For Christmas, because I am insane and he loves me, Tom gave me a home conching machine.
Conching is the penultimate step in chocolate making. Chocolate liquor (the product of grinding cocoa beans that have been roasted and cracked and hulled) is combined with sugar, usually some additional cocoa butter, and sometimes vanilla, milk solids, lecithin, and any other flavorings you want to add, and processed in what is essentially a big, industrialized mortar and pestle for hours or (in the case of the higher-end chocolatiers) days to give the fantastically smooth product that we know and love. This step has always prevented me from making my own chocolate, because there were no home conching machines available before now. But now there are. So here, you can see the steps involved in making a four pound batch of chocolate, starting from raw cocoa beans (plus extra cocoa butter, superfine sugar, vanilla beans, and soy lecithin) and ending in bittersweet chocolate, ready to eat, to chop up into chocolate chunks for use in cookies, to mix with cream for ganache, or for whatever you would want to use bittersweet chocolate for.
My conching machine came from Chocolate Alchemy, also the best source for raw beans. Along with all kinds of chocolate knowledge; as you will see if you go there after reading this account, I learned most of what I know about chocolate-making (pre-tempering) from them. Highly recommended.
The process begins with roasting raw cocoa beans. For this batch
of chocolate, I used three kinds of beans, and each was best roasted
for a different amount of time. (I did fairly extensive experiments
with roasting each kind of bean I had, taking samples at different
time points, grinding and sweetening them, and then blending them in
different proportions. I will hopefully have notes on this process
available on this site at some later point.) Here you can see the
Ghana Forastero beans, raw (on the left) and roasted for 30
minutes. (on the right; as you can see, the husks don't look any
different after roasting)
Here are Dominican Republic "Hispanola" (Yes, I know that's
redundant; that's what it says on the bag.) raw and roasted for 23
minutes. (Some people found the 20-minute sample a bit sharp, while I
thought the 25-minute sample were getting overdone.)
In both cases, the roasting profile (arrived at after some trial
and error) was to preheat the oven to 375
degrees F and put 2 pounds of beans in on an air-cushioned pan,
reducing the heat to 350 immediately and to 320 after 3 minutes. I
stirred every five minutes, reducing the heat again to 300 after a
total of 15 minutes. These next beans, a Venezuelan Criollo, had a
livelier and more delicate flavor that burned easily, so I reduced the
heat earlier and removed them after 15 minutes. They were too tangy
to use as a major component, but a slight admixture (8 oz. with four
pounds of Ghana and Dominican) woke up the other flavors and extended
the finish in a way that I love.
Here are all 4 1/2 pounds of roasted beans, ready for the next
step:
So the next step is to crack them and separate the nibs (broken
pieces of cocoa bean) from the husks. I used my Champion juicer,
without a screen, to crack them, producing this enormous bowl of what
looks like husks with a bit of nib mixed in:
Next I used good, old-fashioned winnowing [from the OED:
winnow, v. To expose (grain or other substances) to the
wind or to a current of air so that the lighter particles (as chaff or
other refuse matter) are separated or blown away; to clear of refuse
material by this method.] to remove most of the husks. I have a
fairly studly fan, so I set this up on the porch and just lifted
double-handfuls of the nib/husk mixture and let them rain back down
into the bowl. A truly alarming amount of material blew away, but on
close inspection it was almost entirely husk.
The result is much more a bowl of nibs with a bit of husk mixed
in:
Now they were ready to be ground and liquified, to make unsweetened
chocolate. That Champion juicer is again the tool for the task, this
time with the fine-mesh screen on it. Here you see the fairly fluid
unsweetened chocolate dripping from the bottom, and a mixture of
incompletely ground nibs plus husk material coming out the side at the
left:
This latter stuff was passed back through about three times,
until it was almost entirely husk and the returns were
diminishing. The total yield (from 4 1/2 pounds raw beans) was about
52 oz. (or 3 1/4 pounds) of unsweetened chocolate.
Next was blending and conching. I measured out 41 oz. of the
unsweetened chocolate (the rest I let solidify for future use), added
6 1/2 oz. of additional cocoa butter (to get the right texture and
workability in the finished product), and melted it all in the
microwave. Then I put it in the conching machine along with 20 oz. of
superfine sugar and started it up. While it was going, I scraped the
seed pulp from two Madagascar and two Mexican vanilla beans and added
it, along with about a teaspoon of soy lecithin (an emulsifier, to
give the whole thing a silky texture and help it incorporate any
moisture in the vanilla beans). Here is what the conching machine
looks like in action:
It is not at all clear from that picture that the central spindle is fixed, with the wheels and scraper attached to it, while the bowl rotates. Or that the wheels and the base of the bowl are stone, so that they are just constantly grinding away at the contents of the bowl while it runs. Or that the bowl is turning fast; we clocked it just above 150 rpm, or 2 1/2 turns per second! This means that in 11 1/2 hours of conching, it went around just a bit more than 100,000 times. I find that oddly satisfying, somehow.
The initial mixture was a grainy, tangy mess, but over the course
of the day it got smoother and mellower and more chocolatey. By four
hours it was already past a supermarket chocolate, and at 11 1/2 hours
I judged it ready to proceed with. The final step in preparing it for
storage is to temper it. (See my notes on
tempering chocolate for a complete discussion of this process.)
Unfortunately, my tempering machine has a capacity of maybe 1 1/2
pounds if you push it, and this was a four-pound batch of
chocolate. (Four and a quarter pounds of ingredients went in, but as
you can see from the picture of the conching machine, it is a large
and complexly shaped piece of equipment, and I lose about a quarter
pound after scraping as much off the various surfaces as I have the
patience for.) So I have to hand-temper. I kind of suck at
hand-tempering; it comes out kind of lumpy, and would be difficult to
work with. Fortunately, all I need is to get it into decent temper so
that it can set up. I can then retemper small batches in the
machine for fine work. So the basic idea in hand-tempering is to pour
out a fraction of the melted chocolate and work it, spreading it out
and scraping it up, until it starts to set, like so:
This provides a source of seed crystals, which is then added back to
the rest of the batch and mixed in so that it will set up
correctly.
All that remains is to pour it out into a prepared form, which I
made by folding up the edges of a large piece of baking parchment, and
letting it set:
Then it can be broken up into pieces and bagged for long-term
storage...
...and I have made four pounds of chocolate from scratch. How cool is
that?!?