Cereals processing technology

28 Cereals processing technology
author recommends referral to this book if the wet milling of corn or wheat is of
interest.
Because the actual milling process in many industries is relatively simple,
technological progress has been limited to increases in efficiency and the
adoption of computer control to the process to improve efficiency and quality
while minimising labour requirements. In contrast, intermediate processes, such
as those milling corn for breakfast cereal manufacture have advanced
considerably as a result of advances in the most complex of the milling
processes, flour milling, because many of the same machines are employed. For
example roller mill capacities have increased dramatically over the last 20 years
and new process philosophies have been adopted, such as double grinding
without intermediate sieving.
It is because the flour milling industry is the most complex and predominant
of the milling industries that most technological development has occurred here
and so the following text focuses initially on the flour milling industry with
notes in regard to the other milling industries where appropriate. The chapter
then discusses a number of other significant developments and then moves on to
discuss research with regard to milling and its current focus. The chapter
concludes by speculating where the industry might progress technologically in
the future.
In discussing technological developments within flour milling it is first worth
considering the historical development of the flour milling process.
3.2 The evolution of modern flour milling
The process of flour milling dates back to Egyptian and earlier times. There are
illustrations from ancient inscriptions showing grain being crushed using a
mortar and pestle, with the resulting material being sieved to produce material of
greater purity. The development that followed this was the use of millstones,
first hand operated, then driven by animals and finally driven by waterpower.
The latter power source allowed the development of the first automatic mills,
where all operations between wheat delivery and flour collection were
performed automatically.
Millstones dominated the process used to produce flour until the 1870s when
roller mills began to supplement them on a large scale, because of the superior
flour that could be produced using them. The method used to produce flour
today was developed during this period of fundamental change in the type of
equipment employed (Simon 1997). This method has its origins in what is now
known as the ‘French process’ (see Fig. 3.1). This process began to emerge in
the sixteenth century and advocated the use of a number of grinding stages with
intermediate sieving of the products to produce final products of intermediate
grades. The other notable feature was the fact that the millstones used were set in
such a way as to perform a gentle grinding action and thus maintain the purity of
the endosperm being separated.