CHAPTER 4:
What is a cereal? (definition)
The term ‘cereal’ describes any cultivated grass that produces an edible grain.
In many countries a type of cereal grain is generally a dietary staple including:
Wheat
Oats
Barley
Rye
Corn (maize)
Sorghum
Millet
Rice
Origin – where do they come from?
WHEAT Has traditionally been the main cereal
grown and used in Australia
Rice has become popular in recent years
Cereals are important in the food industry
Used in breads, pastas, noodles.
CEREAL GRAIN STRUCTURE
A cereal grain has three layers:
1) Bran/husk –
fibrous outer covering (13% of grain)
2) Endosperm
Largest part (85%)
storage cells, stores
starch
3) Germ
Smallest part (2%)
Part of the grain which new grains grow.
Wheat
Rice
Corn/maize
Oats
Rye
1. WHEAT Grown throughout the world
Most popular cereals produced
Wheat grain is usually ground into flour (main ingredient of bread, pasta, noodles, cakes)
Glutelin & gliadin are the main proteins in flour (they combine to produce protein GLUTEN).
Gluten gives dough ____________
Soft Wheat= less gluten (cakes & biscuit)
Hard wheat = > level of gluten (bread & pasta)
Main products made from wheat?
Wholemeal flour (wholegrain – bran, endosperm and germ)
White flour (milled from the endosperm)
Cornflour (finely ground endosperm)
Wheat bran (outside husk of grain)
Burghul (cracked wheat)
Semolina (inner starchy endosperm)
Wheat germ (germ)
See page textbook for pictures
2. RICE Mainly grown in Asia
More grown in Australia due to increase demand
Available in two main forms:
1) Brown rice – unprocessed (whole grain)bran, germ and endosperm
2) White or polished rice (endosperm)
* Rice is gluten free so suitable for people with coeliac disease.
Main products made from rice:
Rice flour/ground rice
Rice noodles
3. CORN/MAIZE Grown as corn on the cob and used as a fresh vegetable or
as field corn that is harvested and ground to make flour.
Corn is gluten free
Main products from corn:
Cornflour (fine flour used for thickening agents in sauces)
Sweet corn
Popcorn (dried wholegrain)
Cornflakes (kernels are baked and rolled)
Ground corn (tortillas, corn chips)
Polenta (Italian porridge)
4. OATS Small proportion of Australia’s cereal
production
Contain some gluten
Used to produce products such as rolled oats (porridge), oat bran, muesli, biscuits (Anzac)
Majority of oats produced in Australia used for stock feed
5. RYE Popular in Scandinavian countries/Russia
Hardy cereal used in the ‘heavier’ breads
Rye flour is dark, lower in protein
Rye flour used to make pumpernickel and some crisp breads
STORAGE OF CEREALS Described as ‘Non-perishable’ or safe
foods because they can be stored for long periods.
Have low moisture content (difficult for bacteria to grow)
Rice, flour & pasta stored in cool dry conditions
Stored in airtight containers
Can be infested with weevils, ants/rodents
NUTRITIONAL PROPERTIES OF
CEREALS
Excellent source of complex carbohydrates (contain both starch and dietary fibre)
Wholegrains – protein, Vitamin B
Bran – dietary fibre
TYPES OF WHEAT FLOUR
Type of flour Physical, chemical & sensory properties
Uses
White plain flour All purpose flour. 10-11% protein
Baking, thickening,coating
Self-raising flour Plain flour + leavening agent – causes to rise
Cakes, muffins, biscuits
Wholemeal flour Plain/SR. Products are dense and darker.
Cakes, pastry, bread
Bread flour Protein 10-15% Bread, pasta, pizza
Functional Properties of wheat flour
Properties of starch and protein give a range of properties in food preparations:
Volume – bread, cakes, biscuits.
Thickening – starch present will swell, thicken and form a gel when heated in liquid (GELATINISATION). Gravies, custard powder.
STRUCTURE – protein gluten enables baked products to hold their structure (bread making).
CONTRIBUTION OF COLOUR – starch contributes to browning of bread when toasted/baked. This is called ---- DEXTRINISATION
MOISTURE ABSORPTION – absorbs liquids which helps bind ingredients together during cake and bread making.
DEXTRINISATION Starch + dry heat = DEXTRINISATION
Is the browning of starch foods when dry heat is applied. This process occurs when bread is toasted.
Dextrins form in flour products during baking. The crust that forms on bread and cakes during baking is the result of DEXTRINISATION.
Many sensory changes occur as a result of
dextrinisation of starches:
Colour – golden brown eg: when bread is toasted
Flavour – sweet taste. Excessively heated will taste ‘burnt’
Aroma – a desirable or ‘cooked’ smell eg: freshly baked cakes
Texture – and mouthfeel change when dextrinisation occurs. Food becomes crisp. Eg: soft fresh bread dough becomes crisp during baking due to the process of dextrinisation.
Comparing the dextrinisation process in a variety of breads
1. Select a range of breads (Rye, white, wholemeal)
2. Use toaster toast each bread product.
3. Record the time taken for this process to occur.
4. Taste each product.
Comparing the dextrinisation process
BREAD PRODUCT
TIME TAKEN TO BROWN
COLOUR: LIGHT/GOLDEN/DARK
IMPACT ON FLAVOUR
TEXTURE
RYE
WHITE
WHOLEMEALRAISIN
GELATINISATION
Starch + wet heat = Gelatinisation
Is the process that causes starch granules to swell and thicken when heated in a liquid.
When starch grains are heated in this way they form a ‘gel’.
Heat starch granules in liquid
Starch granules become swollen
Starch granules burst
The liquid thickens and gelatinises
Starch gelatinises when heated in a liquid, producing a thickened liquid
Syneresis On standing and cooling, many gels lose
liquid and shrink. This is known as ‘weeping’ or ‘syneresis’.