Cereals processing technology

main function of yeast is to produce carbon dioxide gas to expand the dough at
its various processing stages, particularly during proof and the early stages of
baking. The actions of yeast may be shown in a simplified form as follows:
Simple sugar ˆ) Ethyl alcohol + Carbon dioxide
C6H12O6 ˆ) 2C2H5OH ‡ 2CO2
Breadmaking 215
10.7.3 Salt
A basic function of salt in bread doughs is to contribute flavour; too little salt
and the bread tastes insipid, too much and it tastes too salty. Salt also has an
inhibiting effect on the formation of gluten during mixing. In high speed mixing
systems the effect is quite small but increases as the mixer speed becomes lower.
There is a strong relationship between the levels of salt and yeast in a given
recipe. Salt has a significant effect on the osmotic pressure of the yeast cell and
so can be used to control the rate of fermentation. The more salt we use in a
given recipe the more yeast will be needed to achieve a given proof time
(Williams and Pullen, 1998).
10.7.4 Sugar (sucrose)
In the UK, little or no sugar is used in basic breads while around 6% flour weight
may be present in the sponge and dough breads of the USA. Rolls and other
small fermented products may have up to 15% sugar. High levels of sugar
inhibit yeast activity even though it is fermentable. In modern breadmaking
sugars contribute to product sweetness and crust colour.
10.7.5 Fat
Compound bakery fats (mixtures of oil and solid fat at a given temperature) are
used to improve the gas retention of dough and thereby increase volume and
softness. Increasing the fat level in the recipe will increase bread volume up to a
point and thereafter there will be no further significant increase in volume for
further additions. This level will vary according to the type of flour being used,
with wholemeal flours requiring higher levels of fat addition than white, often
2–3 times (Williams and Pullen, 1998). A proportion of the fat should remain
solid in bread dough at the end of final proof, i.e. at 45ºC.
10.7.6 Water
The properties of the dough will vary according to the level of added water; too
little and the dough will be firm, difficult to mould (Cauvain and Young, 2000)
and will give breads which have small volume and poor external appearance, too
much and the dough will be soft, also difficult to mould, will allow the dough to
flow in the prover and will give poor quality bread. The ‘optimum’ level of