Cacao fermentation explained

There are many factors that will affect the colour, flavour, and contents of the cacao beans. These include the variety of cacao tree, the location of the tree, soil conditions, and the fermentation process. Fermentation is one of the most important post-harvest processes for cacao beans as this is when the compounds responsible for the flavour of cacao and its brown colour are able to develop1–4. Without this process, dried cacao beans would be grey in colour, bitter and not possess the characteristic “chocolate” flavour for which it is known5. While fermentation reduces the bitterness of the cacao,3,4 it also increases the presence of important minerals, including calcium and magnesium6. Variation in the timing, length, and conditions of fermentation can result in cacao beans with slightly different flavours, chemical composition and colour7.

How are cacao beans fermented?

Following the initial harvesting, the cacao pods are broken, and the beans removed, either manually or by machine1,3,4,7. It is at this point that any beans defective in some way are removed3. The fermentation process then follows in which a select amount of fresh cacao beans are piled and allowed to ferment for several days3. During fermentation, the beans may be turned or transferred to other containers for aeration3. Typical containers for fermentation of cacao beans include wooden boxes, baskets, drying plates, or open heaps3. Fermentation of Forastero and Trinitario varieties can take up to 10 days fermenting3. Our Criollo cacao beans are typically fermented between five and seven days. The beans are stacked in layers in wooden crates and turned at regular intervals throughout the fermentation process.

Fermented and dried raw Criollo cacao beans.

What happens to the cacao beans during fermentation?

Fresh cacao beans are made up of about 40% seed pulp, which is a combination of spongy tissue and a cell sap, rich in sugars, salts, organic acids, proteins, and pectin, an important component of plant cell walls1. The traditional fermentation process begins with the microbes naturally present, such as yeasts, bacteria, and fungi1. These microbes feed on the sugars and organic acids in the cacao bean to produce heat and carbon dioxide gas1. The temperature of the bean may reach up to 50˚C.1 Many different chemical reactions occur during the fermentation process which change the components in the cacao beans and lead to the development of their colour, aroma, and flavour1.

Anthocyanins are compounds that add to the astringency of cacao and are responsible for its dark deep purple-brown colour when raw1. Polyphenol and flavonoid compounds, such as catechins and procyanidins, are important for the development of the colour and flavour of the cacao during fermentation. These compounds are oxidised causing a reduction in the astringency of the beans and development of the characteristic “chocolate” flavour, as well as a change in colour from deep purple-brown to a “truer” brown1,5. Polyphenols and flavonoids are important as they are precursors for antioxidant compounds that are protective against cardiovascular diseases, cancer and inflammation2.

During fermentation, essential amino acids, antioxidants, and minerals, including magnesium and calcium, are also produced1,5,6. Caffeic acid aspartate is one antioxidant produced during fermentation that has been found to reduce inflammation in the body and is greatest in Criollo varieties of cacao2. Much of the variation in other flavonoids, polyphenols, and other important fermentation precursors between different varieties of cacao is due to differences in the soil quality2.

At the end of the fermentation process, the moisture content of the cacao beans is reduced to about 6-8%3. At the end of the fermentation process, the cacao beans are dried between seven days to three weeks, either by sun drying or mechanical means before being cleaned and packaged3. The resulting cacao beans are now ready for processing into various cacao-based products, such as chocolate, cacao powders, cacao pastes, and more. Chocolate manufacturers may roast cacao beans produce cocoa-based products and enhance the chocolate flavours and ensure a more consistent flavour profile throughout an entire batch1,2,4. However, roasting and other forms of heat treatment can affect the chemical composition of cacao and reduce the presence of beneficial compounds, such as flavonoids and anthocyanins8,9.

References

(1) Leal, G. A.; Gomes, L. H.; Efraim, P.; de Almeida Tavares, F. C.; Figueira, A. Fermentation of Cacao ( Theobroma Cacao L.) Seeds with a Hybrid Kluyveromyces Marxianus Strain Improved Product Quality Attributes. FEMS Yeast Res.2008, 8 (5), 788–798. https://doi.org/10.1111/j.1567-1364.2008.00405.x.

(2) Elwers, S.; Zambrano, A.; Rohsius, C.; Lieberei, R. Differences between the Content of Phenolic Compounds in Criollo, Forastero and Trinitario Cocoa Seed ( Theobroma Cacao L.). Eur. Food Res. Technol.2009, 229 (6), 937–948. https://doi.org/10.1007/s00217-009-1132-y.

(3) Lima, L. J. R.; Almeida, M. H.; Nout, M. J. R.; Zwietering, M. H. Theobroma Cacao L., “The Food of the Gods”: Quality Determinants of Commercial Cocoa Beans, with Particular Reference to the Impact of Fermentation. Crit. Rev. Food Sci. Nutr.2011, 51 (8), 731–761. https://doi.org/10.1080/10408391003799913.

(4) Kadow, D.; Niemenak, N.; Rohn, S.; Lieberei, R. Fermentation-like Incubation of Cocoa Seeds (Theobroma Cacao L.) – Reconstruction and Guidance of the Fermentation Process. LWT - Food Sci. Technol.2015, 62 (1, Part 1), 357–361. https://doi.org/10.1016/j.lwt.2015.01.015.

(5) Fang, Y.; Li, R.; Chu, Z.; Zhu, K.; Gu, F.; Zhang, Y. Chemical and Flavor Profile Changes of Cocoa Beans (Theobroma Cacao L.) during Primary Fermentation. Food Sci. Nutr.2020, 8 (8), 4121–4133. https://doi.org/10.1002/fsn3.1701.

(6) Wiranda -; Syukur, S.; Aziz, H. DETERMINATION OF CALCIUM (Ca) AND MAGNESIUM (Mg) CONTENT IN CACAO (Theobroma Cacao Linn) FERMENTATION AND NON FERMENTATION BY SPECTROPHOTOMETRY. J. Ris. Kim.2015, 3 (1), 96. https://doi.org/10.25077/jrk.v3i1.104.

(7) MacLeod, M. Cacao. In The Cambridge World History of Food; Kiple, K. F., Ornelas, K. C., Eds.; Cambridge University Press: Cambridge, 2000; pp 635–641. https://doi.org/10.1017/CHOL9780521402149.073.

(8) Oracz, J.; Zyzelewicz, D.; Nebesny, E. The Content of Polyphenolic Compounds in Cocoa Beans (Theobroma Cacao L.), Depending on Variety, Growing Region, and Processing Operations: A Review. Crit. Rev. Food Sci. Nutr.2015, 55 (9), 1176–1192. https://doi.org/10.1080/10408398.2012.686934.

(9) McShea, A.; Ramiro-Puig, E.; Munro, S. B.; Casadesus, G.; Castell, M.; Smith, M. A. Clinical Benefit and Preservation of Flavonols in Dark Chocolate Manufacturing. Nutr. Rev.2008, 66 (11), 630–641. https://doi.org/10.1111/j.1753-4887.2008.00114.x.