The chemistry of cookies - Stephanie Warren
-
0:07 - 0:08In a time-lapse video,
-
0:08 - 0:11it looks like a monster coming alive.
-
0:11 - 0:14For a moment, it sits there innocuously.
-
0:14 - 0:16Then, ripples across its surface.
-
0:16 - 0:18It bulges outwards,
-
0:18 - 0:20bursting with weird boils.
-
0:20 - 0:21It triples in volume.
-
0:21 - 0:23Its color darkens ominously,
-
0:23 - 0:25and its surface hardens
-
0:25 - 0:29into an alien topography of peaks and craters.
-
0:29 - 0:31Then, the kitchen timer dings.
-
0:31 - 0:32Your cookie is ready.
-
0:32 - 0:34What happened inside that oven?
-
0:34 - 0:36Don't let the apron deceive you!
-
0:36 - 0:38Bakers are mad scientists.
-
0:38 - 0:40When you slide the pan into the oven,
-
0:40 - 0:43you're setting off a series of chemical reactions
-
0:43 - 0:45that transform one substance, dough,
-
0:45 - 0:47into another, cookies.
-
0:47 - 0:50When the dough reaches 92 degrees Fahrenheit,
-
0:50 - 0:52the butter inside melts,
-
0:52 - 0:54causing the dough to start spreading out.
-
0:54 - 0:56Butter is an emulsion,
-
0:56 - 0:57or mixture of two substances
-
0:57 - 0:59that don't want to stay together,
-
0:59 - 1:01in this case, water and fat,
-
1:01 - 1:02along with some daily solids
-
1:02 - 1:04that help hold them together.
-
1:04 - 1:05As the butter melts,
-
1:05 - 1:07its trapped water is released.
-
1:07 - 1:09And as the cookie get hotter,
-
1:09 - 1:11the water expands into steam.
-
1:11 - 1:13It pushes against the dough from inside,
-
1:13 - 1:16trying to escape through the cookie walls
-
1:16 - 1:18like Ridley Scott's chest-bursting alien.
-
1:18 - 1:20Your eggs may have been home
-
1:20 - 1:22to squirming salmonella bacteria.
-
1:22 - 1:25An estimated 142,000 Americans
-
1:25 - 1:27are infected this way each year.
-
1:27 - 1:29Though salmonella can live for weeks
-
1:29 - 1:30outside a living body
-
1:30 - 1:32and even survive freezing,
-
1:32 - 1:35136 degrees is too hot for them.
-
1:35 - 1:37When your dough reaches that temperature,
-
1:37 - 1:38they die off.
-
1:38 - 1:40You'll live to test your fate
-
1:40 - 1:41with a bite of raw dough
-
1:41 - 1:43you sneak from your next batch.
-
1:43 - 1:47At 144 degrees, changes begin in the proteins,
-
1:47 - 1:50which come mostly from the eggs in your dough.
-
1:50 - 1:51Eggs are composed of dozens
-
1:51 - 1:52of different kinds of proteins,
-
1:52 - 1:55each sensitive to a different temperature.
-
1:55 - 1:57In an egg fresh from the hen,
-
1:57 - 2:00these proteins look like coiled up balls of string.
-
2:00 - 2:02When they're exposed to heat energy,
-
2:02 - 2:04the protein strings unfold
-
2:04 - 2:06and get tangled up with their neighbors.
-
2:06 - 2:07This linked structure makes
-
2:07 - 2:09the runny egg nearly solid,
-
2:09 - 2:12giving substance to squishy dough.
-
2:12 -Water boils away at 212 degrees,
-
Not Syncedso like mud baking in the sun,
-
Not Syncedyour cookie gets dried out and it stiffens.
-
Not SyncedCracks spread across its surface.
-
Not SyncedThe steam that was bubbling inside evaporates,
-
Not Syncedleaving behind airy pockets
-
Not Syncedthat make the cookie light and flaky.
-
Not SyncedHelping this along is your leavening agent,
-
Not Syncedsodium bicarbonate,
-
Not Syncedor baking soda.
-
Not SyncedThe sodium bicarbonate reacts
-
Not Syncedwith acids in the dough
-
Not Syncedto create carbon dioxide gas,
-
Not Syncedwhich makes airy pockets in your cookie.
-
Not SyncedNow, it's nearly ready for a refreshing dunk
-
Not Syncedin a cool glass of milk.
-
Not SyncedOne of science's tastiest reactions
-
Not Syncedoccurs at 310 degrees.
-
Not SyncedThis is the temperature for Maillard reactions.
-
Not SyncedMaillard reactions result
-
Not Syncedwhen proteins and sugars break down
-
Not Syncedand rearrange themselves,
-
Not Syncedforming ring-like structures,
-
Not Syncedwhich reflect light in a way
-
Not Syncedthat gives foods like Thanksgiving turkey
-
Not Syncedand hamburgers
-
Not Syncedtheir distinctive, rich brown color.
-
Not SyncedAs this reaction occurs,
-
Not Syncedit produces a range of flavor and aroma compounds,
-
Not Syncedwhich also react with each other,
-
Not Syncedforming even more complex tastes and smells.
-
Not SyncedCaramelization is the last reaction
-
Not Syncedto take place inside your cookie.
-
Not SyncedCaramelization is what happens
-
Not Syncedwhen sugar molecules break down under high heat,
-
Not Syncedforming the sweet, nutty,
-
Not Syncedand slightly bitter flavor compounds
-
Not Syncedthat define, well, caramel.
-
Not SyncedAnd in fact, if your recipe calls for a 350 degree oven,
-
Not Syncedit'll never happen
-
Not Syncedsince caramelization starts at 356 degrees.
-
Not SyncedIf your ideal cookie is barely browned,
-
Not Syncedlike a Northeasterner on a beach vacation,
-
Not Syncedyou could have set your oven to 310 degrees.
-
Not SyncedIf you like your cookies to have a nice tan,
-
Not Syncedcrank up the heat.
-
Not SyncedCaramelization continues up to 390 degrees.
-
Not SyncedAnd here's another trick:
-
Not Syncedyou don't need that kitchen timer;
-
Not Syncedyour nose is a sensitive scientific instrument.
-
Not SyncedWhen you smell the nutty, toasty aromas
-
Not Syncedof the Maillard reaction and caramelization,
-
Not Syncedyour cookies are ready.
-
Not SyncedGrab your glass of milk,
-
Not Syncedput your feet up,
-
Not Syncedand reflect that science can be pretty sweet.
- Title:
- The chemistry of cookies - Stephanie Warren
- Speaker:
- Stephanie Warren
- Description:
-
View full lesson: http://ed.ted.com/lessons/the-chemistry-of-cookies-stephanie-warren
You stick cookie dough into an oven, and magically, you get a plate of warm, gooey cookies. Except it's not magic; it's science. Stephanie Warren explains via basic chemistry principles how the dough spreads out, at what temperature we can kill salmonella, and why that intoxicating smell wafting from your oven indicates that the cookies are ready for eating.
Lesson by Stephanie Warren, animation by Augenblick Studios.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:30
Krystian Aparta edited English subtitles for The chemistry of cookies | ||
Krystian Aparta commented on English subtitles for The chemistry of cookies | ||
TED edited English subtitles for The chemistry of cookies | ||
Jessica Ruby approved English subtitles for The chemistry of cookies | ||
Jessica Ruby accepted English subtitles for The chemistry of cookies | ||
Jessica Ruby edited English subtitles for The chemistry of cookies | ||
Jessica Ruby edited English subtitles for The chemistry of cookies | ||
Andrea McDonough edited English subtitles for The chemistry of cookies |
Krystian Aparta
The English transcript was updated on 2/13/2015.