Lessons From Chocolate Processing

7/30/2019 Lessons From Chocolate Processing

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[ P R O C E S S I N G

b y J . P e t e r C l a r k

I

t seems seasonally appropriate to talk about

chocolate. Not only is there increasing recognition

of the potential health benefits of chocolate result-

ing from its high concentrat ion of phytochemicalsand antioxidants, but also manufacturers are

introducing new products with dark chocolate,

single-origin cocoa, fair-trade cocoa, and higher

concentrations of cocoa. Furthermore, cocoa

processing to make chocolate is one of the few

examples I know where there are multiple paths or

potential flowsheets, most of which are in use.

In processing generally and specifically in food

processing, there usually is one best way to accom-

plish some desired end. This is usually discovered

incrementally over time, and all manufacturers even-

tually arrive at the same conclusion. With regard to

chocolate, this is not the case. The other exampleof which I am aware is low-calorie beer, for which

there are at least seven processes, all of which

someone uses—that is a s tory for another time.

Chocolate is an old food, discovered first by

the Aztecs of Mexico and brought to Europe by the

Spaniards. Now cocoa beans are grown in many

tropical places, including Africa and South America.

Cost and quality can vary widely. Traditionally, cocoa

beans from several sources have been blended to

achieve a consistent flavor and to control costs.

Cocoa farmers tend to be small and poor and have

not always received a fair price for their crop.

Fair-trade cocoa refers to an effort to help producers

receive a higher return, responding to consumers’appreciation of the issue and their willingness

to pay a higher price for the final products.

Single-origin cocoa recognizes that consumers

can appreciate the subtle flavor differences among

beans grown in various areas, even among different

estates. An origin might be a region of the world,

a country, or a single farm, according to Richard

Benson, Director of Research & Development,

North America for Barry Callebaut, Chicago, Ill.

(phone 312-49 6-7300). Barry Callebaut is the largest

manufacturer of chocolate and has plants all over

the world. It manufactures a wide range of cocoa

and chocolate products mostly used as ingredients

by other food companies and in foodservice by

chefs. Benson says that his company trains about

500 chefs a week in the culinary use of chocolate.

One lesson, then, from chocolate is the potential

for market segmentation, as contrasted with the

more common objective of consistency in flavor.

Lessons fromChocolate Processing

Blending chocola

Photos courtesy of Barry Calleba

»»



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Chocolate Processing continued...

Steps in Processing

Chocolate flavor development begins

shortly af ter harvest. Cocoa beans

are found in a fleshy fruit that is

collected from trees about twicea year. The fruits are cut open and

the seeds spread in a thin layer on

the ground to ferment and dry in the

sun. As the fruit flesh disappears

and the seeds dry, their color

changes and their characteristic

aroma develops. The seeds are

typically packaged in 60-kg jute

bags and sold through cooperatives,government agencies, or directly

to manufacturers, depending on

the country and local practice.

Depending on whether a

single-origin or certified product

is being made or not, beans from

one or several sources are blended

according to a company’s recipe

before roasting. The cocoa beans

consist of a hard shell and a softer

nib on the inside. Beans can be

roasted before or after removing the

shell. There are advantages and dis-

advantages of each approach, giving

rise to one of the steps for which there are process alternatives.

If the shell is removed before

roasting, there is less loss of valu-

able cocoa butter. The roaster is also

used more efficiently, as only nibs

are handled. On the other hand, the

shell is easier to remove after roast-

ing. A compromise process heats

the whole beans to dry the shel l and

make it easier to remove, then the

nibs are roasted. This introduces

an additional piece of equipment.

After roasting, the nibs are

ground to a fine slurry such that the suspended part icles are too

small to be detected by the tongue.

Grinding may be on a multiple roll

refiner, in which up to five polished

steel rolls are mounted in a stack

very close together and the slurry

passes from one to another until the

desired particle size is achieved. The

suspended particles are cocoa, and

the liquid is cocoa butter, a unique

vegetable oil. Cocoa butter gives

chocolate one of its special sensory

properties, its ability to melt just atbody temperature, because it has a

sharp melting point of about 37°C.

The slurry is known as chocolate

liquor and is one component of

chocolate. Additional cocoa butter,

sugar, milk powder (for milk choco-

late), lecithin as an emulsifier, and

other flavors can be added to make a

final product. To get additional cocoabutter, chocolate liquor is filtered

under high pressure (because

of the fineness of the particles),

yielding cocoa powder as press

cake and cocoa butter as filtrate.

It is important to reduce the cocoa

butter content of the cocoa powder

as much as possible, because it

is the more valuable product, so

the press cake may be extracted

with solvent or it can be ground

up to yield a cocoa powder with a

residual fat level (say 10–24%) that

is appropriate for a final application.

The cocoa powder is an important product for making chocolate

drinks, compound coatings, confec-

tions, and other foods. The solubili ty

and color of cocoa powder can be

modified by the addition of a particu-

lar alkali to the cocoa liquor or to the

press cake, leading to another set of

alternative process options, namely,

use alkali (and which one) or not,

and add it at various points if used.

The chocolate mass then

undergoes a process unique to

chocolate, conching. This typically

occurs in a mix muller, a large vesselwith rotating mixing arms that

resembles a mixer/grinder. During

conching, heat is generated, which

helps to drive off some residual

moisture and volatile flavors. Almost

certainly, some chemical reactions

occur among the various compounds

present, including caramelization

of sugars, Maillard or browning

reactions between proteins and

sugars, and probably others. There

may be further size reduction.

Efforts have been made to signif-icantly shorten the time of conching

or to separate some of its functions,

such as evaporation, because

conching of high-quality chocolate

can take many hours and requires

some skill. So far as I know, most

such efforts have not succeeded.

Another lesson, one also seen in the

aging of cheese, wine, and whiskey,

is that some processes just cannot

be accelerated successfully. In the

case of chocolate, the high viscosity,

relatively low temperature, and mild

agitation means that the reactionswill occur slowly because diffusion

is so slow under these conditions.

At the end of conching, additional

cocoa butter is added to control

the final viscosit y of the chocolate,

depending on its intended use.

Chocolate is used in candy bars,

as an enrobing for ice cream, as a

coating for baked goods, as a sauce,

and as an ingredient. Barry Callebaut

and other chocolate companies

supply chocolate as liquid in bulk,

In food processing, there usually is one best way to accomplish

some desired end.…With regard to chocolate, this is not the case.

Molding chocolate bars



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CW Brabender

1/2 Horiz No Bleed

as slabs or blocks, as drops or small

pieces, and in other solid forms.

For most uses, chocolate mustbe tempered, which means heating

carefully to a high-enough tem-

perature to melt all forms of cocoa

butter, which can crystallize in t wo

forms, one of which is unstable and

can cause visual defects in candy.

Chocolate is then maintained at

the proper temperature in use by

circulating through double-walled

tubing heated by hot water. Storage

tanks are also double walled,

agitated slowly, and heated.

Uses for ChocolateA major use of chocolate is in con-

fections made by such companies as

Mars, Hershey, and Cadbury—the

three largest—and Werther, Lindt ,

and many others on a smaller scale.

The largest companies tend to make

their own chocolate from beans,

while smaller companies buy from

firms such as Barry Callebaut, Blom-

mer, and others. However, therehas been a growing trend for larger

companies to outsource their choco-

late supplies, allowing them to focus

resources and assets on their con-

sumer brands and their marketing,

according to Benson. Some of the

processes used by candy companies

include shell molding, enrobing,

panning (discussed in the Processing

column last month) and molding.

For less-expensive uses, such

as enrobing baked snack cakes or

cookies, compound coatings are

made by mixing cocoa powder,sugar, emulsifiers, and a compatible

vegetable fat that has melting

properties similar to those of cocoa

butter. Such fats are made by

partial hydrogenation or fractional

crystallization. In Europe, it is

permitted to add up to 5% of such

fats to chocolate, primarily as a cost

reduction, and still call the product

chocolate. There is a movement to allow this practice in the United

States, which is controversial.

Some manufacturers want to offer

their customers a choice and the

potential cost advantage, while

some users, such as Mars (which

is also a manufacturer), have

stated their opposition. Another

lesson might be that standards

of identity can be contentious.

Chocolate is not only one of

our favorite flavors, an important

article of international commerce,

and a healthy indulgence, butalso a fascinating subject of

complex processing. FT

J. Peter Clark , Contributing

Editor, Consultant to the Process

Industries, Oak Park, Ill.

• [email protected]

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Lessons From Chocolate Processing