Research Group of Industrial Microbiology and Food Biotechnology, Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
FEMS Microbiol Rev. 2020 Jul 1;44(4):432-453. doi: 10.1093/femsre/fuaa014.
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.
经过赤道地区农场的收获后、分批发酵和干燥处理，可可豆被制成发酵干豆。可可豆的果肉发酵主要在堆肥或盒子中进行。这是通过一系列酵母、乳酸菌（LAB）和醋酸菌（AAB）的活动实现的。酵母将可可果肉中的葡萄糖发酵成乙醇，进行果胶分解并产生风味化合物，如（高）醇、醛、有机酸和酯类。LAB 将可可果肉中的葡萄糖、果糖和柠檬酸发酵成乳酸、醋酸、甘露醇和丙酮酸，产生微生物稳定的发酵环境，为 AAB 的必需生长提供乳酸盐作为碳源，并通过产生糖醇、有机酸、（高）醇和醛来贡献可可和巧克力的风味。AAB 将乙醇氧化成醋酸，醋酸渗透到豆胚中以防止种子发芽。种子亚细胞结构的破坏反过来又会在可可豆内部引发酶促和非酶促转化，为后来的发酵可可豆烘焙提供必要的颜色和风味前体分子（亲水肽、疏水性氨基酸和还原糖），这是巧克力制作的第一步。
