Physico-chemical Properties of Starch
Chemical Characteristics
Chemical Composition:
* Major component : amylose & amylopectin
* Minor components
Granules Structure
Shape and diameter
Physical properties
Gelatinization, swelling power, rheology etc.
Enzyme susceptibility of starch
Properties of Starch Molecules
Amylose Amylopectin
Linkage -1,4 -1,4 dan -1,6
linear branched
Molecular weight 105 - 106 106 - 107
Degree of polymerization ~103 104-105
Average of chains length ~103 20-25
Film Forming strong weak
Gel Formation firm Not forming gel
– soft
Coloring with iodine Blue Brown-red
Amylose α-1,4 glycosidic linkage
Straight
chain Reducing end D-glucopyranose unit
model n
6 units of
anhydrous
n glucose per
helix unit
n
Helix Model
Reducing end
n
Starch-Lipid Inclusion Complex
An amylose helix is complexed with the fatty acid chain
of a monoglyceride
CH2OH
CHOH
C-O-CH2
Fatty acid chains
Amylose helix
Amylopectin
α-1,6 glycosidic linkage
The number of α-1,6 glycosidic α-1,4 glycosidic linkage
linkages in starch is 4-6% of
whole glycosidic linkage
Standard Models of Amylopectin
A
o
B
o A A A
B
o
o B
C o ●
o ●
A A A C
Hawort „laminated‟ model
Staudinger‟comb‟ model
o A o
B
o
B
o
● reducing end A
o
O non reducing end o B A
B Meyer & Bernfeld
A
„tree-type‟ model
o
o o
Amylopectin structure model o starch granules
DP short chains - 15
DP long chains - 45
Degree of Polymerization
The molecular size of a polymer, the number of α-1,4 linked
D-glucopyranose unit in starch chain
Amylose & Amylopectin Structure in Starch
Starch can be functioned as matrix to protect the active compounds
Type of starch Amylose Amylopectin
(%) (%)
Dent corn 25 75
Waxy corn <1 >99
Tapioca 17 83
Potatoe 20 80
High amylose corn 55-70 (>>>) 45-30 (<<<)
Wheat 25 75
Rice 19 81
Ratio of amylose:amylopectin plays important role to
The starch functional properties, especially for food products
Starch Granules
Amylose and amylopectin do not exist free in nature, but as
components of discrete, semicrystalline aggregates called
starch granules
Type of starch Source Diameter Shape
(µm)
Dent corn Cereal 5-30 Polygonal, round
Waxy corn Cereal 5-30 Polygonal, round
High amylose corn Cereal 5-30 Polygonal, round
Irregular
Wheat Cereal 1-45 Round, lenticular
Rice Cereal 1-3 Polygonal,
spherical
Potato Tuber 5-100 Oval, spherical
Cassava Roots 4-35 Oval, truncated
Starch Granule Microscopic Analysis
Light Microscopy : to identify the type of starch, shape & size
* Polarized Light Microscopy
„all native starch granules appear to shine while
exhibiting a dark maltese cross‟ (is created by the rotation of
polarized light by a crystalline or highly ordered region, ).
birefringence (indicator of the degree of order in the granules)
* Light Microscopy with iodine staining
To provide information about amylose and amylopectin content
normal corn (25% Am) stains blue
waxy corn (100% Ap) stains reddish brown
Scanning Electron Microscopy
To identify the shape & surface feature in 3 dimensions
Starch granules identity for each starch
Microscopic analysis : shape, size & typical characteristic
Granules of Wheat, Barley & Rye
having two population of granule size
“bimodal distribution”
A : Large granules, oval, lenticular, 35 µm
% B : Small granules, spherical, 3 µm
B A Diameter
Granula
Barley : oval shape, produced after 15 days pollination
while shperical, after 18-30 days (88%)
1.5
1.0
0.5
0.0
10 20 30 Diameter (m)
A : Large granules, lenticular
>= 10 m
B : Small granules, spherical
< 10 m
Granule B 24-28% total volume
90% the number of granules
Composition of Wheat Starch A – B Granules
Components Granule A Granule B
Amylosa (%) 29.2 + 1.0 27.4 + 1.6
Lipid (mg/100 g)
- FFA 84 + 25 162 + 50
- LPL 845 + 65 1062 + 90
Characteristics
Mean volume (m3) 1824 + 221 56.6 + 11.6
Mean Diameter (m) 14.1 + 0.6 4.12 + 0.28
Specific surface area 0.265 + 0.011 0.788 + 0.058
(m2/g)
Gelatinization temperature 62.0 64.8
(oC)
Microscopy Structure of Starch Granule
Light microscopy
Scanning Electron Microscopy
Polarized Light
Microscopy Source : Thomas & Atwell (1997)
Source : Thomas & Atwell (1997)
Source : Thomas & Atwell (1997)
Effect of physical
treatment to starch
granule structures
Effect of enzymatic
treatment to
starch granule
structure
Minor components in Starch Granules
Stach Type Protein Lipid
Minor components (%) (%)
(1) Protein
(2) Lipid Dent corn 0.35 0.80
(3) Water/moisture (+ 12%)
(4) Ash (mineral & salts) Waxy corn 0.25 0.20
(0.5%)
Wheat 0.4 0.90
Minor in the number but Potato 0.1 0.1
highly influence to
- Flavor profile Cassava 0.1 0.1
- Starch extraction process
Source : Thomas & Atwell (1997)
Component minor in starch
Lipid
Forms : Polar Lipid (Lipophosphatydil choline)
Lipid extraction very difficult, starch should be
gelatinized (combination of water and heat)
The best solvent : n-propanol-water (3: 1)
Internal Lipid : amylose helical complexes
Proportion :
Wheat 2.5%, Barley 3.3%,
Rye 3%, Rice 3%,
Sorghum 2.1-5.0%, Corn (4.5-5.5%,
germ 12%)
Corn main cereal to produce commercial oil
Protein
• Lipoprotein (lyso-lecithin)
• Enzymes (starch synthesis, seed germination)
Protein Classification based on its solubility
(Osborn fractions)
• Albumin : water soluble
• Globulin : insoluble in water, soluble in salt solution
• Prolamin: soluble in alcohol 70%
• Glutelin : soluble in acid and base solution
Specific protein influenced to the wheat hardness endosperm.
All gluten-containing cereals are rich in glutamine and proline,
and poor in basic amino acids
Protein in cereals
Cereal Name of protein Percentage
Wheat Gluten (glutelin) 6-27%
(8-16%)
Corn Zein (prolamine) 8%
Sorghum Kafirin (prolamin) 9-10%
Oat Avenin (prolamin) 10-15%
Barley Hordenin (glutelin) ~ 3%
Rice Oryzenin (glutelin) 12%
Composition of different groups of protein in cereals
2008 Insilico Genomics Lab Teachnology
Protein in cereals
Storage protein in cereals : prolamin & glutelin
Active protein (enzyme) : albumin & globulin
Most of protein in cereals lack in amino acid lysine
Wheat protein functional protein
- No enzyme activity
- Produce dough which can retain gas formation
and soft products
Protein in corn highly diverse
high lysine mutant cultivar feed
Corn d high leucine content caused Pelagra
(vitamin B deficiency deasease)
Wheat allergy/Gluten intolerance
A food allergy that is immunoglobulin E (IgE)
mediated and is limited to the seed storage proteins
of wheat
Celiac disease, is an immune mediated enteropathy
triggered by gluten intake and mostly found in
European individuals 1% of world population
gluten free diet
Minor component in starch
Vitamin, mineral, enzyme & pigment
Enzyme : amylase, protease, lipase, lipoxigenase & phytase
Barley : amylase, tripsin inhibitor
Corn : low amylase, lipase,
Millet & Sorghum : amylase, phytase, protease
Rice : amylase, maltase, lipase
Wheat : α-amilase, β-amilase, proteinase, lipase, dll
Pigments
Barley : cyanidin
Corn : carotenoid
Rice : anthocyanin (brown rice & black waxy rice)
Sorghum & millet : tannin
Wheat : xanthofil & xanthofil ester
Non-starch polysaccharides
- Cellulose structural polysaccharide in plants
- Hemicelulose & Pentosan : -glucan, simple sugars,
pentosan consisted polymer, phenolic compounds
- Sugar & Oligosaccharides : glucose, fructose, sucrose,
raffinose, glucofructosan (levosine)
Vitamin & Mineral
Cereals rich in vitamin : thiamin, niasin, riboflavin, pyridoxin
pantotenic, dan tocopherol.
Vitamin are concentrated in aleurone &/scutellum
Source of minerals: P, K, Ca, Mg, Fe, Cu, Mn
60% of minerals accumulated in auleuron layers
Program “Innovation & Technopreneur”
• Special Project for product development
• Team : 5-6 student
• Theme :
1. Product Development of Gluten-free Products
2. Development of Emergency Food
3. Utilization of local commodities
(brown rice flour, sweet potato flour, taro flour)
• Product Development 13-14th week of Laboratory
work
• Presentation of proposed product
• Product profile should be submit on 10th week
