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The secrets of Belgian chocolate
By Laura Cassiday
May 2012
Like a bonbon nestled snugly in a box of chocolates, Belgium sits between France,
Germany, the Netherlands, and Luxembourg. With a land area of only about 30,528 square
kilometers (11,787 square miles), Belgium produces 270,000 metric tons of chocolate each
year and boasts more than 2,000 chocolate shops. Belgium’s chocolate obsession is fueled
by a 150-year-old tradition of producing some of the world’s !nest chocolate. But what is it
about Belgian chocolate that makes it so smooth, "avorful, and melt-in-your-mouth
irresistible? The secret lies in quality ingredients and expert processing, combined with a
spirit of innovation that continues to re!ne Belgian chocolate even today.
The history of Belgian chocolate reaches back to the 17th century, when Spanish explorers
brought cocoa beans from South America. The Spanish nobility, who then ruled Belgium,
enjoyed cocoa as a luxury drink. However, chocolate did not gain popularity with the general
public until the second half of the 19th century, when Belgian King Leopold II colonized the
Congo. During the age of European imperialism, cocoa cultivation began to shift from the
Americas to West Africa, which provided an ideal environment, as well as plentiful slave
labor, for cocoa production.
In 1857, Jean Neuhaus opened a pharmacy in Brussels, Belgium, where, among more
traditional remedies, he sold bars of bitter chocolate. Eventually, the bars became so
popular that Neuhaus focused his e#orts on chocolate making. In 1912, Neuhaus’ grandson,
Jean II, invented the now-famous Belgian praline by !lling hard chocolate shells with soft
cream or nut pastes.
Today, the Neuhaus company continues to manufacture Belgian pralines (known as
bonbons elsewhere in the world), joined by other large manufacturers such as Godiva,
Leonidas, and Guylian. In addition, numerous small manufacturers and artisan chocolatiers
attract loyal customers to their shops throughout Belgium. The country also supplies 20% of
the world’s industrial chocolate (Dewettinck, K., The Secrets behind the quality and taste of
Belgian chocolates, presented at the 103rd AOCS Annual Meeting and Expo, April 30, 2012),
which food manufacturers use to create !nished products such as bonbons, cookies, and
ice creams (Belgian chocolates: the secrets of their quality and taste . Large producers of
industrial Belgian chocolate include Cargill, Belcolade, and Barry Callebaut. The Barry
Callebaut factory in Wieze, Belgium, is the largest chocolate-producing factory in the world,
says Mark Adriaenssens, a native Belgian and the company’s director of research and
development for the Americas.
From forest to factory
The story of Belgian chocolate, however, begins not in a factory but in the tropical rain
forests of Africa, Central and South America, the Paci!c islands, and Asia (Table 1). Cocoa
trees (
Theobroma cacao
) thrive at altitudes of 30–300 m, with temperatures ranging 18–32
°C and annual rainfall 1–5 L/m . The trees bear yellowish, 15–30-cm-long by 8–10-cm-wide
pods that contain 20–60 whitish-gray, almond-shaped seeds embedded in a white pulp.
When the pods ripen, workers at cacao plantations harvest the pods by cutting them from
trees with a curved knife on a long pole. Then, they split the pods open with a machete,
remove the pulp and seeds, and place them on banana leaves on the ground or in boxes.
After covering the cocoa pulp with more banana leaves, they let it ferment for about six
days.
As the cocoa sits in the sun, three types of microorganisms sequentially consume and
transform compounds in the pulp. Because the inside of the unopened cocoa pod is sterile,
these microbes come from the cocoa pod surface, workers’ hands or knives, or elsewhere in
the environment. The !rst microorganisms that act on the pulp are yeasts, which can grow
under the anaerobic conditions found in the dense pulp. Yeasts convert glucose in the pulp
into ethanol and produce pectinases that break down the pulp. The decreased pulp
viscosity allows more air to penetrate, encouraging the growth of lactic acid bacteria. These
bacteria convert fructose and citric acid in the cocoa pulp into lactic acid and acetic acid.
Finally, when the yeast and lactic acid bacteria have consumed all of the sugars in the pulp,
acetic acid bacteria convert the ethanol produced by the yeast into acetic acid. This reaction
gives o# heat, killing the microbes and ending the fermentation process. By this time, most
of the pulp has lique!ed and drained away.
2
Proper fermentation is essential for producing high-quality chocolate, says Luc De Vuyst,
food biotechnologist at the Vrije Universiteit Brussel. For one thing, the acetic acid produced
by the microbes penetrates the cocoa seed and kills the embryo. If the embryo remained
alive, it could start to grow, consuming the fat in the beans needed for chocolate production.
In addition, acetic acid disintegrates membranes within the cocoa bean, releasing enzymes
and substrates that mix and interact. “A whole series of enzymatic reactions takes place in
the fermenting bean,” says De Vuyst. “The chemical products of these reactions contribute
to the color and "avor of the !nal chocolate.”
Scientists used to think that the strains of yeast and bacteria responsible for fermentation
varied with the cocoa-producing region, contributing to subtle "avor variations in cocoa
from di#erent parts of the world. However, when De Vuyst analyzed the microbes present in
cocoa fermentations from Ghana, the Ivory Coast, Brazil, Ecuador, and Malaysia, he found
that the microbial composition and fermentation process were everywhere the same,
provided that the cocoa plantations observed good agricultural and operational practices
(e.g.,
Food Microbiol.
2011, DOI 10.1016/j.fm.2011.06.003). In contrast, farms that harvested
immature or fungus-infected cocoa pods, used defective equipment, or practiced poor
hygiene showed variations in the fermentation process. “Under these conditions, a whole
zoo of microorganisms can develop and destroy the fermentation process, delivering sour
beans from which you make sour chocolate,” says De Vuyst.
Based on these !ndings, De Vuyst developed a fermentation starter culture consisting of
strains of the yeast
Saccharomyces cerevisiae
, the lactic acid bacterium
Lactobacillus
fermentum
, and the acetic acid bacterium
Acetobacter pasteurianus
. He found that adding
this starter culture to newly harvested cocoa pulp shortened the fermentation process from
six to four days (
Food Microbiol.
2012, DOI 10.1016/j.fm.2011.12.021). Commercial use of the
starter culture could enable faster and more uniform fermentation of cocoa beans.
Furthermore, “By manipulating the microbial composition of the starter culture, we may be
able to steer the fermentation process to generate certain "avors in the !nal chocolate,” says
De Vuyst. He is currently working with the Barry Callebaut factory in Wieze to implement
this controlled fermentation.
After fermentation, the beans have a rich brown color. Workers dry the fermented beans in
the sun for 6–10 days, during which the chemical reactions in the beans continue. After
drying, farmers or potential buyers can perform various tests to assess the quality of the
beans. For example, in the grainage test they count the number of cocoa beans present in
100 g, which should be fewer than 100 beans. In the cut test, inspectors randomly select 100
cocoa beans and slice them in half lengthwise, looking for signs of mold, insect damage,
shrinkage, germination, or a gray or violet color, all of which indicate lower-quality beans. In
another test, inspectors weigh cocoa beans before and after removing their shells. If the
mass percentage of the shells is greater than 14%, then the cocoa beans are too small or
insu$ciently fermented. With these tests, chocolate makers can ensure that the beans they
purchase are of su$ciently high quality to produce good chocolate.
Making it Belgian
At this point, the cocoa beans are !nally ready to leave the farm. Workers package the dried
beans and ship them to factories, the sites of roasting and grinding. During roasting, "avor
compounds develop through numerous chemical conversions collectively known as
Malliard reactions. Carbonyl and amino groups of molecules formed during cocoa
fermentation and drying react with each other, producing more than 600 "avor compounds
that together give chocolate its characteristic taste and aroma. After roasting, a machine
called a winnower cracks and deshells the beans. Then the deshelled beans, known as nibs,
are ground into a thick paste called chocolate liquor. The chocolate liquor is pressed to
extract cocoa butter, leaving behind a solid mass that is ground into cocoa powder.
Barry Callebaut produces its own chocolate liquor from cocoa beans, whereas other
industrial chocolate makers purchase liquor from companies outside of Belgium to make
their chocolate. According to the Belgian Chocolate Code, a measure introduced by the
Royal Belgian Association of the Biscuit, Chocolate, Pralines and Confectionary (abbreviated
Choprabisco) industry and agreed on by most major chocolate makers, products labeled as
“Belgian chocolate” must be re!ned and molded in Belgium. However, the grinding of beans
and production of chocolate liquor, cocoa powder, and cocoa butter may occur elsewhere.
To produce industrial chocolate, manufacturers mix chocolate liquor with sugar and varying
amounts of cocoa butter, depending on the type of chocolate (Table 2). Since 2000, the
European Union has allowed chocolate makers to substitute up to 5% of the cocoa butter in
their chocolate with other vegetable fats such as palm oil or shea butter. However, Belgian
chocolate makers pride themselves on using 100% cocoa butter, which enhances the quality
and smoothness of the chocolate, says Bram Beheydt, research and development manager
at Belcolade, in Erembodegem. Milk powder is added to milk and white chocolates. Lecithin
acts as an emulsi!er, producing a smoother chocolate.
Also crucial to obtaining the typical smooth Belgian chocolate is the re!ning step, in which
sugar and cocoa particles are ground down to a size of 18–20 µm. “In Belgium, we’re very
sensitive to having a !ne chocolate—you will never have a grainy feeling in your mouth after
eating our chocolate,” says Beheydt. In contrast, chocolate factories in many other countries
consider particle sizes of 25–30 µm to be acceptable. “The secret is making the size of the
particles smaller than the distance between the papillae of the tongue, so that when you eat
a chocolate you cannot feel the particles on your tongue,” says De Vuyst. The papillae are
the tiny bumps on the surface of the tongue that contain the taste buds. On the other hand,
particles must not be ground too small, or they will produce a dry feeling in the mouth.
The precise conditions for the next step in chocolate making, known as conching, are a
carefully guarded secret at most Belgian chocolate companies. In the conching stage, a
shearing device heats and thoroughly mixes chocolate for up to 78 hours. Unwanted "avors,
such as the acetic acid produced during the cocoa fermentation stage, are removed by
evaporation. Chocolate passes through three phases during the conching stage: dry, pasty,
and liquid. “Belgian chocolate has become famous by the optimization of conching to drive
o# "avors we don’t want in the !nal chocolate,” says Adriaenssens. “The balance between
dry and liquid conching develops the particular caramelized "avor of a good Belgian
chocolate.”
Di#erent conching procedures help distinguish the typical "avors of Belgian chocolate from
those of its major competitor, Swiss chocolate. “Swiss milk chocolate is conched very liquid
—they use almost no dry conching,” notes Adriaenssens. “That’s what makes Swiss
chocolate milkier, less caramelized, and with a di#erent body than Belgian chocolate.”
After conching, the chocolate is !nally ready to be solidi!ed into its !nal form, such as
chocolate bars or chips. But to achieve chocolate that melts in the mouth and has a smooth,
glossy !nish, a crisp snap, and a long shelf life, chocolate makers must heat and cool the
chocolate in a process known as tempering. At the microstructural level, chocolate consists
of particles of sugar and cocoa solids embedded in a cocoa butter matrix. The cocoa butter
can exist in six di#erent crystal forms, designated by the Roman numerals I–VI. Each crystal
form has a di#erent melting temperature. Tempering forces the cocoa butter to adopt form
V, which has the optimal melting temperature of 34–36°C. As a result, form V crystals remain
solid at room temperature but melt in the mouth.
Tempering conditions depend on the type of chocolate, tempering equipment, and
application, but in general the process involves cooling liquid chocolate from 45–50°C to
about 25°C while stirring, bumping the temperature up to 30¬–32°C, and then cooling to the
temperature at which the chocolate is poured into a mold and solidi!ed. The !rst cooling
step initiates mass crystallization of the cocoa butter. Then, by raising the temperature
slightly, the less stable crystal forms melt, leaving primarily form V crystals. In the !nal
cooling step, the form V crystals act as seeds or templates to drive further form V
crystallization. As a result, the molded chocolate will consist mainly of form V crystals, which
confer the desired textural and melting properties.
The fine art of pralines
After this lengthy processing from farm to factory, Belgian chocolate is !nally ready to be
packaged and sold. Belgian chocolatiers purchase chocolate bars and other products from
industrial manufacturers such as Belcolade and Barry Callebaut, melt the chocolate, and
retemper it. Then, they form it into pralines or other chocolates in a variety of shapes, from
simple squares to hearts, seashells, and birds.
Chocolatiers continue to re!ne the art of making pralines, the Belgian specialty. The two
classic methods for praline production are molding and enrobing. In molding, chocolatiers
use a mold to create a hollow chocolate shell, insert a soft !lling through an opening in the
shell, and then cover the opening with a layer of chocolate. Although some chocolate
makers continue to produce their molded pralines by hand, modern “one-shot processing”
machines enable the simultaneous extrusion of the chocolate mass and !lling into the mold.
However, the !lling must be viscous enough that it won’t mix with the chocolate shell during
cooling. Praline manufacturers can temporarily increase the !lling viscosity during
processing by adding pregelatinized starch and malt extract to the !lling. The starch
thickens the !lling during molding, whereas the malt extract contains starch-cleaving
enzymes that make the !lling more liquid during storage.
Enrobing is typically used for !rmer !llings. In this method, a slab of !lling is dipped in
melted chocolate, coating the !lling. Enrobing machines exist, but some artisan chocolate
makers still prefer to enrobe their chocolates by hand. Although time-consuming,
handmade Belgian chocolates fetch a premium price. Also contributing to a high-quality
praline is the use of couverature chocolate for molding and enrobing. Couverture chocolate
contains a higher percentage of cocoa butter (32–39%) than regular chocolate and is thus
shinier, snaps more !rmly when broken, and has a mellow, creamy "avor.
Praline !llings have evolved considerably since Neuhaus’ !rst simple creams, nougats, and
ganaches. Traditional favorites such as caramels and hazelnut creams remain popular, but
they have been joined by a dazzling array of "avors ranging from the expected (fruit, co#ee,
and "ower essences) to the exotic (chili peppers, tomato-basil, and wasabi). Indeed, as a
counterpoint to the traditionally sweet praline !llings, savory !llings with "avors of cheese,
tomato, wine, even goose liver and seafood, are gaining popularity among praline-savvy
Belgians.
Yet for many Belgian praline makers, the "avor of the chocolate itself remains the
paramount consideration. Such is the case for Geert Decoster, artisan chocolatier and owner
of Centho Chocolates in the village of Duisburg, near Brussels (Fig. 1).
Twelve years ago, Decoster was among the !rst to embrace an up-and-coming trend in the
chocolate world: making chocolates with cocoa beans from one region, or sometimes even
one plantation. Such “single-origin” chocolate has subtle "avors that re"ect the unique
cocoa tree variety and growing conditions of that particular region. In contrast, most
industrial chocolate contains a mixture of beans, typically from countries in West Africa.
Blending beans from di#erent geographical regions ensures taste consistency and
compensates for a bad growing season in any one region.
However, Decoster believes that blending sacri!ces the unique character of cocoa beans
from di#erent regions. For example, Ecuadorian beans produce a fruitier-tasting chocolate,
whereas beans from Papua New Guinea confer hints of mushroom and tobacco "avors.
Decoster enjoys concocting praline !llings that perfectly complement the "avor of each
origin chocolate. “The chocolate from Vanuatu, with hints of licorice and cinnamon, pairs
well with a !lling of good Scotch whiskey and pear jam,” he explains. Other tempting pralines
from Centho’s large assortment include spicy Peruvian chocolate paired with a violet and
raspberry !lling, and earthy Ugandan chocolate
harmonized with wild Tuscan fennel "owers and blood
oranges.
For Decoster, chocolate making is a family a#air. His
business name, “Centho,” comes from the !rst three
letters of his children’s names: daughter Centa and son
Thomas. His small factory has only two employees, in
addition to him and his wife, Els, who manages the retail
shop. Nevertheless, Centho pralines have made their way
into some of the !nest restaurants and hotels in Europe,
including London’s Ritz and Savoy hotels. “The reason we
supply all the beautiful restaurants is because after dinner,
there’s nothing as nice as a good praline,” says Decoster.
“And when you have a small praline like ours, you can
taste more than one.” At 8 g, Centho’s square-shaped
pralines are diminutive compared with many of their
competitors. “Here in Europe, the time of eating one big
chocolate and then having enough is going away,” he says.
“I see the young people loving a large assortment of
smaller pralines.”
In 2009, Decoster brought a sampling of his chocolates to the Summer Fancy Food Show in
New York City. “Everybody was crazy about our chocolates,” recalls Decoster. “Our
chocolates were completely new for them because in the States, people are used to a
bigger chocolate that is very sweet.” But even in Belgium, Centho chocolates are unique.
“Everyone has two or three single-origin chocolates in his assortment, but we’re the only
ones to have 40 di#erent types of single-origin chocolates,” he notes.
Decoster’s innovative approach is typical for a country not prepared to rest on its chocolate-
covered laurels. New technology now allows researchers to probe the science of chocolate
making, with the potential to dramatically improve quality and shelf life. In 2009, the
University of Ghent inaugurated the UGent Cacaolab, a small-scale experimental chocolate
and !llings production facility (Fig. 2).
According to AOCS member Koen Dewettinck, food scientist and director of the facility,
UGent Cacaolab researchers partner with industry to create innovative chocolate products,
improve chocolate-making processes, and stimulate the export potential of Belgian
chocolate. Current projects at UGent Cacaolab include e#orts to improve the microbial
resistance of water-based praline !llings, adjust the "ow behavior of chocolate, and develop
sugar-free dark chocolate. Another important focus of UGent Cacaolab is extending the
shelf life of Belgian pralines, which are susceptible to a phenomenon known as fat bloom.
This is a whitish-gray coating that forms on the surface of chocolate, typically after several
months’ storage. Fat bloom is unattractive and gives chocolate a waxy texture.
According to AOCS member Dérick Rousseau,
food chemist at Ryerson University in Toronto,
Canada, fat bloom in chocolate occurs for three
main reasons: improper tempering, temperature
"uctuations during storage or in the hands of the
consumer, and the migration of fats from a
praline’s !lling through its chocolate shell. At the
microstructural level, fat bloom is associated with
the transformation of form V crystals of cocoa
butter into the undesirable, but more stable, form
VI crystals.
“Regardless of how well you temper your
chocolate, eventually the chocolate will transform
to form VI because it’s the most stable,” says Rousseau. However, the consumer can hasten
this process by subjecting the chocolate to temperature "uctuations, for example, storing
chocolate in the freezer or moving it from an air-conditioned store to a hot car.
Rousseau has used scanning electron microscopy to show that the needle-like fat bloom
crystals can grow from imperfections on the surface of the chocolate (
Soft Matter
2008, DOI
10.1039/b718066g). This observation led Rousseau to hypothesize that channels in the
chocolate serve as conduits for lower-melting triglycerides to rise to the surface of the
chocolate and recrystallize, primarily into form VI. Therefore, minimizing surface
imperfections on chocolate may help control fat bloom, he says.
Pralines are more susceptible to fat bloom than un!lled chocolates because their !llings
often contain higher concentrations of speci!c triglycerides than their chocolate shell. As a
result, these fats di#use to the chocolate surface, transforming into form VI crystals.
Because fat bloom is a major impediment to long-term storage, and thus export, of Belgian
pralines, the UGent Cacaolab is working to produce fat bloom-resistant chocolates.
The early results are promising. Dewettinck’s group found that storing pralines at a cold
temperature (4ºC or –20ºC) immediately after production decreased oil migration and fat
bloom during later storage at a higher temperature (
Eur. J. Lipid Sci. Technol
. 2009, DOI
10.1002/ejlt.200800179). Cold storage therefore may cause favorable fat crystallization that
leads to permanent microstructural changes.
Thus, the secrets of Belgian chocolate lie in a mix of quality ingredients, expert processing,
centuries-old tradition, and a willingness to embrace new technology. But the importance of
Belgians’ passion for chocolate cannot be underestimated. “Ever since I was a kid, I knew I
wanted to make chocolate,” says Decoster. “I’m always thinking of chocolate. My brains are
chocolate,” he jokes. Such dedication gives chocolate lovers the world over cause to
celebrate—and what better way than with a !ne Belgian chocolate?
