https://csirspace.foodresearchgh.site/bitstream/123456789/1344/1/FRI_82_Kongor_et%20al.pdf

Factors influencing quality variation in cocoa (Theobroma cacao) bean flavour profile — A review

Modeling using a new thin layer drying model and product quality of cocoa

This chapter focuses on the more comprehensive role of fermentation in cocoa curing and to a lesser extent on the role of fermentation in the production of coffee. The two principal objectives of fermentation are to remove mucilage, thus provoking aeration during fermentation of the beans and facilitating drying later on; and to provide heat and acetic acid necessary for inhibiting germination, which ensures proper curing of the beans. Approximately one-half of the world crop is fermented in some type of box, and the remaining half is fermented by using heaps or other primitive methods. The progress of the fermentation is assessed by the odor and the external and internal color changes in the beans. Fermentation begins immediately after beans are removed from the pods, as they become inoculated with a variety of microorganisms from the pod surface, knives, laborers’ hands, containers that are used to transport the beans to the fermentary, dried mucilage on surfaces of the fermentation box (tray, platform, or basket) from the previous fermentation, insects, and banana or plantain leaves. The actual production of chocolate flavor precursors occurs within the cocoa bean and is primarily the result of biochemical changes that take place during fermentation and drying. There are several environmental factors: pH, temperature, and moisture, in the fermenting mass that influence cocoa bean enzyme reactions. Coffee and cocoa are no exceptions, and it is the proper control of the fermentation process that largely determines the color and flavor qualities of the final products.

Cocoa and Coffee

The quality of commercial cocoa beans, the principal raw material for chocolate production, relies on the combination of factors that include the type of planting material, the agricultural practices, and the post-harvest processing. Among these, the fermentation of the cocoa beans is still the most relevant since it is the process whereby the precursors of the cocoa flavor arise. The formation of these precursors depends on the activity of different microbial groups on the beans pulp. A comparison of fermentations in different countries showed that a well-defined microbial succession does not always take place and that the role of Bacillus spp. in this process remains unclear. Considering the overriding importance of the fermentation to achieve high quality commercial cocoa beans, we discuss the need of addressing the impact of the farming system, the ripeness state of the pods, and the role of microbial interactions on the fermentation in future research. In addition, the problem of high acidification cocoa beans, aspects dealing with the volatile fraction of the flavor, and the cocoa butter properties, all were identified as critical aspects that need further investigation. The standardization of the microbiological methods and the application of metagenomic approaches would magnify the knowledge in this domain.

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Theobroma cacao L., “The Food of the Gods”: Quality Determinants of Commercial Cocoa Beans, with Particular Reference to the Impact of Fermentation

In-vitro formation of cocoa-specific aroma precursors: aroma-related peptides generated from cocoa-seed protein by co-operation of an aspartic endoprotease and a carboxypeptidase

Changes in the pulp during ripening and post-harvest storage of cocoa pods were determined during numerous harvests in Malaysia (1984 to 1987) and Ghana (1985 to 1986), in order to gain a basis for understanding the influence of ripening and storage on acid formation during subsequent fermentation. Changes in the pulp during ripening of fully grown pods were the same but less pronounced than those during dry storage of harvested pods: the percentage of water in the pulp was not changed significantly, but the amount of water and of dry matter per seed was strongly reduced (by 40–50%) due to water evaporation and respiration of sugars. Sucrose was inverted completely. The result of these changes was an equally strong reduction of the pulp volume per seed and increase of the pulp surface to pulp volume ratio. The reduction of acid formation during fermentation with beans from stored pods is ascribed predominantly to these changes rather than to the reduction in the amount of sugars, and is explained not only by the facilitated mass aeration but, above all, by the significant increase in respiration at the pulp surface over ethanol fermentation in the pulp when the pulp volume is reduced prior to fermentation. Ghanaian pods at similar stages of ripeness revealed more advanced stages of the pulp compared with Malaysian pods and consequently less significant change during storage. Water evaporation and respiration during pod storage were significantly higher in the pulp than in the husk.

Lutz Pollmann

Papers

Chemical and physical changes in the pulp during ripening and post-harvest storage of cocoa pods