Cereals processing technology

Breakfast cereals 167
were parallel to those changes being published by scientists studying the staling
of bread, namely, the retrogradation of starch amylase. One of the earliest
revelations of this theory was made by E. G. White in his US patent number
4,179,527. 7 In that patent White discloses the methods of reducing the tempering
or holding time for cooked wheat before shredding by chilling the wheat to 34–
54ºF (1–12ºC). It was the revelation that refrigerating bread caused more rapid
staling, that led to this adaptation to breakfast cereal processing.
Basic research in these two recent decades has left little doubt that that is
exactly what is occurring. These theories have evolved, and been enlightened on
tremendously by the glass transition phase work carried out by Drs Louise Slade
and Harry Levine, and others in the field. 8
Up to this point in the text there are four areas in which there can be no
compromises accepted. They are:
1. Accurate recipe ingredient weights
2. Cooking – either batch or extrusion
3. Drying
4. Tempering conditions
A fifth and sixth, often overlooked, are consistent water quality and consistent
food contact steam quality.
8.3.6 Developments in forming
Recent trends in the development of forming cooked grain formulations into
their final shapes is most easily explained by taking each shape individually, i.e.
gun puffed shapes, shredded shapes, flakes, extruded shapes, etc.
In the case of extruded shapes, a good explanation of how to design an
extruder die hole or holes is given by Miller in Breakfast Cereals and How They
are Made. 6 By following his suggested procedures good progress can be made in
a short period of time. Much time and money can be wasted by just using trial
and error methods. With all of this said, there has not been a plethora of new
extruded shapes on the market. Rather what has evolved has been the refinement
of shapes that appeared many years ago. Letters of the alphabet in one breakfast
cereal, for instance, show much better definition and less distortion than when
first introduced. In a few instances multiple extruders are in use extruding the
same formulation each in a different color and flavor so that a mixed, for
instance fruit cereal, is produced. Multiple extruders are also in use to produce
mixed shape products.
Advances in die designs have evolved from the many and varied pasta shapes
that are available. Transforming these into extruded breakfast cereal-shaped
pieces, however, is much more difficult since the ever present expansion
deformation of the piece must be overcome.
Strides have been made in cutting mechanisms, and in knife blade design.
Some blades now have spring loaded mountings so that the blade edge may run
in direct contact to the die face yielding much cleaner cuts.