Cereals and Cereal Products

1
Cereals and Cereal Products

• Justin Shimek and Jun Kim
• FST 100A
• Discussion Hour 7

Graphic http//www.generalmills.com/
2
Cereal Lecture Outline

• Definition
• Botanical layout of kernel
• Compartmentalization
• bran, endosperm, germ
• Chemical composition
• milling
• Key macromolecules
• proteins, lipids, carbohydrates
• Cereal chemistry in action
• Example 1 Dough
• Example 2 RTE Cereal Product

3
Definition of Cereal

• Websters Dictionary
• 1 a plant (as a grass) yielding starchy grain
  suitable for food also its grain
• 2 a prepared foodstuff of grain
• Botanical
• Members of the grass family (Graminaeae) which
  are cultivated.
• Includes wheat, oats, barley, rye, corn,
  sorghum, rice, triticale, millet

4

• What you may think of when you hear cereal
• USDA Food Pyramid
• 6-11 servings/day
• Ready-to-Eat (RTE) cereals

5
Wheat Kernel

• Biological material
• purpose become plant
• biological tissues
• chemical variation among tissues

Source Hoseney, R.C. Principles of Cereal
Science and Technology, 2nd Edition, pg. 4.
6
1) Bran Layer

• 14 of kernel
• Several thin layer
• Contains aleurone layer
• viable, protected layer, surrounds endosperm
• enzyme activity
• Contains protein, lipid, minerals, vitamins,
  phenolic compounds, cellulose

Graphic http//www.generalmills.com/wholegrain/10
1/
7
Source Hoseney, R.C. Principles of Cereal
Science and Technology, 2nd Edition, pg. 17.
8
2) Starchy Endosperm

• 83 of kernel
• Non-viable, but may have enzymatic activity
• Contains high levels of starch
• 75 of wheat endosperm
• source of fermentable sugars
• Contains extensible gluten proteins
• Very little mineral, fiber, fat vitamins

Graphic http//www.generalmills.com/wholegrain/10
1/
9
Starch Granules in Protein Matrix
Source Hoseney, R.C. Principles of Cereal
Science and Technology, 2nd Edition, pg. 9.
10
Starch Granules and Gelanitization

• In the storage areas of plant (seeds, roots),
  molecules of starch are deposited as tiny,
  organized unit ? granules
• In cold water, starch granule is insoluble.
• In warm water, gelatinization
• - swelling of granule as water is absorbed
• - disruption of the granule structure
• - loss birefringence

11
Starch Granules Birefringence
Gelatinization (heat water)

• Bright field microscopy Polarizing microscopy

Source Hoseney, R.C. Principles of Cereal
Science and Technology, 2nd Edition, pg. 53.
12
3) Germ

• 2-3 of kernel
• Viable tissue
• Contains embryo
• all rudimentary growth tissues
• Responsible for germination
• e.g. during malting of barley
• Contains higher quantities of lipid than other
  fractions

Graphic http//www.generalmills.com/wholegrain/10
1/
13
Wheat Mill Fractions
Source Hoseney, R.C. Principles of Cereal
Science and Technology, 2nd Edition, pg. 137.
Milling is a process which attempts to cleanly
separate the anatomical parts of the grain to
produce a product (flour), which is chemically,
compositionally, and functionally very different.
14
Example Dough Formation

• Doughs are viscoelastic (flows and recoils)
• Structure largely from proteins called glutens
• consist of gliadins and glutenins
• 30 of amino acid residues are hydrophobic
• water insoluble can bind water
• Kneading bread subjects it to shear forces
• promote interactions between glutenin molecules
• H- bonding, hydrophobic interactions, S-S bonds
• creates elastic protein networks (films) which
  trap gas
• viscosity enhanced by gliadins and starch
  molecules

know
15
(No Transcript)
16
Dough Formation

• Knead to optimum rheology ? optimum dough
  strength
• over-kneading breaks protein structure

50 mm
1 mm
before kneading
after optimal kneading
17
Example Wheaties Ingredients Processing
Wheat / Ingredients Cooking Drying Flaking
Toasting Wheaties

• Ingredients
• whole wheat
• sugar
• salt
• corn syrup
• partially hydrogenated soybean oil
• brown sugar syrup
• natural flavor
• tri-sodium phosphate
• freshness preserved by BHT

Graphic http//www.generalmills.com/
18
(No Transcript)
19
Breakfast Cereal Flakes

• Flaking kernel dropped through small gap between
  one-ton steel rolls
• Undergoes viscoelastic flow in flaking process
• water (and heating) plasticizes the flake
• Quality/behavior depends on composition

Well plasticized Flake
Un-plasticized Flake
know