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Home Economics: 01.4 - Carbohydrates > Properties Of Starch > Flashcards

Properties Of Starch Flashcards

1
Q

List the properties of starch

6

A 
Solubility 
Flavour 
Hygroscopy 
Gelatinisation 
Hydrolysis 
Dextrinisation
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2
Q

Describe the solubility property of starch

2

A

Starch is a white non-crystalline powder

It in insoluble in cold water

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3
Q

Describe the physical appearance of starch.

A

Starch is a white non-crystalline powder

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4
Q

What is starch insoluble in?

A

Cold water

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5
Q

Describe the flavour property of starch

A

Starch is not sweet in flavour

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6
Q

Is starch sweet?

A

No

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7
Q

Describe the hygroscopy property of starch

2

A

Starch has the ability to absorb moisture from the air

This can cause uncovered foods, e.g. biscuits, to soften and lose crunch

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8
Q

What can starch absorb?

A

Starch can absorb moisture from the air

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9
Q

What affect can hygroscopy have on foods?

A

This can cause uncovered foods to soften and lose crunch due to starch’s ability to absorb moisture from air

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10
Q

What is hygroscopy?

A

The ability to absorb moisture from the air

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11
Q

Give a culinary application of the hygroscopy property of starch

A

It helps to keep cakes moist and prevents them from drying out

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12
Q

What is an advantage of hygroscopy?

A

It can keep cakes moist

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13
Q

What is a disadvantage of hygroscopy?

A

It can cause biscuits to lose their crunch

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14
Q

Describe the gelatinisation property of starch

3

A

When starch is combined with liquid and heated to 55-70 degrees the grains swell, burst and absorb the liquid around them, increasing the viscosity

As the temperature increases (above 85 degrees) it becomes even more viscous and forms a sol

When the mixture cools, water molecules become trapped, resulting in a gel

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15
Q

What is the first step in forming a gel?

A

Starch must be combined with a liquid and heated to 55-70 degrees for the grains to swell, burst and absorb the liquid around them

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16
Q

What affect does starch grains swelling, bursting and absorbing the liquid around them have?

A

It increases the viscosity of the mixture

17
Q

What must starch be mixed with to form a gel?

A

A liquid

18
Q

At what temperature do the starch grains burst?

A

Between 55 and 70 degrees

19
Q

What happens to the viscous liquid formed from the burst starch when it reaches 85 degrees?

A

It becomes even more viscous and forms a sol

20
Q

What temperatures are needed to form a sol?

A

85 degrees

21
Q

What happens when a sol cools?

A

Water molecules become trapped in the mixture which forms a gel

22
Q

Give a culinary application of the gelatinisation property of starch
(2/4)

A

Moist heat - roux sauce, lemon curd;

Dry heat -popcorn, pastry.

23
Q

Describe the hydrolysis property of starch

2

A

Hydrolysis (the reverse of the condensation reaction) occurs during digestion

Water and enzymes split starch (polysaccharide) into the disaccharide maltose

24
Q

What is hydrolysis?

A

The reverse of the condensation reaction

25
Q

What happens to starch during hydrolysis?

A

It is split into the disaccharide maltose by water and enzymes

26
Q

What two things are needed for hydrolysis?

A

Enzymes

Water

27
Q

Describe the dextrinisation property of starch

3

A

When starch foods are dry-heated, short-chained polysaccharides called dextrins are formed

On further heating these combine to form pyrodextrins

This causes a colour change on the surface of the food, resulting in an attractive brown appearance

28
Q

What is formed when starch foods are dry-heated?

A

Short-chained polysaccharides called dextrins are formed

29
Q

What are dextrins?

A

Short-chained polysaccharides formed from the dry-heating of starch foods

30
Q

What forms dextrins?

A

The dry-heating of starch foods

31
Q

What happens when dextrins are heated?

A

Pyrodextrins are formed

32
Q

What forms pyrodextrins?

A

The further heating of a starch food after dextrins have been formed

33
Q

What affect does the formation of pyrodextrins have on food?

A

This causes a colour change on the surface of the food, resulting in an attractive brown appearance

34
Q

Give a culinary application of the dextrinisation property of starch

A

The browning of bread to make toast

Home Economics: 01.4 - Carbohydrates (12 decks)

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