates who the members are and allows them the right to determine for themselves what is their common need and how the need would mutually be met. The idea of the cooperative was born out of ideally felt need of members. It is a means of self help through mutual help, hence members should participate actively in all activities of the organization. The methodology applied to this study includes descriptive analysis, field work, archival and documentary research, informal discussion and the author's personal observations.

The need to conserve biodiversity of cocoa has become paramount due to the action of a range of diseases, pests and environmental hazards. In 1983 bushfire destroyed 60, 000 ha of cocoa plantation in Ghana and as of 1982 185.5 million trees have been cut down in Eastern region of Ghana alone due to Cacao Swollen Shoot Virus (CSSV) infection. In order to safeguard germplasm of cocoa there is the need to use in vitro-based techniques to support in situ conservation. Successful cryopreservation of cocoa has already been demonstrated using an encapsulation-dehydration method but this is a labour intensive protocol requiring a relatively high level of technical skill and the objective of the current work is to explore the efficacy of a vitrification-based approach. Floral-derived secondary somatic embryos (SSE) of cocoa genotype AMAZ 15 were utilised. In order to optimise the vitrification procedure the effect of preculturing SSEs on sucrose and dehydration with plant vitrification solution 2 (PVS2) was studied. SSEs were precultured on embryo development (ED) medium supplemented with either 0.5 or 0.75 M sucrose for 3 or 5 d and dehydrated with cold PVS2 for 45-105 rin before storage in liquid nitrogen (LN). Preculturing the embryos on 0.5 M sucrose for 5d and dehydrating them in PVS2 for 60 min led to significantly higher post-cryo survival than any other treatment (74.5±6.4%). So as to minimise cryo-injury due to cation- induced free radical formation, nutrient cation sources were removed from the ED solution and/or the recovery medium (ED), the former treatment resulting in a significant benefit. The influence of size of cotyledonary stage SSEs on postcryo' survival was studied for two size ranges. SSEs between 2-3 mm survived better than those between 4-5 mm. The protocol was effective across five other genotypes so far tested without further procedural variation. In order to accelerate bulking up of clones, embryos regenerated following cryopreservation were used as explant sources and the freezing process was not found to have any inhibitory effect on their embryogenic potential. In order to optimise the dehydration process Differential Scanning Calorimetry (DSC) was used to examine SSEs during cooling and warming. Partial vitrification, as evidenced by glass transition and ice melting, was achieved when embryos were exposed to PVS2 for 45 and 60 min which correlated with higher post- cryo survival. Application of somatic embryogenesis and cryopreservation to eradicate Cacao Swollen Shoot Virus (CSSV) was also studied. While somatic embryogenesis was able to reduce CSSV transmission in genotypes studied the assessment of any 'cryotherapy' effect was limited by the availability of post-cryo regenerants. Methylation sensitive amplified.

Given growing concerns regarding the chocolate sector's long-term future, ever more private-sector, public-sector and civil-society stakeholders have become involved in initiatives aiming to make cocoa production more 'sustainable'. However, despite the omnipresent term, stakeholders' understandings of associated environmental, commercial and socio-economic priorities diverge: while transforming cocoa into a more attractive livelihood for farmers is paramount for some, others prioritise links to global environmental challenges. A third dimension encompasses commercial concerns related to securing supply, an increasing qualm given projected cocoa shortages and ever-rising concentration in the marketplace. This research argues there are considerable tensions between different stakeholders' commercial, socio-economic and environmental priorities in cocoa sustainability initiatives especially in light of the sector's intensifying challenges. Further tensions emerge between underlying drivers and representations, as public-facing communication continues to emphasise altruism rather than commercial necessity, locating engagements in 'nice-to-have' rather than 'business imperative' territory. Based on documentary analysis, semi-structured interviews, focus group discussions and participant observation, this thesis aims to capture how cocoa-sector changes have driven shifts in stakeholder priorities and representations, incorporating voices from across the initiatives ranging from cocoa producers to chocolate consumers. Utilising a modified global production networks lens to represent the full spectrum of stakeholders involved, the research maps three cocoa sustainability initiatives incorporating conservation or carbon measures in terms of power and embeddedness, stakeholder drivers and representations. While identifying tensions, it also argues that acknowledging divergent understandings of the polysemic 'sustainability' concept constitutes an opportunity for a much-needed redressing of power and embeddedness asymmetries to address systemic issues threatening the sector's future. However, the thesis also observes that despite protestations of partnership, few actors are willing to contemplate the systemic changes in favour of more equitable treatment and power distribution which would be required to safeguard the sector's long-term viability. This thesis's contributions include its unprecedented critical exploration of the diverging socio-economic, commercial and environmental drivers which diverse stakeholders associate with cocoa sustainability, the meanings they create towards the public, and the link to underlying power and embeddedness structures. These analytical foci have proved instrumental in unpacking emerging tensions, which are likely to grow more marked as cocoa shortages become more acute and understandings of sustainability continue to diverge.

The objectives of the research presented in this thesis were: (1) optimise the processing conditions for the production of water-in-cocoa butter emulsions; (2) understand the role of water droplets on the large deformation behaviour and crystallisation properties of emulsified systems. Results showed that a scraped surface heat exchanger could be used to produce tempered emulsions with a small average droplet size (~3 µm). In all systems stability was provided by the emulsifier and fat crystals forming a network both in the bulk and at the interface of the water droplets. Characterisation of the large deformation properties of emulsions showed that the elastic behaviour remained constant at low aqueous phase percentages while the strength at fracture decreased. This result suggests that water droplets act as stress-concentrator elements, which is probably due to their partial sintering with the bulk network. Results of crystallisation experiments have shown that the effect of droplets on kinetics of crystallisation depends on the degree of supercooling: only at relatively high temperatures (15, 20 °C) the dispersed droplets increased the kinetics of crystallisation compared to bulk cocoa butter (CB). With respect to polymorphic evolution, emulsified systems evolved faster toward more stable forms than bulk CB at all temperatures.