The findings by University of Gottingen, the Institute of Crop Sciences Research and the Institute of Organic Agriculture were published in the Journal of Agricultural Food Chemistry last month.
They say chemical composition of beans – particularly the antioxidant content – changes in the face of higher temperatures and lower rainfall.
But the researchers add growing cocoa in an agroforestry system - with other crops and shade trees - can make beans more reliant to fluctuations.
The researchers analyzed box-fermented and dried beans of the Trinitario variety at five cocoa farms in the Bolivian Andes at the beginning and end of the dry season (April to September 2014) to obtain their results.
They analyzed samples grown in five production systems:
- Full sun cocoa grown as a monocrop (conventional)
- Full sun cocoa grown as a monocrop (organic)
- Cocoa grown in an agroforestry system (conventional)
- Cocoa grown in an agroforestry system (organic)
- Highly diverse successional agroforestry system (organic)
At the study site in Alto Beni, 78% of annual rainfall occurs in the rainy season between October and April.
The study found nitrogen, iron and copper concentrations of beans increased in the dry season.
In other words, the cocoa analyzed in September contained more of these compounds than cocoa assessed in April.
Lead researcher Wiebke Niether of the University of Goettingen said antioxidant content also increased during the dry season.
“We found an increase in phenolics as stress indicators in the ongoing dry season when soil moisture drops but also temperature is lower (dry season and winter coincide),” she said.
Cocoa trees cultivated in these conditions produce more phenolic compounds to protect the beans - the plants’ reproduction unit, suggested the study.
‘We are not promoting stressed grown cocoa’
A press release from the American Chemical Society interpreted this to mean cocoa grown in “stressed out” conditions produces more flavorsome chocolate.
But Professor Niether told ConfectioneryNews: “We are not at all promoting stress grown cocoa.
“The idea is to reduce stresses by buffering temperature fluctuations and maintain humidity as favorable growing conditions for cocoa in agroforestry systems.
“Agroforestry systems have the potential to reduce quality fluctuations over the harvesting season, and when temperatures rise and precipitation patterns change with climate change."
She said agroforestry systems should be further promoted, adding that even if they produce lower yields in the short-term they can provide continuous yield improvements over the long-term.
The study suggested chemical analysis of cocoa should focus on how climate, different harvesting seasons, bean origins, local weather conditions and production systems alter chemical compounds in beans.
“In the [study], we are not talking about flavor and quality, [we] just mention that over the season and under the view of climate change, quality parameters might be affected,” said Niether.
J. Agric. Food Chem., 2017, 65 (47), pp 10165–10173
‘Environmental Growing Conditions in Five Production Systems Induce Stress Response and Affect Chemical Composition of Cocoa (Theobroma cacao L.) Beans’
Authors: Wiebke Niether, Inga Smit, Laura Armengot, Monika Schneider, Gerhard Gerold, and Elke Pawelzik