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PRIMARY PRODUCT > Starch > Flashcards

Starch Flashcards

1
Q

Addition of water breaks up amylose crystallinity and

A

disrupts helices

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2
Q

addition of more heat

A

causes more swelling, amylose begins to diffuse out of granule

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3
Q

granules collapsed and held in

A

a matrix of amylose forming a gel

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4
Q

Starch gelatinization is

A

the collapse (disruption) of molecular
order within the starch granule manifested in irreversible changes in properties

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5
Q

in irreversible
changes in properties

A

granular swelling, native crystalline melting, loss of birefringence, uncoiling and dissociation of the double helices and starch solubilisation

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6
Q

Starch gelatinnization (other definition)

A

Destruction of molecular order and irreversible
swelling of starch granules under the influence of heat and/or chemicals in an aqueous medium to give starch paste

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7
Q

In the presence of water, when starch is heated sufficiently

A

the granule begins to swell

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8
Q

Swelling of granule

A

causes viscosity to increase

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9
Q

FACTORS AFFECTING DEGREE OF GELATINIZATION

A

WATER CONTENT

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10
Q

Starch in excess water (>60%)

A

full gelatinization, with suitable time and
temperature

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11
Q

Starch in limited water (<60%)

A

Partial gelatinization, depending on other factors
(time-temperature

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12
Q

Limited water- mechanism of gelatinization

A

Gelatinization of amylopectin crystalline
happen at higher temperature

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13
Q

excess water-mechanism of gelatinzation

A

-Heat will weaken the hydrogen bonding in amorphous granules, and facilitate the
absorption of water into the granule
-Granule swelling that start from amorphous will destabilized the crystalline region and gelatinization of amylopectin occurred

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14
Q

In baked products –

A

many starch granules remain
ungelatinized

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15
Q

In cookies and pie crust (high fat and low water)

A

about 90% of wheat granules remain ungelatinized

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16
Q
  • In cake and white bread (high in moisture) –
A

90% are gelatinized, although many become deformed

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17
Q

EFFECT OF OTHER INGREDIENTS; sugar

A

Very hydrophilic, compete for water with starch, sugar love water

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18
Q

Smaller size of sugar bind easier to water
molecules,

A

less water available for starch granules

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19
Q

under effect of sugar

A

Shifted gelatinization temperature to higher temperature

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20
Q

FAT/EMULSIFIER

A
  • Coating effect
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21
Q

Formation of amylose-lipid complexes

A

Bind tightly into the hydrophobic region of the helix, absorb less water

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22
Q

fat have Ability to hold amylose

A

reduce the tendency of
starch to retrograde

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23
Q
  • Ability of amylose to leach out during
    gelatinization is reduced significantly
A

shifted gelatinization temperature to higher temperature

24
Q

Swelling Ability

A

Waxy maize > Potato > Hylon VII WPH

25
Q

Amylose give strength to the granules

A

hold structure of granule – reinforce effect

26
Q

High amylose starch (Hylon VII)

A

need more heat, higher pressure, longer time with excess water (>60%)

27
Q

Higher temperature,

A

shorter time

28
Q

Shear enhance

A

e starch gelatinization

29
Q

. Heating period –

A

Gelatinization characteristic of starch

30
Q

Holding period

A

Stability characteristic of starch, ability to hold viscosity

31
Q

. Cooling period

A

Retrogradation characteristic of
starch

32
Q

Pasting Process is a phenomenon

A

following gelatinization, in the
dissolution of starch.

33
Q

pasting involves

A

granular swelling (part of gelatinization),
exudation of molecular components from granule and finally total disruption of granule

34
Q

t pasting is not exactly
separated from gelatinization

A

but rather
continuation of gelatinization

35
Q

Analysis Method

A
  1. Microscopy
  2. Rapid Visco Analyzer (RVA)
  3. Differential Scanning Colorimeter (DSC)
36
Q

Retrogradation

A

Phenomenon is which the regular structure of starch molecules, lost during gelatinization, is restored during storage. Amylose molecules rearranging in an orderly fashion and is accompanied by gel hardening

37
Q

When a hot starch is cooled, it generally forms

A

a viscoelastic, firm and rigid
gel or precipitate

38
Q

realigning of starch molecules (amylose) and forming double helixes
that then will aggregate

A

hydrogen bonds break and re-reform into more orderly crystals
* starch becomes progressively less soluble

39
Q

Retrogradation Happens far more rapidly with amylose

A

than amylopectin

40
Q

During retrogradation, amylose associates more easily compared

A

to amylopectin due to restrictions imposed by the branched structure of the molecules

41
Q

Amylose retrogrades over minutes to hours

A

while amylopectin over hours to days

42
Q

Factors affecting retrogradation

A

Size of linear starch molecule, Amylose/amylopectin ratio, Temperature, Interfering molecules

43
Q

Smaller amylose have more tendency than large molecules

A

to
closely associate into “crystal precipitates”

44
Q

More amylose =

A

more and faster retrogradation

45
Q
  • Fatty acids
A

Form insoluble complex with starch and interfere with retrogradation

46
Q

Emulsifiers/surfactants (both hydrophilic and hydrophobic nature)

A

Inhibit retrogradation by complexing with helical amylose (Commonly used in dough for bread and other baked goods to
increase shelf life)

47
Q

Amylose-amylose bonding

A

◼ Desirable when forming a gel
◼ Undesirable when syneresis
◼ Undesirable when gel cracks upon standing

48
Q

Retrogradation can expel
water

A

from polymer network

49
Q

Separation of water out of an
aging gel

A

due to the contraction of the gel as gel
cools

50
Q

The starch molecules pull together more tightly, the gel network shrink

A

and the water is push out of the gel.

51
Q

Retrogradation is the cause behind firming of bread

A

as it cools after baking

52
Q

during baking amylose leeches out and retrogrades almost fully on cooling

A

positively affects texture by giving an elastic and tender crumb

53
Q

On storage amylopectin branches slowly associate

A

crumb and bread hardens = STALING

54
Q

Happens faster during refrigeration but is inhibited

A

during freezing

55
Q

Retrogradation further develop into

A

resistant starch

PRIMARY PRODUCT (7 decks)

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