To decaf or not to decaf?

Many of you would have started today with a nice, big cup of coffee (or tea). I know I did. It always seems to help, especially on a Monday, to wake me up and get me going. But do you know anything about caffeine, the major cause of that ‘wake-up’? No doubt many of you would have heard of decaf coffee, but we’ll get to that later.


Ahhhh, the saviour of many a Monday morning.

Above is the culprit: caffeine. Caffeine is known to be the world’s most commonly used psychoactive drug (a scary-sounding definition which simply means that it works by stimulating the central nervous system of the human body). Like alcohol, it is a drug that is legal throughout most of the world, and caffeine is recognised as being safe for human consumption because the amount that we would need to consume to make it toxic is around 10 grams, which is far more than we get in coffee or tea (although excessive energy drinks are a little different).

caffeine binding

Caffeine binds to adenosine receptors in the brain. 

Caffeine works by binding what are known as adenosine receptors, which are found in the brain. Above is a great picture which helps describe how it works when the caffeine structure binds the receptors. It causes you to feel more alert and awake, and also increases your heart rate. Because of this, caffeine has also been used to treat shortness of breath in newborn babies, and low blood pressure.

How much caffeine does the average coffee contain? The average cup of coffee is believed to contain approximately 100 milligrams of caffeine (about 1/50th of a teaspoon), but it really depends on what your brand/ size/ bean/ strength is: it could be anywhere from 40-176 mg. Caffeine is not only found in coffee, but also in tea, and how much caffeine is in tea once again depends on what type of tea, and how the leaves have been treated before being made into a teabag for your cuppa. Interestingly, it was recently found that while tea leaves and cocoa beans both contain caffeine, they evolved in different ways to produce this much-desired stimulant (see Evolution of Caffeine for more information)


It’s ALWAYS coffee time! Get it? 😉 The lab technicians here have a good sense of humour.

Now on to decaf. Some of you may have ‘that’ friend who orders the venti soy decaf orange mocha frappucino (yes, I went there… Jitterbug). Personally, I like a weak latte, but to each their own. Anywho, from the word ‘decaffeinated’, you would probably guess that the coffee doesn’t contain any caffeine, and therefore does not give you that ‘buzz’ that coffee is known for. The fact of the matter is, however, that ‘decaffeinated’ does not necessarily mean ‘no caffeine’, but rather ‘much less caffeine’. In a 2006 study (outlined in this video by Mental Floss), it was found that from ten types of ‘decaf coffee’, nine of these contained 8.6-13.9 milligrams of caffeine (a freeze-dried coffee contained none at all). This is because caffeine is actually removed by dissolving the beans or grounds in water, which takes the caffeine out of the coffee and into the water (which is then discarded). This process works pretty well, but doesn’t remove all of the caffeine. So decaf coffees don’t remove all of the buzz, but do give you a much-reduced dose.


One coffee to rule them all…

So feel free to keep drinking your coffee or tea, it’s not going to kill you. Although drowning in that load of paperwork at your desk might.

GC-MS? What is that???

In a few of my previous posts, and a few yet to come, I mention Gas Chromatography- Mass Spectrometry (GC-MS). It is used when we want to be able to separate and identify the different chemicals which may make up a particular aroma, food, blood sample, soil, and the list goes on! This means that it can be used to identify many things, including drugs in urine samples, poisons in blood, explosive chemicals in soil, and as you would have picked up already in my blog (see Sniff Your Soy and Making wine smell like whiskey), the different chemical components which make up a particular smell. Now is as good a time as any to explain exactly what a GC-MS is, and how it works. It is quite a complex instrument, but I will try to explain it as simply as I can, so that you get the gist of why I will talk about it so much!


Here’s the picture of the GC-MS that I use!

The name Gas Chromatography- Mass Spectrometry gives you a hint that the instrument is made up of two separate parts. The GC part of GC-MS is used to separate different chemical compounds. A gas is set up to flow through a column, which is lined on the inside with particular chemical groups (for example, OH or NH or waxes). By injecting a chemical mixture (for example, the volatiles from soy sauce) down the column, the chemicals can be separated. They separate based on how big they are (larger chemicals may take longer to travel from one end of the column to the other), or how sticky they are to the groups lining the column (certain groups on the chemicals to be separated will try to hold on to the lining of the column, and take longer to travel through the column).


A schematic of a GC.

Once the chemical components are separated, they leave the column and are sent on to the detector.  The detector is the part of the instrument that helps us to work out what the compounds are, and even how much of each compound there is. There are many possible detectors, but in this case, we will just talk about a Mass Spectrometer (MS).

The word ‘mass’ gives you a hint that we are able to identify the different chemical components by looking at their mass. The MS is able to determine the identity of the compound coming off the column by looking at the mass of the compound, as well as the way that the structure can break apart. You see, we hit the chemicals with really strong, energetic hammers known as electrons. These electrons breaks the chemicals apart in very distinct ways, which give very distinct patterns depending on the chemical. So it is as though each chemical has it’s own ‘fingerprint’ map that we can identify it by (known as a mass spectrum).


The ‘fingerprint’ of dodecane, a chemical that is made up of 12 carbons bonded to hydrogens.

Using the MS, we can not only identify the chemical by its ‘fingerprint’, but we can also work out how much of each of these chemicals there are. This is because, on the readout produced by the GCMS (known as a gas chromatogram), it shows a series of peaks. Each peak is representative of one chemical that has been separated by the GC (if the separation is a good one), and therefore each peak would have its own mass spectrum. The area under these peaks tells us how much of the chemical there is, so the larger the peak, the more of the chemical.


A gas chromatogram: The larger the peak, the more there is of that particular chemical.

We can also use what we call ‘standards’. These standards are chemicals for which we know the chemical footprint, concentration, and how long it will take to travel through the column. So if we send the standard through the GCMS, we have an accurate description of not only how long it will take to appear in the MS detector, and how big the peak would be for a certain concentration.

Wow, that was a lot of information! If it helps, here is a five minute video which may explain GC-MS to you in a different way:


Sniff Your Soy?

When was the last time you had a sniff of soy sauce? Personally, I don’t think I ever have. Sure, I love pouring soy sauce all over my dumplings when I visit my favourite Dumpling restaurant in Richmond, but I don’t hold the bottle up to my nose and take a whiff. Although the next time I visit XiaoTing Box, I may do just that.

Here is this week’s QJART!

Characterisation of aroma profiles of commercial soy sauce by odour activity value and omission test

Yunzi Feng, Guowan Su, Haifeng Zhao, Yu Cai, Chun Cui, Dongxiao Sun-Waterhouse, Mouming Zhao

Food Chemistry 167 (2015) 220–228

These researchers, from China and New Zealand, looked at the different aroma compounds which make up the smell of soy sauce. They investigated twenty-seven commercial soy sauces, produced through three different fermentation processes; high salt liquid state(HLFSS), low salt solid state (LSFSS) and Koikuchi (KSS).

Soy sauce manufacture

The three fermentation processes use different soybean:flour ratios, salt concentrations, microorganisms, and bacterial fermentation times.

When you are next at your local chinese restaurant, and smell the soy sauce at the table, I’d like you to guess how many different compounds make up that smell. One? No. Ten? No, higher. A billion? Okay, maybe not that many. But this research identified 129 compounds that were volatile (able to enter your nose because they are in their gas form), and of these, more than 41 compounds which produce a smell (“aroma active components”).

dumpling soy sauce

Mmmm, dumplings and soy sauce…

The aim of this research was to identify what impact, if any, the different fermentation processes have on the smell and flavour of soy sauce. The researchers were able to do this by sensory evaluation (where a panel of ten trained judges smell and describe the soy sauce), as well as by analysing the volatile components by Gas-Chromatography-Mass Spectrometry (GC-MS). A GC-MS deserves its own blog post, so while I have not yet described how a GCMS works, I will tell you now that it enables us to separate, identify and quantify these different volatile compounds.


A photo of a GC-MS that I currently work with.

An interesting point that you will come across in many of my future blog posts is that once we separate out the different chemicals which contribute to the smell of something, we find that they each smell like something that in no way represents the smell of the food as a whole. For example, just a few of the chemical compounds in soy sauce include 3-(methylthio)propanal, guaiacol, benzeneacetaldehyde, and 3-methylbutanal, which on their own would smell like cooked potato, smoke, honey and malt. Another interesting point is that we may not be able to smell some of these volatiles until they are at a certain concentration (known as an odour threshold).

The panel of ten judges for sensory evaluation underwent ‘omission experiments’, where the panel were provided with an aroma ‘model’ (made up of most, but not all, of the aroma compounds of soy sauce) to compare against the complete aroma of soy sauce. In all cases, the panel were able to tell which sample was the complete aroma. This is helpful as it allows the researchers to see which particular aroma compounds (omitted from the aroma model’ make the most impact in the smell of soy sauce.

There were many differences in both the GC results and the sensory evaluation across the different soy sauces and fermentation processes, and the authors noted that the differences in the overall aroma of the soy  sauce was due more to the concentrations of the individual aroma compounds, than the variety of compounds.

I think I know what I want for dinner tonight…

MSG: The devil in disguise or disguised as the devil?

Over the past 24 hours on my facebook feed, I have seen two posts on MSG, and so I figured this is as good a time as any to help debunk the myth of ‘evil MSG’. So… here is the suspect: Monosodium glutamate.

I’m not really that bad… or am I?

You may have heard that MSG is not good for you. You may also have heard that it is present in asian foods (I know that I have seen signs on a number of local take-away joints stating ‘We do not use MSG’). So, with a nice little abbreviation, or in its chemical name, it is easy to spread the word that it is an evil chemical which is bad for you. But, with a little extra chemistry knowledge, a look at the history of research into MSG, and the understanding that just because it has a chemical name doesn’t mean that it will kill you (see ‘sodium chloride’- AKA table salt), you can start to see that this ‘evil’ label is not deserved.

So, lets start with that chemistry knowledge. Monosodium glutamate is a sodium salt (where sodium is that ‘Na’ in the diagram above). In chemistry, what we find with salts is that because they have those little positive and negative signs (charges), they are easier to dissolve in water than things without those charges. They also form crystals much more easily (see sodium chloride once again, those nice crystallised pieces of table salt!)


Mmmm, delicious salt. 

That’s all well and good, but what does that have to do with anything? Well, to give you a little more chemistry knowledge, I’d like to show you another chemical structure. This time, it’s glutamic acid.


Glutamic acid.

Wait a minute, that looks just like… ? Before we go any further, let’s talk about glutamic acid. Glutamic acid is an amino acid, which means that it is a part of many of the foods that we consume each day. Why? Because amino acids make up protein. Protein is present in many foods and beverages, including meats, milk, eggs, nuts, and legumes. The funny thing about glutamic acid is that it is considered non-essential in the human diet; in other words, it is’t necessary for us to eat proteins with lots of glutamic acid BECAUSE WE MAKE IT IN OUR BODIES ANYWAY.

So I could go into detail about how MSG got the bad rap it appears with today, but I think that the American Chemical Society have done a much better job: Check out the Video “Is MSG Bad for You?“, which was created by the ACS (You can follow their Facebook page on Everyday Reactions here). The take-home message from the video is one of the very things I am trying to prove in my blog: If someone tells you that something is bad for you but you can’t find a definitive answer as to why, then it is YOUR job to dig in and research.

While you’re out watching and learning, there’s also this fantastic infographic by Compound Interest: You can view the infographic below, or click on this link for a larger version.

MSG infographic


The Undeserved Reputation of MSG.

Enjoy, and feel free to comment with your thoughts, or any questions you have which I can address in future posts 🙂

The Science of Baking

Check out this awesome infographic describing the chemical nature of baking

Mmmmm… cake….

I have heard a number of times the similarities between cooking/ baking and science in a lab. Throw together a few ingredients, stir them, heat them (I’ve even used a scientific form of ‘microwave’), and voila! Delicious products. Although you probably shouldn’t eat the laboratory ones. Unless you really, really, REALLY want superpowers and aren’t afraid to die in your attempt.

Don’t we all…

The similarities don’t end there. Heat it for too short a period, chances are you’ll end up with a gooey mess (assuming that’s not what you wanted). Heat it for too long or set the temperature too high, blackened mess. Use out of date or impure starting materials, forget to add something, and you also miss out on synthesising your desired product.

This infographic (originally posted on Shari’s Berries) shows just that, and it brings together many of the elements of the food science unit I teach to first years: Proteins (in eggs, milk, and flour), fats (in milk, butter and oils), and carbohydrates (in flour and sugars), as well as yeast, baking soda, and water. All of these ingredients come together to perform separate roles. For example, one role of the fats and oils in baking is to repel water (have you ever noticed how oil and water don’t mix? Here’s why: Polar and Non-Polar Compounds – ignore the ‘practical’ explanation). So by repelling water, water is no longer able to interact with certain proteins, in particular gliadin and glutenin, which together with water make gluten (I’ll be posting soon about gluten). If lots of gluten forms quickly, you end up with a dough that doesn’t rise well. So by using fats to repel water, there is a slow and steady production of gluten, which leads to a nicely formed dough which will rise well.

Side note: Gluten is not the enemy (unless you have coeliac disease).

Another example of the chemical interaction of a baking ingredient is baking soda. Baking soda is known as sodium bicarbonate, and is a ‘leavening agent’. This means that when it reacts with acids in the baking mixture, it releases carbon dioxide. It is this carbon dioxide that helps to form bubbles in the dough, helping it to rise.

It’s okay, carbon dioxide in your bread won’t kill you. 

So the next time you’re planning on baking a cake, think about why you add so many different ingredients for a perfect, delicious product.

And then bring me some cake. I love cake.

More Retronasal Bonito, Monsieur?

Generally, if people decide that a food is too bland at the dinner table, they add salt. However, more and more people are being made aware of the problems that salt (in particular, sodium) can cause to the body: high blood pressure, kidney problems, and even stroke. So what do we do?

Add dried bonito stock, according to Japanese researchers.

Bonito is a type of fish, and dried bonito stock and flakes are commonly used in Japanese cooking, especially soups. They are associated with umami flavour.

Bonito Stock

Bonitooooooooooo.. Used in miso soup!

The interesting part here is how we as humans are able to perceive the smell of bonito. It doesn’t come through sniffing food through our nose (known as the orthonasal pathway). Instead, we perceive the aroma of bonito through the retronasal pathway- that is, after we chew (and even swallow) our food, the aroma is released and travels from our mouth into our nasal cavity.    

Retronasal Bonito

A photo of the setup used to provide retronasal bonito aroma (taken from the article).

Using two forms of bonito stock (arabushi and karebushi), the researchers tested if retronasal bonito enhanced the saltiness of foods (which it didn’t) and also if it increased the palatability of food (which it did).

While this is all well and good, one thing that the researchers note is that bonito, while delicious and flavoursome and enjoyed by many Japanese, is not as appreciated in other cultures. Therefore, bonito may not be the answer to everyone’s low-salt-tasteless-diet woes.  

The Article: Retronasal Odor of Dried Bonito Stock Induces Umami Taste and Improves the Palatability of Saltiness

The Authors: Mariko Manabe, Sanae Ishizaki, Umi Yamagishi, Tatsuhito Yoshioka and Nozomu Oginome

The Journal: Journal of Food Chemistry, 2014

All About Lab Safety…

So, here’s a picture of me and my lab mate:


Jumping for joy! That’s me on the right 🙂

Why are we so happy, you ask? We had just finished filming (and photographing) a video based on the correct footwear to wear in a lab. 

I’m a University lecturer, and I love teaching in the lab. It’s probably my favourite part of the job. You can see from the photo above that our School recently got some brand-spanking-new food science laboratories. They’re beautiful and bright and clean. Yet, to be honest, they’re not entirely safe. 

Don’t get me wrong. They weren’t built incorrectly. They don’t have extremely sharp corners for people to bump into. They don’t have people hiding in dark corners, ready to prey on unsuspecting students with handfuls of candy.

But they’re not entirely safe.

Any science lab is not entirely safe.

That’s why every (good) lab that you walk into has a set of strict rules. Some of these rules include that you must tie your hair back, and wear a lab coat, gloves, and safety glasses. Why? Because we’re not dealing with salt and sugar and vinegar, like in your kitchen at home. Some of the solutions and reagents that are used within these laboratories may burn through your clothes. Others may (most likely won’t and definitely shouldn’t, but may) spontaneously burst into flame if a room gets too warm. If you drop some of these solutions on a bench and splash up into your eye, well… you may never see again. So you are asked to protect yourself.

The same applies to shoes. If you walk into a lab wearing sandals, or thongs, or ugg boots, and you drop a strong acid solution on your feet, you are going to know about it. In our lab, if you don’t wear the correct and safe footwear, you are asked to wear the ‘gumboots of shame’. Yup, they’re just as embarrassing as you imagine.

So now I’m sure you understand why we’re so excited about safe footwear in the lab… Because we don’t have to wear the gumboots of shame 😉