http://www.aquimicadascoisas.org/en/?episodio=the-chemistry-of-chocolate
The Chemistry of Chocolate
Some of the most sublime pleasures we have in life exist only thanks to
chemistry! To prove it, today we speak of chocolate!
The chocolate we eat today is the result of a long process of discovery,
experience and innovation. Over the next few minutes, we’ll learn about
some important steps that make it so delicious
!
You may not know this, but the cacao bean that is harvested from the fruit is
far from having the aroma and flavour we associate with chocolate.
The first essential process for the formation of the substances responsible
for cocoa flavour is the fermentation of these seeds, which involves several
chemical reactions. What is important to remember is that it’s during this
process that the seed’s storage protein begins to be broken down into its
constituent amino acids.
The next step is roasting, which allows for the evaporation of water and also
of some compounds of the cocoa beans with unpleasant smell and taste.
But the real beauty of roasting is the chemical cascade of reactions that
occur between the amino acids formed in fermentation and the sugars in the
grain. Such reactions lead to the compounds responsible for flavour and
taste of chocolate (aldehydes, esters, ketones, furans)) and also form the
compounds which give the brown colour to the grain! Chocolate brown!
Before we can enjoy the delights of chocolate, there is still one last step:
crystallization. The main responsible for the texture of chocolate, cocoa
butter, can crystallize in six different ways, a property known as
polymorphism.
Polymorphism is a different arrangement of molecules to form a solid state.
But various physical properties such as colour, brightness and melting
temperature result of this arrangement. Of the six possible forms of
polymorphism for chocolate, only one has the features that consumers
appreciate: it has a silky surface, a smooth texture and it melts on the
tongue.
Unfortunately, this tastier form is not the most stable one. And the ultimate
challenge for chocolate makers is to ensure that all the chocolate crystallizes
in the right way. This can only be achieved through a cycle of heating and
cooling with carefully controlled temperatures.
If you leave your chocolate in the heat it will lose its special features and be
insipid and difficult to melt in the mouth.
Keep your chocolate at the right temperature, to avoid wasting the pleasures
of chemistry!
http://www.mce.k12tn.net/chocolate/made/made.htm
The first cacao trees grew wild in the Amazon basins in north Brazil. Today cacao is
cultivated in tropical climates. The cacao tree likes climates within 10 to 20 degrees of
the Equator. The trees need warm, humid weather and loose rich soil. They also like
shaded sunlight with little or no wind. The largest growers of the cacao tree are Brazil,
Ghana, the Ivory Coast, and Nigeria.
20 to 60 cacao
beans are
inside the pod
Three main varieties of cacao beans are grown today. The criollo
bean is a native of Central America. Approximately 10 to 15
percent of the cacao trees are criollo. These trees are small and
hard to grow. The forastero cacao is much easier to grow and
makes of 70 percent of all the cacao grown. The forastero is more
bitter than the criollo. The third type of cacao bean is the trinitario. It
is a cross between the criollo and the forastero. About twenty
percent of the cacao beans produced are forastero.
Three main varieties of cacao beans are grown today. The criollo bean is a native of
Central America. Approximately 10 to 15 percent of the cacao trees are criollo. These
trees are small and hard to grow. The forastero cacao is much easier to grow and
makes of 70 percent of all the cacao grown. The forastero is more bitter than the criollo.
The third type of cacao bean is the trinitario. It is a cross between the criollo and the
forastero. About twenty percent of the cacao beans produced are forastero.
Although cacao trees grow about sixty feet in the wild, plantation owners trim them to
about 20 feet so that workers can reach the pods at harvest time. Since the cacao tree
prefers shade banana trees, rubber trees, or coconut palms are planted beside the
cacao tree in the orchard.
The pods take five to six months to develop. When the pods ripen they turn from green
or yellow to orange or red. Cacao trees can be harvested twice a year. Workers use a
machete to cut the pods off the trees. They are placed on banana leaves in large
wooden boxes. They are left to ferment for several days. Criollo beans usually ferment
for two to three days while forastero and trinitario beans fervent three to seven days.
During fermentation the beans become darker and wrinkled and lose their bitter taste.
After fermentation the beans are sun-dried for several days. They are then packed in
burlap sacks and shipped to factories. When the beans arrive at the chocolate factory
they are sorted and cleaned. The beans are roasted at 250 to 350° degrees for thirty
minutes to two hours depending on the type of bean. They are roasted in large revolving
drums. The cacao beans give off a wonderful aroma during the roasting process.
After roasting the beans are winnowed. This is the process that removes the outer shell.
The shells are sold as animal feed. The inner nib is then crushed then heated to melt
the cocoa butter and ground to a thick paste. This paste is called chocolate liquor, but
contains no alcohol.
If the nibs are to become Dutch-processed cocoa they are treated with an alkali. If left
untreated with alkali the chocolate liquor becomes cocoa powder. To make cocoa
power a large press extracts all but 10 to 25 percent the cocoa butter from the chocolate
liquor. The remaining cake is then ground and sifted through fine nylon, silk, or wire
mesh. Low fat cocoa contains between 10 to 13 percent fat where high-fat contains 15
to 25 percent. Low-fat cocoa is usually used for cocoa drinks. The high-fat cocoa is
used to flavor desserts.
To make unsweetened or "baking" chocolate the chocolate liquor is molded and
solidified. Dark chocolate is made by combining chocolate liquor with sugar, cocoa
butter, and vanilla. To make milk chocolate chocolate liquor is combined with cocoa
butter, sugar, and milk solids or powder. White chocolate is made without chocolate
liquor. It is the cocoa butter that gives it the chocolate flavor. Dipping chocolate is made
with more cocoa butter than regular eating chocolate.
Chocolate is mixed with .3 to .5 lecithin. This helps it mix more easily and makes the
chocolate smoother. Another type of chocolate is gianduia. It is a blend of chocolate and
roasted hazelnuts.
Once the ingredients are combined the chocolate mixture goes through a refining
process. It is kneaded between large steel rollers. This make the mixture smooth. Next
is it conched. During this process the liquid mixtures is heated and continuously mixed,
ground, and stirred. High quality chocolate is conched for several days and lower quality
chocolate are conched for onbly a few hours.
After conched the chocolate is tempered. This is the process that gradually raises then
lowers and raises the temperature to a set degrees. Now the chocolate is ready to be
molded into chocolate bars.
Science of Chocolate
http://guittard.com/in-the-kitchen/article/science-of-chocolate
MELTING POINT
When the chocolate begins to get warm, it will soften and then it will melt and become liquid. The softening point of
chocolate is about 85F and the melting point is about 93F
FAT CRYSTALLIZATION
Like many substances, the natural vegetable fat in cocoa beans – cocoa butter – will crystallize to form as solid as it
drops below its freezing point – about room temperature. The invisible molecules of natural cocoa butter fat in the
chocolate are arranged in a geometric pattern causing the chocolate to be a solid. When the pattern is properly
formed while making the chocolate, then the chocolate will be shiny, smooth and you can hear it snap when it breaks.
Learn more on how to temper chocolate.
FREEZING CHOCOLATE
Chocolate may be frozen but it must first be protected by wrapping with plastic wrap or waxed paper because when
the chocolate comes out of the freezer the package will get moisture on it like any frozen food, and it will be wet
which can make the chocolate sticky and not shiny.
http://www.cacaoweb.net/nutrition.html
Components of Chocolate
Fat
Cocoa beans contain approximately 50% fat. It is primarily comprised of two saturated fatty
acids (palmitic and stearic acids) and one mono-unsaturated acid (oleic acid). Cocoa butter and
chocolate do not raise blood cholesterol. However, when consuming milk chocolate or lower
grade chocolate where a part of the total fat content comes from milk fat or various other types of
fat, the cholesterol level might be adversely affected.
Sugar
The cacao bean contains quite a lot of carbohydrates, but most of it is starch, soluble dietary
fibers, and insoluble dietary fibers. A very small proportion is simple sugars. Sugar is added
during the manufacture of chocolate.
Antioxidants
Cocoa beans contain polyphenols (similar to those found in wine) with antioxidant properties
which are health beneficial. These compounds are called flavonoids and include catechins,
epicatechins, and procyandins. The antioxidant flavinoids are found in the nonfat portions of the
cocoa bean. The flavinoids also reduce the blood's ability to clot and thus reduces the risk of
stroke and heart attacks.
Theobromine
Theobromine is a very mild stimulant with a mild diuretic action (increases the production of
urine). Theobromine can be toxic to animals like dogs, cats, parrots and horses.
Caffeine
Cocoa beans contains a very low amount of caffeine, much less than found in coffee, tea and
cola drinks.
Phenylethylamine
Phenylethylamine is a slight antidepressant and stimulant similar to the body's own dopamine
and adrenaline.
Serotonine
Cocoa and chocolate can increase the level of serotonine in the brain. Serotonine levels are often
decreased in people with depression and in those experiencing PMS symptoms.
Essential minerals
Cocoa beans are rich in a number of essential minerals, including magnesium, calcium, iron,
zinc, copper, potassium and manganese.
Vitamins
A, B1, B2, B3, C, E and pantothenic acid.
Is chocolate fattening?
Yes, chocolate is fattening. Even dark chocolate contains a lot of calories because of the large
content of fat and sugar. The sugar content in chocolate is worse than the fat content regarding
negative effects on health.
http://www.cacaoweb.net/chocolate.html
Types of Chocolate
The main types of chocolate are white chocolate, milk chocolate, semisweet chocolate,
bittersweet chocolate and unsweetened chocolate. These types of chocolate may be produced
with ordinary cacao beans (mass-produced and cheap) or specialty cacao beans (aromatic and
expensive) or a mixture of these two types. The composition of the mixture, origin of cacao
beans, the treatment and roasting of beans, and the types and amounts of additives used will
significantly affect the flavor and the price of the final chocolate.
White chocolate
Chocolate made with cocoa butter, sugar, milk, emulsifier, vanilla and sometimes other
flavorings. It does not contain any non-fat ingredients from the cacao bean and has therefore an
off-white color. In some countries white chocolate cannot be called 'chocolate' because of the
low content of cocoa solids. It has a mild and pleasant flavor and can be used to make Chocolate
Mousse, Panna Cotta and other desserts.
Milk chocolate
Sweet chocolate which normally contains 10-20% cocoa solids (which includes cocoa and cocoa
butter) and more than 12% milk solids. It is seldom used for baking, except for cookies.
Dark chocolate
Sweetened chocolate with high content of cocoa solids and no or very little milk, it may contain
up to 12% milk solids. Dark chocolate can either be sweet, semi-sweet, bittersweet or
unsweetened. If a recipe specifies 'dark chocolate' you should first try semi-sweet dark chocolate.
Sweet dark chocolate
Similar to semi-sweet chocolate, it is not always possible to distinguish between the flavor of
sweet and semi-sweet chocolate. If a recipe asks for sweet dark chocolate you may also use
semi-sweet chocolate. Contains often 35-45% cocoa solids.
Semi-sweet chocolate
This is the classic dark baking chocolate which can be purchased in most grocery stores. It is
frequently used for cakes, cookies and brownies. Can be used instead of sweet dark chocolate. It
has a good, sweet flavor. Contains often 40-62% cocoa solids.
Bittersweet chocolate
A dark sweetened chocolate which must contain at least 35% cocoa solids. Good quality
bittersweet chocolate usually contains 60% to 85% cocoa solids depending on brand. If the
content of cocoa solids is high the content of sugar is low, giving a rich, intense and more or less
bitter chocolate flavor. Bittersweet chocolate is often used for baking/cooking. If a recipe
specifies bittersweet chocolate do not substitute with semi-sweet or sweet chocolate. Please
ensure that you buy the correct type! European types of bittersweet chocolate usually contains
very large amounts of cocoa solids, and some of them have quite bitter taste.
Unsweetened chocolate
A bitter chocolate which is only used for baking. The flavor is not good, so it is not suitable for
eating. Use it only if a recipe specifies 'unsweetened chocolate'. It contains almost 100% cocoa
solids, about half of it might be fat (cocoa butter).
Ingredients
http://www.thestoryofchocolate.com/What/ingredients.cfm?ItemNumber=3305
Chocolate is a natural product made of these ingredients:
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Chocolate Liquor: Cocoa beans with their shells removed that have been fermented, roasted
and ground until they liquefy. This liquid is made up of cocoa butter and cocoa solids; both
are naturally present in the bean.
Cocoa Butter: Natural fat from the cocoa bean; extra cocoa butter enhances chocolate’s
flavor and mouthfeel.
Sugar
Lecithin: An emulsifier, often made from soy, that makes the ingredients blend together.
Vanilla or vanillin and other flavors.
It also may include
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Milk: For milk chocolate.
Fruits, Nuts and other Add-ins: For specialty chocolates.
Kinds
The Basics:
There are three main kinds of chocolate:
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Dark Chocolate: The bare essentials.
Dark chocolate is simply chocolate liquor (the centers of cocoa beans ground to a liquid), extra
cocoa butter, sugar, an emulsifier (often lecithin) and vanilla or other flavorings. Dark chocolates
may contain milk fat to soften the texture, but they do not generally have a milky flavor.
Dark chocolate also is known as semi-sweet chocolate. Unsweetened chocolate, or baking chocolate,
is 100 percent chocolate liquor and is typically very bitter and astringent.
Darker chocolates often have a higher percent cacao, which means they have a higher proportion of
cocoa beans in them than other chocolates do. See more about percent cacao and how it affects a
chocolate’s taste.
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Milk Chocolate: All of the above, plus milk solids.
Surprisingly, sweet and creamy milk chocolate isn’t usually made with cold, frothy milk. It’s usually
made with dry milk solids, which look like powdered milk. Milk chocolate has at least 10 percent
cocoa liquor by weight, and at least 12 percent milk solids. It’s the most common kind of eating
chocolate.
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White Chocolate: Cocoa butter takes center stage.
White chocolate features cocoa butter—think milk chocolate minus the cocoa solids. In addition to
the cocoa butter, sugar, milk solids, lecithin and vanilla, white chocolate may contain other
flavorings. It has at least 20 percent cocoa butter, 14 percent milk solids, and no more than 55
percent sugar.
The Details
Want to know more? Here’s a quick guide to other terms you might see.
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Baking Chocolate: Chocolate liquor, served straight up, is
all that’s in baking chocolate. Its bitterness comes from
pure nibs, the finely ground centers of roasted cocoa
beans. Also called unsweetened chocolate, it has no sugar
and is used often in dessert recipes with sugar as a
separate ingredient. All other chocolate is called eating
chocolate.
Bittersweet Chocolate: The darkest of eating chocolate,
bittersweet has the highest percentage of chocolate liquor
and may contain extra cocoa butter. Both bittersweet and
semi-sweet chocolate must contain at least 35 percent
chocolate liquor, but bittersweet usually contains at least
50 percent cacao. Chocolates in this range are often
referred to as dark chocolate.
Cacao and % Cacao: Pronounced “kuh-KOW” or “kuh-KAY oh”, cacao represents the three ingredients derived from a
cocoa bean—chocolate liquor, extra cocoa butter and
cocoa powder. The % cacao refers to the total amount of
these ingredients contained, by weight, in the finished
product. See more about cacao percentages.
Chocolate-Flavored Coating: These coatings may contain
chocolate liquor and/or cocoa powder, but use vegetable fats to supplement or replace
cocoa butter. While often used to cover confectionery or ice cream products, they can be
molded into solid bars or shapes. While coatings made with vegetable fats cannot be called
“chocolate,” they may legally use the claim “made with chocolate” if they are made with
chocolate liquor, since U.S. regulations consider “chocolate” and “chocolate liquor” as
synonymous.
Chocolate Liquor: Grinding the nib, or center, of a cocoa bean into a smooth, liquid state
produces what’s called chocolate liquor—also called chocolate mass, cocoa mass, cacao
mass and cocoa paste. According to U.S. regulations, chocolate liquor may also be called
chocolate, unsweetened chocolate, baking chocolate, or bitter chocolate. An essential part of
dark and milk chocolate, this ingredient with the many names does not contain alcohol, or
vegetable fat.
Chocolate Mass: Another name for chocolate liquor (above).
Cocoa Beans: The source of all things chocolate, cocoa “beans” are actually seeds from the
fruit of Theobroma cacao, a tree native to the tropical Amazon forests that is now grown
commercially worldwide within 20 degrees latitude of the Equator. Approximately 20 to 40
seeds cluster inside football-shaped pods and are covered by sweet white fruit pulp.
Cocoa Butter: Cocoa butter is the fat naturally present in cocoa beans. It melts just below
body temperature, giving chocolate its unique mouthfeel. The nibs, or centers of the
cocoabeans, are 50 to 60 percent cocoa butter. There is no connection to dairy butter.
Cocoa or Cocoa Powder: Comes from pressing chocolate liquor, the liquid that comes from
grinding the nibs or centers of cocoa beans, to separate out of the cocoa butter. What’s left
are the chocolate solids, called press cake. The press cake is then ground, becoming the dry
cocoa powder used in hot cocoa mixes and baking. Under U.S. regulations, “cocoa” and
“cocoa powder” can be used interchangeably.
Cocoa Solids: Chocolate liquor without most of the cocoa butter—the ground nibs, or
centers of cocoa beans, with the cocoa butter pressed out. Cocoa solids, sometimes called
chocolate solids, often are ground into cocoa powder.
Dutch (or Dutched) Process: While being ground into chocolate liquor and pressed into
cocoa powder, nibs may be treated with an alkaline solution to neutralize acidity. This
process darkens the color of the cocoa and produces a milder chocolate flavor. When treated
cocoa is used in a food product, the terms “dutched” or “alkalized” are included on the
ingredient declaration for products sold in the U.S.
Nib: The nib is the center or meat of the cocoa bean. Roasted or unroasted cocoa beans are
cracked mechanically to break off the cocoa bean shells and expose the nibs. See more about
how chocolate is made.
Organic Chocolate: Chocolate grown without agricultural chemicals and meeting USDA
Organic requirements. See more about certifications.
Raw Chocolate: Raw chocolate is made from unroasted cocoa beans. See recommendations
on raw chocolate from the National Confectioners Association.
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Semisweet Chocolate: Like bittersweet chocolate, semisweet chocolate is required by U.S.
regulations to contain at least 35 percent chocolate liquor. Generally, semisweet chocolate
contains 35 to 45 percent chocolate liquor. Semisweet chocolate is often referred to as dark
chocolate.
Sweet Chocolate: Sweet chocolate is a combination of chocolate liquor, cocoa butter and
sugar containing at least 15 percent chocolate liquor.
Unsweetened Chocolate: The same as baking chocolate (above).
VISCOSITY
A fluid requires a certain force exerted against it before it will begin to flow and it requires a certain force to sustain
movement, once begun. The greater the force, the greater the viscosity. When a liquid is thick like honey it is called
viscous or it is said to have a high viscosity. By comparison, pancake syrup would be considered a lower viscosity
than honey. When working with chocolate, different viscosities are used and required for different in applications.