Anything that touches fresh produce has the potential to contaminate it, including the materials used in packaging the finished product.

Packaging materials should be manufactured from food-grade materials, be stored away from any industrial chemicals and other possible contaminants, and not be used to store hazardous chemicals to avoid cross-contamination.

Finished products should be labelled or coded in such a way as to allow for the identification of a specific product lot or batch based on raw ingredient supply or production date.

Although good labelling and/or lot identification will not prevent the possibility of a foodborne illness outbreak, it may limit the liability if specific batches or lots can be traced to buyers and the product can be recalled.

We recommend the following practices:

Maintaining an effective system to prevent the use of contaminated, damaged, or defective cartons and totes in order to prevent microbial contamination of the fresh produce during packing operations
Overseeing incoming materials and gases used in packaging to confirm that they are not damaged or defective and are in appropriate working order
Rejecting packaging materials that are damaged or contaminated
Determining the appropriate gas mixtures for products
Using containers and cartons for their intended purpose only. For example, we recommend not using a carton designated for holding fresh produce to hold tools.
Storing packaging containers and other packaging materials in a manner so as to protect them from contamination, such as away from pests, dirt, cleaning chemicals, and water condensation from overhead equipment and structures
Maintaining a program to identify and correct situations where damage to containers may potentially occur
Labelling all finished fresh produce products with recommended storage instructions (e.g., "Keep Refrigerated") or storage temperature to inform all persons handling the product of the recommended storage conditions

1. Modified Atmosphere Packaging (MAP)

Some packaging controls used for fresh produce affect the environment within the package by reducing the levels of oxygen. Low oxygen levels help maintain the quality of fresh produce and extend shelf-life by slowing respiration and senescence in plant tissues. Oxygen can be reduced passively by using gas-permeable films in packaging that results in the natural development of the desired atmosphere; the desired atmosphere is a consequence of the products' respiration as gas diffuses through the film. Oxygen can also be reduced actively by displacing the mixture of gases in a package with a gas mixture that has a low concentration of oxygen (1-5%). Microorganisms respond differently to the surrounding gases depending on their tolerance. While reduced oxygen and elevated carbon dioxide retard the growth of spoilage microorganisms such as Pseudomonas spp (Bacteria), the same gas conditions may provide growth opportunities for pathogenic microorganisms. At extremely low oxygen levels (< 1%), anaerobic respiration can occur, resulting in tissue destruction that affects product quality and creating the potential for growth of foodborne pathogens such as Clostridium botulinum (Bacterium). It is generally believed, however, that fresh produce will spoil before the toxin becomes a concern. Non-pathogenic aerobic and facultative microorganisms are present at the time of packaging and persist after packaging.

MAP is only effective in extending shelf-life if used in conjunction with good refrigeration. Elevated temperatures can promote the growth of spoilage organisms and pathogens that may be present. Thus, we recommend that food processors using MAP adhere to strict temperature controls and appropriate shelf-life parameters. Because refrigeration temperatures may not be maintained during the distribution of the products or while they are held by retailers or consumers, we also recommend that controls be in place to either prevent increases in temperature, as feasible, or to alert the processor, retailer, or consumer that the product may not be safe to consume. Processors may wish to consider providing product handling guidelines on temperature control and washing to the distributor, retailer, and consumer. Another potential source of contamination of fresh produce packed in MAP occurs when the gases, equipment, or packaging materials are not properly maintained. As with any type of packaging, we recommend that controls be put in place to ensure that the process of packaging the product and the packaging materials themselves do not cause the product to become contaminated.

2. Shelf-life

Fresh fruits and vegetables can cause illness due to contamination with a variety of microorganisms because these products do not undergo any processing to ensure the total elimination of microorganisms that might be present. Some packaging and storage techniques for fresh-cut produce (e.g., MAP, refrigerated storage) may slow the rate of physical deterioration by slowing respiration of the produce. However, if packaging and storage are not properly controlled, pathogens may grow to levels that could render the product unsafe for human consumption. The rate of respiration of fresh produce is inversely related to product shelf-life, which means that a higher respiration rate decreases shelf-life. Fresh fruits and vegetables that have been cut or otherwise physically altered will have increased respiration, and thus, a shorter shelf-life. To address the risks of increased respiration, we recommend the following practices:

Communicating (through product labelling) that the consumer should refrigerate the product to prevent product spoilage and the potential for growth of pathogens
Ensuring that any "use by" date on the product package is validated by studies of the product with respect to microbiological safety

We recommend that records of these data and studies be maintained to document the reliability of the "use by" labelling.

In summary, safe fresh produce processing requires the prevention of contamination by microbial, physical, or chemical hazards during all stages of processing. Controlling the potential sources of contamination during processing will significantly reduce the probability of a foodborne illness being associated with fresh produce products that are produced and marketed.