Learning Lesson: Phase Transitions: When energy is added during cooking, food can change in other ways that getting hotter; these changes are precisely the reasons why we cook food.
The first week introduced molecules and the second week showed how these molecules can transform or rearrange when the temperature is changed. This week Bill Yosses shows how these molecular transformations can transform the overall properties of the food.
Overview of this Week's Science
The transformations that occur during sous vide cooking can be represented on a one-dimensional phase diagram, such as these charts from Dave Arnold:
Eggs undergo numerous transitions, separated by just a few degrees in temperature.
The color of a steak changes from red to brown, as the meat becomes tougher.
Salmon changes from raw and toothy to overcooked and dry.
What's special about the phase transitions that occur during cooking?
Simple phase transitions, like freezing and boiling, are reversible. In other words, the state of the material can be entirely described by its position on the phase diagram. The material can be returned to its original phase by getting back to the same conditions (e.g. temperature and pressure).
How can you transform chocolate from a solid bar into a scoopable foam? As demonstrated by Bill Yosses, chocolate chantilly is a whipped mixture of molten chocolate and warm water. Air is incorporated as the chocolate mixture solidies, leaving behind a mousse-like foam.
To read more, check out the Fooducation blog post.