BREAD
Cereals provide Bread
Cereals are the World’s staple
Provide the majority of carbohydrates as
starch for the world’s population
Members of the grass family
Wheat
 Rice
 Maize
 Oat, Rye Barley, Sorghum
How are they used?
 Direct consumption
Rice, Maize, Oats
 Milled for flour
Wheat, Rice, Maize, Rye
 Milled for starch
Maize, wheat, rice
Fermentation substrate
Barley, Wheat, Rye, Rice, Maize
Milling
 Grains crushed by a series of rollers
Remove hull and bran
Remove germ (embryo)
Pulverise endosperm
 Wholemeal flour
Contains bran & embryo
Higher lipid content, rancidity problem
Mills
8,000 BC first grain crops, hand crushing
1,500 BC Millstones
1,000 BC animal powered mills
400 BC watermills
1,000 windmills
1780 steam power
1870 use of steel rollers
Flour
 Carbohydrate
Bulk of endosperm, in intact starch granules
 Protein
Endosperm storage proteins
Wheat 13% protein
Glutenin & Gliadin
 Lipid
Mostly removed with embryo
Types of Flour
 Strong flour
From hard wheat
High protein content
For bread
Soft flour
From soft wheats
Lower protein content
For cakes & biscuits
Bread
 Dough formation
Mixture of flour & water
Water uptake depends on protein content
 Kneading
Developing gluten
 Leavening
Generation of gas to expand dough
 Baking
Straight Dough
 Flour & water mixture
Yeast, leavening agent
Sugar for yeast growth
Salt for yeast metabolism
Fat to soften texture, reduce staling.
• Saturated fats better
• 5% in bread 30-50% in cakes
Milk to improve crumb texture
 Kneading to mix thoroughly
 Develop elastic gluten network
Proofing
 Incubate 30°C 1 to 2h
Yeast fermentation
Production of ethanol & CO2
Gas expands dough
Elastic dough will stretch
 Punching, allows some CO2 to escape
 Moulding & shaping
Cake
All-purpose
Strong bread
Alternative leavening agents
Baking powder
Acid + alkali mix
Cream of tartar & baking soda
Produces CO2 when heated
Mechanical
Beating or creaming to whip in air
 Steam generation
 Whipped egg white
Baking
 250 – 300°C, 30 – 60 min
Further gas generation
Dough rises to final shape
Yeast killed off
Starch gelatinises
Gluten coagulates
 Bread becomes hard
Crust develops and browns
Sponge Dough
 Moderately stiff dough
Only 50 % of the flour + yeast & sugar
Fermented 3 –4 hours
Remaining flour, fats & water added
Finer texture, smaller gas holes
Batter whipped process
Chorleywood Process
Continuous production
Liquid fermentation with little flour
Remaining flour added
Agitated to incorporate air
Extruded into baking pans
Fine uniform texture
Starch
Starch, main polysaccharide in flour
Present in starch granules
Contains 2 polysaccarides
Amylose & amylopectin
As heat increases
Starch granules absorb water & swell
Release amylose from granule
On cooling
Amylose molecules combine to form gel
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Starch Retrogradation
 Realignment of amylose chains
Stick to each other more strongly
Forms more rigid crystalline structure
Slow process so takes time
Inhibited by fats that can interact with amylose
Starch becomes harder
Staling
Stale bread = old bread
Harder texture
Crumb more brittle
Dryer, poor release of flavour
Promoted by low temperature
Regeneration possible by wet heat
Bread deterioration
 Prone to fungal contamination
Fungal growth normally prevented in foods by
low humidity and temperature
Dry storage at low temp. promotes staling
Added mould inhibitors common
Eg. Calcium propionate