INTRODUCTION, STRUCTURE OF AMYLOSE AND AMYLOPECTIN, GELETANIZATIO, RETROGRADATION, STALING OF BREAD, RESISTANT STARCH, APPLICATION

1. STARCH
FOOD CHEMISTRY
Presented By: GEETARANI LOUSHIGAM
Of MSc Food Technology and Quality Assurance, 2020-22
COLLEGE OF INDIGENEOUS FOOD TECHNOLOGY, KONNI

2. INTRODUCTION
01
STRUCTURE
02
CHARACTERISTICS
03
TYPES OF FOOD STARCH
AND RESISTANT STARCH
05
CONTENT
APPLICATION
04
STARCH COMPLEX
04

3. INTRODUCTION
• Starch are made up of glucose molecules synthesized by plants through the process of
photosynthesis.
• They are utilized for energy or stored(chloroplast) in the seeds, stem, or tube, hence serves
the plant as a reserve food.
• Provides 70-80% of the calories consumed by humans.
• They are crystalline in nature and are made up of two components: Amylose and Amylopectin.
• Source:
Roots/Tubers: Potato, Tapioca
Cereal : Corn, Wheat, Rice

4. STRUCTURE
Starch granule
Amylopectin
Amylose

5. AMYLOSE AMYLOPECTIN
It contribute to gel formation. This is because
the linear chains can orient parallel to each
other, moving close enough together to bond.
Amylose is the compound that is responsible
for the blue color produced by iodine with
starch.
The branched amylopectin molecules give
viscosity to the cooked paste. This is partially
due to the role it serves in maintaining the
swollen granule.
Wheat starch granules stained with iodine

6. GELATINIZATION

7. What happens when starch is added to COLD water?
• Starch is added to cold
water at room temperature
• Takes up 30-40% of dry
weight moisture.
• Temporary suspension
• Swollen granules
settles to the bottom

8. But if we heat the water…
Hot water breaks
hydrogen bonds and
increases swelling.
Native starch
HEAT
Amylose leaks out and
thickens the surrounding
liquid.
…this is called gelatinization

9. Collapsing

10. Factors influencing gelatinization:
1. WATER
Sufficient water must be
available for absorption by
starch.
2. TEMPERATURE
• Gelatinization temperature
differs for diff starch acc. to
size of starch
• Gelatinize begins b/w 60 and
70C
3. TIMING
• Starch granules break apart, when
continued heating stresses the bond
holding them together.
• Heating beyond gelatinization
temperature decreases viscosity.
4. STIRRING
• Too much stirring makes starch
granule to rupture prematurely,
resulting in a slippery starch
with less viscosity
• Require in order to assure
uniform consistency and to
prevent lumps from forming
5. INGREDIENTS.
Sugar competes with starch for available water,
delays the onset of gelatinization, and increases
the required temperature
Fat/protein: Delays gelatinization by coating
the starch and preventing it from absorbing
water.
A pH below 4.0 decreases the viscosity of a
starch gel.
TYPES OF THE STARCH: Potato starch has max
gelatinization ability.

11. GEL FORMATION
SPECIAL
DESSERT
• Is dependent on the presence of sufficient levels of
amylose molecules, because amylose will gel and
amylopectin will not.
• The linear amylose molecules form strong bonds,
while the highly branched amylopectin molecules
form bonds that are too weak to contribute to rigidity.
• Best thickening ability: potato starch
• Worst thickening ability: wheat starch

12. RETROGRADATION

13. Retrogradation is a reaction that takes place in gelatinized starch when the amylose and
amylopectin chains realign themselves. The retrograded starch is also known as resistant starch.
The amorphous material obtained after gelatinization of starch and cooling is not in a state of
equilibrium. Upon cooling of the sample, a process of re-association and recrystallization of the
polysaccharide chains occurs, known as retrogradation.
The release of water during retrogradation is called syneresis.

15. STALING IN BREAD
Due to the realignment, crumb firming occurs.
Migration of water occurs within bread and from bread to the environment
causing bread to firm.
Water migrates from crumb to the crust.

16. AVOID STALING
B A K E R Y
Emulsifier (Lecithin, datem esters)
Store in freezer
They combine with the amylose inside the starch granules and
keep it from diffusing out so that it doesn’t contribute as much
strength to the initial crumb set
Incorporation of high fiber flour
Heat stable Alpha Amylases, lipases
Enzymes
They slow the rate of crumb firming in a way that may also
slow the rate of moisture migration.

17. DEXTRINIZATION

18. Dextrinization is the process involving the browning of starch foods when subjected to dry heat.
It is defined as the breakdown of starch into dextrins (disaccharides) and it is a non-enzymatic browning.
WHAT HAPPENS WHEN STARCH IS HEATED WITHOUT WATER?
Producing dextrin therefore results in a change in colour of food to golden brown.
If it is overcooked it goes black and burnt. Overcooking causes the starch to turn to carbon.

19. STARCH COMPLEX
• Amylose chains are helical with hydrophobic (lipophilic)
interiors, they are able to form complexes with linear hydrophobic
portions of molecules that can fit in the hydrophobic tube.
• Iodine (as I-3 ) complexes with both amylose and amylopectin
molecules.
• Again, the complexing occurs within the hydrophobic interior of
the helical segments.
• With amylose, the long helical segments allow long chains of
poly(I-3 ). to form and produce the blue color used as a diagnostic
test for starch.
• Amylopectin forms a reddish-purple color with iodine because the
branch chains of amylopectin are too short for formation of long
chains of poly(I-3 ).
Starch stained
blue contains
amylose and
starch stained
red-brown
lacks
amylose.

20. TYPES OF FOOD STARCH
A. Unmodified
starch
B. Modified
starch
Pre-
gelatinized
starch
Acid-modified
starch
Oxidized
starch
Cross-linked
starch
Starch
phosphates
Natural plant
starch (corn flour,
tapioca, etc.)
Starch which has
been modified to
develop starch with
desired properties
(thickening agent).
Eg. Modified corn
starch.
Starch which has
been cooked till
gelatinized and
roller dried.
Highly digestible.
Starch treated with
inorganic acids such as
dilute HCl or nitric acid at
temp below
gelatinization.(paper and
textiles industry)
Starch treated with
an alkali such as
sodium hypochlorite
(binding in paper
sizing)
Starches that undergo a
molecular reaction at
selected hydroxyl (-OH)
groups of two adjoining intact
starch molecule (stabilizer).
Starch esterified
with phosphate reagents
(frozen food industry).

21. RESISTANT STARCH

22. RESISTANT
S T A R C H
A small fraction of starch resistant to hydrolysis and resists
digestion, functioning kind of like fiber.
There are 4 different types
•Type 1: Is found in grains, seeds and legumes and resists digestion
because it’s bound within the fibrous cell walls.
•Type 2: Is found in some starchy foods, including raw potatoes and
green (unripe) bananas.
•Type 3: Is formed when certain starchy foods, including potatoes and
rice, are cooked and then cooled. The cooling turns some of the
digestible starches into resistant starches via retrogradation .
•Type 4: Is man-made and formed via a chemical process.
.
Health benefits includes improved insulin sensitivity, lower blood sugar levels, reduced appetite
and various benefits for digestion.

23. A P P L I C A T I O N
Main source of energy in human diet
(bakery, confectionaries, etc.).
Used as food additives such as thickening
agent, gelling agent, stabilizing or as a filler.
Used in paper and textiles industry.
Used in many industrial applications as emulsifiers,
de-foaming agents, for encapsulation, and as sizing
agents.
Used in the pharmaceutical industry for a wide variety of
reasons, such as an excipient, a tablet and capsule
disintegrant, a glidant, diluent, or as binder.

24. THANK YOU