Food Safety and Strawberries Trevor Phister, PhD Assistant Professor Department of Food Science [email_address]
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
Harmful Microorganisms & Outbreaks Associated with Produce l f a s p r o u t s , r o o t v e g e t a b l e s , d r i e d s e a w e e d L m o n o c y t o g e n e s C a b b a g e B . c e r e u s S p r o u t s H e p a t i t i s A v i r u s I c e b e r g l e t t u c e , r a s p b e r r i e s , s t r a w b e r r i e s C r y p t o s p o r i d i u m A p p l e c i d e r C y c l o s p o r a R a s p b e r r i e s P a t h o g e n P r o d u c e E . c o l i O 1 5 7 : H 7 I c e b e r g l e t t u c e , r a d i s h s p r o u t s , u n p a s t e u r i z e d a p p l e c i d e r / j u i c e S a l m o n e l l a s p p . T o m a t o e s , b e a n s p r o u t s , s l i c e d w a t e r m e l o n , s l i c e d c a n t a l o u p e , c o l e s l a w & o n i o n s , a l f a
Frequency of Pathogens on Produce
Vegetables (from literature):
Salmonella 1- 8%
L. monocytogenes 2- 30%
No difference was found between organic and conventional
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 FDA Courtesy 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 FDA Courtesy 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
Synthetic organic chemicals
Combustion products from roadways
Courtesy of FDA
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 FDA Courtesy University of Florida
Water Source Will Determine the Possible Frequency of Testing * Obtained from California Strawberry Commission (1998) Quality Assurance Program Courtesy of FDA Courtesy University of Florida Keep records from the municipality/district water system (monthly, quarterly or annual report) Municipal/District water system Beginning, middle and week before harvest Uncovered well, open canal, water reservoir, collection pond One annual test at the beginning of season Closed system, under the ground or covered tank Possible Water Testing Frequency* Source
Sampling criteria can differ greatly <126 MPN for 5 samples <235 single NA NA CLGMA 50%<100 50%<100 50%<1000 Buyer 2 <10 <10 <100 Buyer 1 E. coli (CFU/100mL) Thermotolerant coliforms Cfu/100 mL) Total coliforms (cfu/100 mL)
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
More efficient irrigation method
Less water lost to evaporation
Less transfer of pathogens to plant
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 Water Mark A. Ritenour, Ph.D. University of Florida, Indian River Research & Education Center, Fort Pierce Elizabeth A. Bihn and Robert B. Gravani National GAPs Program Cornell University