How Is Your Produce Being “Washed”?

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Have you ever noticed bagged produce at the grocery store labeled “ready to eat” or “washed”? Do you still wash the produce once you get home or do you eat it right out of the container?

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Washing Produce at the Packinghouse/Processor

It is common for produce to go through a postharvest rinse prior to arriving at the grocery store. Produce is washed in order to clean the produce, and to remove any microbial contaminants (e.g., Listeria, Salmonella, E. Coli 0157:H7). In order for a piece of produce to go through a wash step, it needs to be durable enough to withstand the washing and to maintain its desired shelf-life at the grocery store (e.g., blackberries could not withstand a wash step). Some examples of produce that go through a wash step include apples, oranges, cherries, peaches, plums, avocados, baby carrots, etc.

When harvested produce is transferred to the packing house, the wash step occurs near the start of the packing line after the product has been dumped onto the line. However, produce can also be washed in the field postharvest.

Produce is washed in one of two ways:

  1. Using recycled/reused water, where the same water is used with multiple bins of produce that are dumped onto the packing line prior to being switched out.
  2. Using a single-pass system, where the water from a spray bar (or something similar) is used only once.
Recycled Wash Water - Washing Cherries at the Packinghouse
Single-Pass System - Washing Peaches at the Packinghouse

Sanitized Wash Water

It does not matter if the product is organic or conventional, all wash water contains a sanitizer. The only exception is when the produce has already gone through a rinse with a sanitizer and then goes through an additional rinse with no sanitizer (see the lettuce example below).

It is important to note that each time a bin of produce is dumped onto the packing line, there are multiple pieces of individual fruit/vegetables (some of which may contain microbial contaminants), as well as field debris (e.g., soil and leaves). Thus, wash water needs a sanitizer in order to maintain the potability of the water and to prevent any cross-contamination of microbial contaminants contained in the bins. When these sanitizers are used, the packinghouses have specific controls in place for monitoring the water to make sure they are maintaining adequate sanitizer levels in the wash water. If the correct percentages are not maintained in the water, the wash water can have the opposite effect and act as a contaminant to the product.

Common Sanitizers Used to Wash Fruits and Vegetables

The most common type of sanitizer used during packing and/or processing is chlorine, in the form of sodium hypochlorite (in granules, tablets or liquid). In addition to the dosage amount, the amount of free chlorine, pH, temperature and the amount of organic matter (what is in the water in addition to the sanitizer, e.g., soil) all impact the effectiveness of the sanitizer. Other types of sanitizers used include peroxyacetic acid, ozone, aqueous chlorine dioxide, etc. New types of sanitizers are also currently being researched, such as neutral electrolyzed water and acid electrolyzed water.

What Does it Mean When Lettuce Containers are Labeled as Having Pre-Washed Lettuce?

A common example of “ready to eat” produce is packaged lettuce. The labels normally say something to the effect of “thoroughly washed,” “triple-washed,” etc., which all indicate that it is pre-washed lettuce.

What Does it Mean When Lettuce is Labeled as Triple Washed?

With lettuce and other leafy greens, the reference to “triple-washed” means that the lettuce went through three wash steps in three separate tanks prior to being packaged.  Those three steps are as follows:

  1. During the first rinse, the lettuce goes into an agitating tank to remove any physical debris from the field (e.g., pebbles, soil, etc.). With the high load of debris in this step, more frequent water checks need to occur to ensure that the sanitizer levels are being maintained.
  2. The second wash is where the product is cleaned, and where the sanitizer (chlorine) helps to control the bacterial limits in the wash water that comes into contact with both the product and the equipment.
  3. The final rinse step is with non-chlorinated water and is meant to rinse all of the chlorine from the prior two washes and to continue reducing the temperature of the lettuce. Instead of chlorine, the sanitizer typically used in this final rinse is ozone.

Other packaged produce items to look for the “ready to eat” or “washed” labels are those that are packaged to be cooked/steamed, those that can be eaten with dips or in salads. The individual produce pieces that are sold do not contain any labels referencing that they have been washed.

Frequently Asked Questions

Is the produce that is labeled as ready-to-eat really safe to eat?

Yes, or else they would not be able to label it as such. If you are hesitant, you can always wash it. 

Which fruits are “washed” before arriving at the grocery store?

Apples, oranges, avocados, peaches, nectarines, plums, cherries, and more!

Which fruits are never “washed” before arriving at the grocery store?

Any type of berry, grapes, figs, and any other fruit with sensitive skin that could not withstand a wash step.

Which vegetables are “washed” before arriving at the grocery store?

In addition to all that are packaged and labeled as ready-to-eat or as having been washed, it is common for most leafy greens to get a spritz of sanitized water before being packed in the field. Also, celery, asparagus, potatoes, radishes, carrots, most other root crops and much more!

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Resources:

Gil, M.I., Selma, M.V., Suslow, T., Jacxsens, L., Uyttendaele, M., Allende, A. “Pre- and Postharvest Preventive Measures and Intervention Strategies to Control Microbial Food Safety Hazards of Fresh Leafy Vegetables.” Food Science and Nutrition, 55:4, 453-468 (2015).

Matthews, K.R. “Leafy Vegetables.” The Produce Contamination Problem: Causes and Solutions, 2nd Edition. United States: Elsevier Inc., 2014. 187-206. Print.

This Post Has 7 Comments

  1. Vinod

    Hi Ms Megan, your post about dry fig processing is very useful to me. Thank you so much to post very useful information.

    Good Job. Keep it up…

  2. John

    Very good and helpful information, thank you Megan!

  3. Anthony Radawiec

    A very generous gift that is offered to us all through this website. Thank you.
    How about raisins and other dried fruits, do we know if the fruits are washed before the drying process?

  4. Hotoko

    Amazing post ! Very informing, thank you so much.
    Do you know if tomatoes and cucumbers are also being washed before they arrive the stores?

  5. Ivy Marx

    Hi Megan,

    Since the wash water contains sanitizer, then is it the case there is no need to wash the produce (apple, plum, kiwi) coming straight out of the case? I can understand if the produce is in the grocery store and many hands can touch it, then you’d want to wash when at home. Is it a requirement or standard practice for all processors to use sanitized water when washing the apples and peaches etc?

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