Cleaning and Sanitizing Food Contact Surfaces
Cleaning and sanitizing food contact surfaces is key in preventing fecal contamination from coming in contact with fresh produce. There are also layers of preventative strategies aimed at keeping food handling equipment and surfaces from becoming contaminated, and these include:
- Worker training
- Routine housekeeping
- Optimizing work flow to prevent cross contamination
This document will concentrate on how cleaning and sanitizing food contact surfaces plays a part in a farm’s food safety culture and is the written companion to the video entitled, Plant Science Food Safety Group: Introduction to Cleaning and Sanitizing for Produce Safety (https://www.youtube.com/watch?v=mXtFlWt67z0).
Start by identifying the various sanitary zones that fresh produce contact, from harvest to pack out. Sanitary zones are ranked by their proximity to the fresh produce.
Zone 1 - Does the produce touch the surface? Yes? Then that is a zone 1 food contact surface.
Zone 2 – Is this surface adjacent to a zone 1 surface, such that loose soil could move easily onto that zone 1 surface? Then it is a zone 2 food contact surface.
Zone 3 – These surfaces are adjacent to zone 2 surfaces and include areas such as table legs and equipment housing.
Zone 4 – This area is generally considered outside the packing house but includes areas that harbor microbes. Think in terms of a nearby overflowing dumpster or weeds and debris allowed to collect outside of the packing house.
The FSMA Produce Safety Rule (PSR) and Good Agriculture Practices (GAP) certification require a schedule of cleaning and sanitizing of all sanitary zones, where appropriate. The farm operator determines the frequency of cleaning and sanitizing based on the growing, harvesting and packing of the farm’s products, and the frequency the produce comes in contact with the surface. For instance, harvesting knives may be cleaned and sanitized daily, and floors may be swept daily and mopped weekly. Grader/sorter equipment may get a twice-daily cleaning and sanitizing of the food contact surfaces, but an annual disassembly and deep cleaning.
What food contact surfaces are found in your operation?
- Harvest tools
- Harvest totes, lugs and bins
- Dump tanks
- Grader//sorter conveyer equipment
- Shelves in the cold storage room
- Bed of truck or trailer
- Display bins
Cleaning and Sanitizing: Doing it Right
The goal of cleaning and sanitizing is to remove the soil that we can see and the soil we cannot! Produce coming from the field or even the controlled environment growing area may carry field soil, or in handling, will leave plant residues (bits of leaves, flesh or skin) on surfaces that it touches. That soil and those plant residues which are naturally occurring fats and proteins, can build up in corners, crevices, and on the textured surface of tables and belts. The goal of the first step, cleaning, is to remove that built up material and any of the associated biofilms. Check the detergent label for the required contact time to facilitate its effectiveness. Potable water is required for all cleaning and sanitizing tasks.
Biofilms are bacterial communities that protect themselves from the environment with a polysaccharide coating. That coating takes the action of a detergent and abrasion to remove.
Sanitizing, is the second step. Choose the sanitizer that is appropriate for the surface and the application. Follow the label directions. Be sure to check the label for the required contact time.
A typical cleaning and sanitizing procedure may go something like this:
- Remove loose soil and debris with a brush or stream of air or water.
- Apply appropriate detergent and with a brush or similar device, work up a lather.
- Rinse with clean water.
- Apply sanitizer according to label directions.
- Allow to dry before using.
The Produce Safety Alliance has an interactive spreadsheet to help the farmer choose an appropriate sanitizer here: https://psla.umd.edu/sites/psla.umd.edu/files/files/documents/Food%20Safety/PSA-Labeled-Sanitizers-for-Produce.xlsx.
The University of Vermont Extension has a handy table to help determine the correct amount of sanitizer to use in a particular volume of water to obtain the required ppm concentration: blog.uvm.edu/cwcallah/files/2016/06/Sanitizer-Dose-Calculation.xlsx.
Remember, cleaning comes before sanitizing. Sanitizing alone, regardless of the concentration, will not inactivate microbes. Sanitizing without cleaning beforehand is a waste of time and product.
Keep accurate records of your cleaning and sanitizing. Record templates can be found here: https://psla.umd.edu/extension/produce-safety/record-keeping-templates-1.
Configuring Pack Houses for Efficiency and Safety: https://blog.uvm.edu/cwcallah/2020/02/09/planning-an-efficient-and-safe-wash-pack-area/.
The Food Safety Maintenance Act Produce Safety Rule standards are referenced throughout the video. Those standards can be found here: https://www.federalregister.gov/documents/2015/11/27/2015-28159/standards-for-the-growing-harvesting-packing-and-holding-of-produce-for-human-consumption.
What is Deep Cleaning?
Deep cleaning is featured in the video, Plant Science Food Safety Group: Cleaning and Sanitizing Cold Storage for Produce Safety, (https://www.youtube.com/watch?v=921cLO5Gdxg).
Cold storage facilities can harbor the human pathogen, Listeria monocytogenes. The cooler temperatures slow down the growth of other human and plant pathogens, but do not inactivate them. For that reason, a deep cleaning and sanitizing is a good practice and one of the requirements of the PSR and GAP certificates.
Cold storage rooms are often places where water may stand or a condenser can leak water onto the floor and stored items. Regular maintenance includes removal of standing water and repair of dripping condensers and drip pans. This video also reviews the sanitary zones and their location in the cold storage room.
Consult these references for more information on deep cleaning equipment:
Fact sheet to assist with Hygienic Design of Produce Equipment: https://blog.uvm.edu/cwcallah/2019/05/30/hygienic-and-sanitary-design-for-produce-farms/.
Deep Cleaning Checklists for some Equipment: (conveyor, brush washer, absorber):
Farm Vehicles and Produce Safety
We know that cleaning and sanitizing are an important part of the food safety culture on the farm. How can vehicle use and maintenance reduce the risk of cross contamination and diminish the possibility of food borne illness? The video, Plant Science Food Safety Group: Farm Vehicle Operation for Produce Safety (https://www.youtube.com/watch?v=1MU_q_F6m7U&t=1s) looks at prevention of cross contamination through vehicle allocation and regular cleaning and sanitation.
Power Washing: Correct Use for Produce Safety
Many farmers turn to a power washing tool to make cleaning and sanitizing fast and easy. There are advantages, but there can be disadvantages. The video, Plant Science Food Safety Group, Power Washing Aerosolization, Considerations for Produce Safety (https://www.youtube.com/watch?v=_mV9vcolycY&t=6s) looks at a common issue; the spread of microbe laden water particles that can contaminate nearby food contact surfaces. If a farm’s goal is to minimize cross contamination, additional steps need to be taken to get the job done right. Before using the power washer, consider:
- Power washer operator should wear protective gear to prevent inhalation and exposure to the eyes of power washer mist.
- Remove all portable items to an outside area for cleaning and sanitation if power washing will be employed.
- Cover all non-movable food contact surfaces before power washing floors, walls, or ceilings.
- Clean and sanitize all food contact surfaces after power washing.
Remember to record all cleaning and sanitizing events.