August 4, AppleTalk Conference Call

AppleTalk Conference Call Summary
Tuesday, August 4, 2015, 8:00 – 9:00 AM
Guest speaker: Dr. Keith Warriner, Professor within the Department of Food Science at University of Guelph, Canada
Presenter: John Aue, Threshold IPM
Moderator: Peter Werts, IPM Institute of North America; questions or comments,

August 4th Call download: Click Here

Food safety discussion with guest speaker Dr. Keith Warriner, University of Guelph, Canada
Dr. Warriner is currently a Professor within the Department of Food Science at University of Guelph, Canada. Dr. Warriner received his BSc in Food Science from the University of Nottingham, UK and PhD in Microbial Physiology from the University College of Wales Aberystwyth, UK. He later went on to work on biosensors within the University of Manchester, UK and subsequently returned to the University of Nottingham to become a Research Fellow in Food Microbiology. He joined the Faculty of the University of Guelph in 2002. During the last fifteen years in the field of microbiology and food safety research, Dr. Warriner has published more than 100 papers, book chapters, patents, and conference abstracts. His research interests are focused on enhancing food safety within meat processing and the fresh cut sectors. To this end, his research team have advanced knowledge in the area of emerging pathogens, intervention technologies, water recycling and development of biosensor devices to detection of foodborne hazards. He is frequently contacted by the media to provide commentary on food safety issues and is the past President of the Ontario Food Protection Association.

Outbreaks as drivers of stricter food safety standards

• In the last few years retailers have taken a larger role in developing and implementing food safety requirements for their suppliers to abide by. This new role is a departure from their historic role as the “middle-man” between the grower and consumer.

Basic biology and lifecycles
• Listeria is a genus of a bacteria that can thrive equally as well inside and outside of the human body, compared to E. coli which needs to live in human intestines.
• Thrives in cool, damp environments and is easily found in soils and water.
• Listeria has many species within the genus, only one out of the eleven species are pathogenic.
• The main determinant for severity of illness following infection is the health of the host; small children, elderly and pregnant women are of greatest risk. Different levels of virulence exist within the pathogens of Listeria.

• Patulin is a toxic fungal metabolite (mycotoxin) produced by molds in the genera Penicillium, Aspergillus and Byssochlamys. Species in these genera are likely seen as black, blue, green or orange molds growing on various food commodities, especially fruit. Molds proliferate when temperatures are warm and humid. Visible signs of mold on bruised and/ or damaged fruit is a good indicator that patulin is present. Patulin can contaminate the entire fruit, e.g., cutting mold off will not reduce presence of patulin; one damaged fruit has the potential to contaminate an entire batch.
• The US Food and Drug Administration has produced a regulatory action guidance level for patulin at 50 micrograms per kilogram (50 parts per billion (ppb)). The European Union is attempting to reduce their current acceptance level to 25 ppb.
• Following the discovery of patulin in the 1930s, its antibiotic properties garnered attention to use it as a cold remedy. Research showed that patulin had negligible effects against the pathogen, and toxicity reports suggested it may have a number of toxic effects on humans.
• Patulin is not a carcinogen, yet, reacts with proteins and degrades our immune system. 25 ppb is a safe amount to consume.

Essential procedures that should be implemented during harvest, packing and processing to mitigate risk of contamination:
• Do not harvest apples that have fallen on the ground.
• Orchards applying manure should only apply composted manure. Develop a manure management plan. Decaying plant matter can promote growth of Listeria.
• Use potable water for irrigating and applying pesticides.
• Avoid transporting harvest containers through central food processing facilities; restrict harvest containers to a portion of facility. Clean and sanitize containers frequently; plastic containers are easiest to sanitize. Clean and sanitize any containers that are contaminated with soil before moving into storage or packinghouse. Inspect containers for damage.
• Reduce the amount of standing water and condensation present in storage and packinghouse. Condensation is common when bringing fruit out of coolers. Covering apples until they come up to room temperature will prevent condensation from settling on fruit. Days not hours are required for mold growth, however, pathogens can grow faster.
• Drains can harbor Listeria. Probiotics, rather than sanitizers, can be added to drains to outcompete the pathogen.
• Solid plastic and brush conveyors are the easiest to sanitize. Growers with foam and wood conveyors need to take extra precautions when cleaning and sanitizing, these materials are not recommended.
• Washing fruit with only water will not impact Listeria. Many small retailers choose to keep fruit dry by “dry polishing” rather than rinsing or washing.
• Hand washing and hair nets worn by harvest workers is likely an insignificant source of contamination.


• Do not harvest apples that have fallen on the ground.
• Do not use damaged fruit with visible mold. Patulin is not an issue with whole apples.
• Avoid standing water and condensation.
• High levels of patulin can be diluted by combining with products free of patulin, e.g., cider with 100 ppb patulin can be diluted with clean juice.
• Prevention is better than cure.

Recommended cleaners and sanitizers to use on packing lines.
• Cost effective, with drawbacks, e.g., reacts with organic materials and quickly degrades.
• A 10 parts per million (ppm) concentration of chlorine in wash water, i.e., dump tank, is adequate in eliminating Listeria. It is recommended to use an oxidation reduction potential meter or swimming test strips while adding chlorine to wash water as a certain amount of chlorine will be neutralized by organics present in the water. If wash water is used for continuous production, it is advised to monitor chlorine concentrations manually every 15 minutes or to install an automatic sensor. Note: The pH may need to be adjusted when adding chlorine to water.
• An E.coli outbreak in 2006 resulted from a manual chlorine monitoring system and not being monitored properly, result of the grower being short-staffed.

High pressure
• Extremely effective, expensive.

Electrolyzed water
• Electrolyzed water, electrolysis of sodium chloride. No disinfection bi-products, e.g., bleach smell, are produced. Disadvantage, has to be produced on site by machine ($40K). One apple grower with an electrolyzed water system uses the water for fungicide sprays.

Peroxyacetic acid (also known as peracetic acid)
• Very hazardous to handle, caustic.
• Certified for organic production.

Hydrogen peroxide
• Avoid; needs very high concentrations to be effective.


• Expensive, corrosive. Not a good choice.

• Always use detergents first, then sanitizer.
• Rotate sanitizers, potential exists to select for a resistant population. Good practice is to rotate sanitizers every month. Start rotation if Listeria is repeatedly found in environmental sampling.
• More sanitizer is not necessarily better. Use the recommended amount of sanitizer and contact time to avoid corrosion issues.
• Prevention is better than detection for small producers.

Insect update
Codling moth
Across the region growers are currently 1200-1400 DD from their first generation biofix. Larger flights of second generation moths have been observed in the last four days. Continue to monitor pheromone traps to time insecticides applications. If traps do not exceed threshold an insecticide application is not necessary. Spot spraying blocks where traps exceed threshold may be an option. Continue to monitor and consider treatment for other direct fruit pests, e.g., apple maggot, lesser apple worm, obliquebanded leafroller and oriental fruit moth. With harvest approaching, review pre-harvest intervals before making an application.

Apple maggot

Continue to monitor traps through the first week of September. Clean traps 10-12 days after an insecticide application or one inch of rain to determine if a reapplication is necessary.

Neonicotinoids have limited lethal action on adult apple maggots, but provide strong curative activity on eggs and larvae. It is recommended to apply neonicotinoids as full cover spray to blocks that exceed threshold. Alternate-row-middle applications will not provide adequate control. For more information visit: