Food Protection Trends - March/April 2023 - 133

sanitation in both harvesting and processing operations,
major differences exist in the equipment settings. In food
processing and manufacturing settings, equipment is indoors
and typically fixed in place (20, 98); in contrast, harvesting
equipment is used outdoors, where it is continually being
transported between fields. The ever-changing routine of
harvesting operations requires more strategic planning for
both periodic and risk-based deep cleaning (observation
of environmental conditions necessitating a preventive
intervention) to occur, especially with regards to where and
when equipment can be disassembled. However, even in food
processing and manufacturing environments, deep cleaning
of equipment requires timing considerations because it
necessitates cessation of operations and interferes with
product output (20, 141).
The 2021 deep cleaning of harvesting equipment workgroup
study included a seven-step deep cleaning process that
revealed at-risk areas on the equipment and indicated that
disassembly of the equipment for deep cleaning was essential
for reducing or eliminating the bacterial load in hard-to-reach
niches on the equipment (37, 57). Although deep cleaning
requires longer downtime than routine cleaning, some form
of periodical deep cleaning is critical to prevent pathogen
persistence (i.e., biofilm formation) on equipment used for
harvesting and field-packing operations (57).
Cleaning and sanitizing methods
Current routine cleaning and sanitizing practices for
harvesting equipment generally follow a four- or five-step
process (141, 143). Cleaning and sanitizing of equipment
surfaces are two distinct processes that combine mechanical
action such as scrubbing, spraying, scraping, etc., with
chemicals or technologies (e.g., heat or radiation) to remove
and/or kill contaminants on the equipment (23). The
cleaning process involves chemicals (detergent type and
concentration), contact time, temperature, and mechanical
action (23). Surfaces must be cleaned before they are
sanitized because surface cleanliness greatly affects sanitizer
effectiveness; soil and product extracts (e.g., from cut
surfaces or rotting or damaged products) can interfere with
sanitizer efficacy (45, 73, 90, 141, 143, 158). Even trace
amounts of soil or plant residues may protect bacteria on
surfaces from sanitizer treatment (91, 92).
The specific methods used to clean a surface significantly
impact its cleanliness as does the nature of the material
fouling the equipment (e.g., soil residues or plant material).
Some residues such as soil may partially or fully dissolve
in water, whereas others require detergents or physical
removal (18, 141, 171, 173). Boyd et al. (18) found that
cleaning of fouled unpolished stainless steel with brushes
removed substantially more of the fouling material than
did spray cleaning. Verran et al. (171, 173) reported that
cleaning with detergent produced better results than did
spray cleaning with only water. A study by Lambrecht et
al. (96) revealed that detergents in foam form used with
a low-pressure applicator were also more efficacious than
conventional cleaning methods and reduced the potential
for cross-contamination from pathogen dispersal in aerosols
and droplets. Cleaning of stainless steel with a nonionic
detergent and simulated manual cleaning techniques resulted
in a 2-log reduction in attached bacteria (173). Selection of
appropriate cleaning tools (e.g., brushes) and application
procedures (e.g., foaming) is essential, recognizing that
different equipment, surfaces, and environments may require
different strategies.
Numerous factors should be considered when choosing
specific cleaning and sanitizing agents, far more than could
be adequately addressed here. Although below we briefly
discuss general categories and select research findings, others
researchers have more thoroughly addressed these factors in
relation to cleaning and sanitizing equipment used indoors in
packing and processing operations, and much of this information
is also relevant for harvesting equipment (25, 141, 143).
Cleaning agents or detergents typically contain numerous
chemical components such as surfactants, water conditioners,
fillers, and oxidizing agents, that play specific roles (e.g.,
controlling the pH) in the cleaning process (141, 143).
The primary role of detergents is to facilitate penetration,
breakdown, and suspension of soil with mechanical action,
which prevents redeposition on the equipment surface (23,
189). Knowledge of the type of soil fouling the equipment is
critical for choosing the correct cleaning agent(s) (i.e., acidic
or alkaline) because agents with the wrong pH can hinder
soil removal (143). A surfactant works by reducing the
adhesive forces between a contaminant and the equipment
surface (143, 189). Water conditioners prevent buildup of
mineral deposits, mainly in the form of calcium and magnesium,
which may affect the overall chemistry of the cleaning
agent and may be detrimental to equipment performance and
maintenance (143).
Sanitation is affected by contact time, concentration of
the active chemical, treatment frequency, applied force,
and treatment temperature (15, 23, 54, 55, 63, 141, 143).
Operators of harvesting equipment should consider each of
these factors when developing plainly and concisely written
SSOPs, including the appropriate tools and equipment
needed to conduct each procedure. In their evaluation of
commercial equipment sanitizing processes used in food
manufacturing, Cai et al. (23) reported that sanitizer contact
time was the most important predictor of L. monocytogenes
reduction on surface materials such as high-density polyethylene,
epoxy, stainless steel, and Buna-N rubber. Use of
sanitizers in foam form also enhances efficacy by increasing
contact time compared with liquid sanitizers (96). Solution
temperature affects the sanitizing efficacy of select sanitizers
(e.g., lower temperature slows the oxidizing effect of
hypochlorous acid), their safe use, and their ability to
corrode (141, 143). Fagerlund et al. (54) tested commercially
March/April Food Protection Trends 133
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