Refining and(vs) Conching
The process involves heating and mixing for several hours to several days the ingredients of chocolate - cocoa, cocoa butter, sugar, lecithen and and any "flavoring" such as vanilla or essential oils. For milk chocolate, dry milk powder is also included in the mix. (don't try to use liquid milk, it will seize on you). During conching, the chocolate is heated to temperatures of 110 to 180 F, sometimes externally, sometimes just from friction. Milk chocolate actually needs temperatures over 160 F to allow the lactose crystals to transition into amorphous lactose. This transition is why milk chocolate has that soft and silky mouthfeel. The sharp taste of the fresh cocoa slowly disappears. At the same time the acidity and bitterness of cocoa are lost and the moisture content is reduced (there is actually debate over this) and the delicious chocolate flavor becomes fully developed. Simultaneously in the process, the smoothing of the cocoa and sugar particles takes place with cocoa butter forming around each of the small particles. This is different from refining really. The particles of sugar and cocoa are smoothed out in conching but not substaintial reduced in size. Conching is done for several hours or up to three days. Finally, there are basically two thoughts on conching - low and high shear. When conching was discovered, there was only low shear, and this is probably why it could take up to 3 days. With modern equipment, there have been a number of conching advancements, notably high shear conches. These supposedly (there agian is great debate) can conch a batch of chocolate in under 15 minutes. The high shear causes the volotile components to be quickly liberate from the cocoa mass.
There is no real right way or amount of time to conch. It is up to you and what you want your final chocolate to be like.
All I can do is give you certain guidelines. Certain Criollo cocoa beans are choosen because they are bright and fruity.
You would not really want to conch that for 3 days because you are just going to drive off those qualities that you choose the bean for in the first place. And you will need to keep balance in mind in that desirable and undesireable compounds are driven off during conching. The trick is to find that combination of conditions (low or high shear, high or low heat, short or long time) that give the chocolate flavor you want. Conching is probably the least understood process in modern chocolate making and consequently the most Alchemical of the processes. Finally, try not to worry too much over it. Even if you chocolate is not exactly like to want it, it is still going to be good, primarily because you are using fresh quality cocoa beans.
Right now there are no home conchs but I am working hard to get one developed. The present plan is that it will consist of a heated container (so the chocolate mass is liquid) and a motor that can run continuously with properly shaped scrapers and fins for working the chocolate too smooth silkiness. That is the plan anyway. Stay tuned and I will keep everyone up to date.
Conch Update - 12/28/04
I have been using a slighly modified ice cream maker as a low shear conch, and it does quite the nice job. It does not yet work as a very good combination refiner. That will take a special attachment that I am having made. Hopefully it will fit a number of standard models out there. Basically, what you need to do is get a heating pad and place it under the outside of the whole ice cream maker and put it on high and put eveything in an insulating box, keeping the motor outside (motors do not like heat). Put your chocolate into the ice cream churn, and set it to run. Most of the ice cream maker motors that I have found say they are intermittent use only. I have got around this nicely by putting the motor on a timer, one hour on, one half hour off. I run it days on end this way with out a problem.
Conch Update - 3/30/5
I have been able to do a nice amount of R&D lately with the new stock of beans that are in, and I have made a rather nice potential discovery. The Champion juicer we are using to grind and mix our liqueur and other ingredients may very well be acting as a high shear conch, in some form or another. I basically noticed that the chocolate coming out was actually quite mellow, lacking in sharpness and I had very little inclination to conch. When I did some test conching, the "improvement" was minimal, mostly I believe, because it was going in pre-conched. I have not tried this with milk chocolate, but I expect that may still need a higher temperature to conch properly. So, again, don't worry too much about conching. It is the final most subtle adjustment you are going to make to your chocolate. Focus on your roasting, formulations and refining and I think you will be happy with your chocolate. Decide to conch based on flavor, not because you think it has to be done.
Again, refining is the process of reducing the particle sizes of both cocoa solids and sugar crystals in finished chocolate to about 20-30 microns. There are a number of ways that this is done in the chocolate industry, but not many are applicable to the home chocolate maker. There are large steel conbination refiner/conchs. These work by litterally slapping steel plate together. This both crushes the chocolate particles and shears the choclate as it goes from plate to plate. They are very loud and you can not control you individual levels of conching and refining. You get what you get basically. The other major way that chocolate is refined is with hydrolicly run steel rollers. There is usually 3, 5 or even 7 rollers that process the chocolate over and over, with gradually dimenishing gaps between the rollers. This might be feasible down the road on a home scale
A home alternative might be an idea I came up with some time ago, but never really go to pursue. It is the different paddles I mentioned above in the modified ice cream maker. The fins could potentially be spring steel mounted on a rotating shaft. The steel fins would rub on inner walls of the container holding the chocolate. The container would have to be stainless steel, and both materials (container and fins) would need to be virtually the same hardness so they don't wear each other away (you really don't want steel filings in your chocolate). This would probably give some conching action, but not too much since the refining should happen pretty quickly. We really wouldn't know unless it is tries. Anyone game?
Refiner Update - 12/28/04
I have found a number of chocolate industry referances that ball mills (which is all this tumbler with shot is) refine chocolate just fine. I have begun using an everyday rock tumber as a partial refiner. I fill my container 1/3 with sugar, 1/3 with 1/4" stainless steel shot and set it rotating for 24-36 hours. I usually pre-gring the sugar in a blender just to get the process going well, but this greatly reduces the sugar crystal particles and makes for a smoother chocolate.
Chocolate refined this way runs into a couple of problems. The chocolate begins to outgas after 24 hours. This causes leaks in the container and quite a mess. I think if the whole container was larger, it could handle the pressure better. Unfortunately, the larger the container, the more stainless steel shot you need, and that can be rather expensive. IF I could find a container and tumber to refine 5 pounds of chocolate, and IF it actually did the job, the shot required would probably cost $500. Not real approachable.
Refiner Update - 3/30/05
I have a small scale refiner being put together at a fabrication shop. I have a good feeling about this and I should know more in about a month or so I hope. Sorry, but due to patent concerns, I really can't say any more, except that I hope that it will be highly affordable. I will let you know.
Refiner Update - 4/1/05
Through the questions and recomendations of a customer, I have decided to test out a
It has granite grinding stones, a strong motor and good reviews for durability.
I will see if it will work for refining either sugar (it is the only wet grinder
on the market that can handle dry grinding) or hopefully, the chocolate itself. It should arrive in a week or so and
I plan to have unrefined chocolate ready and waiting. While I am at it, I will see how it does on whole nibs. It would be great to have
more than one option for grinding cocoa into liqueur.