Food Science and Technology, School of Chemical Engineering, The University of New South Wales, Sydney, New South Wales 2052, Australia.
Int J Food Microbiol. 2014 Mar 17;174:72-87. doi: 10.1016/j.ijfoodmicro.2013.12.014. Epub 2013 Dec 27.
Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics.
可可豆（Theobroma cacao）是巧克力生产的主要原料，而豆的发酵对于巧克力风味前体的发展至关重要。在这项研究中，我们采用了一种新方法来确定酵母在可可发酵中的作用及其对巧克力质量的贡献。在添加 200ppm 那他霉素以抑制酵母生长的情况下进行可可豆发酵，并将由此产生的微生物生态和代谢、豆化学和巧克力质量与正常（对照）发酵进行比较。在对照发酵中，发现了汉逊酵母（Hanseniaspora guilliermondii）、毕赤酵母（Pichia kudriavzevii）和马克斯克鲁维酵母（Kluyveromyces marxianus）、植物乳杆菌（Lactobacillus plantarum）和发酵乳杆菌（Lactobacillus fermentum）以及巴氏醋杆菌（Acetobacter pasteurianus）和葡萄糖酸杆菌（Gluconobacter frateurii）等主要酵母。在添加那他霉素的发酵中，同样的细菌生长，但酵母生长受到抑制。物理化学分析表明，没有酵母发酵的豆的外壳含量增加，乙醇、高醇和酯的产量在整个发酵过程中降低，并且在烘焙产物中吡嗪的存在较少。质量测试表明，没有酵母发酵的豆呈深紫色，且不完全呈棕色，而由这些豆制成的巧克力味道更酸，缺乏特征巧克力风味。有酵母生长的豆呈完全棕色，并且赋予巧克力典型的特征，这些特征明显受到感官小组的喜爱。我们的研究结果表明，酵母的生长和活性对于可可豆发酵和巧克力特征的发展至关重要。
