Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FN2232 > topic7 starch > Flashcards

topic7 starch Flashcards

1
Q

what is starch?

A

A carbohydrate, It is a polysaccharide made up of glucose molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

2 major categories of starch?

A

Native Starch
Modified Starch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is native starch?

A

pure starch isolated from original plant material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is modified starch?

A

native starch that has undergone chemical or physical processing to change its properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

2 structures of starch

A

amylose 直链淀粉
amylopectin支链淀粉

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how to distinguish amylose and amylopectin

A

Amylose bule
Amylopectin red purple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

amylose is responsible for gelling or thickening?

A

gelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

amylopectin is responsible for gelling or thickening?

A

thickening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is waxy variety?

A

only contains amylopectins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

sources for starch

A

Cereal grains (corn, wheat, rice, oats)
Legumes (dried beans)
Roots and tubers (potato, tapioca, arrowroot)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

basic ingredients for bubble tea?

A

black tea, water, tapioca pearls, milk, syrup or sweetener

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

why is the tapioca pearls have a dark appearance?

A

added brown sugar or caramal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

wet milling process

A
  1. Cleaning
  2. Grinding or Grating
  3. Slurry
  4. Separation/Refining
  5. Drying
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

maize starch = corn starch

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what’s the difference between whole grain and the white grain

A

no germ(for oil), no bran(for fibre)， so has a little nutritive value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what’s the use of refined starch?(white grain)

A

Added to other foods to act as a thickener增稠剂, stabilizer稳定剂, bulking agent膨松剂 and anticaking agent抗结剂()

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Terminology
Gel and colloid(sol)

A

Gel:colloidal dispersion that holds shape保持形状的胶体分散物
Sol:intermediate between small particles in solution and large particles in suspension介于溶液中的小颗粒和悬浮液中的大颗粒之间

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Starch is deposited in plants in organized units called granules

A

in Seeds, roots and tubers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Birefringence of starch

A

When the starch molecules are observed microscopically under polarized light当在偏振光下显微镜观察淀粉分子时Light is rotated so that the cross-pattern on each granule is observed,光被旋转，以便观察到每个颗粒上的交叉图案This pattern disappears once the starch is heated一旦淀粉被加热，这种图案就会消失

20
Q

what is native starch

A

Developed through traditional plant breeding or genetic engineering No physical or chemical modification of the starch

21
Q

what is modified starch?

A

Chemical or physical modifications may be used to change function in food preparation

22
Q

how to modify starch?

A
  1. Hydrolysis or acid-converted–>used in the confectionary糖果，甜食
  2. Cross-linked or cross-bonded:improved viscosity and texture
  3. Substitution or stabilization prevents retrogradation凝沉
23
Q

the use of hydrolysis or acid converted starch

A

produces Low viscosity paste, stiff gel, Useful in confectionary industry

24
Q

the use of cross linked or cross bonded starch

A

Increased temperature for hydration therefore greater tolerance to heat, Resistant to shear or stirring,Useful for canned soup, spaghetti sauces, and pie fillings

25
Q

steps of hydrolysis starch

A
  1. mix starch with water
    2.add acid
  2. dry
26
Q

steps for physically modified starch

A

1.Instant or pregelatinized –> instant dry mixes, gravies, sauces
2. Cold-water swelling –> pregelatinized\
3. Heat treated —> greater viscosity and stability

27
Q

what is resistant starch

A

Resistant starch is not digested by the human body

28
Q

4 main types of resistant starch

A

RS1 resistant to digestion ex whole grains, seeds
RS2 resists digestion due to compact structure ex green bananas
RS3 retrograded ex cooked and cooled potatoes
RS4 only one chemically modified ex modified starches

29
Q

dry heat and starch

A

Starch becomes more soluble
Reduced thickening ability
Dextrinization –>when starch is broken down into dextrins糊精化——淀粉被分解成糊精
Brown, nutty, toasted flavor develops

30
Q

examples of the use of dry heated starch

A

Examples: Brown Roux and Espagnole Sauce

31
Q

moist heat and and starch

A

Starch granules insoluble in cold water
so
Colloidal dispersion produced with heating
produces Starch paste

32
Q

Changes with Moist Heat and Cooling

A

Gelatinization凝胶化:With heat, starch granules absorb water and swell
Pasting浆糊
Gel formation or gelation –>during cooling
Retrogradation

33
Q

when would retrogradation happen?

A

Occurs upon standing after gel formation

34
Q

what is retrogradation like?

A

Amylose molecules associate more closely, the gel netnork syneresis(脱水缩合)

35
Q

Factors Affecting Starch Pastes

A
  1. Temperature and time of heating
  2. Agitation and stirring
  3. Acidity
  4. Addition of other ingredients
36
Q

Temperature and Time of Heating —> starch pastes

A

Thicker if cooked quickly
undercooked pastes will have a raw starch flavour, and less smooth and silky

37
Q

Agitation or Stirring and starch pastes

A

Stirring is desirable to disperse starch,If excessive – starch granules may rupture破裂 and develop a Slick and pasty mouthfeel口感柔滑，糊状

38
Q

Acidity (pH) and starch pastes:Add acid late in cooking process(lemon pie)

A

May cause fragmentation and hydrolysis,pH below 4 will lead to a thinning of paste
cross-linked starch has a better resistance of acid

39
Q

Addition of Other Ingredients and starch pastes

A

Sugar
Raises temperature of gelatinization,May decrease viscosity
Fats and proteins
Delay hydration of starch
Lowers rate of viscosity development

40
Q

Starch Cookery:Combining starch with hot liquids

A

Roux: prepared by blending melted fat with flour
Slurry: mixing flour or starch with some of the cold liquid which is then added to a hot liquid while stirring

41
Q

how to thickening a liquid with a roux?

A

(a) add cold liquid or stock to a hot
roux or
(b) add cold roux to a hot liquid
or stock.

42
Q

why not recommend to blend a hot roux into hot liquid?

A

it is very difficult to smoothly blend the roux into the liquid before lumps are formed due to the rapid gelatinization of the
starch. 由于淀粉的快速糊化，在形成团块之前，将面粉糊顺利地混入液体是非常困难的。

43
Q

Five Basic Mother Sauces

A
  1. Bechamel 白酱with milk
  2. Veloute 白酱with chicken stock
  3. Espagnole 红酱with beacon
  4. Tomato
  5. Hollandaise 蛋黄酱
44
Q

sauce that thickened by starch

A
  1. Bechamel (white sauce) —>fat, flour, milk, seasonings
  2. Veloute —> fat, flour, veal/chicken/fish stock, seasonings
  3. Espagnole —> fat, flour, beef stock, seasonings
45
Q

sauce that May be thickened with starch

A

tomato

46
Q
A

FN2232 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions