Posts Tagged ‘ density ’

With all of us out there who are trying to cut back on the amount of fats we eat, a particular question keeps popping up around dinner time:

Do you want your (insert tasty food here) baked or fried?

Years ago, I wouldn’t even DREAM of choosing baked chicken over fried.  But time is catching up with me and good decisions NOW will be rewarded in the future.  Nevertheless…

WHICH METHOD BEST COOKS OUR FOOD – BAKING OR FRYING?

Again, we need to review the three main ways that thermal energy can DIFFUSE through our food during cooking:

And since we will definitely be looking at the four main concepts of science, we probably should look at them again too:

Radiation is the transfer of waves of energy from every ATOM in the universe.

Conduction is the transfer of thermal energy between two or more objects that are touching each other.

Convection transfers energy through fluids (this means a gas or a liquid.)

It is important to note that all of these methods of heat DIFFUSION follow the LAW OF CONSERVATION.  We never create or destroy any thermal energy when we are cooking.

HERE WE GO!

In our battle between baking and boiling, we learned how our food uses these methods of DIFFUSION to heat our foods within an oven:

Baking uses radiation and convection to DIFFUSE heat into our food.  Thermal energy is released from the electrical coils or gas flames of an oven in the form of radiation which heats up the food.  In addition, some of this radiation DIFFUSES into the metal walls which heats up the air inside the oven itself.  This is how convection heats the food within the oven.  As the air (a fluid) is heated, it DIFFUSES some of its heat into the food as well.

MMMMM….  FRIED GOODNESS!

The process of frying uses a different method of heat transfer to heat our food – Conduction.

In order to fry any food, however, you need something to keep your food from sticking to the pan.  Therefore, you need some form of fat to heat up in your pan before you add your food.

The thermal energy that is absorbed by the pan DIFFUSES into the ATOMS of the food.  Much like with baking at a very high temperature, you have to be very careful that you do not burn the outside of your food while the inside remains raw and uncooked!

SO WHO IS THE WINNER?

In the battle between baking and frying, I would have to say that for thin cuts of meat – frying is the way to go!  The DENSITY of the metal pan provides a much better rate of conduction than the DENSITY of the air within the oven.  With a greater number of ATOMS within each inch of the pan (as compared to the air in the oven), there is more DIFFUSION of heat into the food.

Plus, you can always heat up your herbs and seasonings within the hot oil before frying your food.  This REALLY adds some good flavor to your food.

However, you cannot cook a whole turkey by frying it in a pan!  This large piece of meat needs slow cooking in an environment that is surrounded by thermal energy to be most effective.  Therefore, the oven would be the best bet in this case!

Don’t get me wrong, I love to bake; however, hands down I prefer frying any day!  Just don’t tell my doctor!!!

Learn more about physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

So far, we have seen traditional ovens go against microwave ovens AND the art of baking doing battle with boiling.  Now it’s time we focus our attention on two methods of cooking which rely solely on a large amount of water:

This week, we watch as two heavy weights battle it out.  Our reigning champion BOILING is about to go a few rounds with a new opponent…

STEAMING

These two opponents will be using all of the four main concepts of science as they fight it out this week…

…and the three main ways to DIFFUSE thermal energy through our food during cooking:

Radiation is the transfer of waves of energy from every ATOM in the universe.

Conduction is the transfer of thermal energy between two or more objects that are touching each other.

Convection transfers energy through fluids (this means a gas or a liquid.)

Don’t forget!  All of these methods of heat DIFFUSION follow the LAW OF CONSERVATION.  We never create or destroy any thermal energy when we are cooking.

LET’S GET READY TO RUMBLE!  BRING ON THE BOILING!

We learned previously that boiling only uses convection to DIFFUSE heat into our food.  Heat is DIFFUSED into a fluid-filled container, and as the container absorbs thermal energy it DIFFUSES some of this heat into the fluid.  Since the food you are cooking is completely surrounded by this fluid, it too absorbs thermal energy through the process of convection very well!

STEAMING HAS A SECRET WEAPON

Much like its opponent, steaming uses convection to DIFFUSE heat into our food.  However, you may be thinking that liquid water has a greater DENSITY than water vapor… And you are correct!

The “trick” with steaming requires us to look a little deeper at what is going during the creation of steam.

I’m certain you understand that it takes a large amount of thermal energy to turn liquid water into a gas.  And as thermal energy DIFFUSES into the liquid water, its ATOMS vibrate faster and faster until water molecules break free from each other and evaporate into the atmosphere.

However, what have we learned about the LAW OF CONSERVATION as it pertains to energy?  Can we destroy energy?  No way!  So all that thermal energy that was DIFFUSED into our water molecules HAS to go somewhere!

Some of this energy is DIFFUSED onto the food that the steam is heating.  However, the “secret weapon” of steaming is that some of this energy is released when the super hot water vapor turns back into a liquid!

It’s a ONE-TWO PUNCH for steaming!  Not only does steaming DIFFUSE energy directly by bouncing its molecules into the food, it also releases energy on the surface of the food as its molecules slow down and turn back into a liquid!  This is known as the energy of vaporization.

AND THE WINNER IS…

Boiling has some serious skills.  There’s no doubt about it.  However, I have to give steaming the win this round.  It’s not a knock out, but the one-two punch is pretty darn impressive!  Congrats steaming!

Learn more about physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

Last week we explored the three main ways that thermal energy can DIFFUSE through our food during cooking:

Radiation is the transfer of waves of energy from every ATOM in the universe.

Conduction is the transfer of thermal energy between two or more objects that are touching each other.

Convection transfers energy through fluids (this means a gas or a liquid.)

Now it is time to see who wins between the push-button speed of microwave ovens and the all-time favorite – the conventional oven!

Naturally, we will be using the four main concepts of science within our study of these two culinary devices:

It is important to note that all of these methods of heat DIFFUSION follow the LAW OF CONSERVATION.  We never create or destroy any thermal energy when we are cooking.  However, a lot of thermal energy can be lost into the environment.  You can notice this whenever you get near a hot oven… the air around the oven is warm because thermal energy is escaping into the environment!

You learned last week how the tradition oven works to bake our food:

Baking uses two of these forms of heat transfer:  Radiation and Convection. Thermal energy is released from the electrical coils or gas flames of an oven in the form of radiation which heats up the food.  In addition, some of this radiation DIFFUSES into the metal walls which heats up the air inside the oven itself.  This is how convection heats the food within the oven.  As the air (a fluid) is heated, it DIFFUSES some of its heat into the food as well.

Microwave ovens do something entirely different in order to cook our food.  In fact, this kitchen appliance only uses radiation to heat our food.

To be perfectly honest with you, I could probably spend pages working on how a microwave oven works.  So let me give you the shortened version:

A microwave sends out billions of waves of energy (radiation) towards your food every second.  The water molecules within your food are vibrated back and forth by these waves very quickly.  With all of these ATOMS in constant motion, they bounce into all of the other molecules in the food.  This motion creates a lot of friction, which in turn, increases the amount of thermal energy within the food.  It doesn’t take long for this large amount of thermal energy to DIFFUSE throughout the food!

Friction is a force that is created between two objects that are rubbed together.  The greater the friction between two objects, the greater the thermal energy that is created!  Friction is the reason your hands warm up when you rub them together.

To sum this up:  Foods that contain water are heated very quickly by a microwave!

SO WHY IS THE CONTAINER INSIDE MY MICROWAVE ALWAYS SO HOT?  IT IS NOT MADE OF WATER!

A microwave may easily heat up your food; however, it does not heat up the container at all (or the air.)  The bowls you place in a microwave are heated as thermal energy with the ATOMS is DIFFUSED into the container because of the process of conduction.

SO WHICH METHOD IS BETTER?

Both methods have their good and bad points.  Microwaves can cook food much faster because they are not slowed down by the DENSITY of the food being cooked.  By this I mean that microwave radiation can reach deeper into the food than the radiation produced by a traditional oven.

However, since a microwave can heat up our food much faster, it also can dry out our food much faster too!  It also cannot turn our Thanksgiving Day turkey a golden brown color because a microwave cannot make the surface of our food any warmer than its interior.  This is very important if you want to brown your baked foods!

So who wins this battle?  I say they BOTH win.  A traditional oven is best suited for slow cooking and baking our foods to a juicy, tender result.  And the microwave is best for reheating or preheating foods that don’t require long amounts of cooking.

Personally, I wouldn’t want to live without BOTH of them!

Learn more about physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

We have focused a lot of time and energy on the science behind certain foods.  However, there is a tremendous amount of information to be gained by studying the tools we use to create our breakfast, lunch, and dinner.

This week we are going to begin a journey into several different methods of preparing food.  Before we do, we need to review a few concepts:

We learned from our previous look at pizza that all ATOMS have a little energy in them AND they are always moving a little bit.  Scientists measure all of this movement and call it thermal energy.  And when thermal energy DIFFUSES heat. from a hot object into a colder object, scientists call this

This DIFFUSION of thermal energy can take place in three different ways:

Radiation is the transfer of waves of energy from every ATOM in the universe.

That’s right!  EVERYTHING in the universe gives off thermal energy.

Conduction is the transfer of thermal energy between two or more objects that are touching each other.

Convection transfers energy through fluids (this means a gas or a liquid.)

WHAT DOES THIS HAVE TO DO WITH BAKING OR BOILING?

Since the process of cooking REQUIRES the transfer of thermal energy into our food, these three methods of DIFFUSION are very important!

Baking uses two of these forms of heat transfer:  Radiation and Convection

Thermal energy is released from the electrical coils or gas flames of an oven in the form of radiation which heats up the food.  In addition, some of this radiation DIFFUSES into the metal walls which heats up the air inside the oven itself.  This is how convection heats the food within the oven.  As the air (a fluid) is heated, it DIFFUSES some of its heat into the food as well.

Boiling uses a single method to DIFFUSE heat into our food:  Convection

The role of convection to boil our food should be very easy to see.  Heat is DIFFUSED into a fluid-filled container.  As the container absorbs thermal energy, it DIFFUSES some of this heat into the fluid.  And, since the food you are cooking is completely surrounded by this fluid, it too absorbs thermal energy through the process of convection very well!

POP QUIZ TIME!

Which of the two methods do you believe are better at cooking your food – baking or boiling?

Need a hint?  It has something to do with DENSITY.

Both baking and boiling follow the LAW OF CONSERVATION as thermal energy is absorbed by our food.  No ATOMS are created or destroyed as our liquid cake batter transforms into a solid cake, or our solid potato boils into a squishy mush.

In addition, both methods use fluids to DIFFUSE thermal energy into the food; however, the DENSITY of water is much greater than the DENSITY of air.  Therefore, the fastest way to transfer thermal energy into our food is through boiling!

A small amount of water has more than a thousand times the number of ATOMS than are found in a same amount of air.  Since there are more heated ATOMS touching the boiling food as compared to the baked food, thermal energy DIFFUSES faster into the boiled food!

You prove this fact every time you reach into a hot oven.  Some of that thermal energy warms up your arm while you are taking a baked potato out of the oven.  But it does not burn you! However, I would not recommend sticking your hand in a pot of boiling water to retrieve a boiled potato!  That amount of DIFFUSION would definitely burn you badly!

So in the battle between baking and boiling, it is boiling that wins this round!  Nevertheless, even though the process of boiling may cook our food more efficiently, I think I’ll stick with baking my cakes and cookies nonetheless…

Learn more about physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

I was blessed to have parents that were avid readers.  I’m not saying we were that family that went around the neighborhood quoting Shakespeare, but there was always something to read by my parents side at home.

Like most habits from parents, this one found its way into me at a very young age and has flourished over the years.

We are very lucky to live in a time where we can literally plug ourselves into nearly any book we want through an army of devices like the iPad, Kindle, Sony Reader, iPhones, or Androids.

Now don’t get me wrong, I know that most people cringe at the thought of sitting down with a cup of coffee and the warm glow of a portable electronic device to read some Thoreau.  (As would Thoreau himself; besides, where would he recharge his laptop out there in his cabin?)

For those of you who have checked out my Classic Science Textbooks, it is quite obvious I am a little biased towards eBooks.  This isn’t because I have some deep-rooted hatred for printed copies, I have simply embraced the world of eBooks/audiobooks and I would like to help you take a few baby steps in that direction this week.  I give you…

Project Gutenberg and LibriVox

Project Gutenberg is something you have to check out if you are looking for the classics!  This producer of free eBooks brings nearly every classic book in the public domain to your computer freely and easily.  With over 32,000 copies to choose from and an additional 100,000 from their affiliates, you have a virtual library at your fingertips 24 hours a day.

These books can be easily downloaded in a variety of ways to be uploaded into nearly all portable electronic devices.  Oh, and did I mention this was entirely free???

You can find Project Gutenberg at http://www.gutenberg.org There is no registration or sign up fees whatsoever!

Now if you thought THAT was cool, wait till you check out LibriVox!

I think LibriVox’s mission statement says it all:

LibriVox volunteers record chapters of books in the public domain and release the audio files back onto the net. Our goal is to make all public domain books available as free audio books.

Basically, LibriVox (http://librivox.org) is taking all of the 130,000+ books within Project Gutenberg’s library, converting them into audio books, and releasing them for free on the Internet.

I have fallen in love with this site.  Recently, I have just completed the audio translation of The Aeneid and will be starting The Prince by Machiavelli this week!

To most of us, nothing feels the same as having a book in our hands. I understand that.  Really I do.  But the older I get, and the more time I spend with my students, the more I see how these devices and the resources they have to offer can reach into their world and spark their curiosity.

For many of us, we grew up in a world without personal computers or cell phones.  But the younger generation has NEVER known a time without these devices.  They will embrace this technology in amazing ways and I love watching it unravel before my eyes.

I hope you will check out Project Gutenberg and LibriVox.  I am certain you and your family will truly love the ease and simplicity of a portable library.

And remember, not all of us who have a set of earphones in our ears at the grocery are rocking out with AC/DC.  Well, not ALWAYS….

We’ve looked at several different types of snack foods so far.  What we are about to study is much more complicated that simply popping popcorn.  It contains a few more steps than making potato chips.  Nevertheless, this baked favorite DOES share one important step that is found in the creation of corn and tortilla chips.  This week, we look at…

THE PRETZEL

Have you ever really LOOKED at a pretzel before?  They usually come with so many in a package that we hardly ever take some time to really look at one.

Think about it.  What other food do you find with a shiny dark brown exterior and a white, crumbly internal texture?  Plus…  both of these sides contain their own unique flavor.

The closest thing I can think of that shares these characteristics (somewhat) is a loaf of bread – although I rarely want my bread to have a “dry and crumbly internal texture.”

Before I give up the secrets of this favorite snack food, let’s review some concepts that we’ll be using today:

Much like baking bread, the first step in making pretzels is making a soft dough.  This dough is rolled and twisted into the shape of the finished pretzel.  However, in order to create that shiny brown covering, another very important step is needed.  Lucky for us, we learned a little about this step when we explored how to create tortilla/corn chips.

After the pretzel dough is rolled into shape, it is sprayed with a hot liquid chemical called lye.  This liquid DIFFUSES into the starch on the surface of the pretzel, turning it into a wet and sticky gel.

After this spraying, the dough goes through a long, slow baking to DIFFUSE the remaining water molecules out in order to produce a crisp internal texture.

As water is leaving the dough inside the pretzel, the starch gel on the surface hardens quickly within the oven to produce a shiny outer texture.  At the same time, the lye causes the surface of the pretzel to turn into a DENSE, brown (and flavorful) layer.

Because of the DENSITY of the pretzel dough, the lye does not DIFFUSE beyond its surface.

FYI – Lye is not the same chemical as lime (which is used to soften the hulls of corn before making tortillas.)  Lime is made up of one ATOM of the element Calcium and two ATOMS each of Oxygen and Hydrogen.  Lye is a smaller molecule and is made of one ATOM of Sodium and only one ATOM of both Oxygen and Hydrogen.  Despite this difference, both would cause very serious burns on your skin if you touched these molecules!

This wraps up our look at the Science of Snack Foods… But I’m not done yet!  There is plenty of food science to go…  See you next week!

Learn more about chemistry and physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

The many varieties of corn may give us the tasty snacks of popcorn, tortilla chips, and corn chips.  However, there is no reason why corn should have ALL the fun.  This week, we are going to look at another type of chip…

THE POTATO CHIP

Unlike corn and tortilla chips, the potato does not need as much preparation before it gets a bath in some very hot cooking oil.  It does, however, follow the four basic concepts of science very well:

Potato chips are nothing more than thinly sliced pieces of potato that are deep fried until they are crisp.

You may have noticed all the different kinds of chips at the grocery store.  Nearly all of them follow the same procedure during their creation; however, there is another type of potato chip called “kettle chips” that are generated a little differently.

PROCEDURE #1 – THE REGULAR POTATO CHIP

First of all, there are two ways in order to fry up your potato chips.  The first method is to simply heat them in a pot of very hot cooking oil whose temperature remains around 350 degrees Fahrenheit.  When the potato is placed into this environment, thermal energy very quickly DIFFUSES into its ATOMS, causing its water molecules to evaporate into the oil.

(This is what causes all of those bubbles when you drop chips or fries into a container of hot oil!)

The starch within the potato’s cells normally acts like a sponge, allowing the DIFFUSION of liquids (like the oil) to enter itself and swell.  However, the rapid DIFFUSION of water molecules OUT of its cells (because of the high temperature of the oil) prevents this swelling from taking place.  Within 3 minutes, your chips are done – nice and crispy!

The DENSITY of the chip does not change much, because the size of the chip gets smaller as it loses its water molecules.  And, no ATOMS are being created or destroyed in the process, so it follows the LAW OF CONSERVATION!

PROCEDURE #2 – KETTLE CHIPS

Scientists have learned that if you alter the environment of a food as it is being prepared, you typically end up with a different kind of food.  Kettle chips are the result of this type of experiment.

Cooking potato chips at a much lower temperature at first (around 250 degrees Fahrenheit) and slowing increasing its temperature ends up with a potato chip with a much crunchier texture.  Here’s why…

Lowering the temperature of the cooking oil lowers the amount of thermal energy that will be DIFFUSED into the ATOMS of the potato cells. This gives the starch enough time to absorb extra water on the surface of the potato and swell up.  And as we have learned about starch, some of the sugar molecules within starch will break away from each other during swelling and create a sticky “glue” to bind things together (the “things” we are talking about here are the potato cells!)

This extra stickiness holds the cells together more tightly during cooking and results in a much harder, crunchier chip!

I’ve said it before and I’ll say it again… BRING OUT THE SALSA!  Regular or kettle fried – I’m not picky whatsoever!

Learn more about chemistry and physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

Next to wheat and rice, corn is the third largest human food crop in the world.  This versatile plant not only provides food for millions of people around the world, it also provides nourishment to livestock.  In addition, it can be converted into oil for cooking, thickening powders like corn starch, corn syrup for flavorings, and a variety of industrial uses as well!

This week, we look at how corn can be modified into a couple of very popular snacks:

CORN and TORTILLA CHIPS

Naturally, the four basic concepts of science will be utilized during our review this week:

As we learned in our exploration of popcorn, a corn kernel is made up of millions of cells, each being surrounded by a protective cell wall.  And the cell walls which are found in the hull of a corn kernel (the outer protective shell) are made up of long, fibrous molecules which overlap each other into a very DENSE layer.

It is not the hull that cooks need in order to transform corn into a tasty snack food, it’s what is INSIDE the hull that we are after!  This inner part of a corn kernel is called the endosperm.

Unfortunately, the hull is, for lack of a better word, “glued” to the kernel by molecules which are very good at bonding cells together.

Luckily, cooks have been using a trick to separate the hull from its endosperm for a very long time.

First the corn is cooked in a weak solution of a chemical called lime (no, I’m not talking about the green fruits here!)  Lime is a molecule that, in its pure form, would not be something you would want smeared all over your skin.  It would react to your body much like acid!

SO WHY ARE WE PUTTING SUCH A DANGEROUS MOLECULE ON OUR FOOD?!?!?

Relax.  Like I said, it is a very weak solution of lime (under 5%) and it will be washed away before the next step!  However, as thermal energy is DIFFUSED into the corn, its ATOMS start vibrating and breaking away from each other.  This is when the lime goes to work!

After the corn is cooked for a short while, it is allowed to cool for several hours.  As it is cooling, the lime DIFFUSES into the cell walls of the hull and starts to separate its DENSE fibrous layers from each other.  As these layers move farther and farther away from each other, they become less DENSE which means the hulls get softer.

The lime doesn’t destroy any ATOMS, it only helps to rearrange them within the cell walls.  This follows the LAW OF CONSERVATION as no ATOMS are created or destroyed during this process.

Once the hulls are softened, they can be easily washed away from the endosperm of the kernel (along with any unwanted lime!)

The wet kernels are then ground down into a substance that resembles dough (called masa.)

The masa is then rolled out into thin sheets which can be either baked to make tortillas or deep fried to make corn chips.   The tortillas themselves can be deep fried too!  This produces the ever popular tortilla chips.

Luckily, the process for opening a jar of salsa for my chips is MUCH easier!  I’m out of here!

Learn more about chemistry and physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

I love to snack on foods.  I can’t lie about it.  My friends have all known of my torrid love affair with chips and salsa over the years.  It is shameful.

Now I HAVE made an honest attempt at curbing this desire later in the evenings.  But if I am near a bowl of queso around lunchtime, it will be gone!

Besides chips (which we will be exploring in a future post), I have to say I am very impressed with the innovations that have appeared over the years with this week’s topic of conversation:

POPCORN

Buttered, salted, or plain…. It’s all good!  And throw in the flavorings too – cinnamon, caramel, and an army of different cheeses!  Oh yeah!

BUT HOW DOES POPCORN ACTUALLY POP?

That is an excellent question and is the main focus for this week!  And, as with nearly every natural event in the universe, the reason for these tiny, delicious explosions is rooted within the four main concepts of science:

A CLOSE LOOK AT CORN

There are several different kinds of corn in the world:  Sweet corn, Dent corn (for animal feed), Flour corns, etc.  Some of them will “pop” if heated; however, there is only one kind of corn that explodes into the large, white fluffy snack we love to eat – Popcorn!

The reason this variety of corn pops so well has to do with the structure of each kernel.  We discovered in a previous post on onions that plants are made up cells which are groups of molecules bonded together.  And we already know that molecules are simply groups of ATOMS.

AN EVEN CLOSER LOOK AT CORN

We also described how each cell acts like a small factory, with lots of small departments within itself that each performs a specific task.  Well, now it’s time to look at what protects each of these tiny “factories.”

Every plant cell is surrounded by something called a cell wall.  This wall is actually made up of a thousands of molecules that resemble fibers and overlap each other to give a plant cell a strong outer covering.

If you think about it, plants need to be protected from strong winds, hail, and constant “attacks” by our feet running over them every day!  Unless you break the stem of the plant, it will probably shoot straight up once again in a few minutes!

Cell walls let good nutrients in (as we learned in “Zombie Salad”) and waste materials out!

SO HOW DOES THIS LESSON ON PLANT CELLS FIT INTO MY BOWL OF POPCORN?

The cell walls that make up popcorn’s hull (the protective outer “shell” of each kernel) has much more of those fibrous molecules than other types of corn.  This makes the hull of popcorn more DENSE than other varieties of corn.

And as we have learned about the DIFFUSION of thermal energy, objects that are more DENSE can conduct heat much faster.  Therefore, the DENSE hull of popcorn DIFFUSES heat very easily into the center of each kernel.

BRACE YOURSELF FOR AN EXPLOSION…

As the inside of the kernel heats up to the boiling point of water, the liquid water evaporates into steam and is trapped behind the protective cell wall.

As more and more water molecules absorb this thermal energy and evaporate, they bounce into the cell wall more and more.  This creates a lot of pressure inside the kernel!  When the pressure gets over seven times greater than the air pressure surrounding the kernel, the cell wall tears open quickly and releases all these water molecules into the atmosphere.

This is the beginning of the “pop!”

As these molecules leave quickly, the pressure inside the kernel rapidly gets lower (there’s no more water molecules slamming into the cell wall anymore!) Because of this rapid change in air pressure, little pockets of steam still inside the kernel rapidly get larger (remember – there are no more water molecules pushing in on them which were keeping them small!)

As the pockets of steam expand quickly, so does the soft interior of the kernel which creates the white, fluffy texture of popcorn.

Were any ATOMS lost in this process?  Nope! Were any ATOMS created in the popping of the corn? Nope!

All of this rearrangement of ATOMS follows the LAW OF CONSERVATION perfectly!

That’s enough for now.  Check back next week as we dive into another favorite snack food!

Learn more about chemistry and physical science concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!

I hope I didn’t scare anyone out there last week with my introduction to chocolate making. It is true that the seeds that are used to make chocolate must be covered in all kinds of tiny organisms which do a very good job at rearranging many of their ATOMS.

It may sound disgusting, and it may not smell very good at the time, but the fermentation of these seeds must be done very carefully or your chocolate will not end up tasting very good at all!

This week, we are shipping our dried cacao beans out to a processing plant where they will be turned into the chocolates we use in the kitchen.

Like every week, we are going to be using the four main concepts of science to describe the processing of these beans:

If you recall from last week, our cacao beans have been drying in the hot sun for several days now and they are still covered in acetic acid (aka – vinegar.)

I don’t know about you, but I have never smelled a candy bar and smelled the sour scent of vinegar before!

ROAST…

So the first step is to remove this acid and start to develop the deep flavor of the beans.  This is accomplished by roasting the beans very gently.  We don’t want to DIFFUSE too much heat into the ATOMS of the beans or they will start rearranging way too much.  This roasting process takes less than an hour at temperatures that are typically lower than what you use to bake a cake in your oven.

GRIND…

After a gentle roasting, the beans are cracked open and ground down to tiny pieces.  During this grinding, the oil that is found within the beans (cocoa liquor) escapes from all of the plant cells and forms what looks like a bowl of chunky brown soup.

AND REFINE…

The refining of this chunky liquid involves much more grinding until it becomes a very smooth liquid with tiny solid pieces of the beans still in the fluid.

ALMOST DONE!

At this stage of the chocolate processing, we have a smooth “milkshake” of mulched up beans.  This fluid is passed through a very fine filter where the liquid portion of the solution (cocoa butter) passes through and the solid pieces in the liquid get trapped.  These solid pieces can then be dried and ground down to make what we know as cocoa powder.

The liquid cocoa butter is the foundation for all of the chocolates we love to eat:

Dark chocolate is made of cocoa butter mixed together with extra sugar and vanilla.

Milk chocolate contains cocoa butter, sugar, vanilla, and some dry milk powder.

Regardless of what kinds of chocolate you want to make, the solution that you mix together needs to have the same DENSITY.  You don’t want large pieces of cacao beans inside your candy bar!  It would make the texture of the chocolate very gritty!

In order to keep an even DENSITY throughout each batch of chocolate, scientists press this mixture of cocoa butter and it other ingredients together and grind them one more time.  This stage is called conching (“kon-ching”) and it involves rubbing and smearing this mixture against a solid surface.

Not only does conching help to mix the solution evenly, it also grinds down the chocolate into a very fine texture AND increases its temperature just a little bit.

This increased temperature DIFFUSES into the last remaining bitter and foul-tasting molecules and causes them to evaporate into the environment – leaving the smooth, sweet, tasty dessert we love!

Depending on what kind of dark or milk chocolate you are trying to create, scientists will add a little extra cocoa butter to the final mix (or other chemicals like lecithin) so that it truly will “melt in your mouth” and not turn into a crumbly paste.

Okay.  No more talking.  I’m tearing into that carton of triple chocolate ice cream in my freezer.  See ya!

Learn more about chemistry concepts (and many more) in the Classic Science: Series for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science during breakfast, lunch, and dinner!