How cocoa beans are graded and assessed

A sample of beans — conventionally three hundred, assessed in hundreds — is cut lengthways and the cut faces are examined.

What the assessor is reading is the INTERIOR COLOUR AND STRUCTURE, because that records what happened during fermentation. A well-fermented bean shows a brown cotyledon broken into visible fissures, the result of the internal changes fermentation drives. The count of defective beans against the sample size is the result.

SLATY beans are the classic failure: grey-purple, dense, unfissured, effectively unfermented. They make harsh, astringent chocolate and nothing downstream fixes them. PURPLE beans are partially fermented, sitting between slaty and brown. Both are counted separately because they are different degrees of the same failure.

The other counted defects are MOULDY, INSECT-DAMAGED, GERMINATED — where a bean began to sprout because pod breaking was delayed — and FLAT beans, which contain too little cotyledon to be worth processing. Mould carries the most weight because it is a food-safety matter as well as a flavour one.

The fermentation index is the same information expressed as a number, which makes it comparable between lots in a way an assessor's tally is not.

BEAN COUNT is beans per hundred grams. It measures size, and it matters for processing rather than for flavour: a consistent count runs predictably through a roaster and a winnower, while a mixed one roasts unevenly because small beans reach temperature before large ones.

MOISTURE CONTENT is a safety specification before it is a quality one. Above a threshold, moulds grow in storage, and mould brings both flavour damage and the possibility of mycotoxins. Below it, beans become brittle and shatter into fragments that are lost in winnowing. Every producing country's standard names a maximum.

FREE FATTY ACID measures how far the fat in the bean has been broken down — by mould, by germination, by poor storage. It is the specification most closely watched by industrial buyers because it is regulated in some markets and because high FFA cocoa butter behaves badly. It is also effectively irreversible.

WATER ACTIVITY is the more precise successor to moisture content: it measures water AVAILABLE to microorganisms rather than total water present, which is what actually determines whether anything can grow.

ISO 2451 is the international standard specification these terms sit inside, alongside national standards that frequently differ from it.

SMOKE TAINT is the most serious flavour defect in cocoa and the cut test cannot see it. It arrives when beans are dried over poorly vented fires — common where the climate makes sun drying unreliable — and the phenolic compounds are absorbed into the fat, where they stay. Smoked cocoa smells of ham or bonfire, and no processing removes it.

It is worth naming as an equity problem as well as a quality one. The regions that need artificial drying are the ones with the least reliable sunshine, so the defect concentrates in origins with the least infrastructure, and it is one of the clearest examples of a quality attribute that is really an investment attribute.

OVER-FERMENTED beans are the opposite failure to slaty ones — hammy, ammoniacal, putrid — and are also partly a flavour rather than a visual judgement.

And beans absorb odours in storage and transport. Cocoa shipped in jute sacks alongside strongly aromatic cargo arrives carrying it, which is why storage and transport specifications exist at all.

Almost nothing about how the chocolate will taste beyond the absence of failure.

The cut test and the specifications establish that a lot is sound: fermented, dried, free of mould, storable, processable. They cannot say it is delicious. A lot can pass every specification comfortably and make entirely ordinary chocolate, which is precisely what the bulk market is: sound cocoa, correctly assessed, blended for consistency.

Quality in the sense a craft maker means it is assessed by making chocolate from a sample and tasting it, which is slower, more expensive and not what a commodity contract is for. That gap between what is measured and what is valued explains most of the price structure of the whole sector — and it is why fine and flavour cocoa is a separate designation rather than a higher grade.