[Continued from Part 1]
Processing of Chocolate
There are two main stages in processing chocolate. First, growers process the seed pod to obtain the dried seeds. Second, manufacturers process the dried seeds to obtain food products. Consider each of these stages. Details are omitted.
The processing of the seed pods by the growers proceeds in something like the following sequence, which has been followed with little change for four millenia [Coe and Coe, p. 22]. (General references are Young [pp. 80-83] and Wikipedia.)
- Harvesting: Judgement and experience are needed to determine when to harvest a seed pod, and this task is complicated since pods on the same tree ripen at different times and since two ripe pods on same tree can be different colors [Presilla, pp. 96, 100]. There is a period of about two weeks when the seed pod is ripe and suitable for harvesting. If it is picked too soon or too late, the chocolate will not be good. The fragility of the plant requires that harvesting be done by hand. The harvester usually cuts the pod off the tree with a machete if the pods are low or with a sharp blade fixed on a long pole if the pods are high [Presilla, p. 2]; see the two pictures below from Presilla [pp. 47, 104].
- Extracting: The seed pod is cut open, usually with a machete. The outer rind, which is tough, leathery, and perhaps half an inch thick, is discarded. See the third picture below from Buford [p. 69].
- Fermenting: The pulp and seeds are placed into a vat, often covered with banana leaves, where the mixture naturally ferments. This step is necessary since, with a heat of fermentation of about 120 degrees F., it destroys the embryo, draws some of the bitter compounds from the seeds, and begins the chemical changes that gives chocolate its characteristic taste and aroma [Presilla, p. 107]. The heat of fermentation causes the fruit to liquify and drain away. You can see small vats in the third picture and a big vat partially covered with banana leaves in the fourth picture [Presilla, p. 107].
- Drying: The remaining seeds are dried, ideally in the sun. This reduces the moisture content of the beans so that they can be stored and shipped without getting moldy. The dried seeds, which are now called beans, are ready to ship to the manufacturer. See the last picture below.
The processing of the cacao beans by the manufacturer involves the following steps. (A general reference is Young [p. 85].)
- Clean the beans.
- Roast the beans. High quality beans are typically roasted for between twenty and forty minutes at between 220 and 240 degrees F [Presilla, p. 114]. Roasting further enhances the flavor.
- Remove the shells from the beans. Nibs is the term used for the roasted, shelled beans. The shells can used as a fragrant garden mulch or as a stock from which to extract theobromine, from which caffeine is synthesized [Young, p. 89].
- (Optional) If a mixture of different varieties of nibs is desired, then mix them.
- Grind the nibs to produce a paste called the cocoa liquor or cocoa mass, which has a fat content of 55 to 58 percent. It is at this point where the processing of chocolate gets tricky. To see the heart of the complication, put chocolate nibs into a blender and grind them up; you will be surprised at how much liquid is produced. This liquid is the fat [Buford, p. 70]. Dealing with this fat is a problem since fat and water don't mix; overcoming this problem was the key to chocolate becoming a mass-market item. The highlights of the development of the processing process are mentioned in the next section. (When you grind the beans, the fat is liquid because of theheat of grinding. If you let this fat sit, it will congeal. Recall the rule of thumb that good fat is liquid at room temperature and bad fat is solid. The chocolate fat is the bad fat, i.e., saturated.)
- (Optional) At this point one has the option of pressing the cocoa liquor to produce two products. The liquid portion is called cocoa butter, which is largely fat. The solid is called variously cocoa cake or cocoa solids, which has a fat content of 22-23 percent. This process is only essential if one is making cocoa powder or white chocolate; if one is making dark or milk chocolate, the cocoa liquor can be used.
- Use the cocoa liquor to make solid chocolate for eating, e.g., a chocolate bar or figurine. There are four steps.
- Mixing the ingredients: Mix the cocoa liquor with sugar, cocoa butter, condensed milk (if milk chocolate is being made), lecithin, and optional flavorings such as vanilla. Lecithin has a long list of properties, but its main function here is to reduce viscosity and prevent sticking. If you think there is something wrong with lecithin, read the Alchemist's Notebook. (You might wonder where you get the cocoa butter. One source is that it is a side product of making cocoa powder.)
- Refining: Pass the chocolate mixture through a series of huge rollers to reduce the particle size and create a smooth mixture. A picture is below. You can watch a relaxing video of refining. Both the picture and the video are of the latter part of the process when the fat has been released and gives the mixture a smooth, wet appearance.
- Conching (pronounced conking): "...knead and agitate the cacao mass until it undergoes some not-fully-understood chemical changes that seem to mellow, ripen, and round both flavor and texture [Presilla, p. 116]." In addition, undesired aromas dissipate [Presilla, p. 118]. Conching, which also further reduces the size of the particles and makes the chocolate smoother, might last for 72 hours or sometimes much more for very smooth chocolate [Coe and Coe, p. 248]. Below is a drawing of a cross-section of a conching machine; this gives you some idea of how conching splashes and agitates the mixture..
- Tempering. Heat the chocolate and let it partially cool. Chocolate is tricky in that, when you have melted chocolate, the form that it takes as it cools depends on the history of how it was heated and agitated, and it is easy to wind up with unsatisfactory chocolate. Tempering consists of melting chocolate and treating it in a way so that it will crystallize properly as it cools. The problem is that cacao liquor can harden into several different crystal forms, and if it does not harden into one uniform crystal form, it will discolor or look grainy [Presilla, pp. 214, 227, 231]. Pictures below illustrate some of the flaws of improperly tempered chocolate. See the Alchemist's Notebook for a chemist's discussion of what happens when chocolate is tempered; one of a series of suggestive cartoons of properly crystallized chocolate is reproduced below. Properly tempered chocolate will have a shiny surface, snap crisply when it breaks, and have no surface bloom [Coe and Coe, p. 257]. When the chocolate has partially cooled, it can be poured into molds.
- If, rather than making solid chocolate for eating, you prefer to make cocoa powder, grind the cocoa cake into a fine powder.
The steps in the process are summarized in the diagram below.
Controversy rages over the relative contribution of the various steps in the process to the quality of the chocolate. A source that places greater emphasis on the activities of the growers says that fermenting and drying go a long way toward establishing the taste of the finished chocolate [Presilla, pp. 110, 117]. In contrast, a maker of gourmet chocolate takes the view that:
Depending on how the cocoa is roasted, refined and conched, the flavor can shift wildly. This is of course great for a chocolate maker, because it allows for wide latitude and artistic license.
My conclusion is that the chocolate can be fouled up at any stage in the process.
[Continued in Part 3]
