food safety basics trevor phister
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Food Safety BasicsTRANSCRIPT
Food Safety and Strawberries
Trevor Phister, PhDAssistant Professor
Department of Food [email protected]
Why Should We Care?
Every year foodborne illnesses result in an estimated:
• 76 million cases of foodborne illness.
• 325,000 people hospitalized for foodborne illness.
• 5,200 needless deaths each year.
• Economic losses between 10-83 billion dollars.
Produce Associated Outbreaks Affect Business
• Strawberry industry lost an estimated $50 million in 1996 after mistakenly being indicated as the source of pathogens in an outbreak.
• Odwalla shareholder value dropped approximately 41% ($12.4 million) in six months after outbreak.
• Work against produce promotions campaigns.
• May result in unwanted legislation or regulation.
Microbes That Cause Foodborne Illness
• Bacteria – Single-celled organisms that live independently.
• Viruses - small particles that live and replicate in a host.
• Parasites - intestinal worms or protozoa that live in a host animal or human.
Parasites
Viruses
Bacteria
Number of Produce Associated Outbreaks by Decade, 1973 - 1997
3.7
6.5
10.5
0
2
4
6
8
10
12
1973-79 1980-89 1990-97
Decade
Outbreaks / year
Main produce items
• Leafy greens• Tomato• Sprouts• Berries• Melons
Harmful Microorganisms & Outbreaks Associated with Produce
Pathogen
Produce
E. coli O157:H7 Iceberg lettuce, radish sprouts, unpasteurized apple cider/juice
Salmonella spp. Tomatoes, bean sprouts, sliced watermelon, sliced cantaloupe, coleslaw & onions, alfalfa sprouts, root vegetables, dried seaweed
L monocytogenes Cabbage B. cereus Sprouts Hepatitis A virus Iceberg lettuce, raspberries, strawberries Cryptosporidium Apple cider Cyclospora Raspberries
Frequency of Pathogens on Produce
• Vegetables (from literature):– Salmonella 1- 8%
– L. monocytogenes 2- 30%
– Shigella 1%
– No difference was found between organic and conventional
• FDA Produce Surveillance Program– Imports - 4% positive rate (Salmonella &
Shigella)
– Domestic - currently being conducted
The Problem
Charles Dharapak/Associated Press
Strawberries
• 1992 Hepatitis A– 35 infected
• 1997– 2.6 million pounds frozen strawberries
recalled– Thousands of children exposed to
Hepatitis A– 262 children infected
What can we do?
Taken up through roots
JFP vol65 p18-23
Solutions
Washes and rinses
• Chlorine• Chlorine dioxide• Ozone• Acetic acid• Electrolized water
Good Agricultural Practices
Good agricultural practices
• Water• Fertilizer • Animal feces• Worker health and hygiene• Field sanitation• Packing facility• Transportation• Traceback
Good management practices
• Growers and packers who successfully pass will be listed on the USDA and NCDA web site
• Participation is voluntary• Program initiated by retailers asking for demonstration of
adherence to food safety practices• http://www.ncagr.com/markets/gradnreg/foodsafety/index.h
tm• Phone: (252)-792-1672
Good management practices
Good agricultural practices
• Water• Fertilizer and animal feces• Worker health and hygiene• Field sanitation• Packing facility• Transportation• Traceback
water
• Anytime water comes in contact with fresh produce, its quality determines the potential for pathogen contamination since water may be a carrier of a number of types of microorganisms:– Escherichia coli, Salmonella spp., Vibrio
cholerae, Shigella spp, Cryptosporidium parvum, Giardia lamblia, Cyclospora cayetanensis, Toxisplasma gondii, the Norwalk virus and hepatitis A
Courtesy of FDACourtesy University of Florida
• Usually, water for agricultural uses comes from:– Surface sources such as rivers, streams,
irrigation ditches and canals
– Reservoirs (open or capped)
– Municipal water systems
water
Courtesy of FDACourtesy University of Florida
Make sure you know your water system
Ground water may be contaminated by a variety of biological and chemical hazards,
which include:
• Bacteria and viruses• Domestic waste • Nitrate nitrogen • Synthetic organic chemicals • Heavy metals • Petroleum residues • Combustion products from roadways
Courtesy of FDA
Microbiological Testing
• Microbiological testing is used in the verification steps of a safety assurance program. • It is important to document the frequency and results of each water test for comparison purposes. • These records would become very important in the event of a microbiological outbreak investigation.
Courtesy of FDACourtesy University of Florida
Water Source Will Determine the Possible Frequency of Testing
Source Possible Water Testing Frequency*
Closed system, under the ground or covered tank
One annual test at the beginning of season
Uncovered well, open canal, water reservoir, collection pond
Beginning, middle and week before harvest
Municipal/District water system
Keep records from the municipality/district water system (monthly, quarterly or annual report)
* Obtained from California Strawberry Commission (1998) Quality Assurance Program
Courtesy of FDACourtesy University of Florida
Sampling criteria can differ greatly
Total coliforms(cfu/100 mL)
Thermotolerant coliformsCfu/100 mL)
E. coli (CFU/100mL)
Buyer 1 <100 <10 <10
Buyer 2 50%<1000 50%<100 50%<100
CLGMA NA NA <126 MPN for 5 samples<235 single
Frost protection
• Water should meet pre-harvest criteria– 126 E. coli per 100 mL
• If it is over this limit– Do not use water until
problem corrected– Examine water source– After actions taken
retest water at sampling point
– Test water for 5 days– sample the crop
• If crops positive do not use
Photo by Donnie Fulks, Belvedere Plantation,Fredricksburg, VA
Drip irrigation
• More efficient irrigation method– Less water lost to
evaporation
• Less transfer of pathogens to plant
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Conclusions
• GAPs best way to prevent foodborne illness
• Water quality for irrigation should be 126 MPN/5 samples (E.coli) although this may vary
• Drip irrigation safer than overhead
Acknowledgments
WaterWaterMark A. Ritenour, Ph.D.University of Florida, Indian River Research & Education Center, Fort Pierce
Elizabeth A. Bihn and Robert B. GravaniNational GAPs ProgramCornell University
Resources
http://www.ncagr.com/markets/gradnreg/foodsafety/index.htm
Trevor Phister Phone: 919-513-1644Email: [email protected]
www.extensionfoodsafety.org