Reviewing the ways researchers are improving cacao beans
Writer: Minh Dang
Artist: Lucie Gourmet
Editors: Nirvan Marathe, Altay Shaw
Have you ever wondered which factors contribute to the taste of chocolate you receive or give out on Valentine’s Day?
And ever wonder about the story behind those cacao beans?
Apart from the additives and flavourings added during chocolate manufacture, the fermentation of the cacao beans in their origin is the key to their unique quality and flavours. Carried out by microorganisms, fermentation reduces bitterness and astringency while enhancing the flavours and aroma.
The biochemical reactions that occur during fermentation lower the pH of the cacao beans, while increasing their internal temperature. This in turn drives pigment degradation by endogenous enzymes and the production of metabolites such as alcohol, lactic acid, esters and pyrazine, which account for the beans’ flavours. As fermentation proceeds, the beans turn dark brown and their bitterness is reduced as alkaloids and polyphenols diffuse out of the beans. Therefore, to assess the quality of cacao beans, cut test and fermentation index measurements based on colour changes in cotyledons-the embryonic leaf- are performed.
However, fermentation does not always go as planned. Weather and soil conditions can reduce the quality of cacao beans produced. Poorly fermented beans would lack richness, while overly fermented ones would be too acidic. The uncontrolled fermentation of cacao beans may therefore detrimentally affect small-scale family-run cacao farms, which account for 95% of the world’s cacao producers. Moreover, the consequent loss of income puts the livelihood of these small businesses into financial jeopardy, while further increasing the disparity between large cacao companies and smallholder cacao farmers. Inevitably, the demand for cheap labour in the cacao industry arises, leading to the occurrence of exploitation. Particularly in Ghana, the world’s second-biggest cacao producer, children as young as 10 have been found harvesting cocoa pods for a prominent manufacturer while being paid less than £2 a day. In Côte d’Ivoire, the world’s leading cacao producer, the number of child labourers amounted to 829,000 in 2016-2017.
To avoid the loss of harvest in small-scale cocoa production, researchers from the University of Nottingham have identified key players in the fermentation of cacao beans. They have been working on a project to understand the microbes’ influence on the fermentation process of cacao beans in collaboration with Luisa’s Vegan Chocolates, an award-winning chocolate maker based in Nottingham, along with a group of Colombian cacao growers. By identifying the microbes present in each batch of cacao beans and their corresponding optimum environmental conditions, farmers can obtain information on what would make a successful batch. The team even took a step further by investigating how different microbes in cacao pulps contribute to the distinct flavours of chocolate. Eventually, the unique flavours of the beans make the products more exotic, which are sold at a higher price. This has not only improved harvest but also secured income for small cacao businesses.
Identifying microbes in the soil and cacao pulps in specific Colombian regions would be arduous without the help of portable Oxford Nanopore DNA sequencers, which allow real-time analysis with accuracy. The Nottingham researchers consequently discovered numerous yeast and bacteria at the beginning of fermentation, which handles acetic acid production. By conducting a sensory analysis of the fermented beans, they managed to show that beans from different Colombian regions possess unique flavours, with some being spicy while the others are more fruity.
With further investigation, the uniqueness of cacao flavours and their optimal conditions can be fully understood to help mitigate social issues like child labour and the disparity in the cacao industry. And voilà, that is how better chocolate leads to sweeter life!