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Foodborne illness from citrus fruit: understanding the food safety risks
S.P. Singh, PhD
E: [email protected]; T: 02 4348 1935; M: 0420 593 129
• Safety
• Quality, healthy & nutritious
• Environmental & ethical values
• Provenance
20 years ago……..
• In March 1999, Salmonella outbreak linked to the unpasteurised orange juice
• In August 2003, the Federal Court’s judgement:
“…...(growers)….breached their contracts to supply fruit that was fit for sale..
….liability for the loss and damage ………found to rest with the…….(growers)”.
Impact of a food safety failure
Product recalls
Economic losses ↓
Consumer confidence
↓
Market access ↓
Supplier contracts ↓
Exports ↓
Reputation ↓
Consumer health ↓
Fo
od
Safe
ty R
isks
Physical
Chemical
Microbial
Food fraud
physical objects
chemical residues,
heavy metals, toxins
bacteria, viruses,
parasites, moulds
mislabelling,
traceability
Citrus Industry’s Food Safety Shield
Microbial Risk Mitigation
Food fraud and traceability
National residue survey program
Postharvest chemical residue
Preharvest chemical
residue control
On-farm
food safety
certification
Microbial Risks
Fungal Bacterial Viral Parasitic
Microbial contamination risks in the field
Microbial contamination risks in the field
Contamination can occur anywhere along the supply
chain, but the highest chances are in the orchard.
• Irrigation water
• Chemical spray water
• Animal manures
• Wildlife incursions
• Dust storms
• Field and harvest workers
• Farm machinery
Microbial hazards & their potential sources in the field
Bacteria
• Salmonella species• Listeria monocytogenes• E. coli O157:H7
Viruses
• Noroviruses• Hepatitis A
Parasites
• Cyclospora• Cryptosporidium
Postharvest sources of microbial contamination
• Entry of contaminated fruit in the packhouse
• Contaminated wash water
• Equipment
• Workers
Key Questions to the Citrus Industry?
Q1. Can citrus fruit be a carrier of foodborne
pathogens to consumers?
Q2. Can foodborne pathogens survive on
the citrus fruit during postharvest handling
and supply chain?
Q3. What is the current status of the
industry practice to mitigate microbial risks?
Citrus as a carrier of foodborne pathogens
Potential route for transfer of bacterial or viral pathogens
and parasites from fruit to the consumer
Rind HandEdible
partConsumer
Transfer of Salmonella from the Orange Peel to the Hands and Edible Flesh
Orange fruit were immersed
in the Salmonella culture for
30 sec
Left to dry in a
biosafety cabinet
+ Control:
whole fruit
in the broth
Fruit inoculated with
Salmonella were hand
peeled
+ ControlPeel Flesh Gloves
Rind/Flesh/Gloves in the broth
Transfer of Salmonella from the ‘Navel’ Orange Peel to the Hands and Edible Flesh
0
1
2
3
4
5
6
+ CONTROL Peel Flesh Gloves
Lo
g10
CFU
/mL
Transfer of Salmonella from the ‘Afourer’ Mandarin Peel to the Hands and Edible Flesh
0
1
2
3
4
5
6
+ CONTROL Peel Flesh Gloves
Lo
g10
CFU
/mL
+ Control:
inoculated
gloves in the
broth
Peel/Flesh/Gloves in the broth
Sterile fruit were
peeled using the
inoculated gloves
+ ControlPeel Flesh Gloves
Sterile gloves were
immersed in the Salmonella
culture for 30 sec
Inoculated gloves
were allowed to dry in
a biosafety cabinet
Transfer of Salmonella from the Hands to the Orange Peel and Flesh
Transfer of Salmonella from the Hands tothe Orange Peel and Flesh
0
1
2
3
4
5
6
7
+ CONTROL Peel Flesh Gloves
Lo
g10
CFU
/mL
Can foodborne pathogens survive through packhouse handling and supply chain?
Postharvest washing and sanitisation
• Postharvest washing and
sanitisation does NOT completely
remove the microbial pathogens.
• Contaminated wash water can
introduce pathogens on to the fruit.
• Pathogens established on the fruit
contact surfaces (e.g. conveyors and
brushes) can be a continuous
source of contamination.
Listeria monocytogenes - an environmental pathogen
A Californian study on 5 citrus packhouses (2017)
Source: Sbodio & Suslow, UC Davis. CPS Symposium 2018
Total environmental samples collected = 355
Tested positive for Listeria monocytogenes = 62 (38%)
0
1
2
3
4
5
6
0 Day Week 1 Week 2 Week 3 Week 4
Lo
g10
CFU
/mL
Survival of Salmonella on ‘Navel’ oranges
during storage at ~20°C
0
1
2
3
4
5
6
0 Day Week 1 Week 2 Week 3 Week 4
Lo
g10
CFU
/mL
Survival of Salmonella on ‘Navel’ oranges during storage at ~4°C
Final remarks
Food safety risks can not be eliminated
but can be minimised.
Prevent contamination of the fruit in
the orchards and packhouses
Packhouse washing can not completely
sanitise the fruit.
Final remarks
Proactive approach
Scientific evidence-based practice
Preventative controls Good agricultural practices (Field)
Good manufacturing practices (Packhouse)
Good hygiene practices (Workers)
NSW DPI’s Horticultural Food
Safety Research Program
Translational research & outreach
Scientific evidence-based practice
Proactive & preventative
Industry-focused
Acknowledgements
NSW DPI Horticultural Food Safety Research Team