How is bread made?
Bread has been made since prehistoric times when grains were ground to a flour,
mixed with water and baked on hot stones. The principles of bread-making have
essentially not changed much since 4000 BC when the Egyptians discovered use
of fermentation to produce a risen or leavened loaf of bread.
Ingredients used to make bread
Flour - wheat flour is mainly used to produce bread because it contains
a unique complex of proteins which, when mixed with water, produces gluten.
Gluten is essential to produce a bread with good structure. In Australia, flour
for making bread is required by law to contain no less than 6.4 mg/kg thiamin.
Raising agent or leaven - usually baker's yeast but baking powder, cream
of Tartar or sourdough can also be used.
Salt - 1.5 to 2% on flour weight is usually added to stabilise the yeast
fermentation, strengthen the gluten protein to assist dough handling and add
flavour. In the manufacture of reduced and low salt breads some of the salt
(sodium chloride) is commonly replaced with potassium chloride.
Sugar - small amounts of sugar (1-2%) are sometimes added to help start
yeast action. During fermentation, the sugar is converted to glucose and fructose.
Larger amounts of sugar are added to sweet buns and fruit loaves.
Fat - 2% fat, usually vegetable oil, is normally added to increase loaf
volume and improve the texture of bread (by softening the crumb and crust).
Fat also improves the keeping qualities of bread. Up to 12% fat can be added
to some buns and rolls.
Improvers - softening agents which make it easier to develop dough, particularly
flours with tough and strong gluten. Includes enzyme supplements, mainly (-amylase,
gluten-modifying agents such as ascorbic acid, sodium metabisulphite and L-cysteine
hydrochloride; yeast foods (such as ammonium chloride, phosphates and calcium
salts).
Preservatives (calcium and sodium propionate, sodium diacetate and acetic acid)
- rope and mould inhibitors are added to prevent bread spoilage.
Water
Optional ingredients
Principles of commercial bread-making
i. Mixing
Mixing is required to stretch the gluten to make it elastic and allow more
gas to be held in the dough. The dough is mixed for up to 35 minutes.
ii. Proofing
The dough is divided into pieces, rounded and allowed to rest for a few minutes.
The pieces of dough are then moulded into loaves and placed in pans in a warm,
moist atmosphere. Carbohydrates in the flour are converted to simple sugars
and carbon dioxide by the action of yeast and enzymes present in the flour.
The gluten, which forms elastic films within the dough, traps the carbon dioxide
in little pockets in the dough giving it a light, spongy texture.
iii. Baking
The oven's high temperature causes the yeast to produce large quantities
of gas which increases the size of the loaf. Further fermentation is prevented
as the temperature inside the loaf rises and finally kills the yeast and inactivates
the enzymes. During baking, protein coagulates, starch gelatinises and gluten
coagulates forming a semi-rigid, three-dimensional structure. The exterior of
the loaf dries out and a crust forms. The extent of starch gelatinisation depends
on the amount of water present and the temperature. Gelatinisation is almost
complete at high temperatures (e.g. in the crust), whereas the starch granules
remain relatively intact with little gelatinisation at lower temperatures (e.g.
in the crumb). The ratio of crumb to crust might therefore have an effect on
the amount of resistant starch present.
iv. Packaging
After baking, bread must be cooled before it is sliced and bagged.
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