Intervention/decontamination strategies for control of foodborne pathogens at slaughter

Question 1

What are the 3 methods of stunning?

Answer 1

• Bolt stun guns
• Modified atmosphere
• Electrical current

Question 2

Describe sticking and bleeding and its considerations

Answer 2

• Shortest possible duration between stunning and bleeding
• Bleeding time: between a minimum of 4 to 6 minutes
• Two types of bleeding: Jugular and pre thoracic

Question 3

Where on the carcass must be tied?

Answer 3

The oesophagus and rectum

Question 4

Describe skinning (dehiding) and its technique

Answer 4

• General hygiene
• Knife technique
• Udder removal
• Mechanical pulling of the hide: downwards is most hygienic

Question 5

The evisceration platform must be designed to:

Answer 5

• Offer ergonomic working conditions for the operator

- Minimise contamination of the carcasses during the work

Question 6

Running water must be at what temp to clean knifes, tools and other equipment?

Answer 6

82 degrees

Question 7

What are the main sources/routes of microbial contamination of carcasses during dressing?

Answer 7

• Microorganisms from hide
• Microorganisms from guts
• Airborne microorganisms
• Microorganisms from equipment
• Microorganisms from people

Question 8

What are the 3 main foodborne pathogens at the abattoir?

Answer 8

• E.coli
• Salmonella
• Listeria monocytogenes

Question 9

What are the main routes of carcass microbial contamination from hide?

Answer 9

• Hide microbiota is regularly transferred from the hide onto carcass meat during dehiding
  Direct transfer: Via accidental in-rolling of hide
  Indirect routes:
• Via workers’ hands
• Via contaminated knives, equipment, aprons, etc
• Via aerosols generated during manipulation with hides (especially after mechanical pulling)

Question 10

What are interventions in abattoirs?

Answer 10

Actions taken during slaughter and processing to reduce microbial contamination of carcasses

Question 11

What are some cattle hide interventions?

Answer 11

Chemical washes with vacuuming and immobilisation treatments

Question 12

Which hide treatments can be used pre-evisceration?

Answer 12

• Animal washing
• Shearing or clipping the hide
• Washing hides with chemicals
• Chemical dehairing
• Knife trimming
• Stream vacuuming

Question 13

Which hide treatments can be used post-evisceration?

Answer 13

• Knife trimming
• Stream vacuuming
• Steam pasteurisation
• Chilling and simultaneously spraying with chemicals
• Washing with chemicals

Question 14

Describe the practicalities of pre-slaughter washing of animals

Answer 14

• Technically difficult and hazardous for workers
• Animal welfare and meat quality concerns – impossible to apply harsher cleaning or decontaminating agents
• Hide of washed animals eventually becomes again re-contaminated until skinning point

Question 15

Describe post-slaughter pre-skinning treatment of hides

Answer 15

• Proactive, deals with “causes”
• No animal welfare concerns - much harsher treatments possible
• Since the hide is inedible, much aggressive and harsher treatments possible

Question 16

What are some possible approaches to hide treatments

Answer 16

• Removal of bacteria from the hide: Water-washing is ineffective microbiologically
• Decontamination: to eliminate/kill bacteria on the hair: it is not possible to completely eliminate/kill all bacteria on hides
• Immobilization: to “stick” bacteria to the hair: no need to kill the bacteria, only to prevent their transfer onto carcass meat

Question 17

What are the limitations of hide decontamination techniques?

Answer 17

• Effectiveness: reported microbial reductions achievable were relatively limited
• Cost and space restrictions: Decontamination equipment is usually expensive and require large space for installation
• Environmental pollution with chemical waste
• Impact on hides value

Question 18

What is an alternative to the pre slaughter clipping of cattle on farm and in lairages?

Answer 18

The VacClip® system to remove hide contamination on line

Question 19

How does the VacClip® system prevent airborne contamination?

Answer 19

Removes dirt within flexible hosing to an enclosed container located away from the kill line

Question 20

Describe the principles of the immobilization treatment

Answer 20

• “Gluing” of bacteria to the hide: various compounds possible, so far the most promising is 23% solution of food-grade insect-produced resin Shellac in ethanol
• Spraying application preferred
• Post-slaughter but pre-skinning application
• The cleaner/dryer the hides, the better “gluing” of bacteria

Question 21

Which of the hide treatments has the highest efficacy in reducing carcass contamination?

Answer 21

Chemical dehairing

Question 22

What are some carcass meat decontamination treatments?

Answer 22

• Carcass wash: Hot water (>74oC)
• Carcass decontamination: Steam Pasteurization SystemTM (105oC)
• Steam vacuuming (spot treatment)
• Carcass decontamination - organic acids: lactic, acetic, citric, fumaric
• Irradiation

Question 23

Describe steam vacuuming

Answer 23

• physical removal of visible faecal contamination and bacteria
• used on locations prone to contamination
• used directly if visible faecal spots <1”
• knife trimming first if >1”, then steam
• reductions up to 2 log cycles

Question 24

Describe ‘multiple hurdle technology’

Answer 24

Combination of 2 to 5 interventions:

• Hide on carcass wash
• Pre-evisceration rinse/spray (hot water/lactic acid)
• Steam vacuum (spot treatment)
• Post evisceration carcass wash (hot water/organic acids)
• Steam or hot water pasteurization
• Final acid rinse/spray
• Spray chill
• Post chill wash