Biotechnological approaches for cocoa waste management: A review.

Cured cocoa beans are obtained through a post-harvest, batchwise process of fermentation and drying carried out on farms in the equatorial zone. Fermentation of cocoa pulp-bean mass is performed mainly in heaps or boxes. It is made possible by a succession of yeast, lactic acid bacteria (LAB) and acetic acid bacteria (AAB) activities. Yeasts ferment the glucose of the cocoa pulp into ethanol, perform pectinolysis and produce flavour compounds, such as (higher) alcohols, aldehydes, organic acids and esters. LAB ferment the glucose, fructose and citric acid of the cocoa pulp into lactic acid, acetic acid, mannitol and pyruvate, generate a microbiologically stable fermentation environment, provide lactate as carbon source for the indispensable growth of AAB, and contribute to the cocoa and chocolate flavours by the production of sugar alcohols, organic acids, (higher) alcohols and aldehydes. AAB oxidize the ethanol into acetic acid, which penetrates into the bean cotyledons to prevent seed germination. Destruction of the subcellular seed structure in turn initiates enzymatic and non-enzymatic conversions inside the cocoa beans, which provides the necessary colour and flavour precursor molecules (hydrophilic peptides, hydrophobic amino acids and reducing sugars) for later roasting of the cured cocoa beans, the first step of the chocolate-making.

Functional role of yeasts, lactic acid bacteria and acetic acid bacteria in cocoa fermentation processes.

Cocoa is an important global commodity. It is mostly grown on small farms by millions of cocoa farmers who depend on the crop for their livelihood. Although potential yields exceed 6000 kg/ha, average farm yields are often around 400 kg/ha. Among the production constraints met by farmers is nutrient limitation. In this review, we compile current knowledge on nutrient cycling in cocoa production systems, nutrient requirements of cocoa, and yield response to fertilizer application in relation to factors such as management, climatic, and soil conditions. Large amounts of nutrients are cycled within cocoa systems, mostly through 5–10 t/ha/yr litter fall. Still, harvesting and small nutrient losses such as leaching lead to nutrient exports causing gradual soil nutrient depletion. Exact nutrient requirements of cocoa are unknown. Leaf and soil test interpretation to identify additional nutrient needs remain ambiguous. Recommended nutrient application rates vary more than 10-fold. In several trials fertilizer application more than doubled cocoa productivity; in other cases response is minimal. Differences in response between regions, fields and even trees have yet to be explained. Interactions with agroecology and management (especially shade) are poorly understood. Without this fundamental knowledge, farm level recommendations have a weak scientific base. Different types of research are recommended to complement current knowledge. Existing data and trials can be exploited through additional analysis and more detailed measurements. Cocoa farms are highly diverse and on-farm trials offer opportunities for understanding variability in production and fertilizer response. Finally, multifactorial shade–fertilizer response trials will be essential to address some of the fundamental knowledge gaps.

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Mineral nutrition of cocoa : a review

Climate change threatens coffee production and the livelihoods of thousands of families in Mesoamerica that depend on it. Replacing coffee with cocoa and integrating trees in combined agroforestry systems to ameliorate abiotic stress are among the proposed alternatives to overcome this challenge. These two alternatives do not consider the vulnerability of cocoa and tree species commonly used in agroforestry plantations to future climate conditions. We assessed the suitability of these alternatives by identifying the potential changes in the distribution of coffee, cocoa and the 100 most common agroforestry trees found in Mesoamerica. Here we show that cocoa could potentially become an alternative in most of coffee vulnerable areas. Agroforestry with currently preferred tree species is highly vulnerable to future climate change. Transforming agroforestry systems by changing tree species composition may be the best approach to adapt most of the coffee and cocoa production areas. Our results stress the urgency for land use planning considering climate change effects and to assess new combinations of agroforestry species in coffee and cocoa plantations in Mesoamerica.

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The future of coffee and cocoa agroforestry in a warmer Mesoamerica

Scientific knowledge, societal debates, and industry commitments around sustainable cocoa are increasing Cocoa agroforestry systems are supposed to improve the sustainability of cocoa production However, their combined agronomic, ecological, and socio-economic performance compared to monocultures is still largely unknown Here we present a meta-analysis of 52 articles that directly compared cocoa agroforestry systems and monocultures Using an inductive, multi-dimensional approach, we analyzed the differences in cocoa and total system yield, economic performance, soil chemical and physical properties, incidence of pests and diseases, potential for climate change mitigation and adaptation, and biodiversity conservation Cocoa agroforestry systems outcompeted monocultures in most indicators Cocoa yields in agroforestry systems were 25% lower than in monocultures, but total system yields were about ten times higher, contributing to food security and diversified incomes This finding was supported by a similar profitability of both production systems Cocoa agroforestry contributed to climate change mitigation by storing 25 times more carbon and to adaptation by lowering mean temperatures and buffering temperature extremes We found no significant differences in relation to the main soil parameters The effect of the type of production system on disease incidence depended on the fungal species The few available studies comparing biodiversity showed a higher biodiversity in cocoa agroforestry systems Increased and specific knowledge on local tree selections and local socio-economic and environmental conditions, as well as building and enabling alternative markets for agroforestry products, could contribute to further adoption and sustainability of cocoa agroforestry systems

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Cocoa agroforestry systems versus monocultures: a multi-dimensional meta-analysis

This paper reviews the present condition of cocoa growing in West Africa where some six million ha are planted with cocoa which provide about 70 percent of the total world production. Cote d’Ivoire and Ghana are the largest producers, followed by Nigeria and Cameroon. In the beginning of the 21st century the cocoa production increased from about 2,000,000 tons to about 3,000,000 tons in 2010 and subsequent years. While in this period expansion of the cocoa area (at the expense of forest land) contributed to increased production, nowadays more cocoa has to come from higher yield per ha which is very low at present. This paper highlights at first cocoa growing in each of the cocoa producing countries and then deals with the common constraints and options to higher yields, especially those in Cote d’Ivoire and Ghana. The major causes of low yield are a high incidence of pests and diseases, the old age of cocoa farms and lack of soil nutrients. Concerns about declining output due to aging and diseased trees have urged the government of Cote d’Ivoire and Ghana to launch large rehabilitation and replanting schemes which provide farmers with improved planting materials, plant protection chemicals and fertilizers. As owners of small farms do not earn enough income from their cocoa to purchase external inputs, the traditional mixed planting of cocoa and forest and fruit trees and some oil palms is discussed as an alternative to a high input approach. This low input low output system is sustainable but not the way forward to higher yields. It is thought that in the short run higher cocoa prices and improved management including pest and disease control and to a certain extent fertilizer use offer scope for a larger cocoa output. In the more distant future the predicted climatic change and increased land use for food production will reduce the size of the cocoa area and affect the leading position of West Africa on the world cocoa market. This review shows that at present the conditions for sustainable production are not met and concludes that important structural changes in the cocoa sector are needed to reach this goal. These changes concern the economic viability of cocoa on small farms, extensive land use and the ecological impact of the current cocoa growing practice. The implementation of these changes requires area specific programs with as their common goal increased economic and environmentally sustainable cocoa production on less land.

P.M. Foluke Quist-Wessel

Papers

Cocoa production in West Africa, a review and analysis of recent developments