From farmer to chocolate maker, every actor in the cacao supply chain has to deal with humidity. Humidity comes in many forms and shapes: rain, moisture, dew, pulp, evaporation, and much more. Whatever form it has, humidity can have an impact on the quality of cacao and thereby on chocolate. Time to take a closer look at humidity as a cross-cutting theme in the cacao supply chain!

Drying enhances the flavour development of cacao and is therefore a critical step in the production of high quality cacao. But you can ask any cacao farmer or cooperative, they will all confirm it is challenging to dry cacao in a humid climate with erratic rainfall. The elements of weather are often not helping to get the beans’ humidity level from 60% after fermentation to the targeted 7.5%. If there is rain during the drying process, this will increase chances on the much-dreaded mould. Therefore, farmers will go a long way to make sure drying is done properly. Drying can be improved by:

• Drying beds: instead of drying the beans on the ground, they are placed on a rack or bed, so that the wind can flow around the beans and moisture will evaporate.
• Raking the beans: frequently raking the beans will make sure they dry evenly.
• Solar tunnels: the beans are dried in a structure covered with plastic to protect the beans from rain
• Artificial-dried: in some countries cacao is dried inside with warm air coming from fire. Unfortunately, the beans will absorb smoke from the fire, making the cacao taste smoky in an unpleasant way.

The international standard for cacao humidity is maximum 8%. At Silva we aim for a humidity percentage between 7 and 7.5%.

Once the specialty cacao beans are below 7.5% humidity, they are packed in bags. Jute bags are commonly used in the sector. The advantage of jute bags is that they allow for some ventilation. Of course, this becomes a disadvantage when the bags are in a humid environment, so it is important to check the humidity of the storage. A solution for a humid environment is to pack cacao in jute bags with inner propylene lining. These are used, for example, in India during the monsoon period.

A third option is hermetic packaging, like Ecotact or GrainPro. With these bags the beans are in a closed environment that keeps them stable. While hermetic packaging is on the rise in specialty cacao, it is still not available in many cacao countries.

Silva cacao is shipped from origin by sea freight, a journey that often takes weeks (or months in COVID times). Since there is no environment with more water than the ocean and sailing routes go from warm tropical regions to our colder moderate climate, a lot of attention goes into preventing water damage during sea transport. Containers are lined with cardboard to absorb possible condensation, and desiccants are placed to eliminate humidity in the container. First thing we check upon arrival of cacao in the harbour of Antwerp is the humidity level of the beans.

Silva cacao stocks are placed in a warehouse specialised in cacao storage: a dry, clean and ventilated environment with humidity between 50 and 60% and a temperature between 12 and 18°C. In an environment like this, cocoa beans quality can be stored properly and chances on moulds are limited. We advise chocolate makers to store their cacao in a similar environment.

After so much information on the impact of humidity on cacao, it is high time to say something about the different methods to measure the amounts of moisture.

• Dry Mass Method: the International Organisation for Standardization issued ISO2291 standard for measuring moisture content of cacao. The beans are placed in a ventilated oven at 103°C, and after 26 hours all water has evaporated. The difference between the remaining dry mass and the original beans is moisture.
• Moisture balance instrument: because the Dry Mass Method is a very accurate but rather cumbersome and time-consuming most cacao labs use a moisture balance instrument (or thermo-gravimetrics). This instrument heats the cacao sample and weighs it simultaneously, reducing the time to measure humidity to minutes or hours, depending on the level of accuracy.
• Capacitance based instrument: this tool uses the electrical properties of water to determine the moisture level. Simply place cacao raw beans (or roasted nibs) in the machine, and you will have a fairly accurate measurement of the humidity level in just a few seconds (or minutes if the machine needs to warm up).

The third moisture measurement tools – capacitance based instruments – are widely used in the cacao supply chain. They are easy, quick and relatively inexpensive. If you are considering buying one yourself, you can think of brands like Wile, Drawinski or Sinar. Always select an instrument that is calibrated according to ISO standards and check accuracy and precision. Better to choose quality over price, if the instrument is very cheap there might be a reason for that.