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Foodborne illness from citrus fruit: understanding the food safety risks

S.P. Singh, PhD

E: sp.singh@dpi.nsw.gov.au; 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