A new and revolutionary type of feather meal for fish feed by Franz-Peter Rebafka / Ashish Kulshrestha, GePro Gefluegel-Protein Vertriebsgesellschaft mbH & Co KG, Germany / Thailand

1. November | December 2010
Feature title: New dimension in the production of hygienized feed meal
The International magazine for the aquaculture feed industry
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2. D
ifficult to clean, conven-
tional meal coolers can
be a potential source for
cross- and recontami-
nation. A new process solution has
been developed by Buhler Group,
Switzerland, utilizing thermopneu-
matic conveying for drying and cooling
as a smart alternative to meal coolers.
Contaminated raw materials
Agricultural products are a natural
source of microorganisms such as bacteria,
yeasts and molds.The degree of contamina-
tion is subject to parameters such as
type of raw material, origin, transport and
storage conditions and the season.Whereas
most of the microorganisms are harmless,
some species like enterobacteriaceae show
pathogenic potential, with salmonella being
the most common subspecies of enterobac-
teriaceae in animal feed.
Infection doses for salmonella are
comparatively low, with an incubation
period of a few hours to two days,
depending on animal species and age.
Salmonella can cause serious animal dis-
ease like diarrhea, reducing feed digest-
ibility and conversion, impairing animal
growth and performance.
Hygienizing by heat
treatment
Sensitive to heat, salmonella are usually
killed at temperatures above 55°C.
However, high concentrations of fat,
protein or starch in formulated feed may
form a protective colloid layer and thus
increase the heat resistance of bacteria.
Hence, a hygienizing temperature of about
85°C has become common practice in the
feed industry to ensure that virtually all
pathogenic bacteria are destroyed.
The temperature is achieved by the
addition of steam into the conditioner
and retained for a certain dwell time in
the subsequent retentioner to guarantee a
reliable decontamination process.
Recontamination
after hygienizing
After the hygienizing process, the hot
and moist feed has to be cooled and dried
to prevent recontamination and growth of
microorganisms.
This usually takes place in conventional
meal coolers utilizing the principle of fluid
bed cooling. Ambient air enters the cooler
at the bottom side, flows through the
perforation and fluidizes the meal.
Even though providing efficient cooling,
meal coolers are often described as a ‘five
New dimension in the production of
hygienized feed meal
Pathogenic bacteria in feed meal are a major risk factor for animal health and performance.Thermal
meal treatment significantly reduces microorganisms in feed, but requires a subsequent cooler after the
hygienizing section. Difficult to clean, conventional meal coolers can be a potential source for cross-
and recontamination. A new process solution has been developed by Buhler Group, Switzerland, utilizing
thermopneumatic conveying for drying and cooling as a smart alternative to meal coolers.
by Stefan Hoh
20 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 21
F: Feed meal
star hotel’ for microorganisms: The han-
dling of hot and moist feed meal can cause
condensation in the meal cooler, with free
water being a major growth factor for
bacteria which has resist the hygienizing
process or airborne bacteria from the high
air volumes applied.
Furthermore, cross- and recontamina-
tion can occur due to product residues in
the system, which are difficult to remove
and require tremendous cleaning effort.
Thermal meal treatment
The Buhler Group has developed
a new process solution utilizing ther-
mopneumatic conveying for drying and
cooling of hygienized
feed meal. The ther-
mal meal treatment
process is divided into
the sub-processes of
hygienizing and ther-
mopneumatic drying/
cooling.
The Hymix and
Hytherm modules carry
out hygienizing.
In the Hymix, the
compound feed particles
can be heated to a tem-
perature of 80 to 90
degrees C by the addition of steam. The
heated formulated feed is then retained in
one or optionally two Hytherm modules.
This allows retention times between
60 and 240 seconds to be achieved as a
function of the throughput rate.
In addition, the Hytherm system is
characterized by its very narrow dwell
time distribution, thus getting very close
to the ‘first in – first out’ principle, which
ensures reliable hygienization.
In a second process step, the hygien-
ized feed enters the Triple Air Control
(TAC) system for drying and cooling. In
the first stage, pre-heated air is applied
for drying and cooling, utilizing the effect
of evaporation. Final product tempera-
ture is achieved in the subsequent two
pneumatic conveying lines, utilizing ambi-
ent air for cooling.
The optimized concept of Hymix and
Hytherm ensures low product residues
and easy cleaning. Thanks to the high
air velocities applied, the TAC system
is self-cleaning, which prevents product
deposits.
Cooling by a thermopneumatic
conveyor greatly reduces the risk
"Heat and steam treatment causes fines
to agglomerate on coarser particles,
which reduces dust generation and
improves flowability. Choke-ups during
discharge from storage bins and silos are
greatly reduced compared to untreated
feed meal"
20 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 21
F: Feed meal

3. reduces the incidence and severity of
diarrhea disorders in the animals. Besides
improving the animals’ health, this also
enhances feed digestibility, which in turn has
a positive impact on the weight increase of
the animals.
The Maillard reaction occurring during
the thermal treatment process creates a
bundle of roast flavors, which improve the
palatability of the feed. Thermally treated
swine feed may thus have a positive influ-
ence on the animals’ appetite and – accord-
ing to feedback Amrein received from its
customers – results in outstanding feed
acceptance.
Moreover, thermal meal treatment
improves the water solubility of the feed.
Product lumps in the feed slurry are effec-
tively prevented, as well as deposits of
high-density particles in the feed trough.
Lastly, the heat and steam treatment
causes fines to agglomerate on coarser
particles, which reduces dust generation
and improves flowability. Choke-ups during
discharge from storage bins and silos are
greatly reduced compared to untreated
feed meal.
The new process increases the uptime
of the processing lines thanks to reduced
downtimes when formulations are changed
in comparison with hygienizing systems
consisting of pellet mills and conventional
meal coolers.
The new thermal meal treatment sys-
tem can be easily tailored to specific
customer needs or adjusted to feed
recipes for other animal species, e.g.
layer and breeder feed. This is made
possible by the following options:
microfiltration of the air for top sani-
tation standards; addition of solid and
liquid microingredients; post-mixing
application for unsurpassed product
homogeneity; and monitoring of the
steam quality and/or of the moisture
content.
Improved feed
The pig feed produced by the new proc-
ess is characterized by its extremely low
count of microorganisms such as bacteria,
molds, and yeast fungi.
Pathogenic bacteria such as salmonella
are virtually destroyed, which significantly
of cross-contamination and recontamina-
tion in comparison to conventional meal
coolers. The new thermal meal treatment
system has a small installation footprint.
This enables the space available in existing
feed production plants to be utilized in the
best possible way.
The system was installed at the Amrein
Futtermühle AG, Switzerland, which pro-
duces hygienized swine feed.
Operation of the new facility is fully
automated and is controlled exclusively
from the control room. This cuts labor
costs and allows just-in-time production.
"Thermal meal treatment improves
the water solubility of the feed.
Product lumps in the feed slurry
are effectively prevented, as well as
deposits of high-density particles in
the feed trough"
22 | InternatIonal AquAFeed | november-December 2010 november-December 2010 | InternatIonal AquAFeed | 23
F: Feed meal
disease control & management in the global aquaculture sector
An online publication specialising in health and
disease control in the global Aquaculture sector
Individual features talking about specific topics
available online
For more information contact Martin Little on
martinl@aquafeed.co.uk
The solution behind the solution.
Bühler AG, Feed & Biomass, CH-9240 Uzwil, Switzerland, T +41 71 955 11 11, F +41 71 955 28 96
fu.buz@buhlergroup.com, www.buhlergroup.com
Fatten up your bottom line. Buhler high-performance animal and aqua feed production
systems are used by leading companies around the world. These producers know they
can rely not just on the technology itself, but also on the support that accompanies it. A
service combining local presence with global expertise both lowers feed mill operating
costs and increases capacity utilization. So the question is not whether you can afford to
choose Buhler – it’s how a solution from Buhler will feed your profits. To find out more,
visit www.buhlergroup.com.

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Volume 13 Issue 6 2010
the international magazine for the aquaculture feed industry
Seaweeds as Ingredients
in Aquatic Feeds
A new and revolutionary type
of feather meal for fish feed
New dimension in the production
of hygienized feed meal
Chromium
- the forgotten mineral that plays an essential
role in the utilization
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