The Science of the Perfect Grilled Cheese Sandwich

The Science of the Perfect Grilled Cheese Sandwich

August 4, 2019 82 By William Morgan


Alright folks, today we’re talking the
dos and don’ts of one of the world’s best
foods, the grilled cheese sandwich.
And yes, we’ve got the science to back it up.
There are so, so many different types
of cheese out there, but there’s one
type you want when it comes to grilled
cheese – the kind that’s nice and stretchy.
So then how does chemistry get you that
perfect stretchy, gooey grilled cheese?
(Reactions SPLASH INTRO!)
Time for a primer on cheese.
The first step of cheesemaking
is to form curds out of milk.
Milk is 90% water, plus a mix of casein and
whey proteins, lactose, calcium, and fats.
Casein proteins float around in milk in
tiny molecular clumps called micelles
that refuse to stick together because
they have same charge on the outside.
These micelles hold around 2/3rds of
the calcium in milk, and believe it
or not, calcium is the key to
the perfect grilled cheese.
To form curds, bacteria and enzymes
are added to milk to make it coagulate,
or go from a liquid to a solid or semisolid state.
The bacteria converts lactose into lactic
acid to drop the pH, which eliminates
the charge of the casein micelles
to help them stick together.
Enzymes called rennet are
used to speed the process up.
Once the curds are formed, the whey and
excess moisture is drained, and the little
clumps can then be heated, bathed in salt
water, and pressed together to meet the
specifications of different types of cheese.
Once pressed, the cheese is left to age
from days to years depending on the style.
The longer the cheese sits, the more
lactose is converted into lactic
acid, and the lower the pH.
The lower the pH, the “sharper” the cheese.
Remember that folks, because with grilled
cheese, that pH level has a huge effect
on the calcium found inside, and in
turn, the texture when heated.
If protein is the structural backbone
of cheese, than calcium is the rebar
that reinforces the backbone.
It’s what grips all of the casein
molecules together to form the micelles.
Melty, stretchy cheeses have casein
proteins that can break away and go with
the flow and what that takes is a lower
pH which lets the calcium ditch its job
of holding all the casein together.
That means more proteins break out of
their cages to interact with the fats
and moisture in the cheese,
to make everything flow
together as one big, lovely, gooey mess.
But if the pH is too low the cheese will
release all of its oils when heated,
leaving a curdly, clumpy disaster.
The secret to getting the perfect cheese
for a grilled cheese sandwich is to find
one with the right pH to perfectly balance
out the calcium and protein structure.
Cheeses with a pH range between 5.3 and
5.5 are right on the money, and here’s
a handful of perfect examples.
Here’s a Reactions Grilled Cheese Pro tip:
If you’re in the cheese aisle confused
about all the different types of cheddar,
go with the mild one, it’s gonna have
the texture you’re looking for,
unlike its broken down, sharp older siblings.
Oh and what about those perfect yellow
squares of processed “American” cheese?
This type of cheese is made by melting
together two or more different cheeses
like colby and cheddar, and adding an
emulsifier such as sodium or potassium
phosphate, which limits the amount of
calcium holding everything together,
all the while increasing the pH, sometimes up to 5.8.
This makes for a highly meltable cheese
product with an exceptionally mild flavor.
Okay folks, so now you get the picture,
so get the darn cheese already.
If any of you out there have any food
related questions, post them down in
the comments for us but if you’re
hungry for more food chem, check out
this video on the chemistry of pizza.
Today’s episode was inspired by an
absolutely amazing book called the
kitchen as laboratory, check out the
first chapter by Jennifer Kimmel,
The chemistry of a grilled cheese sandwich.
A link’s down in the description,
get yourself a copy! Thumbs up,
subscribe, we’ll see you again soon.