bioprocess:chocolate production A2Z

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CONTENT

INTRODUCTION

MATERIALS (INGREDIENTS)

METHODS

CURRENT USAGE AND DEVELOPMENT

SUGGESTION

REFERENCES

University Malaysia Kelantan 2009

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INTRODUCTION

The cocoa tree (Theobroma cacao) is a native of the dense tropical Amazon

forests, but wild varieties also occur from Mexico to Peru. The Mayas of Yucatan

and the Aztecs of Mexico cultivated cocoa long before its introduction to Europe, and

Montezuma, Emperor of the Aztecs, is stated to have consumed regularly a

preparation called “chocolate made by roasting and grinding the cocoa nibs, followed

by mashing with water, maize, anatto, chilli and spice flavours. The richness of this

mixture no doubt had some connection with the Aztec belief that the cocoa tree was

of divine origin and later led the Swedish botanist, Linnaeus, to give the name

“Theobroma” - Food of the Gods - to the genus including the cacao species. The

Aztecs also considered the drink to have aphrodisiac properties.

The genus Theobroma consists of some twenty-two species of small bushes

and trees. Theobroma cacao is the only one of commercial value and this species is

divided into two main groups:

Criollo

Forastero

There is a third group known as “Trinitario” which is basically a cross of the two.

95% of world production are used Forastero, but better quality is Criollo.

In Malaysia, the first cocoa planted area was found in Melacca in 1778.

Subsequently, the cocoa planting was started in a plotted area at Serdang Agriculture

Station and Silam Agriculture Research Center, Sabah. The earliest cocoa

commercialization started from 1853 to 1959 where cocoa types Amelonado was first

planted at Jerangau, Terengganu. The planted area was 403 hectarages.

Cocoa trial was further undertaken at Serdang, Cheras, Kuala Lipis and

Temerloh from 1936 to 1940. However, cocoa was only actively planted after World

War II. Cocoa officially came to Quoin Hill, Tawau, Sabah in 1960. From then on,

there was no turning back to cocoa fever.

Malaysia is the seventh largest supplier of chocolate in the world. In Malaysia,

the State of Sabah produces more than 70 per cent of the total production of cocoa

beans (1998 data).


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Fermentation of cocoa is important before it can be used or consumed. Cocoa

is the most important ingredient in manufacturing chocolate. Differences in microbial

activities between different heap fermentations can result in dried fermented cocoa

beans and chocolates with different flavour characteristics. Hence, fermentation

control may direct the flavour of chocolate.

MATERIALS


Cocoa tree

Inside of cocoa bean - nibs

Well fermented unroasted cocoa

beans

Cocoa bean in the pulp

Natural cocoa powder Butter cocoa

Molten chocolate

Fermented beans

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(INGREDIENT)

Main ingredient used in the chocolate making process is cocoa beans.

Spontaneous cocoa bean fermentation is characterized by succession of

microorganisms’ activities such as yeast, Lactic Acid Bacteria (LAB) etc. There are

different ingredients for different type of chocolate. The beans must be processed into

the raw ingredients needed for mixing chocolate: cocoa mass, cocoa butter, and cocoa

powder. Chocolate liquor is blended with the cocoa butter in varying quantities to

make different types of chocolate or couvertures.

The basic blends of ingredients for the various types of chocolate (in order of

highest quantity of cocoa liquor [pure chocolate] first), are as follows:

Dark chocolate: sugar, cocoa butter, cocoa liquor, and (sometimes) vanilla

Milk chocolate: sugar, cocoa butter, cocoa liquor, milk or milk powder, and

vanilla

White chocolate: sugar, cocoa butter, milk or milk powder, and vanilla

Some manufacturer added an emulsifying agent such as soy lecithin. Others

use (PGPR) an artificial emulsifier derived from castor oil that allows them to reduce

the amount of cocoa butter while maintaining the same mouthful.

We can say that different manufacturers develop their own "signature" blends

based on the above formulas, but varying proportions of the different constituents are

used.

Chocolate Products

Microorganisms are also used in the production of finished chocolate products. Alpha

amylase obtained from Aspergillus is used to hydrolyze starch for chocolate syrup and

invertase from Saccharomyces is used to hydrolyze sucrose in filling mixtures to

make soft-centered chocolate-covered candies.

METHODS


http://en.wikipedia.org/wiki/Mouthfeel

http://en.wikipedia.org/wiki/PGPR

http://en.wikipedia.org/wiki/Soy_lecithin

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Explanation of the flow chart above:


Cocoa pod harvested

The pulp and cocoa bean removed and rind discarded

Piled in heaps or placed in baskets, or fermented tanks

The pulp undergoes fermentation process

Drying in the sun or artificial heat

Fermented cocoa graded

Shipped or transported to manufacture of chocolate

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Cocoa pods are harvested and split open, cocoa beans with the adhering pulp

removed and the rind is discarded. Each seed consists of two cotyledons (the nib)

and a small embryo plant, all enclosed in a skin (the shell).

The beans are embedded in a pulp. When the pods are broken the beans and pulp

are sterile but they become contaminated with the variety of microorganisms from

the pods, labourers, hands, insects, vessels used for transport, etc.

Fermentation is carried out in a variety of ways but all depend on heaping a

quantity of raw fresh beans with their pulp and allowing micro-organisms to

ferment and to produce heat. Most beans are fermented in heaps. Better results are

obtained by the use of fermentation boxes which give more even fermentation.

Raw cocoa beans are fermented for about five days. While in this heap, the sticky

pulp becomes a turbid broth and the cacao seeds absorb flavors from the

surrounding broth.

Without the fermentation process there will not be any chocolate flavor. The seeds

undergo biochemical changes during this time. This process also known as

“sweating”. Sweating is important for the quality of the beans, which originally

have a strong bitter taste.

If sweating is interrupted, the resulting cocoa may be ruined; if underdone the

cocoa seed maintains a flavor similar to raw potatoes and becomes susceptible

to mildew.

During fermentation, flavour develops, bitterness subsides, and the seeds turn a

rich shade of brown. It is necessary to occasionally stir the beans to aerate and to

ensure that the beans initially on the outside of the heap are exposed to temperature

conditions prevailing in the interior.

The duration of the fermentation depends on the variety and is from 2 to more than

7 days. The length of the fermentation also affects the aroma, so if well-developed

aroma is wanted the beans are fermented for a longer time.

After fermentation the cocoa beans are dried. The beans are placed in shallow trays

to dry. In some growing areas, the beans are dried by being spread out in the sun

in layers a few centimeters thick. Sun drying trays may be movable on rails so that

they can be pushed under canopies. Where the weather is less sunny, artificial heat

are used.


http://en.wikipedia.org/wiki/Mildew

http://en.wikipedia.org/wiki/Potato

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There are numerous types of heater/dryer but an essential feature of all must be

that any smoky products of combustion do not come in contact with the beans

otherwise taints will appear in the final product.

Drying in the sun is preferable to drying by artificial means, as no extraneous

flavors such as smoke or oil are introduced which might otherwise taint the flavor.

Drying should take place slowly. If the beans are dried too quickly some of the

chemical reactions started in the fermentation process are not allowed to complete

their work and the beans are acidic with a bitter flavour. However, if the drying is

too slow, moulds and off-flavours can develop.

The beans are shuffled and trodden about (often using bare human feet) and

sometimes, during this process, red clay mixed with water is sprinkled over the

beans to obtain a finer color, polish, and protection against molds.

The coca is graded and dried cocoa beans are bagged and ready for shipment or

sale to chocolate manufacturing companies.


http://en.wikipedia.org/wiki/Water

http://en.wikipedia.org/wiki/Clay

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PROCESS TAKING PLACE DURING FERMENTATION:

In the first stage of fermentation, the wild yeasts rapidly multiply in the sweet,

fruity pulp, converting the pulp's sugar into alcohol. This initial phase takes place

in the absence of oxygen - hence, it is known as anaerobic fermentation. The yeast

population peaks within 24 hours.

The yeasts found during cocoa fermentation come from the surrounding

environment, for example, soil, trees etc. The species most frequently found at this

stage are the Saccharomyces spp (in particular S. cerevisiae, Candida krusei,

Kloeckera apiculata, Pichia fermentans, Hansenula anomola and

Schizosaccharomyces pombe )

In addition to producing ethyl alcohol, the yeasts hydrolyze the pectin that covers

the seeds. S. cerevisiae decreases the bitterness of the final product. Without

pectin, the bitter alkaloids may leach out of the seed or be altered by alcohol that

can now enter the seeds.

After the yeasts have done their work, the yeast are killed by the alcohol they

produce and on the other hand, bacteria (lactic acid bacteria such

as Lactobacillus and Streptococcus) begin to take over the fermentation process,

converting the alcohol into acid. This acid slowly penetrates the bean.

The bacterial phase of fermentation takes place in the presence of oxygen - hence,

it is known as aerobic fermentation. The presence of oxygen and the lower pH

now favor the growth of acetic acid bacteria, Acetobacter and Gluconobacter.

This phase requires a significant amount of oxygen, so the beans are typically

turned at least twice during the fermentation process, to allow oxygen into the

heap, and to ensure that all of the beans are fermented evenly. Typically, the beans

are turned at about 48 and 72 hours after fermentation begins.

The bacteria population peaks roughly 72 hours after fermentation first begins, and

decreases rapidly over the following 72 hours. Hence, the entire fermentation

process typically takes about 144 hours (six days).

Phase 1 of cocoa fermentation (anaerobic): sugar + yeast alcohol + carbon dioxide + heat

Phase 2 of cocoa fermentation (aerobic): alcohol + bacteria + oxygen acid + water + heat


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As well as producing alcohol and acid, the fermentation process also generates heat

which is trapped by the cover on the heap, typically raising the temperature of the

fermenting beans to about 45 to 50 0C (113 to 122 F).

The acid and heat generated by the fermentation kills the cocoa bean (plant embryo).

In turn, the bean's death causes cell walls within the bean to break down, allowing

enzymes to come into contact with their substrates. . These enzymes bring about

some very important chemical changes within the bean.

There are three major changes happen inside the cocoa bean during fermentation:

I. Acid penetrates the bean. The acid kills the bean, lowers its pH, and produces a

sour, acidic taste.

II. Bitter and astringent flavonoids are converted into milder-tasting substances.

III. Aroma precursors are produced. These aroma precursors are transformed into

aromas during roasting.

Explanations of the major changes:

I. Acid penetrates the bean

As previously mentioned; some of the acid which is produced by bacteria during the

second phase of fermentation penetrates the bean. This acid is primarily acetic acid: the

same acid that gives vinegar its sour taste. Most of this acid is later evaporated out of

the bean, during drying and conching. However, a moderate amount of residual acidity

can lend a desirable, fruity complexity to cocoa.

II. Bitter and astringent flavonoids are converted into milder-tasting substances

Freshly harvested cocoa beans are extremely bitter, astringent, and unpalatable. This

unpleasant bitterness is primarily due to high levels of water-soluble flavonoids (a.k.a

antioxidants) in the bean. During fermentation, these flavonoids undergo a complex

series of chemical transformations. For example:

Some flavonoids combine with other flavonoids to produce larger molecules

known as condensed tannins, or proanthocyanidins. This process is very similar to

the mellowing process that fine red wine undergoes as it ages. Incidentally,


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proanthocyanidins are a category of antioxidants that are widely believed to be

very good for you (this is why the media often hypes chocolate as a "health

food").

In a multi-step process, some flavonoids oxidise and condense, producing the

classic chocolate brown pigmentation in cocoa. This process is known generically

as enzymatic browning.

During cocoa fermentation, flavonoids combine with each other, and with proteins

and amino acids, in myriad ways - not all of which are perfectly understood by

science.

For example:

anthocyanin [purple] + glucosidase enzymes anthocyanidin [purple] + sugar

anthocyanidin [purple] + polyphenol oxidase enzymes + oxygen quinone

[yellow]

quinones [yellow] + other flavonoids + amino acids condensed tannins

condensed tannins + proteins melanin [brown, water insoluble pigment]

Changing colour of the cocoa bean;

Freshly harvested cocoa beans range in colour from white to dark purple.

If the flesh of an unroasted cocoa bean is brown, then it has undergone enzymatic

browning.

If cocoa beans are dried without first being fermented, they become a slaty grey

colour. (So-called slaty beans are considered to be defective under international

standards.)

Under-fermented beans remain bright purple. Purple beans are much more bitter

and astringent, and have fewer aroma precursors, than fully fermented beans.

III. Aroma precursor development.

Freshly harvested cocoa beans taste nothing like chocolate. The bulk of the chocolate


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flavour-production happens during roasting, when a chemical reaction known as

the Maillard reaction takes place.

The Maillard reaction is a reaction between so-called "aroma precursors" - namely,

amino acids and reducing sugars. When cocoa is roasted, the aroma precursors

combine in different ways to create dozens of different flavor compounds.

These all-important aroma precursors are produced during fermentation as a result of

enzyme activity.

For example:

Protease enzymes break proteins down into peptides and amino acids.

Invertase enzymes break sucrose down into fructose and glucose. Fructose and

glucose are known as "reducing sugars"

After fermentation, the cocoa beans are dried and as they dry, molds including

Geotrichium grow. Geotrichium oxidizes the lactic acid to acetic acid and succinic

acid. Drying reduces the moisture content in the bean from about 55% to about 7%.

With a moisture content of 7%, cocoa beans can keep for many years (in ideal storage

conditions).

Off-tastes result when Bacillus and filamentous fungi,

including Aspergillus,Penicillium, and Mucor, hydrolyze lipids in the beans to

produce short-chain fatty acids. As the pH approaches 7, Pseudomonas, Enterobacter,

or Escherichia may grow and produce odors and off-tastes.

EXAMPLE OF FLOW DIAGRAM OF COCOA PROCESS


http://en.wikipedia.org/wiki/Reducing_sugar

http://en.wikipedia.org/wiki/Maillard_reaction

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Before cocoa can be made into chocolate, it goes through several steps of processing.

Cocoa processing includes converting the beans into nibs, liquor, butter, cake and

powder. It is as below:

Cleaning


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After receiving the raw fermented cocoa, the cocoa beans are cleaned to remove all

extraneous material such as bean clusters and other large pieces using rocking and

vibratory sieves; light material like dust, loose shell and fibre using a gentle

upward air stream; iron particles using a magnetic separator and stones and heavy

material using a fluidised bed with air aspiration to lift the coca beans.

Once the beans are cleaned, the processor has the option of roasting them before or

after the shell is removed. The inside of the cocoa bean is called the nib.

Generally chocolate manufacturers prefer to roast the beans before shelling them,

while cocoa processors favor the nib-roasting process. It may also be necessary to

grade the coca beans according to size to ensure even roasting.

Roasting the whole bean allows for more variety in the degree of roast and

development of flavor, but requires beans of a uniform size, while nib roasting is

more even and does not require uniform bean size. Roasting the nib directly also

prevents migration of cocoa butter from the bean into the shell, which is discarded.

Once the beans have been shelled and roasted (or roasted and shelled, as the case

may be), the nib is ground into a paste. The heat generated by this process causes the

cocoa butter in the nib to melt, earning it the name “cocoa liquor.” The paste, further

refined, may be sold as unsweetened baking chocolate.

Winnowing

A winnowing machine is used to remove the shells from the beans to leave just the

cocoa nibs. This process is done either before the roasting or after the roasting.

According to the diagram it is done before roasting.

All cocoa products start with cocoa liquor, although the liquor required in the

manufacture of chocolate has a different texture from the liquor required to make

cocoa butter, cake and powder.

Chocolate liquor destined for processing into cocoa butter and cake is refined to a

very small particle size, while chocolate liquor for chocolate production need not

be as finely ground.

roasting


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Cocoa beans roasted in large, rotating cylinder. Roast the beans at 121°C. Roasting

kills most of these microbes although some species of Bacillus may survive the

roasting process.

The roasting process determines the desired cocoa aroma as well as colour. The

shell of the bean comes loose from the kernel during roasting and the heat of

roasting removes any bacteria in the bean.

Roasting the cocoa bean is a critical step, with time and temperature the most

important elements as well as the degree of moisture involved in roasting depend on

the type of beans used and the sort of chocolate or product required from the process.

(Optional) the cocoa nibs undergo alkalization, usually with potassium carbonate, to

develop the flavour and colour. (Dutch process )

Milling

The nibs are then milled to create cocoa liquor (cocoa particles suspended in cocoa

butter). The temperature and degree of milling varies according to the type of nib used

and the product required.

Manufacturers generally use more than one type of bean in their products and

therefore the different beans have to be blended together to the required formula.

Cocoa mass

The cocoa liquor is pressed to extract the cocoa butter leaving a solid mass called

cocoa presscake. The amount of butter extracted from the liquor is controlled by the

manufacturer to produce presscake with different proportions of fat.

The processing now takes two different directions:

The cocoa butter is used in the manufacture of chocolate.

The cocoa presscake is broken into small pieces to form kibbled presscake which is

then pulverized to form cocoa powder.

Cocoa liquor is used to produce chocolate through the addition of cocoa butter.

Other ingredients such as sugar, milk, emulsifying agents and cocoa butter

equivalents are also added and mixed. The proportions of the different ingredients

depend on the type of chocolate being made.

The mixture then undergoes a refining process by travelling through a series of rollers

until a smooth paste is formed. Refining improves the texture of the chocolate.

The next process, conching, further develops flavour and texture. Conching is a

kneading or smoothing process. The speed, duration and temperature of the kneading


http://en.wikipedia.org/wiki/Dutch_process_chocolate

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affect the flavour. An alternative to conching is an emulsifying process using a

machine that works like an egg beater.

The mixture is then tempered or passed through a heating, cooling and reheating

process. This prevents discolouration and fat bloom in the product by preventing

certain crystalline formations of cocoa butter developing.

The mixture is then put into moulds or used for enrobing fillings and cooled in a

cooling chamber.

CURRENT USAGE AND DEVELOPMENT

Current usage


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Cocoa beans are also processed to produce various medicines, skin care products,

chocolate and other foodstuffs.

Cocoa used in producing various type of chocolate product. It can be drinks or

foods-snacks, chocolate bar, cakes, syrups, candy.

Increasing demand on organic cocoa.

Current development

Some cocoa countries distill alcoholic spirits using the liquefied pulp.

In effort to obtain consistent and high quality flavour, researchers investigating

how to improve and search for better technique.

Microbiologists also examining the roles of each microbe in the fermentation, in

order to find better method of fermentating with wild-type microorganisms.

Biochemists and food scientists are also studying the chemicals responsible for the

chocolate flavour.

Efforts to diversify cropping patterns and improve production are done.

Effort to increase the functional nutrient in the cocoa product.

Current study shows, the aromatic plup of two tropical fruit species (Theobroma

grandiflorum and Anona muricata) that added to Amelonado cocoa beans during

fermentation process to futher assess the possible effect of the cocoa bean flavour

environment on the flavour attributes of cocoa nibs and of chocolate.

There are significant variations among cocoa genotypes and significant parent off-

spring correlations for cocoa flavour astringency, fruity flavour and viscosity.

Unpublished experiment undertaken in Brazil carried out in 1998 have shown that

depulped cocoa beans, when fermented within a mass of cupuacu (thobroma

grandiflorum) pulped and beans, are capable of absorbing flavour s from the

cupuacu pulp (Smilja Lambert pers. Com 2008)

In recent years, cacao growers have turned increasingly to hybridization as a means

of improving the quality of the bean and making it more disease resistant.

Scientists using state-of-the-art biotechnology techniques are trying to improve the

quality of cacao and its resistance to disease.

The presence of a brilliant shiny surface which is achieved by the addition of extra

cocoa butter.

Suggestion


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To optimize the fermentation process, few variety of appropriate species should

used as starter cultures

Quantitative information of microorganism species associated with the

fermentation, and quantitative information on the growth profiles of individual

species throughout the process is lacking. These data are necessary to determine

which microorganism’s species are important to the fermentation. More research

must be done.

Produce more variety of cocoa species through hybridizations, currently only have

three main varieties of cacao: Forastero, Criollo, and Trinitario.

Consider genetic engineering to modify desired features.

Vary the technique of fermentation in term of duration, temperature,

contamination involved, population dynamic, and microorganisms involved.

Increase the variety of flavour by mix with other product as well like fruits.

Improve the technology of producing cocoa.

Produce chocolate with different shapes. This will attracts more people to buy

chocolate.


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References

1) Beckett, S.T., Industrial chocolate manufacture and use. 2nd edition.

Blackie/Chapman & Hall, 1994

2) International Cocoa Organization (ICCO) - http//www.icco.org/about/process.aspx

3) World Cocoa Foundation – http//www.worldcocoafoundation.org/how_we_do/

4) Cocoa – http//www.absoluteastronomy.com/topics/Cocoa

5) Christine L. Case, Ed.D.-Biology Professor-Skyline College - The Microbiology of

Chocolate, - http//www.smccd.edu/accounts/case/biol240.html

6) Cocoa fermentation 101 – http//www.thechocolatelife.com/

7) Opportunities for fermented food products in developing countries- food_chain_23pdf

- http//www.oneworld.org/itdg


http://www.worldcocoafoundation.org/

http://www.icco.org/

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bioprocess:chocolate production A2Z