A
friend of mine, Mr. Leo Nathan innocently sent me this video through a WhatsApp
chat, and I am sure he does not know what this experiment was all about?
Neither could I.
https://www.youtube.com/watch?v=M-KopIH3zAY
At
first, I could not understand what the experiment was all about. She used two
cans of gas to freeze a can of Coca-Cola. Then she allowed it to catch fire
before adding an entire bag of baking powder onto it before putting a lot of
new batteries onto the jar and so on.
Finally,
the experiment ended with some white dry powder without any water or liquid
coming out from the can after she opened it. I was quite confused with her
“experiment” as I did not know what the experiment was all about, her objective
of doing the experiment, or what she was trying to prove?
Then
another lady friend Ms Violet Ho, a former schoolmate of mine told me the lady
in the video was trying to show there was a lot of sugar in a can of drink but
was unable to figure out where the water in the can went after the can was
opened?
I
then thought of this, only to realize it was some trick. They may have opened
the bottom of the can, drain out all the content there, add some white powder
or sugar into the empty can, sealed the bottom before conducting the ‘magic
show’
Obviously,
it was a scam out to swindle viewers into believing that was the way to demonstrate
the presence of high sugar content in that can of drink. Following that there
were also doubts by others. Hence, I decided to write this article to explain
to which I dedicate this article to Mr. Leo Nathan and Ms. Violet Ho.
Allow
me to teach viewers and readers how to calculate the amount of sugars and other
substances inside any drink that can be calculated without needing all those
“magic show” shown by the lady, or needing an analytical chemical laboratory.
Anyone can do this in his own kitchen if he has a small food weighing machine
that gives measurements in grams and some kitchen measuring vessels that gives
the volume in millilitres or ml.
First, take a bottle or can or bottle of any drink of a known volume, let’s say
250 ml. You need only take out a small amount of its volume, say one tenth of
the amount (25 ml) or even less.
Next, take a cup and weigh it. Then pour out 25 ml. of the drink into the
cup. Weigh the cup together with the 25 ml of the drink inside. Then
subtract the weight of the cup. This should give the weight of the drink.
You
may expect the drink to be 25 gm. since the density of water is 1 g / ml.
But no. There is sugar and other food additives inside.
So,
the weight of the drink should be more than 25 g even though the volume of the
drink (water) is the same at 25 ml.
Another
way of putting this is, if we weigh out 25 ml of water, we expect the weight to
be 25 gm. since the density of water is very nearly 1000 kg per cubic metre (1
gm per ml). The density of water varies only very slightly with temperature as
water contracts when cooled. At 4 degrees Celsius it is almost 1 gm / ml. We
can safely use the density of water as 1000 kg / cubic metre or 1 g per ml.
But
if we now add, let us say 5 gm of sugar into the 25 ml of water, it will now
weigh 5 + 25 = 30 gm. The volume of water is not affected by what is dissolved
inside.
This
is because the sugar that is dissolved into the water occupies the vast spaces
between the water molecules. These intermolecular spaces of water increase with
temperature allowing more sugar to be dissolved as the temperature increases
until it reaches saturation point when no more sugar can be dissolved after all
the intermolecular spaces between the water molecules have been occupied by
molecules of sugar and other substances dissolved in the drink. In
other words, the solubility of sugar increases with temperature
Hence
if we take 25 ml. sample of the drink and found it weighs 30 g instead of 25 g,
remembering that the density of water is 1 g / ml. then the extra 5 g. must be
due to all dissolved substances, principally sugars inside the drink
We
can now calculate how much sugar plus other food substances was in the original
250 ml drink. This works to be:
5
gm ÷ 25 ml sample × 250 ml = 50 g
For 100 ml of the drink, it is 5 ÷ 25 x 100 ml = 20 g
Hence,
all we need is to pour out a known volume of any drink and weigh it. Any extra
weight (1 ml = 1 g) registered is just due to sugars and all other added
soluble substances in it.
So
simple as that! We can clearly see no freezing, no fire, no baking powder, no
battery, no extra cans...nothing is needed here.
We
did it by taking only a small sample of the drink of a known volume and just
weighing it. We then merely subtract the weight from the volume, and that’s it,
giving us the weight of the sugars plus other substances dissolved in it.
After measuring and weighing, we still get back the original volume of
the drink. Nothing is wasted or destroyed. There was no freezing or boiling
even.
The
only disadvantage we need to assume the extra weight was principally sugar. In many
ways this is true with all sugary drinks
Of
course, we can do it another way by taking a sample of the drink of known
volume, then distilled or boil off all the water, and weigh the residue left,
and from there we can calculate the concentration of sugar and other dissolved
substance in it and express it in the same way as in a 100 ml. Using this second method
we can look and examine the residue left to see if sugar is the major ingredient which
is not possible with the first method by just looking at the weight difference. We can even taste the residue if it is sugar. But
this method involves using heat, distillation or boiling which are all unnecessary.
Then after boiling, we cannot get back what has already been boiled off and be
content with what is left.
What
we want to do, is to do it in the simplest and in the least destructive way
possible so that we can get back the drink and everything.
This
practice in chemistry is also the same as what we do in the practice of
medicine. As doctors, we want to be as least destructive and invasive as
possible to the patient. We shall describe this practice in medicine
shortly.
This
method gives us a good estimate how much sugar was there in any drink without
considering other food additives like colour and flavouring agent that were
also present. This method can be done by anyone at home in a
kitchen. No license for practicing chemistry is needed here. We shall
talk about this later.
However,
if we want analytical precision how much other substances were also present in
a drink or any food sample, we need to send it to an analytical chemical
laboratory or a food quality control laboratory where they have qualified
experts in chemical analysis and sophisticated instruments there such as
High-Performance Liquid Chromatography (HPLC), spectrophotometers of various
kinds and types and even nuclear magnetic resonance spectroscopy.
Alternatively,
sugars may also be determined by using a small hand-held refractometer, or by
calorimetry. We can also use titration method as in the classical Lane-Eynon
method with a burette containing the reducing sugars and titrating the amounts
in a flask containing a known amount of boiling copper sulphate solution using
methylene blue as an indicator for endpoint.
Sugars
may also be determined by other chromatographic procedures besides HPLC, such
as using gas chromatography- flame ionization detection (GC-FID), liquid
chromatography-borate complexes (LC), high performance liquid
chromatography-ethylenediamine derivatives (HPLC-EDA), high performance liquid
chromatography-p- aminobenzoic acid derivatives (HPLC-p-AMBA), and
high-performance anion, etc.
Perhaps
we may also use column chromatography to separate the sugars from other
undesirable substances we have no interest in measuring. But we need to find a
suitable absorbing and separation medium for the chromatographic column for ion
and resin exchange, or maybe we can use silica gel and water as an eluent. What
we chose depends on what other substances are also present in the drink other
than sucrose.
It
all depends on the skills of the chemical analysts, his training,
qualifications and experience, his discretion, and the lab. facilities
available to him.
However,
these days, analytical chemistry has become so advanced that a chemist
analysing a substance can detect substances down to just ppm (parts per
million) or even ppb (parts per billion.
They
may need only a few drops or a tiny sample in micrograms or even in nanograms
such as a fragment of DNA for sequencing. We can do that. That’s not a problem
for us.
But
for ordinary people, we merely make it very simple, convenient, and easy for
them using what is available in their kitchen as most people are not scientists
or analytical chemists working in a sophisticated analytical laboratory.
We don't expect them to have these.
Using this kitchen method, we can only determine the total substances dissolved
inside. But if we want only the sugar content then we need to send the sample
to an analytical laboratory where they need to isolate the rest of other
substances from the sucrose.
As
scientists we try to be as less destructive as possible unlike that lady using
all kinds of "magic" and tons of materials including several new
batteries just to show some white substance inside that can.
Many people may be interested in finding out only the amounts of sugars in a
drink or in the food they eat for various health reasons we shall not go into
them. An estimate using the kitchen method is more than good enough.
Furthermore, they do not need a qualification in chemistry or a license to
practise chemistry in this country. They only need a kitchen with a small
weighing scale and some measuring cups or jugs.
The
practice of chemistry in Malaysia is a certified profession by law. Its
practice is empowered by the Chemist Act 1975 and is controlled by the
Malaysian Institute of Chemistry to regulate the practice of chemistry. Just
like medicine, the practice of nutrition, dietetics are also regulated by law
in this country like other professions such as pharmacy, optometry, law,
engineering…etc
Title
designations such as doctor, nutritionist, chemist are protected titles and are
licensed. Not everyone can use these professional titles except those
qualified, and their qualifications must be registrable with their various
councils and regulatory bodies.
On
the issue mentioned earlier, a medical doctor practices in the same way as an
analytical chemist, both trying to be as little destructive and invasive as
possible during an examination. This also applies to all professional
scientists and researchers.
For
instance, in the practice of medicine, we try to use as simple as possible an
examination for the diagnosis of a disease. The simplest method is just to
listen carefully to what the patient tells us. We then analyse what they tell
us to try and come to a diagnosis if possible. If not certain, we just ask
questions, take their medical history, and ask more questions, and just listen
carefully to what they tell us, while analysing the information for tell-tale
signs.
If
a doctor is not sure, he may look at the presentations such as signs and
symptoms to try to diagnose or differential diagnosis from the other diseases
as sometimes diseases mimic each other in their presentations. If a
doctor is still unsure, he may do a clinical examination by palpating,
percussing with the fingers, or auscultate (listen) for body sounds with a
stethoscope such as listening to the various types of murmurs in the heart,
their pitch, nature and loudness.
He
may listen to breath sounds for crepitations, rales, bubbling, stridor,
rhonchi, wheezes, vascular murmur or bruits in blood vessels that may be
stenosed (narrowed), or bowel sounds for intestinal hurry or gasses, etc, etc.
By
then, he would already be able to come up with a diagnosis with at least 70 %
accuracy if the doctor is a good diagnostician. But if he is still
uncertain due to multiple complications with other disorders having the same
features such as signs and symptoms, he may request for a laboratory support such
as haematological, microbiological, serological, immunological, biochemical,
urinary examinations or even requesting genetical and molecular cellular
assays…etc.
He
may also decide on radiological examinations such as x-rays, ultrasonography,
CT, MRI, PET or even nucleotides examinations to confirm a diagnosis. Some of
these investigations can be invasive if not destructive. But we try as best as
possible to be conservative, not invasive, least of all - destructive.
Hence,
we can see a doctor is like an analytical chemist who initially uses as simple
as possible a method to derive a finding or a diagnosis.
Like medicine, the practice of chemistry is a registered profession under the
Chemist Act 1975. A chemical analyst needs to be qualified in chemistry and his
degree must be registrable under the Act before he is allowed to practise,
analyse, and sign an analytical report or give evidence before a court of law
just like in medicine.
The same with the practice of nutrition or dietetics. Both are also registered
professions that require a licence to practice, and they have their codes of
professional ethics.
But
what we describe here using the kitchen method does not require a practicing
license in chemistry or any qualification except just follow the very simple
procedure I gave above.
Hope
this helps
jb
lim
