Cereals processing technology

168 Cereals processing technology
Some double extrusion products have made brief appearances on the market.
These, of course, are made by using two extruders pumping dough into the same
die simultaneously – one being the casing the other being the filling. It is unique
technology; however, in some of the products tried, due to the heavy weight of
the filling, non-competitive carton weight cereals resulted, i.e. they were too
heavy and therefore required too high a price. Several of these have survived,
however, where the second product introduced is only a color mix. In these
instances producers are able to keep carton weights competitive. One finds these
products in the children’s category of RTE cereals.
Gun puffed shape technology, however, has been on the decline, or at least
been stagnant, and for a good reason. In order to make a shape for puffing one
must first cook the grain formulation, form it in a forming extruder into the
desired shapes, dry the shapes to a very narrow moisture range, and temper
them. All this must be accomplished before gun puffing can take place. The
rapid advancement in the development of twin screw extrusion of puffed shapes
has replaced all of the steps listed above, and, in fact accomplishes all those
steps, including the puffing, in one piece of highly controlled equipment.
The major gun puffing advance that has come to light in the 1990s, however,
is the prominence of two world class manufacturers of automatic guns. Most
automatic or continuous puffing guns have been developed in-house by those
companies who wanted to produce gun puffed products. However, today a
manufacturer in Belgium and another in Italy are actively supplying automatic
batch guns. These units rely on technology taught in such patents as ‘Cereal
Puffing Apparatus’ by Elmore F. Maehl. 9 This teaches the preheating of grain
before introduction into the heated gun body, then once in the heated gun
chamber, pressurizing the chamber by direct steam injection, and then releasing
the hot, cooked, pressurized grain back to normal atmospheric pressure through
a very quick opening valve. These automatic guns can fire in the order of forty
times an hour instead of six times for pure, older style batch guns.
Changes in shredded cereals have seen additions in numbers of products on
the market. However, the shapes are still limited to geometric shapes, such as
squares, rectangles, or triangles, and not to curvilinear shapes which would
necessitate scrape pick-up and reuse. The number of layers has been reduced to
as low as two layers in some cereals from the early ones on the market of ten or
twenty layers. Shredding has also seen the introduction of a two layer–two grain
cereal composed of one layer of corn and one of rice. This is quite an
accomplishment since shreds of both of these grains must be expanded or
bubbled in the toasting step or the shreds are hard, flinty, and inedible.
Some of the most significant developments have taken place in the
technology of building shredding lines. Water-cooled shredding rolls are in
common usage now. The cooling reduces roll wear which in turn maintains
groove dimensions longer, and therefore more uniform shredded piece weight.
Drives have been reduced in size and noise level by the use of hydraulic motors
on each roll in place of big, horsepower electric varispeed units. Metal bucket
chains used to collect the webs of shreds under each roll pair have been replaced