Physics and Chocolate By year 12 Physicists

Believe it or not physics is involved in chocolate production. Without the careful use of temperature and pressure we wouldn’t have the wonderful confectionary that adults and children alike have grown to love.

On October 17th year 12 physics students went to the Chocolate Show to learn more about the production of chocolate.


The above images show sculptures made out of chocolate

Chocolate is produced from the ripe seed of the tropical Theobroma Cacao tree and was initially cultivated in Mexico, Central and South America.


The seeds naturally have an intense bitter taste so must be fermented to develop the flavour. After fermentation, the beans are dried and then roasted (requiring a high temperature). The shell is then removed to produce cacoa nibs which are then ground (high pressure) to produce cocoa mass (pure chocolate in rough form).

Cocoa mass is usually liquefied (high temperatures and/or pressure are used to form what is commonly called chocolate liquor) and then moulded with or without other ingredients to form many types of chocolate products such as milk chocolate.

Chocolate liquor may be processed into two components cocoa solids and cocoa butter, the latter being used for white chocolate.


The penultimate process of chocolate production is called conching. A conche is a container filled with metal beads, which acts as grinders to reduce the gritty and uneven texture of the chocolate. The refined and blended chocolate mass is kept in a liquid state by friction and heat. The length of the conching process determines the final smoothness and quality of the chocolate. High-quality chocolate is conched for about 72 hours. After the process is complete, the chocolate mass is stored in tanks heated to approximately 45-50 degrees Celsius until final processing.


The final process is called tempering which involves manipulating the temperature to produce the most stable crystals to provide the best appearance, texture and prevention of degradation.


Generally the chocolate is first heated to 45 degrees Celsius to melt all the crystals. It is then allowed to cool to about 27 degrees to allow crystal types IV and V to form. At this temperature, the chocolate has to be agitated to create many small crystal “seeds” which serve as nuclei to create small crystals in the chocolate. The chocolate is then heated to about 31 degrees Celsius to get rid of type IV crystals. This process can be done manually but most chocolate manufacturers use a tempering machine with computer controls to produce consistently tempered chocolate. The Greer temper meter can measure the degree of temper at any required time.


LCM coating machines come with continuous tempering and are equipped with level controls.


Ramz finding out about and tasting some chocolate


Of course once the chocolate has been produced this may not be the end of its processing. Chocolate is often use to decorate and cover other confectionary like cakes and for this it has to be able to flow. The flow characteristics (viscosity) are important; too runny (low viscosity) and the chocolate won’t “stick” to the cake and certain moulding and depositing machines will not work right; too thick (high viscosity) and the chocolate is difficult to pump from one part of the factory to another and the apparatus may get blocked, or more importantly the manufacturers will lose money by using too much chocolate. The viscosity of the chocolate has to be carefully controlled.

Chocolate viscosity is a physical property that is carefully monitored and tightly controlled within defined limits. It is measured in various ways with the most basic apparatus being the falling ball viscometer.

The Höppler principle is used to measure the viscosity of Newtonian liquid by measuring the time required for a ball to fall under gravity through a sample-filled tube that is inclined at an angle. The average time of three tests is taken; the result is converted into a viscosity value using a simple formula.


There are several factors that affect viscosity of chocolate. Increasing moisture and/or the particle size of the mixture will create higher viscosity. Conversely, increasing temperature and adding emulsifiers will tend to reduce viscosity.


A chocolate chef


More chocolate sculptures


Chocolate couture


Chocolate art


Abinayan, Milan, Alex and Karthikeyan about to learn how to make a chocolate torte – get your orders in for Christmas!!!!


Sambath and Kishok learning about (and eating) Lindt chocolate


Ahlaq, Ramz and Seyar after a little retail therapy


Vinnoja, Shefali, Karthikeyan and Sambath at the end of a very busy day. A lot of chocolate was bought (and eaten) that day.

Shelly Preston, an award winning chocolatier, gave a talk about how she became involved in the world of chocolate and what inspired her.

She originally worked as a product developer in the natural beauty and wellbeing industry and used ideas from this in her chocolates.


Chocolate by Alex Pregal 12I

We carried out a visit to “The Chocolate Show London” exhibition which was held on the 17th of October at Olympia West.

At the exhibition there were many chocolate making companies who had set up stalls and were selling chocolates. There were also various displays of chocolate sculptures and chocolate clothing worn by models on a catwalk.

Chocolate has been enjoyed as a drink for an extremely long time, with evidence showing that cacao beverages were drunk in Mexico as early as 1900 BC. Chocolates were not introduced to Europe until the 16th century, where Christopher Columbus and his son encountered the cacao bean when they seized a ship. Chocolate was only consumed as a drink until about 1847 where Joseph Fry discovered that you could make solid chocolate by adding back melted cacao butter.

Physics is important in the production of chocolate, because chocolatiers can use temperature to change the viscosity of liquid chocolate and therefore change its use. Lower temperatures make the liquid chocolate more viscous (thick) whilst higher temperatures make the liquid chocolate less viscous (more runny). The viscosity may need to be low if the chocolate has to set around a biscuit or sweet, or it may have to be more viscous if the chocolate has to be moulded.

Temperature is also utilised during the tempering of chocolate which can change its texture. This stage is where the chocolate mixture is repeatedly heated, rapidly cooled and then gently warmed again. This process causes the crystalline structure of the cocoa butter to change, eventually giving the perfect outcome of a glossy finish and a snap when breaking it. There are 6 types of crystal which the cocoa butter can take and these are listed below


As you can see, crystal type V gives the best type of chocolate, and is what chocolatiers strive for when making chocolates. To achieve this crystal, the chocolate has to be carefully monitored making sure the temperature is perfect.


The Chocolate Show 2014 by Abinayan Rasaratnam 12G

My report gives some information into how chocolate is made and what conditions are needed. In it you will also how physics principles such as temperature and viscosity can be utilised in the processes.

To help with my research, I went to “The Chocolate Show” at Olympia West Kensington on the 17th October 2014.

“The Chocolate show” was an amazing event, as it was a place for people, who love and enjoy chocolate. The show featured more than 50 types of chocolates from the world and at the show you could taste and buy your favourite brands. The exhibition also featured a cooking demonstration and a behind the scenes exhibition from the “Charlie and The Chocolate Factory” musical.

At the show it was hard to find out about the physics principles that are involved in the making of chocolate, as the chocolatiers were not physicists, but I did gain some information and supplemented this with research from books and the internet.

The physics terms that are involved with the making of chocolate are temperature and viscosity. Viscosity can be considered as a frictional force in a fluid.

The temperature plays a massive role, because as the temperature increases the viscosity of a liquid decreases. In order to produce the correct type of chocolate you need to control its temperature and therefore its viscosity. If you want to shape the chocolate you would need a high viscosity but if you want to cover a biscuit or a sweet you would need a low viscosity.

There are many problems that occur with the large scale production of chocolate, as it has an impact on the environment as well as people who work on the production.

Producing chocolate can affect the environment because high temperatures are required for the chocolate to have the correct viscosity. The processes can result in a large amount of greenhouse gases being released. Chocolate production is not an efficient process and this makes the prices of chocolate higher.

The social problems include the fact that some chocolate manufactures do not pay the people who grow the coca beans to make the chocolate a fair price for their cocoa beans. You should always buy fair trade chocolate.

Chocolate show report by Ahlaq Hyder 12V

The chocolate exhibition took place in Kensington Olympia (west), London. The point of the exhibition was simply for many chocolate companies to showcase their latest treats, and for the public to taste and ask questions about their products, from how it is sourced to how it’s made.

The reason for us, however, was to find out how physics can be related to the production of chocolate. We did this by talking to many of the people at stalls of various different companies and asking them about the production of their chocolate, mainly about the controlling of various temperatures and atmospheres throughout the production process of the items.

I talked to a few people and also managed to gather some leaflets, and looked online. These are my sources of information:

Elisa – Rococo Chocolates [1]

Arietta – TORTAPISTOCCHI – Firenze [2]

Jacob – Paul. A. Young Chocolates. [3]

Rainforest Foundation UK mini booklet [4]

Http:// [5]

[1] Elisa from Rococo Chocolates told me that for their signature truffle balls, the chocolate on the inside has to be kneaded at mixed at a steady temperature of 47°C and once the mass has been mixed well, it has to be stored at 45-59°C until it’s ready for final processing. Then the chocolate has to be tempered, this is because cocoa butter gives out an unstable crystal formation so the mass of chocolate must be cooled very carefully so to allow the crystals to stabilise in the right order to produce the right consistency, texture and look. To temper their chocolate, the chocolate is cooled in mini stages from 45°C to all the way to 26°C, then after that it is heated up again to 38°C, this will allow them to shape the truffles easier but also adds to the softness of their truffle balls.

[2][3] The viscosity of chocolate is very important; depending on what exactly is being made. For certain products, the viscosity of the chocolate being used has to be precise, and this can only be achieved by controlling specific temperatures during the manufacturing process. As the temperature of the chocolate increases, the viscosity of the chocolate decreases. [3] For the inner filling of most types of soft filling chocolates, the chocolate has to go under various changes of temperatures (heating and cooling) in order for it to reach the required viscosity; this can be a lengthy and time consuming process.

[4] The Rainforest Foundation UK has made it their priority to protect the rights of the indigenous people in the Peruvian amazon, which includes Ecuador, where many cocoa beans are sourced for the production of chocolate. They aim to protect the environment of the indigenous people and fulfil their rights to land, life and livelihood in the region.

In 2010 an association was formed in which cocoa is marketed under Organic and Fair trade certifications. This has allowed better standards if farming and cropping, improved prices and more secure market access to be implemented in the region and has enabled the locals to increase their income and wellbeing whilst respecting their culture and environment. With all of this improvement there have also been other additions, including a school to provide training on cocoa growing and harvesting techniques on sustainability and also a ‘management school’ which aids the association with cocoa marketing and financial management.

These locals primarily depends on the forest for their subsistence, the cocoa production there is the most important source for monetary income for them and all this money is needed in order for them to live well and provide themselves with the basic necessities, such as medicine, education, fuel, batteries, clothing and food so it has to be made sure the cocoa that is being farmed here, manufacturers have to pay fairly for them.

For an experiment involving the physics, we have to identify why as the temperature of a certain liquid substance increases, the viscosity decreases. This can be experimented using a thick substance, such as honey, and heating it to various different temperatures and then letting it slide down an angled surface, recording the time it takes to pass a specific point.

[5] The main reason why temperature affects the viscosity of a liquid is due to the fact that when the temperature is lowered, the kinetic energy of the liquid molecules also lowers. This in turn causes the molecules to somewhat tighten together – the force of attraction between them increases and thus this increased force increases the viscosity. This is the same the other way round – as temperature increases the kinetic energy of the molecules also increases, and the molecules separate out more.


Visit to the Chocolate Show by Vinooja Thurairethinam 12V


I visited The Chocolate Show at Olympia West in London on the 17th October 2014. This was a festive programme about chocolate with talks and tastings, exhibitions and workshops where people would be able to meet famous chocolatiers and chef. There were also live demonstrations of the making of chocolate and many chocolate stalls selling creatively made delicacies from all over the world.

It is mainly believed that chocolate originated in the Amazon area. Sources claim that the ancient Aztec and Mayans were the first to discover and make use of the cacao plant, from which cacao beans are processed into chocolate. Mayans and Aztecs took beans from the cacao plants and made a drink using them.


They learned how to roast and grind the cacao seeds, making a nourishing paste that could be dissolved in water. They added spices and called this drink “chocolatl” (meaning bitter water) and believed it brought wisdom and knowledge to the ones who drank it.

The first person to introduce cacao beans to people outside of the Amazon basin was Christopher Columbus, who brought back cacao beans to King Ferdinand. However, eating chocolate was only introduced in 1674 in the form of rolls and cakes.

Daniel Peter of Vevey, Switzerland, experimented for eight years before eventually finding a way to make milk chocolate for eating in 1876. He brought his creation to a Swiss firm that is the world’s largest producer of chocolate today: Nestle. A few years later, in 1879 Rodolphe Lindt of Berne, Switzerland, then produced chocolate that melted on the tongue. Before this invention, chocolate had a very coarse and grainy texture.

Physics can be very useful in changing the taste and texture of a chocolate product and ensure that it is relatively consistent from day to day.

In the making of chocolate it is crucial that liquid chocolate flows at speeds to match the needs of the process. The chocolate needs to flow at a rate that allows the correct thickness to fill a mould and to keep up the required rate of production. Ensuring the correct viscosity of the chocolate ensures that the chocolate will remain solid at room temperature but also easily melts in the mouth.


Only about one-third of the chocolate consists of fat, which is capable of melting at moderate temperatures, helping chocolate flow. Apart from fat, chocolate is made of solid particles, such as sugar and cocoa. Thus, these ingredients must be coated with fat in order to make them smoothly past one another when the chocolate is melted in the mouth.

The viscosity of the chocolate can be measured by measuring the mass or volume collected in a given time interval. This value could then determine the mass flow rate (the mass per unit time) or volume flow rate (the volume per unit time). However, this would interrupt the manufacturing process and it is preferable to use a flowmeter that can be left in position during the whole process.

Furthermore, the finer the particles are, the bigger is the surface that must be coated by fat to ensure it will flow. This will result in thicker chocolate.

Physics is then used to measure the size distribution of these solid particles. This is done by dispersing the chocolate in a liquid and then shining a laser through the dispersion. The distribution of the solid particles is calculated by looking at the intensity of the light scattered at different angles.

Moreover, it is also vital that the chocolate’s temperature is monitored and controlled to ensure that it is glossy and has a good ‘snap’ when broken.

Tempering is a traditional method that has been used for many years to ensure that the chocolate liquid will solidify as desired to obtain beautiful chocolate.

Chocolate can solidify in six different forms, all of which are edible. However, only form 5 creates the chocolate people really like. All six forms are made of the same molecules but they have different arrangements. This variation leads to their large-scale differences in properties and appearance.



The above pictures show some of the interesting things I saw at the show

Below is a diagram showing the different forms and their properties.


When molten chocolate is cooled, very small crystals are formed. These crystals are known as “germs”. The germs grow until the chocolate solidifies.

Germs of form 4 will appear if molten chocolate is cooled down to below 29 degrees C. Germs of the forms 6 and 5 can appear if molten chocolate is cooled down below 36 and 34 degrees C. However, formation is extremely slow if the temperature is above 29 degrees C. Above this temperature, it would take weeks before weeks the first germ would appear. Therefore, if molten chocolate is cooled down, it is impossible to obtain germs of only the desired forms. This means that the undesired form 4 will always be made. Unfortunately, the germs of this undesired form will eventually dominate, giving an unattractive chocolate.

Tempering is used to overcome this problem. During this process, the chocolate is first cooled to below 29 degrees C. This leads to desired and undesired germs being formed. Then, the molten chocolate is slightly heated to 32 degrees C. This leads to the unwanted germs being destroyed and also allows the desired germs to grow.

The bars are then removed from the moulds and passed along to wrapping machines to be packed for shipment to distributors, confectioners and others throughout the country.

The production of chocolate often emits large amounts of greenhouse gases, since high temperatures have to be maintained. These gases are known to contribute to global warming.

Moreover, Chocolate is so widespread that it is not often thought of as exotic. However, the ingredients for most chocolate bars have almost certainly travelled at least halfway around the globe; nearly all cacao is grown in West Africa or Latin America. The shipping of the chocolate also leads to the emission of greenhouses gases.


Salters Horners Advanced Physics AS

Students’ Book

University of York Science Education Group, 2008

ISBN: 978-1-40589-6023

Pages 66-87


Visiting the Chocolate Show by Shefali Srivastava 12I

On the 17th of October 2014 we went on a trip to West Olympia, Kensington to an international chocolate exhibition to learn about the physics principles involved in the production of chocolate.

At the chocolate show we got the opportunity to talk to a number of master chocolatiers and taste a variety of different chocolates with a number of flavours infused in them. We saw a presentation of how orange infused chocolate was made in a demo kitchen. There was even a chocolate fashion show with dresses made completely of chocolate. We spoke a number of people about the various ways in which different types of chocolate were made.

Physics can be considered to play a part in chocolate making as the process requires changes in temperature and pressure and the viscosity of liquid chocolate dictates its uses.

Melting chocolate or tempering is the art of crystallizing the cocoa butter to form a solid that is easy to snap and that melts in the mouth. Melting is especially important because it controls how well the chocolate disperses and releases flavour onto your tongue.

According to the table below it is clear that the ideal temperature for the chocolate to melt and harden is 34 degrees Celsius. The viscosity of chocolate is determined by carefully altering the temperature and the flow rate so that the chocolate sets properly or ‘enrobes’ the centre fully. The viscosity of chocolate is also important in determining the shelf life of the chocolate and the way it melts in the mouth.


At the chocolate exhibition I also came across stretched candy that seemed to have stripes on it as a result of the stretching. Stretching is essential for determining the state of the candy. If the cooled sugar is not stretched, it would form chewy candy but to turn it to a more desirable taffy consistency, it has to be stretched. Then if food colouring is added and the sugar is stretched very carefully, this would form coloured stripes on the surface of the taffy. This is because the stretching changes the structure of the sugar crystals, breaking them up into smaller crystals resulting in opaque stripes appearing on slightly less opaque taffy candy.

I learnt that the moulding of chocolate was dependent on the solidification of the cocoa fats into the correct polymorphic form. This form is often referred to as Form V. This gives the liquid chocolate the ability to take the shape of the mould successfully. The time it takes for the chocolate to solidify is dependent on the viscosity of the chocolate.

As mentioned before the applications of the laws of physics in the production of chocolate have a number of advantages. The viscosity of chocolate is essential for determining various features of not only the chocolate but also the product being made.

Light gate flow meters used give a very reliable value for the flow rate which is used to control the viscosity of the chocolate as the number of ‘’darkenings per minute’’ is used for determining how thick the chocolate is. If the number of darkenings is lower than usual, then that would mean that the viscous force is too low and the chocolate is too dense and the density can be lowered by altering the temperature. Moreover, the thixotropic property of chocolate also helps in determining how the chocolate flows in processes such as enrobing different substances. A viscometer can be used to test for the viscosity of the chocolate at various intervals during the production process. This saves the company potential losses that could have been the result of chocolate being the wrong consistency. This shows that physics is advantageous in the production of chocolate.

The manufacture of chocolate can determine the amount of waste produced. For example, if 70% of the cocoa is used to make bitter dark chocolate then there would be less waste produced than when 20% of the cocoa is used to make milk chocolate.

The production of cocoa has raised environmental and social concerns. Cocoa farming can only occur 15 degrees north or south of the equator. It can take approximately three years after the planting for the trees to be fruitful enough to harvest the pods. These farms are generally small, family owned and operated businesses. Farms’ cocoa crop outputs struggle to match the increasing demand for the chocolate. Farmers have shifted towards unsustainable, less environmentally friendly practices to meet these demands.

Below you can see the pictures I took of some of the interesting and tasty exhibits




1) Salters Horner’s Advanced Physics for EDEXCEL AS physics Students’ Book University of York Science Education Group. Published in 2008 by Pearson Chapter 2 page 66 to 73


3) article by Anita Watts, FJI Concessions Editor

4) Youtube video by Chin Wu titled ‘falling ball’



The Making of Chocolate by Milan Divecha 12Y

To carry out research on how chocolate is made and how physics is related to the production of chocolate, I went on a trip to the chocolate exhibition at the Olympia centre in West Kensington on Friday 17th October 2014. The chocolate exhibition involved numerous leading chocolate manufacturing companies showcasing their chocolate and explaining to the public how they made their chocolate. I talked to representatives from Lindt, Rococo, Goufrais as well as a chocolate making expert named Paul A Young. I was able to use the information they gave me to consider how physics was related to the production of chocolate. I have also used other sources from the internet for my research into chocolate making, which are listed in the bibliography.

Basic chocolate making method: 1 & 4

1. Farmers harvest cacao pods from the cacao tree (called theobroma cacao) using long sticks or a machete.

2. Then, the pods are split open and the white seeds are scooped out along with the sugary pulp.

3. The seeds and pulp are fermented, which causes them to turn brown and “produces several flavour precursors, eventually resulting in the familiar chocolate taste” 2 (this can take up to 7 days). From then on, they are known as cacao beans (or cocoa beans).

4. The beans then must be left in the sun to dry so that microorganisms are killed and decay is prevented later on.

5. Now the beans are used to make chocolate. They are roasted for anywhere from 30-120 minutes to develop the aroma of the chocolate and affect its resultant taste. 1

6. After the beans have cooled, the beans have their shells removed. The part of the bean that is left is known as a “nib”.

7. The nibs are crushed and grinded repeatedly under high pressure. The friction and high pressure liquefy the nibs and turns them into a brown liquid known as chocolate liquor. (The chocolate liquor can be compressed under extreme pressure to squeeze out the cocoa butter and it leaves you with a solid than can be crushed to make cocoa powder.)

8. The manufacturer then adds different ingredients to the chocolate liquor to alter the flavour, texture, colour and consistency of the final product. For example, milk is added to make the chocolate lighter in colour and give it a slightly different taste, sugar is added to sweeten the chocolate, extra cocoa butter is added to give the chocolate “a richer flavour and smoother texture”, and lecithin from soya beans is sometimes added to make the mixture flow better to make pouring into moulds easier. Generally, these basic ingredients are used to make the three main types of chocolate: 4

a. Dark chocolate: sugar, cocoa butter, cocoa liquor and sometimes vanilla

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

c. White chocolate: sugar, cocoa butter, milk or milk powder, and vanilla (usually no chocolate liquor)

However, some companies (e.g. Lindt) incorporate many other ingredients to produce a unique taste. For example, at the chocolate show, Lindt had used ingredients like sea salt, lime, raspberry and even red chilli in their chocolate mixture to produce a completely original product. 5

9. The mixture is refined and then undergoes “conching”, whereby rollers knead the mixture to make it thinner, to make the chocolate have a smoother texture and to improve the flavour by removing acids and astringents (e.g. acetic acid and lactic acid which were produced by yeast and bacteria during fermentation.)

10. The chocolate is tempered, meaning it is cooled carefully and gradually whilst constantly being stirred. This is important as it gives the chocolate a smooth, glossy look, which is often desired by consumers and it is considered a sign of quality.

11. The mixture is poured into moulds or is used to coat confectionery and is then cooled to make it solidify.

For a lot of these steps, the duration of the process can vary greatly and it is up to the manufacturer to decide how long they spend on each of these processes, since time will affect the flavour of the chocolate.

The physics of chocolate production

In order for chocolate to be desirable in consistency and texture and usable by manufacturers, the chocolate mixture used must have the right viscosity. Viscosity is a measure of how much a fluid resists movement of a mass through it 3 (i.e. the thickness of a liquid). The SI unit for viscosity is the Pascal-second (Pas) and its derived unit is kgm^-1s^-1.

Temperature is an important factor that can change the viscosity of a fluid. Manufacturers will vary temperature exclusively to make the viscosity of the chocolate mixture right. They do this because adding other ingredients to change viscosity will make the chocolate taste different and they must follow a recipe to get the best flavour. Therefore, they must change the temperature of the mixture. It is important that the mixture is heated to a warm enough temperature because this makes its flow rate greater 9. As shown in the table, when the chocolate mixture is at 30 degrees C, it has a viscosity of 100 Pas, but when it is 50 degrees C, it has a much lower viscosity of 60 Pas. This is important because it means that it will flow through pipes quicker so it will not get stuck and clog up machinery and it will also increase production rate, so the chocolate can be made quicker. Hence, the use of physics here helps to increase profit. Furthermore, the use of physics here can help manufacturers if a variation in the recipe has occurred (e.g. due to a different cocoa bean supplier) because the flow rate can be changed back to its original rate simply by altering the temperature of the mixture. One downside of the use of physics here is that it increases energy costs and trained experts are needed at all times to monitor the temperature of the mixture. Also, if the mixture is hotter, it will take longer to cool later on and the flavours may have changed (as well as the texture of the chocolate.)

It is sometimes desirable to have a more viscous chocolate mixture as this is better for mixing with other flavours and for chocolate fillings because viscous chocolate mixtures have a purer chocolate flavour. Other times a less viscous chocolate mixture is better as it makes pouring and coating things easier. Hence, a manufacturer can use physics knowledge to make sure the chocolate mixture is suitable for its desired purpose by simply changing the temperature of the mixture to alter its viscosity.

Physics is also involved in the tempering process, when the chocolate mixture is cooled gradually. During the tempering process, the size of the crystals of the fats in the cocoa butter is dependent on the temperature to which the mixture is cooled (as shown in the table below). The fats in cocoa butter can crystallize in six different forms, which ultimately will dictate how the chocolate will look like, feel like, how it snaps, how it melts and its consistency. The primary purpose of tempering is to assure that only the best form (V) is present so that the chocolate appeals to customers. The six different crystal forms have different properties:


Therefore, physics is important and useful to know here because knowing the right temperature can help you increase the production rate (which lowers costs and increases profit) and can help you get the right look, texture and consistency for the chocolate. For example, you know that if the temperature is too low, crystal types I-IV will be present so the chocolate will melt too easily. If the temperature is too high, it will take too long for the mixture to cool and you will have a poor rate of production. However, if you cool the chocolate mixture to 34 degrees C, the texture will be glossy, the consistency will be good, and it will not melt easily and will have the best snap.

Historical context of chocolate:

Chocolate has been around for over 2000 years, although it was not like the form of chocolate we have today. 1 It was the Mayans and Aztecs who first discovered and started growing cacao trees. The Mayans were the first to brew a hot drink with crushed cocoa beans, though. It was considered a luxury and was often consumed at sacred ceremonies by the elite. Later the Aztecs called the drink “cacahuatl” (ca-ca-WAH-tel), meaning warm or bitter liquid. 6 The Aztecs and Mayans mass produced the cocoa beans as they were very highly valued. When Spanish explorers came across the Aztecs, they learned of the drink and brought back cocoa beans to Spain, where it became extremely popular. However, to suit their tastes, the Spanish added sugar to the drink to make it sweeter. It was believed to be a very healthy beverage. 6 From Spain, chocolate spread across Europe and eventually became popular worldwide and people added ingredients and altered recipes, resulting in the variety in types and flavours of chocolate that we have today. In 1847, Francis Fry, discovered a way to mix some of the cocoa butter back into the cocoa powder and adds sugar, creating a paste that can be moulded. He called this “eating chocolate” (“chocolat delicieux a manger”). This was the first modern chocolate bar, although conching had not yet been invented, so it was not the smooth, silky bar we know today but a rough, grainy chocolate. 6 In the 1900s, people began to mass produce chocolate and now it is even more popular today than ever. Currently, the Ivory Coast is the world’s largest exporter of cacao beans, (1.4 million tons), and the Netherlands both imports and grinds the most cacao. 6

Social and environmental issues

One large problem with the production of chocolate has been labour. Since hundreds of years ago, many companies have used slave labour for growing and harvesting cocoa beans. Although slavery no longer exists, nowadays some cocoa bean farmers are forced to work very long, hard hours for very little pay. Many companies choose to do this because it lowers costs and increases product output. 11 Some companies have even been reported for using child labour 11. This is why many believe there are ethical issues with the production of chocolate. In recent years though, these issues have gained attention and now larger companies have started “Fair Trade” programs. Representatives of Lindt have said that their Lindt and Sprüngli Farming Program ensure that when they pay their cocoa bean farmers, they pay fair wage as well as a “price premium for farmer investments and community development” 5. These sorts of programs have been commended by many fair trade organisations and eradicate a lot of the ethical issues of chocolate production.

Another issue is obesity. Many claim that the rise in obesity is largely due to the increased consumption of sweets and chocolate. This is partially true because a lot of types of chocolate (especially milk chocolate) are high in fats and high in sugar. Milk chocolate products are usually high calorie foods and many people nowadays have a less active lifestyle. As a result of these two factors, people end up storing the fats and sugars in the chocolate as body fat. On the other hand, many claim that some types of chocolate like dark chocolate are in fact healthy! In recent years, scientific evidence has begun to indicate that the nutrients, phytonutrients and fatty acids found naturally in cocoa may be associated with a lower risk of cardiovascular disease. 12 Furthermore, even the 2010 Dietary Guidelines Advisory Committee (DGAC) Report identified evidence to support that “modest consumption of dark chocolate or cocoa, as part of a balanced diet, is associated with a reduced risk of cardiovascular disease” as well as lower cholesterol. 12 In addition to its pleasing taste, scientists have also found that it stimulates endorphin production, which gives us a feeling of pleasure. 12

One environmental benefit of producing chocolate is that the cacao trees require shade and protection from other (larger) trees, meaning that farmers end up promoting biodiversity when they plant these other trees in their cocoa bean farms. This is also good because it provides habitats for wildlife and so helps to protect them and increase their population sizes. 1


1. Video (documentary):

2. Internet link:

3. Internet link:

4. Direct conversation with chocolate maker Paul A Young (at the chocolate exhibition)

5. Information from Lindt representatives at the chocolate show

6. Internet link:

7. Internet link:

8. Internet link:

9. Edexcel AS Physics Student Book (By Miles Hudson and Patrick Fullick) – Page 58

10. Edexcel AS Physics Student Book (By Miles Hudson and Patrick Fullick) – Page 59

11. Video (documentary):

12. Internet link:

Chocolate Report by Seyar Azizi 12O

To find out about the physics involved in making chocolate, I went to a convention in London which was about this. The visit took place on the 17th October 2014 at Olympia West, Kensington London.

Whilst there I was able to ask some of the exhibitors about the making of chocolate and I was also able to pick up leaflets as another source of information. The venue contained multiple companies with their own style of chocolate and unique ways of flavouring it, e.g. using alcohol, plants such as chilli or even sea salt. There were also new ways of using chocolate e.g. chocolate clothes and sculptures

I asked some of the exhibitors about the physics involved in the making of chocolate. They told us that the viscosity of the liquid chocolate increases when the temperature decreases. If the temperature is too low the chocolate will eventually turn in to a thick, dull paste and will not be suitable to be sold and will not taste good either. On the other hand, if the temperature is too high the chocolate will be very runny because viscosity will become much lower. The viscosity is one of the factors that dictate how thick the actual chocolate will become.

The risks of making chocolate are that using high temperatures can burn you. However, the benefits are that you can control how high or low you want the viscosity to be, so you can adjust it for different styles of chocolates.

However, this raises environmental issues. If you want to decrease the viscosity of the chocolate you need higher temperatures and for this you need more energy. This could mean that more fossil fuels will need to be burnt causing more greenhouse gasses and therefore increasing the speed of global warming. There is also the social issue of people’s health, since there are no regulations on how much you can consume (there is only a recommended daily amount) unlike alcohol or medication, people are taking too much chocolate, not having a balanced diet and not keeping fit.

Chocolate Show Report by Kishok Inderaraj 12G

I visited The Chocolate Show on the 17th October 2014, in order to learn about how physics can be related to chocolate production. During the visit I was able to talk chocolate makers and experts in order to increase my knowledge into how chocolate is made. This is a link to the website of the venue –

‘The chocolate show’ exhibition was based in Olympia West, Kensington and featured many stalls including major chocolate brands from around the world such as Lindt, as well as independent chocolatiers who were prepared to talk to me about their products.

I was given a brief description of the history of chocolate. I learnt that chocolate use may have begun as far back as fifteen hundred years in Central American. The rain forests, where the tropical mix of high rain fall combined with high year round temperatures and humidity provided the ideal climate for chocolate plants and cocoa beans to grow. We then fast forward in time to when the first chocolate factories were being opened in Spain using beans brought back by the Spanish treasure fleets. By the early 17th century chocolate powder was being made as a drink and was being exported to other parts of Europe. The Spanish kept the source of the drink a secret for many years. The chocolate was so expensive at that time that it was worth its weight in gold. Not long after the first Chocolate House in England opened in London followed rapidly by many others. They were used as clubs where the wealthy and business community met to smoke a clay pipe of tobacco, conduct business and socialise over a cup of chocolate. Fry was the first person to have made solid chocolate bars

In my conversations I learnt about different stages involved in making chocolate and it is a rather long process. The journey begins with harvesting and fermentation, which happens within 24 hours of the pods being opened, and can take up to 8 days depending on the variety. Fermentation produces the flavour by reducing sugars, glucose and fructose, and amino acids. Next the beans are washed and dried, which can last for weeks. They are cleaned once again and packed in sacks for storage and shipping, which must satisfy with strict conditions to avoid any damage or decomposition. After this it is up to the chocolate maker to continue the process that brings out the flavour and create fine chocolate. By gently roasting the beans which are further dried and browned to release their full flavour. The shell of the bean will then be removed, the more the shell is removed, and the better the quality of the chocolate will be. The beans are then crushed to reduce them into even finer particles before the refining process converts the crushed particles into liquid cocoa. It is then ready for conching which is the process of rolling and spreading the mixture against a hard surface. This releases the cocoa butter, makes the consistency smoother and improves the flavour by removing unwanted flavours such as acids. Depending on the wanted quality of the end product, this process can take several days. The final step is known as tempering which is the art of transforming liquid, or semi-liquid, chocolate in to a glossy, crunchy chocolate with a hard snap. Tempering is a very delicate process, which involves gently cooling and heating the chocolate and requires skill and experience.

By doing further research I discovered how physics can be related to chocolate. One of the reasons that chocolate is incredibly good to eat is that its melting point is just below body temperature. When you place a piece of chocolate on your tongue it immediately starts to melt, spreading the sweet, satisfyingly fatty taste across your mouth. Chocolate also contains chemicals such as caffeine and theobromine which are thought to contribute to that feel-good lift that gets people addicted and gives them the urge to have more. Chocolate behaves in a rather strange way when heated and cooled; this is because the structure of chocolate can change when heated. Viscosity is the frictional force in fluids. Viscosity can be affected by the temperature of the fluid. When the chocolate is liquid its viscosity will decrease if you increase the temperature. In the production of chocolate the temperature must be average, so that it flows quickly while being produced, but must be viscous enough to be shaped. Also the cross sectional area affects the stress required to break it and this will in turn affect the texture. When a liquid is able to move quicker it is less viscous. Also, when the cross sectional area is greater, the force required will also be greater to break the chocolate piece.

While making chocolate maintaining the high temperatures can increase the emission of greenhouse gases causing global warming. If the final prices of product manufacture costs are higher and in turn making the retail price higher, this may deter people from buying the chocolate.

The chocolate show by Ramz Hkimi 12V

The chocolate show was held at Olympia West, Kensington and I visited there on the 17th October 2014.

Physics can be applied to chocolate production as the temperature has to be adjusted to suit the needs of the chocolate you want to produce. At the show there were many different types of chocolate which had been crafted into different shapes and flavours.

Chocolate has to be heated to melt it and then cooled down so it can be shaped in to the desired shape.

There were many different types of chocolates for sale at the show including the usual white chocolate and dark chocolate.

Chocolate is very popular around the world and it is shipped from countries in Africa and South America.

Chocolate production can have a negative effect on the environment as many trees in the amazon get chopped down to grow the chocolate beans. The high temperatures need to produce chocolate can cause the release of greenhouse gases.

Chocolate has been around for a long time, however in the past only the rich and high status people could afford chocolate as it was seen as a luxury food.

Report for the chocolate show by Sambath Uruthirakumar 12G

The trip took place on the 17th of October 2014, in Olympia West, Kensington and I visited the show in order to learn how physics is involved in the production of chocolate.

The visit gave me an opportunity to talk to the chocolatiers and sales staff and I got to taste lots of chocolate made with different flavours added to them.

During the show there was even a chocolate catwalk show, where the dresses were completely made out of chocolate.

There are many stages involved in making chocolates: harvesting, fermenting, drying, shipping, cleaning, winnowing, roasting, grinding, milling, mixing, conching, tempering and forming. Harvesting is when the beans are cut and cracked, and it can take up to 24hours. Fermenting produces the flavour and reduces the glucose level and the amino acids. Drying and shipping is where the beans are sun dried and sent to the chocolate factories. Cleaning removes the dirt and makes sure the beans are very clean before they are used. Winnowing is where the shell of the bean gets removed from the ‘cotyledon’. Roasting the beans increases the flavour. Grinding and milling is where the cocoa butter gets released. Mixing is the blending of cacao, cocoa butter, milk, sugar and flavours. Conching continues the mixing but at this stage the mixture is also heated so that the liquid chocolate gets a smooth texture. Tempering is when the cocoa butter is crystallized to a solid form but will melt in the mouth. Finally the forming is where the chocolates are shaped.


The word chocolate comes from the Spanish language and it’s root is from the South American ‘Nahuati – xocolātl’ and means bitter water. The first evidence of chocolate is in pre Columbian Mexico. The Mayans and Aztecs used the berries from the cocoa tree to make a drink (a similar drink was made for a royal wedding in France in 1615). England first welcomed chocolate in 1662 and ‘Chocolate’ was spelled in various ways before reaching the form it is now known as. In 1847 the first eating chocolate was made in England, which didn`t attract much attention at first. However it didn’t take long for chocolates to get accepted.

Eating chocolate can have a positive psychological effect and it is a high energy source owing to the high levels of sugar and fat in it. Chocolates can also have risks. If too much chocolate is eaten then there is a risk of getting fat, a possibility of a high cholesterol levels which can in turn lead to a heart attack.







Visit to the Chocolate Show by Karthikeyan Theivendrarasa 12B

In order to do some research into how physics is involved in the making of chocolate, the school physics department arranged for me to visit the Chocolate Show, which took place in West Olympia, Kensington on the 17th October 2014.

At the show there were companies from all over the world producing unique types of chocolate which they wanted to present.

There were lots of different activities at the show including a fashion show where women wore dresses made mostly from chocolate and live cookery shows on how to make fascinating foods from chocolate.

Physics is involved in how the flavour of the chocolate is released and the physical condition of the chocolate after cooling down from being melted at a certain temperature. Most Chocolatiers recommended that the chocolate is melted between the temperatures of 32 degrees Celsius to 34 degrees Celsius in order to give the best taste however some chocolatiers said that the best temperature, at which the chocolate is melted, depends on the use of the chocolate.

The temperature that the chocolate is melted at determines the viscosity of the chocolate, which in turn dictates the rate of flow of the liquid chocolate.


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