Squishy, Gooey, Stretchy: The Science of Making Pizza

The Holiday Science LectureHarvard University Science CenterDecember 15, 2007

Little Miss MuffetSat on a tuffetEating her curds and whey;There came a big spider,And sat down beside her,And frightened Miss Muffet away.

Little Miss Muffet knows about cheese

What everyone should know about pizza

The average American eats 1 slice of pizza each week!

How much pizza do you eat?

How many football fields long is the world’s longest pizza? About 5 football fields long, made by Domino’s Pizza in Guatemala.

For the whole USA, that equals about 100 football fields per day.

a football field

Where does pizza come from?scientists are curious:

crustcheese sauce

I make milk. Over there’s the wheat & tomatoes.

This is where pizza really comes from…

sunlight

water(H2O)

carbon dioxide (CO2)

oxygen (O2)

plant

sugars

Atoms to molecules to networks

simple molecules

carbon dioxide (CO2)

oxygen (O2)

H

C

O

N

atoms networks

simple sugar

(C6H12O6)

(H2O)

complex molecules

fat

protein

carbohydrate

C

Atoms are the building blocks of matter

H

C CHH

H

Molecules link together to form a chain…

H

C CHH

H

H

HCH

HC

H

Molecules link together to form a chain…

H

C CHH

H

H

H

H

CCH

H

HCH

HC

H

Molecules link together to form a chain…

H

C CHH

H

H

H

H

CCH

HHCC

H

HH

HCH

HC

H

Molecules link together to form a chain…

H

C CHH

H

H

H

H

CCH

HHCC

H

H

C

H

HH

C H

H

HCH

HC

H

Molecules link together to form a chain…

H

C CHH

H

H

H

H

CCH

HHCC

H

H

C

H

HH

C H

CH HCH H

H

HCH

HC

H

Molecules link together to form a chain…

This is a very long molecule

called a polymer.

Networks: how things bind together

sodium has one + charge

Na+

Na+

Cl-

Cl-

NaCl

Ca2+

Ca2+

Cl-

Cl-

Cl- Cl-

calcium has two + charges

CaCl2

-Alginate polymers have many negative charges.

- - - - - --

-------

-

- - - - - - --

-------Ca+

+

Ca+

+Ca+

+

Alginate chains form a network

Cheeses of the World

All cheese starts as milk

another word is pasteurized

Milk is complicated stuff

fat (oils) protein carbohydrate

Louis Pasteur (1822-1895)

…yet another breakthrough

in microbiology?

!

Avenue Louis Pasteur, Boston, MA

How do you get cheese from milk?

+ =

0.000 075 meters

this is a piece of my hair

a piece of my hairHow small is small?

75 fat drops

milk

+ acid

what do you see?

+50 μm

scientists are curious:Let’s take a closer look at milk

milk + acid

10 μm

milk

+ acid

Cheese is a network of milk particles

fat drop

casein particle

(casein = protein)

+ acid

network of particles+

Steps for making cheese from milk

+ =

3. squeeze out the water

2. sprinkle in acid, network forms

1. start with milk (fat &

protein blobs in water)

live demonstration: help needed!

20 network-makers

40 water molecules

Let’s make cheese

We need:

Now let’s make cheese!

curdswhey

But we don’t put paneer on pizza – we need…mozzarella!

whey

curds