Learning Objective: Develop an understanding of how chocolate is processed

Processing overview

We used the Program Glossary to start you thinking about the process of chocolate making from tree to couverture. This lecture will build on that general knowledge. For the moment, we will not include a discussion of the chemistry of the cacao species that leads to differences in flavor and properties. We'll leave that instead to the next Program Module where we concentrate on taste.

We start this lecture with an overview of processing, a diagram of the manufacturing process and then online resources where you have access to more processing details with pictures and even videos that help you to visualize the process.

Before the Industrial Revolution, chocolate manufacturing mostly took place in small mills or shops. Chocolatiers and small grinders produced chocolate themselves and often had a narrow specialty. But once the age of industry took hold, chocolate production moved to large processing plants and the smaller shops stopped making their own chocolate. It became easier to buy bulk from a few large manufacturers whose modern equipment allowed them to make chocolate much cheaper. These manufacturers offered larger, more diverse product lines to satisfy many different requests from their customers for specific flavors or price ranges.

In the 21st century, the chocolate giants are bigger than ever, but there has also been a trend back to smaller operations where micro manufacturers use vintage equipment. Amano, Askinosie, Patric, Theo, TCHO, DeVries Chocolate and Original Hawaiian Chocolate Factory are examples of such smaller chocolate-manufacturing operations.

Chocolate processing practices haven’t changed much from the Maya. It's just that the equipment and processes have been refined. These processes can be divided into six major steps:

In the cacao orchard or plantation

Harvest and fermentation

Cacao trees produce buds on a continuous basis — this can be year-round in subtropical areas, such as Central America, or it can be tied to the rain cycle in areas such as Africa. Fluctuations in growth cycle and harvest can occur because of changes in climate conditions.

Harvesting the cacao pods is still done by hand, as the mature pods need to be identified and cut from the tree without damaging flower buds, immature pods or the stem area from which the bud grows.

The pods are carefully broken open to release the cacao beans which are embedded in a moist, fibrous white pulp.

The beans and pulp are scooped out quickly and either:

• Heaped in a pile on mats or banana leaves and covered

OR

• Put into a bin or box with a lid

Fermentation occurs when the pulp surrounding the cacao bean is converted into alcohol by the yeasts present in the air and the heat generated by the pile or box. The beans are mixed gently during this process to introduce oxygen into the pile or box which turns the alcohol into lactic and acetic acid. The resulting liquid, with its alcohol content, slowly leaks out of the pile of beans during the fermentation process, leaving just the beans.

Germination in the cacao bean is killed by the high temperatures produced during the fermentation process. The beans gather moisture from the environment and plump up. Their flavor begins to change from mainly bitter to the beginnings of the complex flavor called chocolate. The fermentation process can take up to eight days, depending on the species of cacao bean. Better fermentation results in better flavor and less roasting time needed to bring out that flavor.

Drying and storage

The cocoa beans, as they are now called after fermentation, come out of this process with a high moisture content. In order to be shipped or stored, they must be dried.

The drying process differs, depending on the climate or size of the plantation. Cocoa beans can be dried out in the sun on trays or mats, where climate permits. Sun drying usually happens in smaller plantations in drier environments. In tropical areas, where daily rainfall is the norm, the beans can be dried in sheds as long as there's enough air circulating around the flats of beans. The use of wood fire to speed the drying process is disliked by the manufacturers as the process leaves the beans with a smoky taste.

During the drying process the beans need to be turned and picked over for debris, broken bean bits and germinated beans. The cocoa beans shrink and lose 50% of their moisture in a process that can last from five to ten days.

The dried cocoa beans are then sorted and bagged. The sorting process is very important because the cocoa beans are classified and sold in the industry by their size and quality.

The bagged cocoa beans are then loaded onto ships to be delivered to chocolate manufacturers. They must be fumigated for insects and pests and stored in a ventilated, humidity-controlled environment on the ship itself, which adds to the cocoa bean’s final cost.

Cocoa beans are usually bought by cocoa manufactures using brokers in London, New York or Amsterdam who act as intermediaries between the growers and manufacturers. Cocoa prices are futures commodity prices, per metric ton, set by the New York or London stock exchange.

In the manufacturing plant

Each chocolate manufacturer has its closely guarded "secret recipe" for every chocolate product it produces. This secret begins with the type and quality of the cocoa beans used.

I will use the symbol § to indicate points in the process where the manufacturer may use its own secret formula.

Here's a fun online video of Jacques Torres touring his chocolate factory.

Testing, cleaning and roasting

When the § cocoa beans arrive at the manufacturing plant, they go through a very extensive sampling and testing procedure. The sample cocoa beans are tested for size and defects, such as insects or mold, and then converted into chocolate liquor, which will be evaluated for flavor and aroma by company tasters. Once the testing is complete and the shipment is accepted by the manufacturer, the beans are thoroughly cleaned to remove any foreign matter.

The cocoa beans then go into the roaster for anywhere from § 10 to 35 minutes. Temperatures vary and the better "flavor" beans are roasted as low as possible from § 250° - 350°F.

Cracking (or fanning) and winnowing

During the roasting process, the shell of the cocoa bean separates from the bean kernel and is removed in the first step of the cracking or fanning process. The beans are cracked (not crushed) by being passed through serrated cones. The cracked beans are now called cocoa nibs.

As the shell is dry and lightweight, it can be winnowed from the cocoa nib. Winnowing is done by exposure to a current of air so that the shells are blown free of the heavier nibs. If the manufacturer desires, at this point the nibs can be § treated with an alkali salt to increase pH value and neutralize the acidity (called Dutch Process). The nibs contain approximately 53% cocoa butter, depending on the cacao species.

First grinding to produce chocolate liquor

The nibs are ground or crushed to liquefy the cocoa butter and produce what is now called chocolate liquor or liquid. The traditional method was done by using a mélangeur-broyeur or grinder mill. The two granite wheels rotate and turn on a granite bed to crush and pulverize the nibs. The heat from the friction is all that is needed to turn the nibs into a melted mass.

Vestri uses this traditional mélangeur-broyeur

Add flavor ingredients and refine

After ingredients are added (sugar, vanilla or milk powder) the chocolate mass needs to be refined. Most chocolate manufacturers use a roll refiner which has two functions: to reduce the particle size of the cocoa mass and to distribute the cocoa butter evenly throughout the mass, coating all the particles. Finesse is the industry term for the measurement of the average particle size in a batch of chocolate.

Roll Refiners come from Buhler, Carle & Montanari, Lehmann or Bauermeister

The rolling process itself creates heat that melts and distributes the cocoa butter. In addition to deciding on the flavor of the chocolate, manufacturers must decide on the § particle size for each of their chocolates. This is the first step in developing chocolate's smooth and creamy mouth-feel.

Cocoa powder or chocolate

At this step in the process, the manufacturer decides whether a specific chocolate liquor will become chocolate or cocoa powder.

For cocoa powder:

The liquor can be heated and compressed to release the cocoa butter and separate it from the cocoa paste — using, in some cases, the Broma process discovered by Ghirardelli Chocolate. This yields two products:

• Cocoa butter, which can be stored and added to other chocolate products or sold to pharmaceutical or cosmetic companies.
• Cocoa solids, which are pressed into a cake and then ground to produce cocoa powder. The § percent of cocoa butter left in the cocoa cake determines the resulting cocoa powder's quality and use. The cocoa cakes can be treated § with an alkali salt to increase pH value and neutralize the acidity (called Dutch Process). This deepens the cocoa powder's color and improved its suspension in liquids.

For chocolate:

Different percentages of § cocoa butter are removed or added to the chocolate liquor. Cocoa butter carries the flavor of the chocolate and produces a cooling effect on your tongue, which you might notice when eating dark chocolate. Also, depending on the chocolate flavor desired, some or all of the following § ingredients are added: sugar, lecithin, milk or cream powder or milk crumb (to produce milk chocolate), and spices such as vanilla. The formula the chocolate manufacturer develops for combining specific ingredients with the chocolate liquor is what gives the chocolate its unique taste.

Conching

This process develops the flavor of the chocolate liquor, releasing some of the inherent acids and bitterness. It also gives the resulting chocolate its smooth, melt-in-your-mouth quality by decreasing particle size and dispersing the cocoa butter evenly around all the particles. The conch machine has rollers or paddles that continuously knead the chocolate liquor and its ingredients over a § period of hours or days depending on the quality desired by the manufacturer.

About particle size

Our mouths can detect particles at 35 μm (μm = micrometer or micron, as it is called in some industries) or more so chocolate manufacturers usually refine their chocolate to less than that size. In the luxury chocolate end of the spectrum, chocolate makers like to generate an even smaller particle size of about 16 - 20 μm, which can't be felt on the tongue.

Research on particle-size distribution in milk chocolate seems to indicate that a small proportion of particles up to 65 μm (0.0026 in) gives better texture. If refining is carried to the extreme and produces a milk chocolate with a particle size of less than 25 μm (0.0010 in), the texture becomes slimy.³

Another factor concerning particle size is whether the large particles are sugar, cocoa particles or milk powder (or milk crumb). Each produces a different sensation on the palate. Large sugar crystals are obviously gritty, but disperse; cocoa particles give a persistent sensation of roughness; and milk crumb aggregates soften and disperse in the mouth after a short while and, it is, thought, this overcomes the sensation of sliminess.³

Tempering and forming chocolate

For the last two steps in the couverture process, the conched chocolate mass is tempered and molded into bars or pistoles, or it may go into another production cycle to end up as specialized products such as enrobed centers and molded items.

The molds are passed along a vibrating belt to settle the chocolate into the mold crevices and remove any air bubbles before cooling.

Cooling and hardening the chocolate

The cooling process is critical to the shine and shelf life of the finished product. The liquid chocolate must not meet very cold air, which will make the still-liquid cocoa butter unstable. The air in the first stage of cooling should be at a temperature of 59° - 62°F (15° - 17°C). Under these conditions, the chocolate will cool from about 87°F (30°C) to 68° - 70°F (20°C) and the formation of stable crystals will be ensured.

The second stage introduces cooler air to lower the chocolate temperature to 50° - 55°F (10° - 13°C) and speeds the solidifying process.

The third stage is to bring the temperature of the chocolate back up to 60°F (15°C) before it is at the end of the cooling process, in preparation for the warmer storage temperature. Note that these temperatures are the temperature of the chocolate itself, not the cooling tunnel of air.³

Diagramming the process

Manufacturing chocolate at home or in a chocolatier's facility

Over the years, I have had students ask me if it's possible to manufacture chocolate at home. It certainly is possible — you'll need to access dried cocoa beans and then experiment with equipment for roasting, grinding and conching. Can you replicate the quality of the manufactured products? Yes and no, depending on how much time you want to put into searching out good cocoa beans and refining your processes and equipment..

Chocolate Alchemy is what I consider to be the best resources for making chocolate at home. If you start at this page:http://www.chocolatealchemy.com/cocoabeans.php and then click on the titles in the top right corner, Alchemist John takes you through the processes of: Roasting, Cracking/Winnowing, Grinding, Conching/Refining, Tempering/Molding using basic home equipement. He also sells cocoa beans.

Chocolatiers making chocolate on premises for own use

The following are examples of chocolatiers who are making chocolate on their own premises for their own use:

Theo Chocolate

Soma Chocolates - Here are pictures of Soma's facility.

Black roaster and gray grinder in the back and blue mélangeur-broyeur in the front

Panning machine on the left and tempering machine in the back (see yellow panel). 
Storage is probably through the door on the far right.

A closer view of tempering machine, which probably has an enrobing attachment 
which is not set up (you can see the belt to the right of the machine).

Resources on chocolate manufacturing and processing

Read through the following:

World Cocoa Foundation
There are a number of online videos to illustrate how chocolate is processed.

Callebaut
This is an overview of the process at their website.

Kara Chocolates
There is a good overview of the manufacturing process, after the section on history.

Peter's Chocolate
Check out their All About Chocolate section, including Chocolate FAQ sub-section, which talks about the standards of identity for each flavor of chocolate.

Resources and Bibliography

¹ The New Taste of Chocolate: A Cultural and Natural History of Cacao with Recipes by Maricel E. Presilla

² The Chocolate Bible: The Definitive Sourcebook by Christian Teubner

³ Chocolate, Cocoa, and Confectionery: Science and Technology by Bernard W. Minifie