What does science says?
Pods should be broken within 2-3 days after harvest. Germinated, black and diseased beans or pieces of husk and placenta fragments must be removed from the scooped beans. The beans are embedded in sweet, white mucilaginous pulp, which serves as a substrate for fermentation (Picture 1).
Picture 1: broken pod with sugary pulp
Fermentation begins the same day the pods are broken. Raw cocoa has astringent flavour and fermentation should develop chocolate precursors in the beans. The bean itself does not undergo fermentation but the pulp surrounding it. The pulp in undamaged pod is microbially sterile but during breaking, it gets contaminated with microorganisms from pod surface, knife and workers’ hands. Micro-organisms involved are yeasts, lactic acid bacteria and acetobacter. Fermentation occurs in two stages:
Stage 1 (Anaerobic): Occurs within first two days when the pulp does not allow air circulation. Yeast and lactic acid bacteria fermentation begins. Yeast fermentation transforms sugar into alcohol resulting in an increase in temperature. The increase in temperature, in turn, favours growth of lactic acid bacteria which then produce lactic acid. The pulp then breaks down, drains away and air penetrates the beans.
Stage 2 (Aerobic): Occurs from day three and aeration allows growth of acetobacter which transforms alcohol to acetic acid. Temperature increases up to 50°C. Acetic acid penetrates into the beans causing formation of chocolate flavour precursors. At the end the temperature reduces and if prolonged putrefaction bacteria will grow and cause off-flavours and over-fermentation.
What do farmers say?
I had the chance to interview about 40 farmers in two communities of Asamankese district in Eastern Ghana in August 2013. This was a focus group type of interview. Most of them retain pods for 1-4 days. 1 day for the pods cut on last day of harvesting and 4 days for the pods cut during 1st day of harvesting. We are talking about farmers who have 3-4 acres of cocoa farm and need couple of days to cut and collect pods in one or several points for further fermentation.
Most farmers in Ghana, except few hundreds out of almost 1 million, do fermentation in heaps which is fine as long as heap height is not too much and at least 2-3 mixing is done over 6 day fermentation period. Here, farmers and science divide: height of heaps is too high between 1m and almost 1.6m and most farmers mix cocoa beans only once and few do twice.
Why is that a problem? Good quality and uniform fermentation occurs in top 10cm of heap because temperature in this layer is also highest and most even in the heap and when heap height is 100cm, it needs to be mixed at least 3 times over 6 day period. Otherwise there will be too many purple colour beans and chocolate flavour precursors will not develop sufficiently.
In next 4 videos, you can see real field farmers talking about their own fermentation operations.
Video 1: Farmers share with their
cocoa pod harvesting experiences
Video 2: Farmers describe their
pod breaking experience
Video 3: Farmers share with their
current fermentation method
As we can see from 3rd video, farmers make one heap per 1 acre and some make one heap per 2-3 acres and as they have shown, heap height is very high which should not be ending with desired high quality fermentation.
The main reason why they make less number of heaps is related to labour cost at heap making stage as well as heap mixing stage. More heaps need more labour and more payments to workers. One solution to improve fermentation efficiency and ensure quality cocoa beans is tray fermentation method which by design guarantees that each fermentation process will occur in 10cm high trays and also by its design ensures that it suits farmers interests since NO mixing is needed during tray fermentation at all during 6 days. It will save mixing costs as well as costs of banana and plantain leaves.
On next video, we can see farmers reactions on tray method. They quickly figured out themselves advantages of new method.
Video 4: Farmers provide their
opinions about tray fermentation method
Tray as well as Box fermentation methods were developed by Cocoa Research Insitute of Ghana many decades ago. At CRIG there is a dedicated facility which is using box and tray fermentation methods. We have been guided by Dr. Asare who explained us how all that was happening. See next videos.
CRIG fermentation tour part 1
CRIG fermentation tour part 2
CRIG fermentation tour part 3
CRIG fermentation tour part 4
CRIG fermentation tour part 5