A. Acidulant and Acidity Regulators
Sprouting in rye and wheat results in a high level of amylase activity
in the grain itself with the usual effects on baking properties. It is
generally known that even flours with very low Falling Numbers can produce good
baking results if well acidified.
However, not every bread consumer likes
acidity and bakeries may also have less and less time and personnel available
to develop acidity by sour dough fermentation.
Other ways are available, and
these consist in adding fruit acids, the salts of these and also carbonates and
phosphates approved for use in foods. It is then possible to adjust the pH of
the dough slightly so that it moves out of the range in which the enzymes of
the grain have their strongest effect.
Moreover, these substances (Acidulants and Acidity Regulators)
influence the swelling of the flour constituents and the protein structure, and
this helps to counteract the negative effects of excessive enzyme activity
(e.g. water release).
The most suitable preparations are those that stabilize
the pH at the level to which it has been adjusted, i.e. so-called buffer substances, mixtures of different salts or acids.
In most cases the dosage is in the
range of about 50 to 200 g to 100 kg of
flour. Fig. 136 shows the effect of an alkaline buffer agent on the Falling Number and on the volume yield.
Nevertheless, with the inorganic phosphates and carbonates care has to
be taken not to exceed the limits of the flour grades, as these substances (Acidulants
and Acidity Regulators) pass into the ash.
With sprouted grain it is in any
case advisable, whatever the treatment, to use a smaller proportion of the
enzyme-rich outer layers of the grain (reduce the yield) and produce
lighter-coloured flours that then tolerate the addition of flour improvers
containing ash.
B. Bleaching Agents
1. Benzoyl Peroxide
For a long time, benzoyl peroxide was a familiar oxidative bleaching agent and it is still used to this day in many countries. In addition to its good bleaching effect it has a slight influence on the structure of the gluten, but this is not apparent when other flour improvers such as acetic acid are used.
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| Fig. 132 : Decomposition of benzoyl peroxide |
The dosage for benzoyl peroxide is about 5 - 10 g to 100 kg of flour (50 - 100 ppm) into the flour stream. It is usually sold as a 27 - 32% product (to enable safe transportation it is diluted with an inert carrier), and the dose is then correspondingly higher.
The effect of benzoyl peroxide on the flour is already visible after 6 hours of storage and complete after 24 to 72 hours. Benzoyl peroxide decomposes to benzoic acid (Fig. 132), a substance found in various fruits and berries and used as a food preservative, e.g. in cream and fruit fillings for pastry at dosages of 0.05 - 0.15% (500 - 1,500 ppm).
2. Enzyme-Active Bean Flour and Soy Flour
Enzyme-active flour made from soy or horsebeans can also be used to achieve a lightcoloured crumb. The quantity that can be used is limited by the formation of an undesirable bitter taste.
For this reason the maximum quantities used are usually 0.5% for soy flour and 2% for horsebean flour. Another legume from which flour with a bleaching effect is produced is lupin seed. But again, the efficacy is much lower than with soy flour.
The classic application of soy flour is doubtless French baguettes, in which it is increasingly replacing the less effective bean flour. A typical dose of 0.3% already has a definite bleaching effect.
It is used at about the same concentration in flours for toast and flat bread. Soy, horsebean and lupin seed flour only become active after the addition of water; they do not bleach the flour in its dry form.
3. Other Agents with a Bleaching Effect
The brightening effect noticed when ascorbic acid, emulsifiers or some enzymes are used has a physical cause; the finer texture changes the reflecting properties of the crumb and the colour appears lighter (smaller holes have smaller shadows).
On the other hand strong oxidizing agents such as bromate or chlorine really do remove the colour from the dark pigments, although this is only a desirable side-effect.
As already mentioned in the section "steamed bread", lipase also has a bleaching effect provided that enough oxygen is present to convert the liberated unsaturated fatty acids – with the help of flour lipoxygenase – into hydroperoxides that then bleach the carotenoids.
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