Energy is a great subject in science. It covers so many things and I have many other aspects that I hope to share with you soon but one thing that explains energy so well is a simple rubber band; it can demonstrate elasticity, kinetic energy and potential energy and it great to use in some really cool experiments. Here are just a few short facts on the topic.
What is Elasticity?
Elasticity is the ability of an object to return to its original size and shape after it has been stretched or squeezed.
When we pull an elastic object we are applying a force on it called a stress. If we apply too much stress to an object it will eventually reach a limit called its elastic limit.
When an object is pulled beyond its elastic limit is cannot return to its original shape.
All objects will eventually lose their elasticity due to wear and tear, friction and stress.
Potential and Kinetic Energy
Potential energy is energy stored within something. Kinetic energy is energy in motion.
If we take the example of stretching a rubber band…
When we use force to stretch an elastic object, such as an elastic band we are filling it with potential energy. When we let go of the rubber band and it springs back to its original shape, the energy released is Kinetic Energy.
Did you know… kangaroos and other animals use the combination of potential and kinetic energy to save energy while jumping and springing?
Rubber
Rubber is a material that has very good elasticity. It is a polymer, made up of a long chain of repeating molecules, that can be easily stretched and bent.
Rubber exists in both a natural and synthetic form; the natural form is latex from the sap of rubber trees.
A bit of history
The ancient Aztec and Mayan civilisations are thought to have been the first to discover and use this natural rubber. They used it to make balls for sport and rubber shoes, although the quality of this rubber was sensitive to heat and cold.
Columbus is credited with bringing rubber to Europe.
In 1839 Charles Goodyear discovered that he could stabilise rubber by mixing it with sulphur at high pressure; he called this process vulcanisation.
When Goodyear died in 1860 he was completely impoverished due to constant legal costs regarding his rubber patents.
Did you know… the largest rubber band ball ever made weighed 4,097kg and was made using 700,000 rubber bands?
An experiment to try
Want to try an experiment that combines rubber, elasticity and kinetic and potential energy? Why not make a catapult? Or use elasticity to launch a paper plane. You’ll find out how, and a lot more of the science behind these experiments in this post!
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A new venture
This article originally appeared in Science Spin magazine. Although the magazine is no longer in print I am delighted to be sharing some science facts and experiments in a new venture… you’ll find my new SCIENCE FOR KIDS page in each edition of Easy Parenting Magazine. I share one of our favourite experiments in the April/May edition, currently in shops. Take a look…
Dreams, we all have them, some we remember, some we don’t! There are those who want to analyse every detail of their dreams, seeing them as portents to future events or windows into our souls. Some dismiss dreams as a nothing more than random images as a byproduct of brain activity.
Regardless of what camp of dream analysis you belong to, you may like to know a bit more about the why, how and when of dreams, to fill in the blanks and give a better understanding of what happens when we close our eyes at night.
Are there different types of dreams?
Dreams are a series of images, emotions, senses or events that we experience while we sleep. They are created in the brain, during different brain impulses and can last from a few seconds, to more than half an hour. There are a number of different types of dreams, the classifications vary depending on who you talk to, but in general we experience regular dreams, lucid dreams and nightmares.
The three basic types of dreams are…
Regular dreams usually occur when we are in a deep sleep phase, such as the REM (Rapid Eye Movement) stage of sleep.
Lucid dreams usually occur when we are in a lighter stage of sleep. We are at least partially aware that we are dreaming and we can consciously change the course of the dream if we so choose.
We are all familiar with nightmares and they are not just for children. They are dreams that evoke strong emotions and reactions within us, usually fear, terror, anger or anxiety.
What happens when we dream?
In order to talk about dreaming we must first look at what happens when we sleep and the different stages involved. There are five stages of sleep, stages 1, 2, 3, 4 and the Rapid Eye Movement (REM) stage.
We pass from each stage of sleep sequentially, usually falling into a deeper sleep with each stage. Once we have completed a full cycle (stages 1, 2, 3, 4 and REM) we return to the first stage and the cycle repeats. A full cycle takes between 90 and 110 minutes.
Stage 1
This is a very light stage of sleep, our bodies relax, our muscle activity slows and we experience slow eye movement.
Stage 2
Our eye movements stop, our muscle movements reduce and our brain waves slow down; Our heart rates slow and our body temeratures drop a little. We also experience burst of rapid brain wave activity in this stage, these are called brain spindles. Adults spend about 50% of their sleep time in this stage, this reduces with age.
Stage 3
We enter deep sleep, with some periods of very slow brain waves recorded.
Stage 4
The periods of very slow brain waves extend.
REM Stage
Our eye movement becomes erratic and jerky, our heart rates rise, breathing becomes more rapid and our limbs become temporarily paralysed. We spend about 20-25% of our sleep time in this stage (infants can spend up to 50% of sleep in the REM stage).
The REM stage of the first cycle of sleep is fairly short (about ten minutes) but increases in duration with each cycle (up to an hour in the final cycle).
Stages 1 to 4 of sleep are collectively referred to as the non-REM stages (NREM).
We dream at all stages of sleep but most of our dreams are thought to occur during the REM stage. Studies show that we tend to have different types of dreams at different stages of sleep; In the early stages, we have very short dreams but they are more realistic and relatable. As we move into deeper sleep our dreams tend to become more fragmented. As the night progresses and we experience longer REM states our dreams become more obscure and disjointed.
Why do we dream?
There are a number of theories as to why we dream, but scientists are still not sure. Some say that dreaming is an asinine activity that serves no purpose, but most agree that this is not the case, although they may argue as to the true value of dreams.
Dreaming has no purpose at all
In 1977 psychiatrists J. Allan Hobson and R.W. McCarley theorised that dreams don’t actually mean anything at all. They called their theory the ‘activation-synthesis hypothesis’ and stated that dreamsare merely electrical brain impulses that pull random thoughts and imagery from our memories.
Dreaming is an ancient biological defence mechanism
Evolutionary biologists studying dreams and their function have proposed the Threat Simulating Theory (TST) of dreaming.
The threat simulation theory of dreaming states that dream consciousness is essentially an ancient biological defence mechanism, evolutionary selected for its capacity to repeatedly simulate threatening events.
Basically, dreams are seen as a simulation, a way to prepare our bodies and hone our skills for the right response in potentially threatening situations. By experiences threats and events in our mind (like being chased by a wild animal!) we can train our bodies to respond correctly if or when the threat really does appear in real life. We can develop our neuro-cognitive mechanisms.
The TST also suggests that people under threat in their everyday lives will dream more, as a way to exercise and prepare for the dangers they may experience each day. There is some evidence to suggest this is the case.
Scientists in favour of this theory also quote the fact that a convincing 70% of our dreams are made up of such threatening scenarios.
Dreams help us solve problems
It is possible that dreams help us unravel and review all the complexities we have experienced during our waking hours. Without the restrains of our conscious, logical thinking we can view things from a completely different angle. Some people can wake after a night of sleep with their eureka moment, solving a niggling problem, literally while they catch some z’s. Perhaps the most famous case is that of the chemist August Kekule, who supposedly discovered the benzene ring structure after dreaming of atoms linking together in a chain and then twisting, like a snake biting his own tail, into a ring structure.
The famous American writer, John Steinbeck called this the ‘committee of sleep‘…
It is a common experience that a problem difficult at night is resolved in the morning after the committee of sleep has worked on it
How does all this free thinking work? Daytime events and often recorded in fragmented forms in different regions of the brain. The ‘memory’ is held together by interaction of those brain parts with the hippocampus. During certain stages of sleep these connections are lost, but brain activity in each of these regions may continue. This ‘untethered’ brain activity can provide the freedom of thought and creativity that is constrained in the waking hours.
We dream to fulfil our desires
This brings us back to Freud who believed that our dreams were a manifestation of our basic, unconscious desires and urges. He believed that to better understand our own psychological makeup, and issues, we needed to record and analyse the content of our dreams.
We dream to help us process our emotions
Do we dream to help us process emotional events in a safe way? When we sleep the levels of certain stress hormones in our bodies are reduced, therefore we can reflect on a stressful situation or event, in a safe place, where the stress response has been toned down.
Studies have observed high activity in the amygdala during the REM stage of sleep. This is the area of the brain associated with emotions. This suggests that, while sleeping, our brains access emotional events and memories while the stress neurochemicals (norepinephrine) are suppressed, allowing us to process and resolve any emotions or traumas. We wake feeling better about an event that may have caused us stress the day before.
Dreaming is an important part of our memory storing process
The process of dreaming may help us strengthen, connect and store memories. In order to full consolidate our memories we need to strengthen links between different areas of the brain that have recorded information from the memory, and to integrate the information with previously stored knowledge.
The most basic function of dreaming consists of connecting new material with old material in memory systems; reorganising the memory systems, guided by emotion. (Hartmann, 2011).
Sleep creates an optimal environment to allow memory links to be repeatedly activated without the interference of external stimuli. This reactivation strengthens the neurological pathways that link the various parts of the memory as well as creating links with older memories and learning.
MRI studies have shown that brain areas associated with short and long term memory consolidation (hippocampus and amygdala) are activated while we dream.
Different types of memories may be consolidated at different stages of sleep; the episodic memories are best processed during NREM stages, while more sensory, procedural and emotional events are likely integrated during REM stages.
How long do dreams last?
Dream length varies, but on average our dreams start off short and get longer as the night progresses. Although some dreams may only last for seconds, our first dream of the night is usually about five minute long, our last dream can be as long as 45 minutes. As most of our dreaming occurring during the REM stage of sleep, as this stage gets longer, so too do our dreams.
Most people have at least two to three dreams per night, with the average being six to seven. We spend about two hours a night dreaming, which can add up to a whopping six years of dreaming in a lifetime!
These theories and insights are fascinating but there is still much to learn. Scientists will continue to research, study and debate the importance of the dreaming process, but, looking at how much of our lives we spend dreaming it is certainly a worthwhile study.
So far this Irish Summer has been a bit of a washout. As I type, the wind is howling and the rain is sheeting down. We brave it when we can, and, when we can’t, we come up with indoor activities to amuse us. Sometimes though, there is nothing for it but to take out the blankets and turn on Netflix.
Here are some of our viewing recommendations this Summer. I’ve noticed a bit of a trend when comparing the adults choices to the children’s… both seem to include scifi, history and humour – not a bad mix!
THE CHILDREN
Scifi – the children were delighted to see Guardians of the Galaxy come to Netflix (this movie has a 12s rating) and it has already served them well as a ‘movie night’ option with friends.
Tech – We have introduced a bit more coding in the house this Summer, after a wonderful introduction from Galway’s Coderdojo classes. The children have loved the hour of code and have completed the Minecraft and StarWars challenges. This has sparked their coding imagination, and now they have found Gaming show (in my parents’ garage) they are completely hooked.
History – Horrible Histories is a constant entertainer in this house, even the adults have watched most of the episodes. It is amazing how the children are quoting historic facts, learned from the programme. When they finish the series they just start again from the beginning.
Humour – Apart from the giggles they get from Horrible Histories, the children are also loving the newest series of King Julien. I often pop my head in the room to find three laughing children snuggled on the couch.
THE ADULTS
Scifi – we stumbled across a scifi film called Push and loved it. It certainly deserves more than the three stars it currently has in the rating. The movie is about people with special powers, some can read minds, see the future, implant memories in people’s heads and move objects with their minds. And when the good guys and the bad guys have similar talents the story line keeps moving at quite a pace.
History – I am lucky if I get near the remote control these nights, since the second series of Marco Polo arrived on Netflix my husband has been binge watching. He is curious about the Mongol empire and enjoys the way the drama is portrayed.
Humour – The full second series of Better Call Saul is now available on Netflix. Although the plot thickens and the story gets a little darker, there is still plenty of the humour that so impressed us from the first series.
Image credit: Ben Leuner/Netflix
Regardless of what we watch, we usually round off the night’s viewing with a good belly-laughing episode of The Big Bang; It is consistently brilliant!
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Disclosure: As a member of the Netflix Stream Team I have received a year’s subscription to Netflix, free of charge, and an Apple TV, for streaming purposes. As part of Netflix Stream Team I will be posting regular updates on what we are watching and what is on offer. All opinions expressed are my own.
If you have ever wondered about the science of pancakes, their history, why they are round or even the formula for the perfect pancake flip then read on!
I know that pancakes Tuesday is late this year but it still seems to have come around awfully quickly. In this house the pancake does not just feature once a year but every weekend and with that kind of frequency we have covered a lot of questions about this not so humble food.
So if you have ever wondered about the history of the pancake, the science of getting them just right, why they are round or even the formula for the perfect pancake flip (L = 4 H /P- D / 2 if you’re interested) then read on!
…..”WHAT IS THE SCIENCE BEHIND A GOOD PANCAKE, AND WHO’S IDEA WAS IT?”…..
Made in the name of Science
A BIT OF HISTORY…
So, before I delve into the science behind the PERFECT PANCAKE, I thought I’d look at a little bit of history first. The pancake as we know it seems to be accredited to the ancient Greeks, who in the 6th century started combining ground wheat with olive oil, honey and milk – and so the first pancake was born. If we expand on our concept of what a pancake really is we could look back further still to the process of making flat bread from ground grains and nuts mixed with milk or water, dating back to the neolithic period.
WHAT DO WE FIND IN A MODERN PANCAKE?
If we start within Europe a modern pancake can be classified as the round flat variety similar to the french crepe which contains some form of flour, and a liquid such as milk or water. These flat pancakes usually also contain eggs and butter, and sugar in the sweetened variety. Then we also have the thicker, fluffier pancakes that contain a raising agent, the name and variation of these include drop scones, Scottish pancakes and of course the well know buttermilk pancakes that are most common in America.
In our house the three most common pancakes made are the buttermilk pancakes, drop scones and the sweet flat crepe like ones.
WHAT GOES INTO A PANCAKE…
If we take a closer look at the primary ingredients we begin to see the complexity and science that really goes into making these delights:
FLOUR… this ingredient can be considered the backbone of the pancake as it provides structure
SUGAR….as well as adding the nice sweet taste and contributing to the colour of the pancake, sugar also keeps the pancake from getting to thick and stodgy
EGGS…. the proteins in the eggs add to the structure of the pancake and to the overall flavour
BUTTER/FAT… as with the sugar, the fats keep the pancake tender and prevent them becoming overly stodgy
MILK/WATER… the liquid portion of the pancake adds to the structure and is necessary for certain chemical reactions to occur
RAISING AGENT… as the name suggests, these agents help raise the pancake, making them light and fluffy
You can of course find many varieties with their own local changes and substitutes, potatoes are commonly used as the starch ingredient instead of flour.
First lets take a look at the thin flat pancake or crepe… in this case we will assume they contain flour, milk and sugar. From the above list we can now predict that the flour is the body of the pancake, it provides the structure, but how does it do this? There are two proteins found in flour called glutenin and gliadin. When moisture is added to flour (in this case the milk) these two proteins link together to form gluten. Gluten is a “sticky” protein, this stickiness allows it to form a network and it is this that adds structure to the batter. Finally we come to the sugar which caramelizes with the heat adding sweetness to the mix and contributing to the colour of the pancake as it cooks. The sugar also prevents the pancakes becoming too thick and stodgy by reducing the amount of gluten produced.
So now we move on to the thicker pancakes; the main difference with these is that they contain a raising agent! Yeast is a biological raising agent used in some baking, it produces carbon dioxide gas while digesting sugar and this gas forms tiny bubbles within the yeast. When heat is added during baking these bubbles expand making the bread/cake “rise”.
The main drawback with baking with yeast is that it requires time and who really wants to wait too long for their breakfast? That is why, when using raising agents in pancake mixtures, we substitute the yeast for bread soda and/or baking powder; but who can really tell what the difference is between these two?
Bread soda (also known as baking soda) is pure sodium bicarbonate. Baking powder contains bread soda but it also contains a powdered acid (usually cream of tartar – potassium bitartrate). Bread soda is an alkali/base and will therefore react with an acid (such as the buttermilk used in pancake batter) producing salt, water and carbon dioxide gas…
BREAD SODA + ACID —–> SALT + H20 + CO2
This carbon dioxide gas gets trapped in thousands of tiny bubbles within the gluten making the pancake batter rise on cooking into light and fluffy wonders! (The same process as with the yeast but a lot quicker).
The baking powder has the added advantage of having the acid already present, so once a liquid is added the dry acid and alkali can react in the same manner as above.
So now that we are starting to understand the science of it all how do we use this knowledge to make the best pancakes. before we jump into this one we first have to consider the science of flavour and odour!
THE SCIENCE OF FLAVOUR
The Maillard reaction describes a chemical reaction requiring certain amino acids and sugars and the addition of heat to produce the molecules responsible for the odours and flavour of food. Now there is a science worth studying!
So what does this have to do with our pancakes? Well, Maillard reactions work best in alkali conditions so bread soda is a definite plus is making golden tasty treats. HOWEVER, add too much bread soda and the pancake will brown too quickly and will have an acrid burnt flavour, not to mention the unpleasant taste produced from the left over breadsoda. It is trickier than we think and yes, of course, someone has already done the science bit for us to work out the ideal amount of bread soda required.
WE ARE HUNGRY – SPEED IT UP
You will be glad to hear that speed is recommended when preping pancakes; Although it is good to allow the batter sit for a few minutes to allow the gluten to “relax” (build up a sufficient network) it has been shown that if left too long the bubbles will have burst and the pancakes will be flat and dense once cooked.
SCIENCE IN MY KITCHEN
I decided I had to try some of this pancake science out for myself so turned to my original buttermilk pancake mix from the wonderful NIGELLA LAWSON. This recipe actually uses both baking soda and baking powder (I omitted the banana). I decided to test out two theories…
1. Does the amount of bread soda determine the colour and flavour of the pancake?
2. Does the length of time the batter is left standing really make that much of a difference?
To keep it simple, I decided to keep everything else (including the amount of baking powder) constant.
So I donned my apron in favour of my labcoat and I set to work. I prepared the basic batter mix excluding the addition of bread soda. To digress for a moment, I also followed another golden pancake rule – not to over-mix the batter (a few small lumps of flour allows it better absorb the liquid and produce gluten).
My “slightly lumpy” pancake batter
I divided my basic batter mix between four bowls and then added different amounts of bread soda to each (the first bowl had no bread soda, the second had half the recommended amount, the third had the recommended amount and the fourth had double what was recommended!). Then I let the batter sit for five minutes before cooking the pancakes.
Here are my results… the pancake on the top left had no bread soda, top right had 1/2 the recommended amount, bottom left had the ideal amount and bottom right had twice the recommended amount. You can see how the pancake gets darker with the addition of more bread soda, with the last one being just a bit too dark. The taste test revealed that the one on the bottom left had the best taste (and texture) and that the one with the most bread soda had that unpleasant taste of bread soda!
To investigate my second question I left the same pancake batters sit for two hours before cooking them. As you can see the pancakes cooked after two hours were indeed a lot less light and fluffy and were a bit soggy inside!
The batter for these pancakes was left for five minutes
The batter for these pancakes was left for two hours
WHY ARE PANCAKES ROUND?
Pancakes are round for two main reasons: gravity and surface tension. Assuming that the pancake pan is flat then once the batter is added gravity will pull on all parts of the batter uniformly in all directions, pulling it out into a round shape. Surface tension pulls evenly on the edges keeping them restrained into the round shape.
According to University Professor of Mathematics Frank Smith, the simple mathematical formula for the perfect flip is: L = 4 H /P- D / 2
(L = hand distance from inner edge of the pancake / H = height of flip / D = diameter of pancake)
Dr. Tungate, a senior physics lecturer at Birmingham University, found that “a pancake should be flipped into the air at a speed of 10 miles-an-hour, which means that it takes less than .5 of a second to reach the top of its trajectory.”
AND THEN THERE IS THE SCIENCE OF WHAT YOU ACTUALLY PUT ON YOUR PANCAKES…
… but I think that is a whole other blog! So whatever toppings you choose I hope you enjoy your pancakes today!!
All that Science made me hungry!
And if you still want more….HERE IS AN EXPERIMENT YOU CAN TRY….
This experiment shows two fun ways of inflating balloons, kids will love it, it’s easy to do and it teaches some kitchen science… like the difference between using yeast and bread soda as raising agents in baking!
A rocket can describe any object that is propelled by fast moving liquid or gas!
Most rockets have a nose or cone at the top, a body that houses the fuel and fins at the base.
Rockets are usually powered by a chemical reaction (explosion) within the rocket itself. This chemical reaction requires both fuel and oxygen, both of which must be carried within the rocket.
The fuel and oxygen are called the propellant. There are two types of propellant, liquid propellant and solid propellant.
A solid propellant rocket is easier, simpler and cheaper to make. However, these rockets are harder to guide and control as once the chemical reaction is started it is hard to stop.
A liquid propellant rocket is more complex and expensive to make but the burning of the liquid fuel is allot easier to control.
photo credit: Flying Jenny via photopin cc
A bit of history
The Chinese were the first to invent rockets when they started filling bamboo tubes with gunpowder and lighting them.
Rocket science really began with an English man called Isaac Newton. He formulated three laws to explain the physics of motion. These laws explain how rockets work!
Newton‛s 3rd Law of Motion states that every action has an equal and opposite reaction!
To understand this law think of a balloon full of air.
Demonstrating Newton’s 3rd Law of Motion
If the balloon is untied and the air suddenly let out, it will escape the balloon with such force that it will propel the balloon in the opposite direction.
The force of the air leaving the balloon is called the thrust! The thrust that powers the launch of a rocket comes from the force of the gas (generated by the burning fuel) being ejected from the rear of the rocket!
The first liquid propellant rocket was launched in 1926 by an American called Robert Goddard. He is considered the father of modern rocket science!
Rocket to the Moon
Neil Armstrong… photo credit: NASA’s Marshall Space Flight Center via photopin cc
In 1969 Neil Armstrong and Edwin Aldrin became the first men on the moon.
Armstrong and Aldrin traveled to the Moon in a rocket called Saturn V. It was 100 metres tall and weighed more than 3,000 tonnes! It was the largest rocket ever launched!
An Experiment to try at home
Make a stomp rocket!
You will need… an empty 2L plastic bottle, paper, insulation tape, a 1/2 inch PVC pipe, a length of rubber tubing;
What to do… tape one end of the rubber tubing to the neck of the bottle and tape the other end to one end of the PVC pipe. Next make the body of the rocket by wrapping a piece of paper around the PVC pipe and secure it with tape at the overlap. Remove the rocket from the pipe. Cut four triangles of paper and attach to the body of the rocket near one end; these are the rocket fins. Make a nose (cone shape) for the other end of the rocket and attach it with tape. You are now ready to launch your rocket. (Best to do this outside!).
Sit your paper rocket over the PVC pipe and place the 2L bottle on the ground on its side. Stomp on the bottle and watch your rocket shoot off!
This is what your stomp rocket should look like
So what is happening?… when you stomp on the bottle the air inside it shoots out through the tubing and the pipe, forcing the rocket off the end of the pipe! Just blow into the pipe to re-inflate to bottle to start again!
An Experiment to try at home
Make a teabag rocket
I have shared this one with you before, but for those of you who have not seen it I thought it would be a nice addition here…. a double for the Bank Holiday Weekend ;0)
If you try any of the experiments or have any comments or questions, please let me know in the comments below!
Ok, this week’s blog inspiration is slightly different to the norm. Usually the idea comes from a question that a child has posed – this time there is a slight deviation, but only slight…. this weeks question came from an adult, but only in the chronological sense – as in fact he is classified as the biggest kid in our house- it was posed by my husband. I was making pancakes the other morning (as I do every weekend on the request of my son) when my husband pondered aloud…”I wonder what the reason behind each ingredient is… and who made the first pancakes”. As I was wondering what next to blog about the two ideas seemed to merge into one, and so was born the question…..
…..”WHAT IS THE SCIENCE BEHIND A GOOD PANCAKE, AND WHO’S IDEA WAS IT?”…..
Made in the name of science
A BIT OF HISTORY…
So, before I delve into the science behind the PERFECT PANCAKE, I thought I’d look at a little bit of history first. The pancake as we know it seems to be accredited to the ancient Greeks, who in the 6th century started combining ground wheat with olive oil, honey and milk – and so the first pancake was born. If we expand on our concept of what a pancake really is we could look back further still to the process of making flat bread from ground grains and nuts mixed with milk or water, dating back to the neolithic period.
WHAT DO WE FIND IN A MODERN PANCAKE?
If we start within Europe a modern pancake can be classified as the round flat variety similar to the french crepe which contains some form of flour, and a liquid such as milk or water. These flat pancakes usually also contain eggs and butter, and sugar in the sweetened variety. Then we also have the thicker, fluffier pancakes that contain a raising agent, the name and variation of these include drop scones, Scottish pancakes and of course the well know buttermilk pancakes that are most common in America.
In our house the three most common pancakes made are the buttermilk pancakes, drop scones and the sweet flat crepe like ones.
WHAT GOES INTO A PANCAKE…
If we take a closer look at the primary ingredients we begin to see the complexity and science that really goes into making these delights:
FLOUR… this ingredient can be considered the backbone of the pancake as it provides structure
SUGAR….as well as adding the nice sweet taste and contributing to the colour of the pancake, sugar also keeps the pancake from getting to thick and stodgy
EGGS…. the proteins in the eggs add to the structure of the pancake and to the overall flavour
BUTTER/FAT… as with the sugar, the fats keep the pancake tender and prevent them becoming overly stodgy
MILK/WATER… the liquid portion of the pancake adds to the structure and is necessary for certain chemical reactions to occur
RAISING AGENT… as the name suggests, these agents help raise the pancake, making them light and fluffy
You can of course find many varieties with their own local changes and substitutes, potatoes are commonly used as the starch ingredient instead of flour.
First lets take a look at the thin flat pancake or crepe… in this case we will assume they contain flour, milk and sugar. From the above list we can now predict that the flour is the body of the pancake, it provides the structure, but how does it do this? There are two proteins found in flour called glutenin and gliadin. When moisture is added to flour (in this case the milk) these two proteins link together to form gluten. Gluten is a “sticky” protein, this stickiness allows it to form a network and it is this that adds structure to the batter. Finally we come to the sugar which caramelizes with the heat adding sweetness to the mix and contributing to the colour of the pancake as it cooks. The sugar also prevents the pancakes becoming too thick and stodgy by reducing the amount of gluten produced.
Image credit: jbeancuisine.com
So now we move on to the thicker pancakes; the main difference with these is that they contain a raising agent! Yeast is a biological raising agent used in some baking, it produces carbon dioxide gas while digesting sugar and this gas forms tiny bubbles within the yeast. When heat is added during baking these bubbles expand making the bread/cake “rise”.
The main drawback with baking with yeast is that it requires time and who really wants to wait too long for their breakfast? That is why, when using raising agents in pancake mixtures, we substitute the yeast for bread soda and/or yeast; but who can really tell what the difference is between these two?
Bread soda verse baking powder
Bread soda (also known as baking soda) is pure sodium bicarbonate. Baking powder contains bread soda but it also contains a powdered acid (usually cream of tartar – potassium bitartrate). Bread soda is an alkali/base and will therefore react with an acid (such as the buttermilk used in pancake batter) producing salt, water and carbon dioxide gas…
BREAD SODA + ACID —–> SALT + H20 + CO2
This carbon dioxide gas gets trapped in thousands of tiny bubbles within the gluten making the pancake batter rise on cooking into light and fluffy wonders! (The same process as with the yeast but a lot quicker).
The baking powder has the added advantage of having the acid already present, so once a liquid is added the dry acid and alkali can react in the same manner as above.
So now that we are starting to understand the science of it all how do we use this knowledge to make the best pancakes. before we jump into this one we first have to consider the science of flavour and odour!
THE SCIENCE OF FLAVOUR
The Maillard reaction describes a chemical reaction requiring certain amino acids and sugars and the addition of heat to produce the molecules responsible for the odours and flavour of food. Now there is a science worth studying!
So what does this have to do with our pancakes? Well Maillard reactions work best in alkali conditions so bread soda is a definite plus is making golden tasty treats. HOWEVER, add too much bread soda and the pancake will brown too quickly and will have an acrid burnt flavour, not to mention the unpleasant taste produced from the left over breadsoda. It is trickier than we think and yes, of course, someone has already done the science bit for us to work out the ideal amount of bread soda required.
WE ARE HUNGRY – SPEED IT UP
You will be glad to hear that speed is recommended when preping pancakes; Although it is good to allow the batter sit for a few minutes to allow the gluten to “relax” (build up a sufficient network) it has been shown that if left too long the bubbles will have burst and the pancakes will be flat and dense once cooked.
SCIENCE IN MY KITCHEN
I decided I had to try some of this pancake science out for myself so turned to my original buttermilk pancake mix from the wonderful NIGELLA LAWSON. This recipe actually uses both baking soda and baking powder (I omitted the banana). I decided to test out two theories…
1. Does the amount of bread soda determine the colour and flavour of the pancake?
2. Does the length of time the batter is left standing really make that much of a difference?
To keep it simple, I decided to keep everything else (including the amount of baking powder) constant.
So I donned my apron in favour of my labcoat and I set to work. I prepared the basic batter mix excluding the addition of bread soda. To digress for a moment, I also followed another golden pancake rule – not to over-mix the batter (a few small lumps of flour allows it better absorb the liquid and produce gluten).
My “slighlty lumpy” pancake batter
I dived my basic batter mix between four bowls and then added different amounts of bread soda to each (the first bowl had no bread soda, the second had half the recommended amount, the third had the recommended amount and the fourth had double what was recommended!). Then I let the batter sit for five minutes before cooking the pancakes.
Here are my results… the pancake on the top left had no bread soda, top right had 1/2 the recommended amount, bottom left had the ideal amount and bottom right had twice the recommended amount. You can see how the pancake gets darker with the addition of more bread soda, with the last one being just a bit too dark. The taste test revealed that the one on the bottom left had the best taste (and texture) and that the one with the most bread soda had that unpleasant taste of bread soda!
To investigate my second question I left the same pancake batters sit for two hours before cooking them. As you can see the pancakes cooked after two hours were indeed a lot less light and fluffy and were a bit soggy inside!
The batter for these was left sit for five minutes
The batter for these was left two hours
WHY ARE PANCAKES ROUND?
Pancakes are round for two main reasons: gravity and surface tension. Assuming that the pancake pan is flat then once the batter is added gravity will pull on all parts of the batter uniformly in all directions, pulling it out into a round shape. Surface tension pulls evenly on the edges keeping them restrained into the round shape.
According to University Professor of Mathematics Frank Smith, the simple mathematical formula for the perfect flip is: L = 4 H /P- D / 2
(L = hand distance from inner edge of the pancake / H = height of flip / D = diameter of pancake)
Dr. Tungate, a senior physics lecturer at Birmingham University, found that “a pancake should be flipped into the air at a speed of 10 miles-an-hour, which means that it takes less than .5 of a second to reach the top of its trajectory.”
AND THEN THERE IS THE SCIENCE OF WHAT YOU ACTUALLY PUT ON YOUR PANCAKES…
… but I think that is a whole other blog! So whatever toppings you choose I hope you enjoy your pancakes today!!
All that science made me hungry!
And if you still want more….HERE IS AN EXPERIMENT YOU CAN TRY….
Inflating balloons… This experiment shows two fun ways of inflating balloons, kids will love it, it’s easy to do and it teaches some kitchen science… like the difference between using yeast and bread soda as raising agents in baking!
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