Processing and Packaging Fresh-cut Produce
Preparation for Processing
Appropriate preprocessing of incoming produce can help minimise microbial, chemical, and physical hazards. We recommend that fresh-cut produce processors consider the following activities to help minimise microbial, chemical, and physical hazards in in-coming produce:
Inspecting fresh produce throughout the processing stream for field contaminants that may not have been noticed during the incoming produce inspection
Removing from the processing stream damaged or decomposed produce, extraneous matter, and produce that appears to be contaminated by animal faeces, fuel, machine grease, or oil
Removing as much dirt as possible from incoming produce
We recommend, when appropriate, washing incoming Raw Agricultural Commodities (RACs) prior to further processing (such as cutting or chopping) to reduce the overall potential for microbial contamination from the surface of intact fruits and vegetables.
Processing Water
Water is used extensively in almost all aspects of processing fresh-cut fruits and vegetables, including during cooling, washing, and conveying of produce. Although water may be a useful tool for reducing potential contamination, it may also introduce or spread contaminants. When used for washing, cooling, rinsing, or conveying food, we recommend that water complies with applicable Federal, State, and local requirements.
In a fresh-cut processing operation, water quality changes as the water is used and, thus, maintaining the quality of processing water should be considered. Reusing processing water may present a risk of a new or increased number of microbial populations, including human pathogens.
We recommend the following practices:
Where water is reused in a series of processes, arranging water flow to be counter to the movement of fresh produce through different operations, with the result that as produce is further processed, it is exposed to the cleanest water
Monitoring and treating processing water for level of disinfectant chemical to ensure the water is maintained in a condition suitable for the application (e.g., washing, cooling, or transporting) and does not become a source of microbial contamination
Routinely inspecting and maintaining equipment designed to assist in maintaining water quality, such as chlorine injectors, filtration systems, and backflow devices, to ensure efficient operation
We recommend that ice used on fresh or fresh-cut produce be included in routine water quality testing.
A) Maintaining Water Quality
When used appropriately with adequate quality water, antimicrobial chemicals help minimise the potential for microbial contamination of processing water and subsequent cross-contamination of the product. The effectiveness of an antimicrobial agent, as well as the amount that should be used, depends on the treatment conditions, such as;
Water temperature
Acidity (pH)
Water hardness
Contact time
Amount and rate of product throughput
Type of product
Water to product ratio
Amount of organic material
The resistance of pathogens to the particular antimicrobial agent.
For example, the antimicrobial activity of a chlorine-based disinfectant depends on the amount of hypochlorous acid (also called "free chlorine") present in the water. The amount of hypochlorous acid in the water depends upon the pH of the water, the amount of organic material in the water, and, to some extent, the temperature of the water. If the amount of hypochlorous acid is not maintained when the amount of organic material increases, the antimicrobial agent may lose effectiveness in maintaining water quality.
If a fresh-cut processor uses a chlorine-containing compound as a disinfectant, we recommend that the processor monitor the processing water for free chlorine or hypochlorous acid concentrations. As another example, the measurement of Oxidation-Reduction Potential (ORP) is used as an indicator of the activity of any antimicrobial agent that is an oxidiser and as a measure of the agent's effectiveness during processing. Variables that affect antimicrobial activity during processing directly affect the ORP value and may also be used to determine the effectiveness of these oxidisers such as hypoorous acid, hypobromous acid, chlorine dioxide, ozone, and peroxides.
We recommend that fresh-cut processors consider options for maintaining the quality of water most appropriate for their individual operations. Producers may wish to contact a local agricultural extension agent, their chemical supplier, or a food safety consultant for help in deciding what water treatment chemicals to use.
We recommend that fresh-cut processors also consider the following regarding water quality maintenance:
Following the manufacturer's directions for correct mixing of antimicrobial agents to obtain effective concentrations and to minimise safety hazards
Manufacturers' suggested or allowable levels of antimicrobial chemicals in wash water should not be exceeded.
Monitoring disinfectant levels frequently in water used for various processing operations to ensure appropriate concentrations are maintained
Test strips or test kits may be useful for monitoring some disinfectant levels.
Minimising the build-up of organic material in wash water
For some operations, filtering recirculating water or using a net to scoop plant material or other debris from tanks may help reduce the build-up of organic material.
Following contact between produce and processing water containing antimicrobial chemicals with a clean water rinse of adequate quality to remove any treatment residues where appropriate and consistent with the manufacturer's directions
B) Washing Fresh Produce
Prior to arriving at the processing facility, RACs may be washed in the field or in a place such as a cooling facility. RACs may also go directly from the field to the processing facility to be washed after receipt. Regardless of where the initial washing of the fresh produce takes place, washing produce can reduce the overall potential for microbial food safety hazards because most microbial contamination is on the surface of the produce. If pathogens are not removed, inactivated, or otherwise controlled at this initial stage, they can potentially spread the contamination to additional produce during processing. Washing RACs before any processing of the fresh produce occurs may reduce potential surface contamination. However, washing, even with disinfectants, can only reduce, not eliminate, pathogens, if present. Washing has little or no effect on pathogens that have been internalised in the produce.
A number of post-harvest processes, such as hydrocooling, use of dump tanks, and flume transport utilise a high degree of water-to-produce contact. We recommend that fresh-cut processors use practices to maximise the cleaning potential during these processes and to minimise the potential for cross-contamination.
We recommend the following practices:
Using a series of washes, if appropriate
For some operations, a series of washes may be more effective than a single wash. An initial wash treatment may be used to remove the bulk of field soil from produce followed by an additional wash or washes containing an antimicrobial chemical.
Using appropriate wash methods
Vigorous washing of produce not easily bruised or injured increases the likelihood of pathogen removal. Different methods may be used to wash different types of produce, including submersion, spray, or both. Regardless of the method used, maintaining the quality of the wash water (see section 2.a. above) is important in order to minimise the potential for contamination.
Maintaining the efficacy of wash treatments
Using wash water of an appropriate temperature
Produce is susceptible to infiltration of wash water if warm produce is placed in water that is cooler than the produce. Such infiltration occurs when the temperature difference creates a pressure differential causing air spaces inside the fruit or vegetable to contract, thereby allowing water to be pulled into the fruit or vegetable. If pathogens are present in the cooling/wash water, they may infiltrate the produce, and subsequent washing will not reduce levels of these pathogens. Therefore, water used for washing or cooling produce should contain sufficient levels of disinfectant to reduce the potential for pathogens to persist in such water. When it is not practical to reduce the temperature differential between the wash/cooling water and the produce, it is especially important that processors follow practices to minimise pathogens in the water or on the surface of produce. Such practices may include using antimicrobial chemicals in the wash water or using spray type wash treatments instead of submerging produce. Alternatively, produce may be cooled by means other than hydrocooling and then washed with water that is warmer than the produce.
Precooling and Cold Storage
Sanitary cold storage of RACs and fresh-cut produce is important to reduce the risk of microbial contamination and potential for subsequent growth. However, most current temperature recommendations for both whole and fresh produce are based on temperatures that maintain quality attribute. Although we recognise that more research needs to be done to identify the types of whole and fresh-cut produce that will support the growth of human pathogens and the temperatures at which this pathogen growth will occur, certain practices can reduce the potential for pathogen growth and contamination during precooling and cold storage. We recommend the following practices to reduce this risk:
Holding RACs and fresh-cut produce at appropriate cold storage temperatures to reduce the potential for microbial growth
Preventing condensate and defrost water from evaporator-type cooling systems (e.g., vacuum cooling, cold storage) from dripping onto fresh and fresh-cut produce
Designing and maintaining forced air cooling to avoid contaminating fresh produce
4. Washing Fresh-cut Produce: Post-processing Controls
Final washing of fresh produce after cutting, slicing, shredding, and similar fresh-cut processes helps remove some of the cellular fluids that could serve as nutrients for microbial growth. Monitoring the quality of water used in such operations and replacing it at an appropriate frequency as indicated by such monitoring may help prevent the build-up of organic material in the water and reduce or prevent cross-contamination of processed produce. We have the following additional recommendations for use after the final wash of processed produce:
Where appropriate for the product, removing as much excess water as possible from processed produce through draining methods such as spin-drying
Keeping containers used to hold produce (e.g., spin baskets) from direct contact with the floor and away from containers that have had direct contact with the floor (e.g., in cold storage)
