How Bean-to-Bar Chocolate Is Made: Roast, Winnow, Grind, Conche, Temper, and Where the Flavor Is Decided
A bean-to-bar chocolate maker's raw material arrives in jute sacks: dried, fermented cacao beans, brown and brittle, smelling faintly of vinegar and fruit, each about the size of an almond. Everything that will make them taste like a Madagascar or a Dominican or a Peru has already happened on the farm, in the fermentation box we describe in our piece on cacao fermentation. What the maker does over the next two weeks is decide how much of that flavor to keep, how to frame it, and how to turn a sack of seeds into a bar that snaps. Five machines, a dozen decisions, and this is the order they come in.
Sorting
Before anything, the beans are spread on a table and sorted by hand. Flat, broken, moldy or germinated beans are pulled, along with the stones, twigs and occasional bits of jute that come with any agricultural product. A single moldy bean in a batch can be tasted in the finished bar. Good makers cut a sample of beans across to check the fermentation, as the farm did, and reject a sack that shows too much purple.
Roasting
The roast is the maker's biggest single decision, and it works the way a coffee roast does. Beans go into a drum or convection oven and are heated for anywhere from twenty minutes to over an hour, at temperatures generally lower than coffee, and the Maillard reaction turns the amino acids and sugars that fermentation created into the hundreds of compounds we recognize as chocolate. A light, short roast keeps the bright, fruity, acidic notes of the origin and risks tasting raw or sour. A dark, long roast builds deep roasted, nutty, caramel flavors and buries the origin under them. Craft makers tend to roast light to medium, because the whole point of paying for a single farm's beans is to taste that farm, and many develop a different roast profile for every origin they buy. The roast also loosens the husk, kills any remaining microbes and drives off the acetic acid left from fermentation, which is why the workshop smells of vinegar on roasting day.
Cracking and winnowing
Roasted beans are cracked into pieces, and the papery husk that surrounds each one is blown away from the heavier fragments of kernel, the nibs, in a winnower: a column of air, a vibrating screen, a vacuum, or, in the smallest workshops, a hair dryer and a bowl. The husk is about a tenth of the bean by weight and is bitter and fibrous; any left behind gives the chocolate a harsh, woody edge. What remains is roasted cacao nib, which is already edible and tastes like extremely dark, slightly bitter chocolate with the texture of a nut.
Grinding: the melanger
Nibs are about half cocoa butter, and when they are ground the friction melts the fat and the nibs turn into a thick liquid, cacao liquor. Craft makers grind in a melanger, a stone mill with two granite wheels turning on a granite base, sometimes for a day, sometimes for three. As the wheels turn, the particles of cacao and, once added, sugar are ground finer and finer, from the grit of the first hour to a smoothness the tongue cannot detect, below about twenty microns. Sugar goes in here, and, for milk chocolate, milk powder; for a two-ingredient dark bar, sugar is all that is added. The percentage on the label is set at this moment: a seventy percent bar is seventy percent of everything that came from the bean, liquor and any added cocoa butter, and thirty percent sugar.
Conching
The long grind does a second job that the trade calls conching, after the shell-shaped machines Rodolphe Lindt used when he discovered it in 1879, as our chocolate history recounts. Hours of warm agitation and exposure to air drive off the last volatile acids and bitter compounds, round off the harsh edges and coat every particle of sugar and cacao in cocoa butter, which is what gives finished chocolate its melt. Too little conching leaves a bar sharp and gritty; too much strips the origin's character and leaves something smooth and dull. Small makers often use the melanger for both grinding and conching, running it for two or three days and tasting along the way; larger ones use separate machines. The decision of when to stop is the maker's second great choice after the roast.
Aging
The finished chocolate is poured into blocks and often rested for weeks or months before it is made into bars. Like a wine or a sauce, it settles; sharp notes soften, flavors integrate, and a bar made from aged liquor tastes rounder than one made the day it left the melanger. Not every maker ages, and some prefer the brightness of fresh chocolate, but many of the best do, and a few note it on the wrapper.
Tempering and molding
Cocoa butter can set in several crystal forms, and only one of them, the form the trade calls beta or Form V, is glossy, snaps cleanly and melts at just below body temperature. Tempering is the process of melting the chocolate completely, cooling it while stirring to seed the right crystals, then warming it slightly so only those remain. Done by hand, it is a slab of marble, a spatula and a thermometer; done by machine, it is a tempering unit that holds the chocolate at the right point. Tempered chocolate is poured into polycarbonate molds, tapped to release bubbles, cooled, and unmolded as bars that shine and snap. Untempered chocolate sets dull and soft and blooms gray, which is what happens to a bar left in a hot car and why our chocolate guides tell you to keep bars cool and never in the refrigerator.
Where the flavor is decided
The farm's fermentation decides what flavors exist in the bean. The roast decides which of them survive and whether roast notes join them. The conche decides how smooth and how rounded the result is. Everything else, sorting, winnowing, tempering, is about cleanliness and texture. Two makers buying the same sacks from the same cooperative will roast and conche differently, which is why a Madagascar bar from one is red fruit and citrus and from another is dried cherry and toast, and why our guides to single origin and tasting tell you to compare makers as well as origins. The bars on our chocolate shelf are at 263 Josephine Street in Cherry Creek, Denver, and ship nationwide from theambrosianpantry.com. Snap one, look at the shine, smell the break, and you have just checked the maker's temper, roast and conche in three seconds.
