Pre-blending
Pre blending and processing
The
preprocessing of raw materials serves several functions, namely: weighing, preblending
raw materials, premixing types of flour, combining small ingredients, and
bringing basic raw materials into a workable form, such as grinding granulated
sugar into powder, roasting nuts, crystallizing fat, processing crumbs, etc.
The
premixing of types of flour is carried out in many bakeries equipped with silos
for basic flour and types of flour. For instance, a bread factory with flour
for white bread and whole meal for whole wheat bread can create mixtures, like a
50:50 blend, to bake wheat bread. A pastry or biscuit factory producing
multiple types of products can easily start with two basic types of flour: one
with higher protein content, or a 'stiffer' flour, and one with lower protein
content, or a 'softer' flour.
By blending
mixtures of these two extremes, many product requirements can be met. It is
also convenient to make minor adjustments by varying with one of them. For
pastry products that should not spread or expand much, a higher proportion of 'stiff' flour is needed, e.g., for vanilla batons. At the other specturm we have products that require good spreading, like spiced biscuit, 'stiff' flour is often
undesirable. The influence of flour quality also depends on the proportions of
other major ingredients such as fat, sugar, and liquid.
Mixing two
types of flour or flour and whole meal can be done in several ways. One way is to
weigh both types separately and feed them into the mixing machine, where they
need to be mixed and/ or kneaded thoroughly. This is not a problem for bread dough,
which uses a lot of water and is mixed and kneaded intensively with the flour,
or for most biscuit doughs with a relatively long mixing time. However, for
pastry dough and batters with a much shorter mixing time with flour, there are
disadvantages to this system because the chance of inhomogeneity is 'high'.
Another
method is to pour both types into a premixer after weighing, where they can be
mixed with a simple stirrer or another mixing system before being sent to the
main mixer.
A third
approach involves allowing both types to flow simultaneously into the correct
ratio into a small silo above the scale. Afterwards, they are weighed and fed
into the mixing machine. The drawback of this system is that it's challenging
to precisely regulate the flow rates of both flour streams.
Another
option is to use small intermediate silos where a day's supply of blended flour
or meal is prepared. If these intermediate silos have self-weighing
capabilities, you can introduce the flour types one by one by weight, then mix
them, and use this blend for weighing and feeding into the dough machine.
Another alternative is to have certain types pre-mixed at the flour mill and
delivered as a blend. This system requires multiple silos.
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