Chocolate is a sweet confectionery made
from cacao beans. These are seeds that originate from the cacao plant. They are
found grouped in several large pods, and are harvested once ripe. The beans
have a bitter sensation, which is generally weakened through a fermentation
process to allow for the proper roasting and hulling of the beans, which give
it their flavour. The beans then move onto being grounded into a chocolate liquor
substance and hardened to form the solid chocolate that is renowned today, made
up of cocoa solids and particularly cocoa butter, believed to make chocolate
melt. To be more specific, cocoa butter is a highly stable polymorphic fat of
the cocoa bean, melting at 36 Degrees Celsius. The butter comprises of different
types of unhealthy fats such as palmitic, stearic and oleic acids, that remain consistently
solid at room temperature, as opposed to healthier fats that are liquid at room
temperature. When it is exposed to heat, it changes into a fluid state because
it is made up of six different crystal forms, subsequently meaning that the arranged
atoms within the chocolate are constant but positioned differently. The
scientific principle of Polymorphism becomes cleverly introduced. Polymorphism
is “the condition of occurring in several different forms.” (Wikimedia Foundation, Incorporation. 2014, Polymorphism (Biology). Retrieved: April
28, 2014, from http://en.wikipedia.org/wiki/Polymorphism_(biology)). In this experiment, the cocoa butter
and the chocolate appear to be solid at first, and eventually turn into a
liquid from the heat generated by the stove. This heat forces the particles
within the confectionery to move apart and vibrate as they gain more thermal
energy and obtain a runny texture.
In this experiment, it was seen that,
the white chocolate took the longest time to melt, on average 3 minutes across
all 5 trials, while the dark chocolate took the quickest time to melt, on
average 1min 40sec, and the milk chocolate was second fastest, melting in 2min
20sec, on average for all 5 trials combined, according to my graph. The results
obtained in this experiment clearly identify a trend and relationship between chocolate
and cocoa butter; the chocolate with the most amount of cocoa butter content
took the longest time to melt, whilst the fewer cocoa butter content present
within the chocolate resulted in a much faster melting speed. However, I
originally hypothesised that the amount of cocoa butter will affect the melting
speed of different types of chocolate. Therefore, I was expecting that the
white chocolate containing 34.8% cocoa butter to melt the quickest, whilst both
the dark and milk chocolates contained 29.6% cocoa butter. Yet, the opposite
happened, meaning that my hypothesis was not entirely correct. Considering that
the milk and white chocolates had the same cocoa butter quantity, the
expectation was that they would take the same time to melt. However, according
to the table of ‘Cocoa Butter Polymorphs’, dark chocolate took the quickest
time to melt, because not only is it the most glossiest of all chocolates, but it’s
melting point is 33.8 Degrees Celsius (Form V), as opposed to Form IV, belonging
the milk chocolate, as it was kept in room temperature throughout the entire
experiment. Despite this same principle applying for the dark chocolate, the
dark chocolate possessed higher qualities of Form V, leading to its subsequent
classification. The known melting temperature of chocolate/cocoa butter,
generally speaking is 36 Degrees Celsius, and in the experiment, the three
different types of chocolates were exposed to a heat of 100 Degrees Celsius
(boiling temperature of water). Additionally, the dark chocolate would have
clearly melted the quickest already having the highest melting point.
Of all the three types of chocolates,
Cadbury’s dark chocolate is the healthiest, containing less milk, sugar and
other elements, which all have different melting points. An increase of the addition
of these ingredients, purposely affects the entire melting process, and speed
of the chocolate, becoming more heat sensitive as it interferes with the cocoa
butter. The additional fats therefore significantly reduced the white chocolate’s
melting point, taking it longer for the Beta Crystals to loosen and turn into
a fluid state of matter.
Whilst performing the experiment, I accidentally
ate some chocolate that I was going to use for my second trial. Waiting for the
water to boil, I didn’t realise that the chocolate that I had put to the side
of my kitchen bench had been weighed and was ready to melt. As a result, I had
to re-weigh my dark chocolate, to make sure that I was using the same intended
amount (24g). This could have been minimised if the chocolate was put in a separate
container or already in the bowl, so that it was evident, that it had to be
melted and used for the experiment. I also found that when I cut an entire row
of chocolate for my first experiment, the weight was 24g, rather than 25g,
stating at the back of Cadbury’s nutrition panels. Therefore, I had to use this
measurement for all of my trials, if I wanted the experiment to be as
consistent and as accurate as possible. I found myself, having to either add or
take away chocolate to the serving size that had already been sliced for the
experiment. To ensure that the weight was exact for each time I measured the
recording (weight), a more accurate and precise or sophisticated cutting
instrument/tool should have been used.
Conclusion
The amount of cocoa
butter does not affect the melting speeds of different types of chocolates.
Originally through research it was believed that cocoa butter did affect a
chocolate’s melting speed, because it was the ingredient that contained special
polymorphic properties, making the chocolate less resistant to heat and causing
Beta Crystal to separate more. However, this is only so, if the cocoa butter
does not interact with other elements and ingredients found within the
chocolate. For example, due to white chocolate’s excess milk and sugar content,
the melting speed of the chocolate is decreased as all of the elements have
different melting points, and interact with the cocoa butter, making it
resistant to heat. Therefore, the melting speed of chocolate is affected by the
quantities and types of ingredients comprised within a chocolate, not
necessarily the cocoa butter itself.
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