The Chemistry of Nutella

The people that make Nutella are in a bit of trouble:

The makers claimed the product  was a healthy spread made with “simple, quality ingredients like hazelnuts, skim milk and a hint of coco,” according to its commercial. But in fact, mother of three Laura Rude-Barbato found that the product was no healthier than a candy bar. Two tablespoons of Nutella packs 200 calories, 21 grams of sugar and 11 grams of fat.  

Oops!

So should we turf out our Nutella as an unhealthy food with no redeeming virtues?

No – it has one redeeming virtue that has received no publicity – until now that is. There is at least one reason why you should continue to use it in moderation: it has a low glycemic index.

In essence, the idea that obesity is a function of the energy balance – calories in and calories and out – is old hat.  If you try to lose weight by simply reducing the amount of food that you eat, the body goes into starvation mode, and starts storing fat.  When you start eating normally again, your body now stores more fat than it would normally store, and you just get fatter.  This is the great danger with dieting.  Your body’s metabolism adjusts to its food intake.  A lower energy food intake simply lowers your metabolism and your body weight will adjust accordingly.

Have you noticed that obese people are often also diabetic?  This has been recognised for some time – and up until fairly recently it was thought that the diabetes was the result of the obesity.  So that to reduce your diabetes, all you do is lose weight.  So these people would go on a diet to lose the weight, and it just wouldn’t work, and they would just get fatter and the diabetes would remain.

In recent years this has been turned on its head.  It is now seen that the obesity is the result of the diabetes.  And the diabetes is the result of eating too much sugar – or, more specifically, the wrong type of sugar.

In just the same way that cars run on petrol, the human body runs on glycogen.  It’s a form of glucose which is the simplest carbohydrate that there is.  Whatever carbohydrates we may eat, they are converted to glycogen before our body can use them.

Our pancreas has the job of regulating the concentration of the glycogen in our blood.  And if it gets too high, because we just eaten too much sugar, it makes insulin, whose job is to cut down on the glycogen.  But it usually overcompensates, with the result that people who eat a lot of sugar and up with high amounts eventually in their blood, and this has result of putting on weight (by a mechanism that I don’t quite understand).

So modern thought has it that the best way to control your weight is to eat foods that do not result in your system being flooded with glycogen.  And this is what he glycaemic index is all about.  High GI is bad, low GI is good.

But how can Nutella be low in GI?  We’ve seen it’s full of fat and sugar – how can it be low in GI?  The reason simply is that it is also high in fat (palm oil which is a saturated fat that is not very good for you).  Because it is high in fat, the fat lines your stomach, and does not allow the sugar to be digested quickly.  Because it is absorbed slowly, it results in a low GI index for the food.

I’ve seen this with other foods as well – there was a particular brand of ice cream (Peters I think) that had the low GI logo on it.  Ice cream, is of course high in both sugar and fat – but in this particular case the fat resulted in the uptake rate of the sugar being slowed down, and therefore a low GI index.

And this is a great trap for people who want to buy healthy food – often we see food advertised as “lite” because it is low in fat, but often this means that it has extra sugar, to compensate for the taste that is missing by taking out the fat.

Of course, if you like something sweet then most fruits and fruit juices are low in GI, because the sugar that is in there is in the form of complex carbohydrates, which are not quickly broken down.  But, if you do want something yummy and tasty on your toast for your breakfast, then Nutella won’t kill you, and because it is low in GI it won’t go your waistline.

But I wouldn’t sit there with a tablespoon scooping it into your mouth while you’re watching a movie

 

The Chemistry of Chewing Gum

Everything is a chemical.

That includes chewing gum.

So, what is it?

Well, what do you think it might be? As you’re happily chewing on it, what does it feel like? Well, when you are chewing on it, it kind of sort of feels rubbery.  Not that I’ve ever eaten rubber, mind you, but it does kind of feel rubbery.  Well, as it turns out that’s no coincidence, because that’s exactly what it is: rubber.

Here is the formula:

As to why it’s rubbery, or why rubber is rubbery, that’s kind of a rubbery question. It’s quite a complex explanation, but essentially the long chains of the molecule are a lot like coiled rope with weak interactions with their neighbours.  When it is stretched the straightening effect reduces the entropy of the system while at the same time increasing the enthalpy, and thus the stored energy is actually thermal energy and…… see, I told you it was complex!

Anyhow, so it is rubber. That means, of course, that it is essentially nonbiodegradable.  Can you swallow it?  Yes – it would just go straight through you.  There been cases where people have eaten too much chewing gum, and it’s actually stuck to stuff in their stomach, and got stuck in their bowel later on.  Nasty.

there has been some suggestion that is potentially carcinogenic, due to the vinyl acetate that some formulations use.  But as far as I can see, the jury is still out on that.

and on top of the fact that is made from rubber, it’s sickly sweet with either sugar (rots your teeth and expand your waistline), or various types of artificial sweeteners.

Anyway, now I know why I never use the stuff.

 

 

Why Don’t Water and Oil Mix? Part 3 – alcohols

We have seen that water and oil don’t mix because of their fundamentally different properties.

Water, because it contains an exposed oxygen atom, is polar, and hydrocarbons (molecules containing only carbon and hydrogen) are nonpolar. They therefore don’t mix, and the liquids when mixed together will separate into two layers.

But here’s a question – are there molecules that are partially non-polar and polar, that may be able to interact with both types of molecule?

Yes, there are – but only a very small number.  To fall into this category, the structure of the molecule must be such that neither the polar nor the nonpolar part of the molecule dominate the behaviour.  For this to be the case, the molecule must have an exposed electronegative atom (typically oxygen) and a short hydrocarbon chain.  If the hydrocarbon chain is too long, it will dominate the behaviour of the molecule, and the molecule will behave as a nonpolar molecule.

There are essentially only two molecules that we can put in this category (apart from surfactants, which are a special case that we will talk about later).

Let’s look at acetone and isopropanol:

Acetone looks like this:

this is an abbreviated form of a molecule, that kind of looks like a man with no arms.  The full structure looks like this:

 

Now let’s look at isopropanol in its abbreviated form:

They are remarkably similar, aren’t they?

Each of them has a hydrocarbon chain of three carbons, and each of them has an oxygen coming off the central carbon. The difference is that the acetone has an exposed (ketone) oxygen, whereas the isopropanol has an oxygen attached to a hydrogen (which makes it an alcohol).

The combination of the single polar group, with a short hydrocarbon chain, means both of these molecules will interact with both hydrocarbons and water.  For this reason, they are both very common solvents in laboratories across the world – mainly used for rinsing glassware, as they will dissolve what ever is on the glassware, whether lipophilic or hydrophilic.  That is, they will dissolve both oils and water from the glassware.  Acetone is particularly useful, as it is also very volatile, and evaporates very quickly, so the glassware can be cleaned and dried very easily.

Both of these solvents find their way into the marketplace.  Acetone is nail polish remover, and isopropanol is “rubbing alcohol”.

In terms of the chemical properties, acetone is the more aggressive of the two.  It will chemically attack many plastics and paints, which is why it is used as nail polish remover – nail polish is essentially an acrylic paint.

Isopropanol, on the other hand, is far more useful.  It is simply the best solvent in existence for general-purpose cleaning.  As the name “rubbing alcohol” suggests, it can be used for rubbing excess oil off your skin, as a skin cleanser.  Because it is miscible with water, it is also an excellent general-purpose solvent for all other forms of cleaning.  Used on your kitchen benchtop for example, it will successfully wipe up whatever might happen to be on there, with a water-based or oil based.

For some reason, the isopropanol has not found its way into any kitchen products unlike “vanilla fresh” which is an alcohol based cleaner (ethanol) which will simply not work as well on oil based things as the isopropanol will.

So go and get yourself a bottle of “rubbing alcohol”.  Whether it’s cleaning a kitchen benchtop, leather seats, or even texta or ink, it will do a good job of removing it– is a remarkable chemical, and the second-best general-purpose cleaning compound in existence.

 

Why Don’t Water and Oil Mix? Part 2

We know then water and oil don’t mix. We are considering the reasons for this in terms of their various chemistries.

Water, as the have seen, is polar – that is, there is an uneven distribution of charge, and so water molecules like attaching themselves to other water molecules so that they can balance their charges.

Let’s now look at oil.  Oil is organic in nature.  By organic, we mean carbon-based.  Broadly speaking, all chemistry is split up into organic chemistry and inorganic chemistry.  Carbon atoms have the ability to form themselves into long chains, and these long chains are what make up all living organisms – this is called carbon chemistry, organic chemistry, or simply life chemistry.

It is quite funny really – one entire branch of chemistry is devoted to one element in the periodic table – carbon – whereas the other major branch of chemistry, inorganic chemistry, is devoted to the other hundred and seven elements.

So carbon has this incredible ability to link itself together in long chains, rather like Lego.  In just the same way that we can take a box of Lego bricks, and put them together into all sorts of shapes and configurations, carbon atoms can be linked together to form an infinite number of molecules, these molecules are the amino acids, the carbohydrates, the proteins that make up our bodies and make up life.  They also the chemistry of oils and fats.  So it’s look at them now.

Let’s consider the simplest organic molecule that there is: methane.

Methane consists of a single carbon atom, with four hydrogens attached to it in the shape of a tetrahedron:

because the molecule contains no electron withdrawing atoms, like oxygen, there is no uneven distribution of charge.

But of course methane is a gas.  Let’s consider a simple organic molecule such as octane:

We can see immediately that there is no imbalance of charge on this molecule.  There is therefore no requirement for it to mix with anything to balance a charge.

Now consider what happens if we mix the octane with the water. If you are a water molecule and you bump into an octane molecule, you’re not going to get along.  The reason is that as a water molecule, you are going to be looking for other water molecules so you can balance your charges.

So if you mix water and octane together all the water molecules will run around until they bump into each other and link up with each other so that the positive and negative charges can be balanced out.  That’s why we get to separate layers – the water molecules want as little interaction with the oil as possible because they want as much interaction with each other.

Or to put it another way, they want to minimise the surface area of the interaction between the water and the oil.

We could put it this way – the octane is a pretty easy-going molecule, it has no problem with water. it has no particular agendas or issues.  But the water – well – ensure handsome agendas and issues.  It needs to balance its charges. So the water has a problem with the octane because you can’t help it balance its charges.

And this affinity or hatred actually expresses itself in chemical terms such as hydrophilic (water loving), hydrophobic (water hating), lipophilic (oil loving), and lipophobic (oil hating).

So we can see now why oil and water don’t mix.  Tomorrow, we’ll look at some molecules that kind of fall between these two categories – that is, they are partially hydrophilic and partially hydrophobic, and by their nature these molecules make excellent cleaning compounds.

And then will go on look at the wonderful world of surfactants (detergents) – how they work and how they clean your dishes and your clothes.  Stay tuned

 

 

Why Don’t Water and Oil Mix? Part 1

I remember the first time I saw kerosene and water mix together.  We used to have an old kerosene heater and I was curious to see what would happen if you mix the kerosene and water together.  Since the kerosene was a nice sky blue colour, I wondered whether it would make the water blue.

Much to my surprise, the kerosene and water separated into two discrete layers, with the kerosene on top.  I was fascinated by this – I’d never seen this before.  Two liquids were mixed together, but not mixing at all.

This phenomenon explains an awful lot of what we see in the world around us, particularly in the kitchen, so let’s look at – why don’t oil and water mix?

In a later post, I’ll look at oil – and other organic compounds , but for now let’s just look at water.

You see, strange as this may seem, water is a very unusual molecule.  It is only because it is so abundant that it doesn’t seem unusual, but if it was a lot less abundant than it was, it would be considered quite unusual.  The reason is, that it is the second most polar molecule in existence.

By the use of the term polar I simply mean that the charges on the molecule are unevenly distributed.  That is, in just the same way that the Earth has the North Pole and the South Pole, and magnets have a north and south ends, the water molecule has a positive end and a negative end,.

The oxygen (the red atom) sucks all the electrons up its end, thereby causing a negative charge.  At the other end of the molecule, is the hydrogen is (the blue atoms).  There is a net positive charge at this end as the oxygen has pinched all its electrons.

Another simplified way to look at it might be like this, with a charge separation:

Now we all know that opposites attract.  A negative change it attracted towards a positive charge and a positive charge is attracted towards a negative charge.

Some of the molecules in water will align themselves to look like this:

In other words, the negative end of one molecule will be attracted towards the positive end of another molecule, and this provides a very energetically stable structure for the water as it stacks into a regular lattice.

Oil, on the other hand, is very different, and we will look at it tomorrow