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Applied nutrition
How to melt three cereals
into one mixed package
Under the brand name optigrainВ® the
German feed milling company deuka
introduces a newly developed piglet feed
consisting of a combination of wheat,
barley and corn. This is mechanically-hydro
thermally processed into a mixed package
with opticonВ® technology.
By Dr Heinrich Kleine Klausing, deuka Deutsche
Tiernahrung, DГјsseldorf, Germany
ooked” cereals are mostly used in nutrition of young animals, especially the
feeding of weaned piglets. Weaning
represents a drastic change for the piglets. Under
nutritional physiology aspects this is characterised by
a shift from a diet of highly digestible protein, fat and
lactose originating from the sow milk to nutrients of
plant origin. During this weaning phase the activity
of various digestive enzymes changes, in particular
the activity of amylase, which is important for starch
Figure 1 shows an overview of the results of a study
by Makking dating back to 1993. By comparison with
Figure 1 - Enzyme production in pig after weaning
Relative activity per g Mucosa
100 100 100
26 25
Age (weeks)
Optigrain: 50% wheat, 25% barley and 25% maize
after being treated with the opticon system of �cold
extrusion’. (Photo: deuka Deutsch Tiernahrung)
weaning time, the amylase, chymotrypsin and lipase
activity dropped to just a quarter to a fifth. In the second week after weaning the concentration of lipase
was still low, and the chymotrypsin and amylase
activity rose to 70% and 74% respectively of activity at
the time of weaning. This situation must be taken
into account when making up piglet diet and selecting raw materials.
After weaning, grain is, as ever, the most important
source of energy. For many years now it has been successful practice to “break down” the starch in part of
the feed grain so that enzymes are able to digest most
of it in the small intestine with distinctly limited
amylase activity.
In addition to a “performance effect” through
improved digestibility and increased feed intake connected with the breakdown of starch, it is especially
important to avoid excessive flooding of the large
intestine with undigested starch. This eliminates a
major viability basis for potential harmful germs
such as E. coli and thus prevents diarrhoea. Every
feeding measure that makes a contribution to keeping the gastro-intestinal tract naturally healthy
should therefore be specifically reviewed and used.
Starch breakdown technologies
Various technical processes are used in practice to
break down the starch in grains. Thermal methods
Feed Tech 9.3 2005- - 12
Applied nutrition
characteristic, visible texturing is achieved. The
process heat enters the product in one or more of the
following ways:
в—Џ Transfer of mechanical energy input into a change
in viscosity of the material,
в—Џ Heat transfer via steam or electric heating of the
With such material treatment high temperatures up
to 200В°C can be achieved, also known as High
Temperature, Short Time (HTST) processing.
A further distinction lies in the preconditioning
and the moisture content added here with steam.
With “moist extrusion” where water and steam are
added in a conditioner (up to good 30% moisture content in the material) it is absolutely necessary to dry
the material after the extrusion process. This very
energy-intensive and thus cost-intensive treatment up
till now prevents broad application of extrusion technologies to make livestock feeds.
Figure 2 - Manufacturing cycle deuka optigrain
“Cold” extrusion
such as infrared radiation or hot air treatment make
use of temperature and dwelling time. In hydrothermal methods moisture is used in addition. A combination of hydrothermal processes and mechanical
treatment processes using pressure and shear forces
is found in extruder technology. The principle of
extrusion can be derived already from the name. The
word “extrude” comes from the Latin and means,
“pushing and pressing out or through”.
Depending on the machine design the material is
kneaded in the extruder barrel by one or two augertype shafts of different configuration - single or double shaft extruder – with a forward feed motion and
is pressed through a die. A model-specific high pressure - more than 100 bar is possible – is built up in the
extruder barrel. As soon as the product leaves the
extruder it is suddenly exposed to ambient pressure
and expands (�popcorn effect’). As a result of these
forces the material structure is modified clearly and a
Figure 3a - Wheat, untreated
Figure 3b - opticon treated wheat
The “opticon” process technology developed by deuka
is a major further development of known extrusion
technology. Figure 2 provides a look at the engineering. This achieves targeted intensive material conversion like the “moist” extrusion process described
above. Thanks to the plant concept in accordance
with the invention, however, no energy-costly drying
of the treated material is necessary. Only a conventional cooler follows the treatment process. This
newly developed technology is applied to improve the
nutritional value of various components for productive livestock and pets.
One of its features is to largely break down the
starch in various grain species as mentioned above.
Now also a mixture of wheat, corn and barley is
processed by the opticon technology. Branded as optigrain the mechanical-hydrothermal processed “grain
package” is used as a high-digestible source of starch
for piglet diets. Additional this new-developed prod-
Figure 4a - Barley, untreated
Feed Tech 9.3 2005 - - 13
Figure 4b - opticon treated barley
Applied nutrition
Figure 5a - Maize, untreated
Figure 5b – opticon treated maize
uct is at the disposal to other feed manufacturers and
home-mixing pig breeders. Already for a longer time
with this technology processed wheat is sold with
success under the brand name optiwheatВ® and
processed maize under the name opticornВ® to other
compound feed manufacturers in Germany and other
neighbouring countries.
The process has already proved successful in the
clear reduction of the rumen degradability of protein
in a mixture of soybean and rapeseed meal (“rumenprotected protein”). The opticon process technology is
also used to inactivate the urease in raw soybeans and
is thus a complete high-grade substitute for the customary toasting process.
Opticon treatment
In order to understand what influences starch breakdown in cereal grains it is first necessary to look at
the morphology and structure of starch. Grains contain 40 – 60% starch depending on the cereal species.
In purely chemical terms starch can be broken down
into amylase and amylopectin. The amylase, accounting for about 20 – 30% of grain starch, consists of 1,4␣-glycosidically bonded glucose molecules that in this
bonding represent long helical chains. Amylopectin
with about 70 – 80% of the starch is a branched polysaccharide in which between 2,000 and 200,000 glucose molecules are bonded 1,4- and 1,6-␣-glycosidically. The 1,6 bonding generates side chains and hence
the complex branching of the molecule. The ratio of
amylose to amylopectin, the chain length and the
degree of branching of the glucose chains have a clear
influence on the technical properties of the various
grain species and their starch digestibility.
Starch is present in the floury portion of the grain
as individual granules with a size between 2 and 200
?m. These starch granules can be seen clearly under
an electron microscope (1000-fold magnification).
Figure 3a to 6a show untreated starch granules of
wheat, barley, maize respectively and a mix (2:1:1
Figure 6a – optigrain mix, untreated
Figure 6b - optigrain
resp.) of the three grains.
The starch granules are held together very stably in
their interior by hydrogen bridges. The branched
molecule chains of the amylopectin can form semicrystalline to crystalline areas in these granules
together with the un-branched amylase molecules.
This firmly organised structure is water-insoluble and
in its native, non-crushed form highly resistant to
enzymatic degradation.
By intensive mechanical-hydrothermal treatment
of grain (customary milling and subsequent extrusion using the opticon technology) these structures
are modified right down into the molecular range.
The treatment results in a clear enlargement of the
surface and far-reaching disintegration of the semicrystalline and crystalline areas and of the amylopectin and the amylase (Figures 3b to 6b). The typical starch granules are largely destroyed and chiefly
melted together to form flat areas like melted plastic.
This modification results in improved starch
digestibility that is achieved in young piglets with distinctly limited amylase activity in the small intestine.
Degree of starch breakdown
The process technology used and the effective physical parameters influence the degree of starch modification substantially. This modification can also be
determined analytically as “starch breakdown
degree” with the “Amyloglucosidase Method” (AMGMethod) (Agricultural Testing and Research Institute,
LUFA Nord-West, 2003). In this method the cereal is
mixed with the enzyme amyloglucosidase after various preparatory steps have been taken. This enzyme
splits off glucose on starch molecules solely at the
end of the chain. (вђЈ-amylase cannot be used because
it is not specific enough). The glucose split off is measured after an incubation period of 15 minutes. The
content of hydrolysed starch is calculated from this
and set in relation to the crude starch content. The
values determined can only be compared directly
Feed Tech 9.3 2005- - 14
Applied nutrition
with one another within the same grain species.
Within the framework of quality assurance production samples are examined for their starch breakdown degree using the AMG method (15 min., 50В°C)
in accordance with a fixed code. The tests conducted
resulted in an average starch breakdown degree of
72% for the optigrain product. In addition appropriate studies have also resulted in starch breakdown
degrees of over 70% on average for optiwheat and
opticorn too.
Tempering effect
In piglet feeding one should notice that besides size
and form of the starch granules also their internal
structure (crystalline as well as amorphous, gel-similar ranges) varies between the mentioned varieties of
grain. Especially the treatment of cereals after the
harvest has a determining influence on that. In
maize, for example this is attributable to a change in
the order condition of starch during drying. Due to
the much higher moisture content on harvesting by
comparison with wheat and barley, maize must
always be dried intensively.
Individual molecule chains associate during such
intensive thermal treatment, either by amorphous
areas of the starch gradually transferring to a thermodynamically more stable condition, or by the
starch crystallite being perfected by further aggregation of the compacted sequences. Grain specialists
describe this change as a “tempering or annealing
effect”. This makes the starch less prone to thermal,
hydrothermal, mechanical and pressure-mechanical,
as well as enzymatic and microbial attacks. It is also
the reason why native maize starch is more poorly
digestible for young monogastrics than, for instance,
wheat starch.
Therefore it is important for an optimised starch
digestion in the first part of the small intestine to use,
besides mechanical-hydrothermal processed wheat,
also parts of the corn in the feed formulation.
In addition, also the use of mechanical-hydrothermal processed barley should be considered for piglet
feeding. Trials in practice, carried out in Spain and
other European countries, show that both daily gain
and feed conversion ratio could be improved. Next to
an improved starch digestibility a reason is seen in
the intensive conditioning of the fibre fractions,
which take place during the processing. Thus the
structure carbohydrates become better soluble and
receive an increased water binding ability. This factor
is important for an improved manure consistency. в—Џ
Feed Tech 9.3 2005 - - 15
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