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PHOTO of sewage contamination leaking to a yard surface from a broken sewer pipeProduce Disinfecting Vegetable Wash
Which home methods for washing vegetables provide effective disinfections?

Disinfect vegetables, fruits, salads & other produce in the home: this article describes the use of several approaches to washing & disinfecting produce: salad & vegetable products for home consumption.

We include research pointing out which vegetable wash disinfection methods work and might be used successfully in the home and which others must be used with caution, or perhaps not at all.

Interestingly we report that where fruit or vegetable disinfection washes are needed, using distilled water can perform as well as or even better than some store-bought vegetable washes!

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A Guide to Safe vs Questionable Vegetable Disinfection Washes & Treatments

Vegetable wash with forced immersion (C) Daniel FriedmanVegetable disinfecting wash chemicals sold at many produce stores or grocery stores (Sin Bac™, for example, is a product we use in Mexico) often contain a disinfectant that can be used for producing a produce disinfecting wash and that can also be used at a different concentration to disinfect water for drinking.

We describe how to use SinBac or similar products in detail below.

Watch out: If you have one of these products, read the label for the required amount of chemical to add and the wait time to use before consuming the water.

The Best Way to Wash Raw Fruits & Vegetables

The best ways to keep raw vegetables fruits safe have been outlined by a number of sources (REFERENCES) including both independent organizations (e.g. University of Maine) as well as companies selling vegetable wash products.

The following is adapted & expanded from Bolton (ret. 2014) et als, there are a few basic veggie or fruit washing steps that are key:

Vegetable wash with forced immersion (C) Daniel Friedman

Let washed produce dry in air (C) Daniel Friedman

- Bolton, Jason, Bushway, Alfred, Crowe, Kristi, El-Begearmi, Mahmoud, "Best Ways to Wash Fruits and Vegetables", Bulletin $4336, University of Maine, retrieved 4/1/14, original source: http://umaine.edu/publications/4336e/

Use of Chlorine-Based (Bleach-based) Hypochlorite Disinfectants for Washing Produce

Above we describe a "best practices" sequence of steps and recommendations for cleaning and washing produce. Details about bleach and water disinfectant limitations,contact time and the role of pH in the effectiveness of disinfectants in water are given by the article links below.

Concentration & contact time: Hypochlorite used as a produce disinfectant is commonly at a 50 - 200 ppm concentration range and requires a 1-2 minute contact time.

Commonly used concentrations of hypochlorite bleach solutions produce a maximum 1 to 2 log reduction in many pathogens on many commodities. (U.S. FDA 2016).

Warnings: Bleach or hypochlorite has a long history of use as a produce disinfectant but should be used with the following caveats (U.S. FDA 2016 cited below in our discussion of use of iodine as a produce disinfectant and again atReferences or Citations ):

Watch out: for these limitations on the effectiveness of bleach or chlorine disinfection of drinking water or grey water:

Alternatives to Use of Chlorine for Wash-Disinfecting Produce

Using distilled water as a vegetable wash

Sears water distiller (C) Daniel FriedmanVeggie washes: Bolton et als reported that some vegetable wash products such as Proctor & Gamble's Fit® reduced the level of residual pesticides and bacteria at the same level as using distilled water.

Ozone water purifier systems such as Air Zone's Ozone Water Purifier XT-301 and Indoor Purification Systems' J0-4 Multi-Functional Food Sterilizer removed microbes from the test produce but distilled water was found to be more effective than either of the ozone washes.

Distilled or clean water wash for produce: We have been using the Sears water distiller shown at left to produce distilled water for home use for over twenty years. The product is elegantly simple to operate and produces distilled water suitable for washing vegetables and fruits.

Why does distilled water work well as a produce wash? For two reasons at least:

  1. Besides not contributing any contaminants itself, distilled water is a very good solvent.
  2. Important, and on some produce even the dominant contaminants are in dust and soils that are removed by physical washing of the produce.

Advice for using SinBac or similar iodine-based vegetable disinfectant washes

SinBac vegetable wash disinfectant (C) Daniel FriedmanWith many years of experience washing locally-grown produce in Mexico we report that failure to wash and disinfect these products can be risky. Typically the products that we have used for at home produce disinfection in Mexico contain iodine.

Sin-Bac's disinfectant is (Cloro Dimetil Hidantonia or 1-Bromo-3-chloro-5,5-dimethyl-Hydantoin is a mixture of chlorine and bromine to form a useful antiseptic agent having bacteriostatic and bacteriacidal capabilities that have antibacterial, anti fungal, antiprotozoal, and anthelmintic activity) that can be used to disinfect water for drinking.

The Sin-Bac disinfectant concentration requires 4 caps per liter of water for a produce disinfecting wash.

Notice that next to our bottle of Sin-Bac we have a timer set to 5 minutes - the immersion time required for this product. In five years of vegetable wash using this product in central Mexico we have not had a bad result.

Sin-Bac is produced in Mexico by GV Products, Parque Chapultepec No. 61, Col Lomas Del Parque,

BacDyn vegetable disinfectant wash (C) Daniel Friedman at left is another disinfectant produce wash product, BacDyn Plus (www.bacdyn.com). Unlike the disinfetant-based SinBac, BacDyn Plus uses 0.08% colloidal silver. The manufacturer recommends a 10-minute immersion for produce disinfection. We don't use this product, preferring the Sin-Bac described above.

The BacDyn concentration instructions are on the package, typically 1/2 capful per liter for a disinfectant wash.

Concentration of Iodine or Lugol's Iodine in Vegetable Disinfection& Wash Solutions

Watch out: ... iodophors are not approved for direct food contact. According to the U.S. FDA article cited below, while iodine is commonly used on food contact surfaces and equipment, it is not advised for direct contact use on produce. The article notes (in Table V-1) that the possible usefulness of iodine on some whole produce deserves investigation and that this disinfectant may have significant sporocidal capacity. (U.S. FDA 2016).

More about using iodine as a disinfectant for drinking water is

at IODINE for WATER DISINFECTION.

Research on use of iodine solutions as a vegetable disinfectant

Using Hydrogen Peroxide as a Vegetable Wash

Katadyne Micropur chlorine dioxide kit Some websites describe use of 35% food grade H202 but without citing authoritative sources. "Vegetable Soak: (CLOROX substitute): Add 1/4 cup of 3% Hydrogen Peroxide into a gallon of Cold Water. Soak light Vegetables (Lettuce, etc.) 20 minutes, thicker skinned Vegetables (like Cucumbers) for 30 minutes.

Drain and dry, (they keep LONGER too). If time is a Problem, you can spray the Vegetables with straight 3% Hydrogen Peroxide, let stand for a couple of minutes, rinse and dry." But is this treatment effective for just for Ecoli or also for Giardia?

Watch out: Cryptosporidium cysts might survive a typical chlorine disinfection process (such as at a municipal water treatment plant) and these or other cyst-like pathogens are likely to survive casual vegetable washing.

[Click to enlarge any image]

For this reason some municipalities where Cryptosporidium cysts are a concern add a water treatment step using chlorine dioxide.

Others may use a combination of UV light and chlorine in the water treatment procedure. This treatment is also available to hikers, travelers, and for emergency water supply use.

Using Vinegar as a Vegetable Wash

Vinegar disinfectant wash for vegetables or fruit (C) Daniel FriedmanVinegar produce washing be effective as a limited-scope disinfectant wash for vegetables as well.

Rough Calculation: use 1 cup of white vinegar to a large bowl of water; soak clean produce (already washed in fresh clean cold water) for 15 minutes. Do not rinse off the disinfectant solution.

See VINEGAR for PRODUCE or WATER DISINFECTION for details about using vinegar to disinfect produce or drinking water.

Watch out: some sources recommend only a clean water wash for produce but in our view that does not consider sanitary conditions in all situations nor in all countries.

Abstract The giardiacidal efficacy of simple disinfecting materials, ie lemon juice, vinifer, and vinegar, for uncooked foods with Giardia cysts was investigated to help travelers in Giardia-endemic areas.

The cysts were obtained from stools of individuals with Giardia intestinalis infection by modified sucrose gradient procedure.

A pooled batch of 3 x 10(4)/ml Giardia cysts was made from all specimens. The cysts were kept at 4 degrees C until use. Before each experiment, the number of cysts was determined by hemocytometer. Two sets of Eppendorf tubes were used for the experiments, one set at 4 degrees C and one at 24 degrees C.

One thousand microliters each of lemon juice, vinifer, or vinegar was poured into each tube, and 1,000 microl of Giardia cysts were added. Variables were disinfectant materials, temperature, and time of exposure. Cyst viability 140 was determined by eosin inclusion procedure.

Viability of at least 250 cysts in each tube at 0, 0.5, 1, 2 and 3 hours after the beginning of the experiments was determined. The mean giardiacidal activity at 4 degrees C after 3 hours for lemon juice, viniger, and vinegar was 18.9, 12.8, and 28.4%, and at 24 degrees C, 28.3, 16.2, and 40.6%, respectively.

In conclusion, the giardiacidal activity of vinegar was more than the other materials, and as exposure time and temperature increased, giardiacidal activity also increased; the highest giardiacidal activity of vinegar was at 3-hours exposure at 24 degrees C.

A second useful citation on the effectiveness of vinegar as a disinfectant that can treat giardia is below. Notice that the temperature of the process is important.

Abstract The inactivation of Giardia duodenalis cysts by vinegar was investigated. Experiments were carried out in 100 ml volume of vinegar (acetic acid 4%), undiluted or diluted in distilled water in ratios of 1:1, 1:15.6, and 1:62.5 (vol/vol), which were inoculated with 5 × 105 cysts obtained from human feces. Experiments were performed at room temperature (21 ± 1 °C) and at 4 °C.

After contact times of 1.5 min, 10, 30, and 60 min, the cysts were recovered from the treatment fluid and subjected to an in vitro excystation assay to determine their viability. The relative viability, which was calculated in relation to controls (maximum excystation percentage), was significantly affected (p < 0.1) by the vinegar concentration, contact time, and temperature.

At 21 ± 1 °C, no cysts remained viable after being treated with undiluted vinegar for 60 min, while the treatment with 1:1, 1:15.6, and 1:62.5 vinegar–water mixtures decreased the relative viability to 1.8%, 19.4%, and 56.4%, respectively.

The relative viability after corresponding treatments at 4 °C also decreased, but 23.6% to 48.8% remained viable after 60 min, and thus complete inactivation was not obtained with any treatment at that temperature.

Other Produce Washes & Disinfectants: alternaties to chlorine

Li (2008) and Ölmez (2009) and certainly other researchers have proposed some alternatives to use of chlorine for disinfecting produce:

The challenge to achieve appropriate disinfection without forming harmful disinfection byproducts by conventional chemical disinfectants, as well as the growing demand for decentralized or point-of-use water treatment and recycling systems calls for new technologies for efficient disinfection and microbial control.

Several natural and engineered nanomaterials have demonstrated strong antimicrobial properties through diverse mechanisms including photocatalytic production of reactive oxygen species that damage cell components and viruses (e.g. TiO2, ZnO and fullerol), compromising the bacterial cell envelope (e.g. peptides, chitosan, carboxyfullerene, carbon nanotubes, ZnO and silver nanoparticles (nAg)), interruption of energy transduction (e.g. nAg and aqueous fullerene nanoparticles (nC60)), and inhibition of enzyme activity and DNA synthesis (e.g. chitosan).

Although some nanomaterials have been used as antimicrobial agents in consumer products including home purification systems as antimicrobial agents, their potential for disinfection or microbial control in system level water treatment has not been carefully evaluated.

This paper reviews the antimicrobial mechanisms of several nanoparticles, discusses their merits, limitations and applicability for water disinfection and biofouling control, and highlights research needs to utilize novel nanomaterials for water treatment applications. - Li (2008)

Ölmez proposes Chlorine dioxide, ozone, organic acids, peroxyacetic acid, electrolyzed oxidizing water and hydrogen peroxide for produce disinfection:

Disinfection is one of the most important processing steps affecting the quality and safety and the shelf-life of the end product in fresh-cut processing. Chlorine is the most widely used disinfectant in fresh-cut industry. However, recent outbreaks associated with pathogen contamination in fresh-cut vegetables raised the concerns about the efficacy of chlorine treatment in assuring the safety of the products.

Moreover, due to the environmental and health risks posed by the use of chlorine, there is a trend in eliminating chlorine from the disinfection process.

Thus, there is a need for alternative sanitizers to be used for the disinfection of fresh-cut vegetables, not only for the organic food sector but also for the conventional food processors. Another challenge for the food industry is the minimization of water consumption and wastewater discharge rates.

The United Nations Environment Programme stated that Europe is one of the two global regions where more water is used for industry than for agriculture. Among the different industries, the food industry ranks third in water consumption and wastewater discharge rates coming after the chemical and refinery industries.

The adoption of less water consuming systems is required for improved water management in the industry. Therefore the food industry is now seeking alternatives to chlorine which assure the safety of the products, maintain the quality and shelf-life, while also reducing the water consumption rates in processing.

Chlorine dioxide, ozone, organic acids, peroxyacetic acid, electrolyzed oxidizing water and hydrogen peroxide are the main alternative sanitizing agents that gained interest in recent years. The effects of these disinfecting agents on the microbiological, nutritional and sensory quality of fresh-cut produce, and also the possible environmental impact and the potential on minimizing water consumption rates in the food industry are reviewed in this manuscript. - Ölmez (2009)

 

Research: Fruit & Vegetable Produce Disinfection & Soaks, Sprays, Washes

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-03-25 by (mod)

Re-posting from private email:

Fruit & Vegetable washing advice for the COVID-19 Pandemic

Fruits and vegetable surfaces are often sticky and may hold onto pathogens. From living in Mexico we learned to wash our fruits and vegetables.

Things that can be washed using dish soap and a scrubby sponge, esp. things with a rind to be cut-off or to be peeled are hand scrubbed.

Examples: canteloupes, watermelons, tomatoes, carrots, oranges, apples (that are also waxed) all can be scrubbed off.

From my reading on bacterial infections on F&V I learned that even using soapy water and physical scrubbing will remove nearly all hazards.

Non-scrubbable fruits and vegetables like grapes, lettuce, cauliflower and broccoli are disinfection-soaked.

In MX we use a 5 minute disinfecting soak in a Sin-Bac soution not easily found in the U.S. But there are easily-prepared disinfection solutions given above on this page.

For example, you can use a vinegar solution to disinfect everything - esp. things that are not going to be individually scrubbed with soap and water by hand - like stringbeans.

Fruit and vegetable disinfection steps:

1. First rinse items thoroughly in clean water. For example we rinse aggressively items like parsley, lettuce, and anything that is likely to hold dust and debris.

2. Second, hand-scrub using dish soap (best an anti-bacterial soap) and a scrubby-sponge, hard items that can be scrubbed clean such as cantaloupe, watermelon, carrots, oranges, apples. Rinse all soap off carefully.

3. Soak non-scrubbables (or everything) in a disinfectant solution such as those described above, for the time recommended - varying by the disinfectant solution chosen, typically 5 minutes.

4. DO NOT rinse off your disinfectant-soaked items, just let them dry in a dish rack.

Note: it's most important to wash off visible mud, dust, debris before cutting or peeling fruits and vegetables. Otherwise your knife may push unsanitary dirt and debris onto the newly-cut surfaces.

On 2016-07-05 by danjoefriedman (mod)

Sheila

As you'll read in the article section above discussing iodine and iodine-type vegetable disinfection approaches,

Watch out: ... iodophors are not approved for direct food contact. According to the U.S. FDA article cited below, while iodine is commonly used on food contact surfaces and equipment, it is not advised for direct contact use on produce. The article notes (in Table V-1) that the possible usefulness of iodine on some whole produce deserves investigation and that this disinfectant may have significant sporocidal capacity. (U.S. FDA 2016).

We discuss iodine as a water disinfectant and concentrations of lugol's solution or Lugol's Iodine in a separate article at

inspectapedia.com/water/Iodine_Drinking_Water_Purification.php

On 2016-07-05 by Sheila

Hello:

I have read that iodine is a powerful disinfectant, also for raw vegetables. but I have never came across for what is the dosage of Lugol's iodine 2% to disinfect vegetables? Could you inform to us more about it? Thanks for your attention and have a great week!



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