Breaking and Winnowing

Optimal fermentation and roasting have a direct impact on breaking and winnowing performance. Under-fermented and low- roasted beans tend to have shell that adheres tightly to the nib and makes efficient breaking and winnowing difficult.

Breaking and winnowing should occur immediately following cooling of the beans after roasting (usually between 20 – 60 minutes) for efficient breaking and to ensure that no off-flavours are picked up from the environment. Cooling to room temperature can be done on an elevated rack or by using a small fan to accelerate the cooling process. The area where sample preparation is done should be neutral smelling.

Note: prior to roasting, the beans are considered to be a raw agricultural product that is likely to be contaminated with large numbers of microbes, potentially including pathogens. Roasting conditions should ensure the killing of pathogens, though samples should be checked for presence of pathogens prior to sensory analysis. It is essential that precautions are taken to prevent cross-contamination between raw and roasted beans as part of an active HACCP programme to ensure the wholesomeness of any products which will be tasted.

Where only a few samples are to be processed, breaking and winnowing can be done most simply by placing cooled beans in a high quality snap seal bag, removing as much of the air as possible and using a rolling pin to lightly break the beans. Afterwards a home use hand-held hairdryer can be used to blow off the free shell from the nibs in a flat tray in a well ventilated area. Higher throughput sample preparation for flavour evaluation will require at least a mechanised winnowing system. Industrial winnowing systems include mechanisms to adjust airflow to the size of the nib/shell particles (a process known as “sizing”) to optimise shell separation. Laboratory scale mechanised individual cocoa breakers and winnowers are available but since the broken nibs/shells are not “sized”, separation is less efficient with nib yields frequently as low as 62 – 78% of the starting raw beans. This is an important point in planning the sample size of beans needed for the roasting process in order to meet the volume needs for flavour evaluation.

It is recommended that the residual shell in the winnowed nibs (including both loose shell fragments and pieces of shell adhering to a piece of nib) be manually removed with tweezers to take the shell content to effectively zero. This ensures low contamination from residual shell with an additional benefit of producing cocoa mass samples which have much lower levels of microbiological contamination (i.e. extremely low Standard Plate Counts/Total Plate Counts) since most of the microbes reside on the shell.

Nibs will pick up both environmental humidity as well as off flavours if they are present in the environment, therefore storage of nibs following winnowing and before hand picking as well as after hand picking should be in airtight storage containers or in high quality snap seal bags suitable for food use. Nib samples deteriorate quickly and every effort should be made to convert them to cocoa mass within 48 hours of roasting. Where necessary nib samples can be stored for a maximum of seven days at 10-24°C in sealed bags.

More details are provided in Chapter 12 - Breaking and winnowing cacao beans in “Guide for the Assessment of Cacao Quality and Flavour” (Cacao of Excellence, 2023) https://www.cacaoofexcellence.org/