CONCEPT 20: STARCH KEEPS EGGS FROM CURDLING Flashcards Preview

THE SCIENCE OF GOOD COOKING > CONCEPT 20: STARCH KEEPS EGGS FROM CURDLING > Flashcards

Flashcards in CONCEPT 20: STARCH KEEPS EGGS FROM CURDLING Deck (49):
1

How does stirring affect the strength of protein networks in eggs for custards? What does this mean?

Besides preventing overcooking or burning, it reduces the extent to which the proteins bond into a solid mass. This means that stirred custards form a thinner sauce while oven-cooked form solid gels.

2

How do starches affect the temperature of coagulation?

Starch granules release spindly threads of amylose that interfere with the cross-linking of proteins, increasing the temp at which eggs coagulate.

3

Name two starches used.

Cornstarch and flour.

4

What dishes are starches important for?

Things like quiche, puddings, pastry cream and hot soup to keep wisps of raw egg added feathery and fine.

5

TEST KITCHEN: FRENCH PASTRY CREAM WITH AND WITHOUT CORNSTARCH.

W/O cornstarch Cream with cornstarch thickened into a creamy, smooth, pudding-like consistency; starch less broke into two phases, becoming a thin, watery base with bits or curdled egg throughout.

6

Why would you brush a raw quiche dough with egg white?

To seal any possible cracks.

7

Do onions make eggs curdle? How?

Yes, the acids they release alter electrical charges on the egg proteins, causing them to clump.

8

Does starch prevent onions from curdling eggs in a quiche?

Yes, starch granules act as a barrier between the proteins, which prevents them from squeezing out liquid.

9

Good ratio of eggs to dairy for quiche filling.

9 eggs to 3 cups of dairy.

10

What is a traditional thickener in hot and sour soup?

Cornstarch

11

If you can't find Chinese black vinegar what's a good substitution?

Equal parts of red wine and balsamic vinegar.

12

How does cornstarch help keep pork tender?

Cornstarch clings to the meat during cooking, creating a protective sheath that slows the loss of moisture.

13

Hot does the heat from chiles and pepper differ?

Unlike chiles, pepper delivers direct spiciness but doesn't leave a lingering burn in its wake.

14

What is Chinese black vinegar made from?

Toasted rice

15

Wood ear mushrooms are also known as what?

Tree ear or cloud ear.

16

What are lily buds and golden needles?

Dried buds of tiger lily flower.

17

Describe the taste and texture of bamboo shoots.

Tangy and mildy crunchy.

18

Should you press tofu for a soup? Why?

Yes, spongelike tofu contains a lot of moisture; weighting it beneath a heavy plate yields firmer, cleaner tasting cubes.

19

When adding egg to a soup, what components help creates fine, feathery shreds and not muddy the appearance?

Acid, cornstarch and a calm surface.

20

How do acid and cornstarch help eggs create a fine, feathery texture in soup?

The vinegar neutralizes some of the electrical charges so they bind and bond together; cornstarch stabilizes the liquid proteins, preventing them from contracting excessively in hot liquid.

21

What is referred to as dark or Asian sesame oil?

Toasted sesame oil

22

What is toasted sesame oil produced from?

Deeply roasted sesame seeds.

23

Does cold-pressed sesame oil have a large flavor and aroma?

No

24

What is toasted sesame oil usually used for?

Flavoring agent for distinctive character rather than a cooking oil.

25

Can cold-pressed sesame oil be used interchangeably with other vegetable oils?

Yes

26

Why should toasted sesame oil only be purchased in a tinted glass and stored in the refrigerator?

It is particularly prone to damage from heat and light.

27

Do white and green area of scallions differ in texture and flavor?

Yes

28

Describe taste of scallions.

Green portion has grassy notes and a peppery bite; white had a delicate, sweet taste similar to shallots.

29

Is the texture of scallion sections different after cooking?

Yes, the whites softened nicely while the greens took on a limp texture; only use greens as a garnish.

30

Should you chop scallions in advance? Why?

No, a dull, soapy flavor takes place of the sweet onions flavor when pre-chopped and left to wait.

31

Flour is 75% what?

Wheat starch

32

What does chocolate pudding usually suffer from?

A dearth of chocolate or grainy texture that's caused by too much cocoa butter.

33

Should you add cornstarch or eggs to a pudding?

Both, pudding made with cornstarch only is a hollow affair; not as texturally dense and creamy as we prefer--eggs add richness and body.

34

Can you add unlimited amounts of bittersweet chocolate in pudding to increase its flavor? Why?

No, manufactured chocolate's fat is made to stay solid at room temp and melt in your mouth. When the cocoa butter resolidifies, its crystalline structure is reorganized and becomes more stable; melts much more slowly. In high amounts it will create a grainy texture.

35

Does cocoa powder have less cocoa butter than bittersweet chocolate?

Yes, it has far less cocoa butter.

36

What adds more chocolate flavor without increasing overall amount of cocoa butter?

Cocoa powder

37

How can you thicken pudding with chocolate?

Using chocolate with a higher cacao percentage will result in a thicker pudding; a higher cacao % means more cocoa butter and cocoa solids, both of which act as thickeners.

38

Compare cacao % in chocolate to fat % in cream.

Just as more fat in heavy cream makes it thicker than milk, a higher % of cacao makes it thicker as well.

39

What does expresso powder do to chocolate?

A little bit of coffee flavor serves to reinforce, but not compete, the flavor of chocolate, enhancing its roasted undertones.

40

Why is pastry cream considered an anomaly among custards?

Overheating typical leads to curdling; however, it's vital to bring pastry cream to a boil--doing so sets the egg and activates (gelatinizes) the starch, ensuring proper consistency.

41

What ingredient makes pastry cream an anomaly? Why?

An enzyme in the yolks called amylase can break down the starch and make pastry cream runny; brining it to a boil destroys the amylase.

42

When it's hot enough, 3 or 4 bubbles will burst on a pastry creams surface. What is the temperature?

200 degrees

43

Which thickener is less potent, cornstarch or flower?

Flour is a less potent thickener.

44

What happens chemically when starch is heated in water?

The granules absorb water, swell, and eventually burst, releasing a starch molecule called amylose that diffuses through the solution, trapping additional water and forming a gelatinous network.

45

Why does cornstarch contain more amylose than flour?

It is a pure starch.

46

If pastry cream isn't heated enough, how does amylase ruin it?

Weakens the starch gels so the custard never fully sets up.

47

Better thickener for pastry cream, cornstarch or flour? Why?

Flour contains proteins and lipids that dilute its capacity to form starch gels, so that more of it is needed for thickening. But these components also act as binders, keeping water trapped and ensuring it's only used for thickening.

48

What happens is pastry cream is heated too much?

The starch granules can burst.

49

What does over-whisking do to pastry cream?

Break the bonds of starch gels and thin it out.

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