Cocoa Research Inst. of Ghana, Tafo-Akim, Ghana.
J Food Sci. 2010 Aug 1;75(6):S300-7. doi: 10.1111/j.1750-3841.2010.01710.x.
Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher a* and b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application: The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies.
可可豆的出口对加纳和其他几个热带国家具有重要的经济意义。生可可豆具有涩味和不愉快的味道和风味，必须经过发酵、干燥和烘焙才能获得可可特有的味道和风味。为了更深入地了解可可豆在发酵过程中的变化，并探索未来开发客观评估发酵程度方法的可能性，采用了一种新的方法组合，包括切割试验、比色法、荧光光谱法、近红外光谱法和 GC-MS 以及化学计量学方法，来检查不同发酵时间取样的可可豆样本以及来自加纳所有可可种植区的完全发酵和干燥的可可豆样本。比色法发现，随着发酵的进行，样品向更高的 a和 b值移动。此外，所使用的光谱方法通常可以很好地描述发酵程度。此外，还可以将挥发性化合物的分析与发酵时间的预测联系起来。基于比色法、荧光法、近红外光谱法和 GC-MS，沃尔特地区和西部地区的发酵和干燥可可豆在得分图中聚类分开，表明加纳可可豆的成分存在区域差异。该研究表明，比色法和光谱法具有潜力，可以作为确定可可豆发酵程度的有用工具。使用 GC-MS 可以证明在发酵过程中形成了几种重要的香气化合物，如 2-苯乙醇乙酸酯、丙酸和乙酰基，以及其他如双乙酰的分解。实际应用：本研究表明，比色法和光谱法具有潜力，可以作为客观方法用于确定加工链中可可豆的质量。开发客观评估可可豆质量的方法对于可可加工领域和巧克力生产公司原材料控制的质量保证将非常重要。
J Food Sci Technol. 2020-1
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