Knowledge Transfer Task Force

Article 8 - Strive for Food Safety Perfection, Settle for Excellence

October 7, 2019

Related Resources:
Lu - Detection, validation, and assessment of risks implied by the viable but non-culturable (VBNC) state of enteric bacterial pathogens in fresh produce
Munther - Mathematical modeling tools for practical chlorine control in produce wash process
Suslow - Resolving postharvest harborage sites of Listeria protects Zone 1 surfaces

This article originally appeared in The Packer, and is reprinted here with permission. © 2019 The Packer

We all know there is no food safety “kill step” for fresh produce consumed in a raw state. Unlike processed foods, we can’t use heat pasteurization to kill microbes, nor can we use food preservatives and consumer packaging like tin cans and Tetra Paks to prevent their growth.  

It’s also impossible to eradicate every pathogen that might occur along our complex supply chain. Contamination could happen at many points throughout farming, harvesting, packing, processing, distribution and retailing. Trying to kill pathogens can also be complex. Some microbes can go dormant, become resistant or even more virulent. 

Since it’s just not feasible for us to control all risks to create risk-free produce, our goal then as an industry should be to minimize pathogens throughout the supply chain. We can’t be perfect, but we can “settle” for excellence by striving for low levels to minimize potential illness.  

For grower/shippers, this requires a deep understanding of their operations because it requires a holistic approach of identifying all potential pathogen entry points, assessing risk, and then prioritizing and implementing solutions. 

Few people in our industry understand more about striving for food safety in apple packing processes and facilities than Matt Miles from Allan Bros. Inc., Naches, Wash. After a 15-year career in aerospace engineering, he has enjoyed the switch to agriculture and his eight years at Allan Bros. Originally hired to create processes around new packing technology, his responsibilities now include food safety and compliance for this 100-plus-year-old, fourth-generation farming operation. 

Allan Bros. has invested heavily in new apple varieties and diversified into vineyard operations. Their staff of 500 peaks to 1,200 during harvest, including 150+ H2A workers; they also pack for about 120 other growers.  

Miles recalls back in 2014 when the apple industry was rocked with a serious outbreak of listeriosis traced back to Listeria monocytogenes-contaminated caramel apple production. This outbreak was a wake-up call for apple producers to seriously look inward at their operations and practices. Yet with every threat comes opportunity. Miles was part of an Allan Bros. design team that collaborated on a 290,000-square-foot expansion to its packing facility that prioritized food safety, worker safety and efficiency. The new layout is easier to clean and sanitize to minimize cross-contamination. 

Allan Bros.’ food safety focus begins in the orchard. While growers in desert regions such as Yakima Valley have historically used overhead sprinklers to cool growing fruit and prevent sunburn, in an effort to minimize the potential food safety risk associated with applying irrigation water directly to product, Allan Bros. and others are transitioning to overhead shade cloth or netting — which also helps to conserve water. 

Allan Bros.’ packing line then runs just-picked fruit through multiple wash water systems, and then either packages product for immediate sale or pre-sizes it back into bins for future packing and sale. To minimize cross-contamination, wash water is treated with either sodium hypochlorite or peroxyacetic acid. 

Miles and his staff follow Center for Produce Safety’s produce-specific food safety research closely. He points to two studies in particular regarding packing lines. In 2016, California State University’s Steven Pao, Ph.D., evaluated sanitizing in stone fruit packinghouses. He found very low levels of contamination on hard-to-clean Zone 1 surfaces. This may allow for less costly sanitation practices, as clean-in-place sanitation can be done more frequently instead of having to disassemble equipment to clean parts separately. 

Another study by UC Davis’ Trevor Suslow, Ph.D., investigated postharvest harborage sites of listeria on Zone 1 surfaces. The study found significant prevalence of listeria in citrus packhouses, influenced by standing water and moisture. Effective cleaning and sanitation processes disrupted aged biofilms and achieved considerable decreases in listeria counts.

Miles comments, “Listeria is everywhere, and most of us have processes that potentially enable it to be spread across multiples sites. This is a boots-on-the-ground study that the produce industry should take to heart.” 

Miles also points to 2017 work done by University of British Columbia’s Xiaonan Lu, Ph.D., which demonstrates how difficult it can be to eradicate some pathogens, such as enteric bacteria that can be present in viable but nonculturable (VNBC) levels. Miles comments, “The concept that there is such a thing as a living but dormant microbe that can’t be cultured is shocking. It reinforces the need for an active environmental monitoring program to detect microbes that may come out of dormancy.” 

The team at Allan Bros. focuses on assessing risks across their supply chain and ensuring the rigor of their food safety program. Their risk assessments are data- and process-driven, which helps them understand the “why” before coming up with solutions. Miles cites CPS-funded work by Cleveland State University’s Daniel Munther regarding mathematical modeling tools for practical chlorine control in the produce wash process. Miles comments, “Using mathematical models might help get answers sooner, but it’s important to understand the validation methodology and properly interpret the data. Don’t always trust what the computer tells you.”   

To ensure the rigor of their food safety efforts, Miles’ main priority is to partner with compliance manager Greg George to properly train their compliance team’s six members to assess risk and collaborate within the company, outside growers and the produce industry. Miles also notes that Allan Bros.’ food safety culture starts at the top; the ownership and senior management fully support focus on food safety. 

Miles notes that Allan Bros. has a pragmatic approach to food safety. “There is no silver bullet, so you need to understand the issue well and do the right thing,” he says. Sometimes it is the simple things — such as ensuring that field staff or sanitation team members’ boots don’t cross-contaminate the packing facility — that can keep that one bad apple from ... well, you know the rest.