Meat+Poultry - December 2021 - 68

POULTRY PROCESSING TECH
CAS stunning keeps
birds calm and provides
a gentle, controlled
and consistent stun.
controlled stun. The system mixes
atmospheric air with CO2. Once the birds
lose consciousness the CO2 levels increase by
65% to 85% by volume.
" Due to the system design, the gas cannot
seep out since CO2 is heavier than air and will
" The consumer
demand for
increased
animal
welfare is
the driving
force behind
controlled
atmosphere
stunning.
Consumers
and
distributors
drive
processors to
change their
process. "
- OLIVER HAHN
therefore remain below ground, " Hahn said.
" Gas consumption is less than 3 grams per kg
live weight using this method. Additionally, this
option requires a smaller footprint. "
Baader's above ground system moves
birds horizontally through the stages of
increasing gas levels. The induction phase
uses a pre-mixture of O2 and CO2 to ensure
gentle and humane stunning. Like the below
ground system, gas concentration levels
increase once birds are rendered unconscious.
Operators can adjust stage length and gas
concentration for optimal performance based
on product variables.
" The footprint of the stunning system
is determined by slaughter line speed and
the number of birds per drawer, " Hahn said.
" Although this system requires a larger
footprint compared to the below ground
system, it offers advantages such as: simpler
installation, easier access for maintenance and
cleaning, and precise control in the induction
phase by using premixed gasses in exactly the
right concentration. "
Marel installed its first CAS system in
Belgium in 1996. The two-phase system
anesthetized birds in the first phase with
a mixture of CO2 and oxygen. The second
stage stunned them irreversibly with a higher
concentration of CO2.
" When birds left the system, their hearts
68 MEAT+POULTRY | 12.21 | www.meatpoultry.com
were still beating, although they could not
recover consciousness, " Schaik said. " At the
time, the use of CO2 and oxygen in a two-phase
tunnel in high volume processing plants was a
definite world first. "
Over the years, Marel has continually
improved on its Atlas live bird handling
system and its Smoothflow CAS system. The
Atlas system keeps birds in its trays and
moves them through the SmoothFlow CAS
tunnel. SmoothFlow is a five-stage system
separated by curtains. In each stage the CO2
gradually increases.
" Atlas and CAS SmoothFlow are
mechanically straightforward, " Schaik said.
" Automation of the Atlas in-plant system for
handling live birds consists only of conveyor
belts and an automatic tray de-stacker. This
de-stacks individual trays from the SmartStack
transport module. CAS SmoothFlow is the
perfect seamless add-on to Atlas. It is an in-line
tunnel system with a single conveyor running
through it on one level only. "
As animal welfare and humane treatment
continue to gain ground in the hearts and
minds of consumers, CAS will continue to
become the norm in poultry stunning.
" The installation of a CAS system will
become 'a license to produce' in an increasing
number of situations and with an increasing
number of retail and fast-food customers, "
Schaik said.
Hahn added, " The consumer demand for
increased animal welfare is the driving force
behind controlled atmosphere stunning.
Consumers and distributors drive processors
to change their process. "
Marel
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