Making chocolate and biomanufacturing

Theo chocolate is situated in a neighborhood called Fremont, in the city of Seattle, in the former Redhook brewery. I used to consult for Redhook in my microbiology days, when I had access to a -80°C freezer and a proper microscope, so the building has a comfortable feel and some pleasant memories.

These days the bar is gone and the aromas are more like roasting coffee than brewing beer. Most of machinery, though, is surprisingly similar. The equipment is very much the same as the equipment you'd find in many kinds of biotech manufacturing facilities. There are giant scales, fermenters, pipes, computers, and lots of valves to control the movement of materials from one stage to the next.

Chocolate making it turns out shares many common features with cheese making, brewing, and manufacturing pharmaceuticals.

First the raw ingredients arrive. In chocolate making, the raw ingredients all come from somewhere around the equator. Fruit are harvested from the Cacao plants (Theobroma cacao) fermented in white trays and when the fermentation is complete, the beans are packaged for export.

No one has really characterized the bacteria and yeast that participate in the fermentation process, as I wrote earlier, except to say that there are yeast and lactic acid bacteria. We haven't yet sequenced the bacteria to find out who they are. Anyway, all the fermentation takes place on the farms, outside, in a less than sterile environment.

The exporting part is tricky. If the fermentation wasn't complete or the beans get wet, they won't be any good. If anything gets moldy, the beans won't be any good. Quality control is a constant battle at this stage and inferior beans produce inferior chocolate. At least that's what we hear from the Theo tour guides and it seems to make sense.

Once at the chocolate factory, Theo samples the volatile compounds that gather in the air above the beans. Chocolate beans have distinct profiles of volatile compounds. The area above the beans is called the head space and knowing the identity of the volatile compounds by sampling the head space helps Theo evaluate the quality of the beans and predict the quality of the resulting chocolate.

Being agricultural products, beans need to be cleaned and separated from small rocks and stones.

The destoner is shown below.

Next the beans are roasted. Roasting chocolate beans contributes to some great chemistry. [Mailliard reactions](http://en.wikipedia.org/wiki/Maillard_reaction) are very important at this stage, just like they are when roasting coffee.

After roasting, the cacao beans are ground a bit, and the nibs are separated from the husks by a winnower.

Theo prudently sells the husks as garden mulch. Just imagine, a garden that smells like chocolate when it rains.

The nibs are ground even more to micron sized pieces called cocoa liquor. The next task is to make chocolate flakes and aerate the chocolate. This takes about 3 days is called conching. Conching contributes to the flavor and reduces the acid by circulation and oxidation.

Then there is a tempering machine that forms bonds between the cocao solids and cocoa butter.

And of course, there are steps where sugar and flavorings are added and bars are made.

It's a delicious process.