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’.