Sunday, June 14, 2015

How to Better Ensure Your Produce is Clean and Safe

[Recipes and Technique]

Fresh produce can harbor dirt and debris, pests, bacteria, fungi, and other microbes along with trace amounts of chemicals including pesticides, fungicides, herbicides and wax treatments. Fortunately, there are steps you can take to help improve the healthfulness and safety of fruits and vegetables.

Steps to Limit Bacterial and Chemical Contaminants
  • Start clean. Cleanliness and safe produce go hand in hand. Before preparing fruits and vegetables, always wash your hands well with soap and water. Clean counter tops, cutting boards, and utensils with hot soapy water before peeling or cutting produce. Bacteria from the outside of raw produce can be transferred to the inside when it is being cut or peeled.
  • Buy organic. Pesticides, herbicides and fungicides sometimes penetrate the produce, or may even be systemic, so these are not always affected no matter how you wash your produce.  Buying organic at least takes the chemical contaminate out of the equation, however, you will still have to deal with the dirt and debris, fungi, pests and microbes, and perhaps even more so. 
  • Buy local. Reducing transport time and distance can help limit the chances of contamination and bacterial growth. Produce that needs to be refrigerated at home should also be kept cool at the market. Cut melon and salad greens should be kept on ice at the market.
  • Select based on condition. Look for produce that’s not overripe, blemished, bruised or dented. These factors offer pathways for pathogens.
  • Limit quantities. Most fresh vegetables can only be stored for two to five days, although apples, onions, potatoes, and winter squash can last much longer at appropriate temperatures.
  • Wait to wash. Washing produce before storing may promote bacterial growth and speed up spoilage, so it is often recommended to wait and wash fruits and vegetables just before use. Generally, soil has been removed from fresh produce but if not and you chose to wash before storing, dry thoroughly with clean paper towels before storing.
  • Store safely. Produce that requires refrigeration can be stored in vegetable bins or on shelves above raw meats, poultry, or seafood to prevent cross contamination. Storing fresh produce in cloth produce bags or perforated plastic bags will allow air to circulate. Do not keep cut, peeled or cooked fruits and vegetables at room temperature for more than two hours (one hour if the temperature is above 90F) and store in the refrigerator in covered containers.
  • Trim well. Cut tops and the outer portions of celery, lettuce, cabbage, and other leafy vegetables that may be bruised and contain more dirt and pesticide residues.
  • Be diverse. Eat a wide variety of fruits and vegetables. This is not only nutritionally beneficial but may help limit exposure to any one type of pesticide and/or herbicide residue.

Washing Fresh Produce

No washing method completely removes or kills all microbes which may be present on produce but studies have shown that thoroughly rinsing fresh produce under running water is an effective way to reduce the number of microorganisms. Washing fruits and vegetables not only helps remove debris, dirt, bacteria, and stubborn garden pests, but it also helps remove residual pesticides.

Under running water, rub fruits and vegetables briskly with your hands to remove dirt and surface microorganisms. If immersing in water, a clean bowl is a better choice than the sink because the drain area often harbors microorganisms. Produce with a hard rind or firm skin may be scrubbed with a vegetable brush (obviously it is important to keep your vegetable brush clean and dry).

Wash water should be no more than 10 degrees colder than produce to prevent the entrance of microorganisms into the stem or blossom end of the produce. Do not wash fruits and vegetables with detergent or bleach solutions. Many types of fresh produce are porous and could absorb these chemicals, changing their safety and taste.

Wash Your Food Properly

Wash all your fruits and vegetables. According to the CSE (Centre for Science and Environment), washing them with 2% of salt water will remove most of the contact pesticide residues that normally appear on the surface of the vegetables and fruits. Almost 75 to 80 percent of the topical pesticide residues are removed by cold water washing. Also, be more thorough with specific fruits and vegetables such as: grapes, apples, guava, plums, mangoes, peaches and pears and vegetables like tomatoes, and okra as they might carry more residue in their crevices. 

Vinegar Soak

Whip up a solution with 10% white vinegar and 90% water and soak your veggies and fruits in them for 10-20 minutes. Others recommend 30% white vinegar for maximum effectiveness, just washing with cold water is proposed to be 98% effective.  Yet others recommend a presoak in a baking soda solution first, and then a vinegar solution, all in the attempt to remove chemical residues.  In any case, stir them around and rinse thoroughly. Be careful while washing fruits like berries, and those with a thin peel as the solution might damage their porous outer-skin. 

Commercial Fruit and Vegetable Rinses

Chemical rinses and other treatments for washing raw produce, usually called fruit and vegetable washes, are often advertised as the best way to keep fresh fruits and vegetables safe in the home. But are these washes effective? The FDA advises against using commercial produce washes because the safety of their residues has not been evaluated and their effectiveness has not been tested or standardized.

In the fruit and vegetable product industry, chlorine is commonly used to remove microbes such as bacteria and mold from produce. In the home, a water wash, either with or without the help of a produce brush, is typically used to clean fruits and vegetables. So how do water washes hold up to the new “fruit and veggie” washes?

In the Department of Food Science and Human Nutrition at the University of Maine, researchers tested three commercial wash treatments:
  • Fit® (Proctor & Gamble, Cincinnati, OH)
  • Ozone Water Purifier XT-301 (Air-Zone Inc., Leesburg, VA)
  • J0-4 Multi-Functional Food Sterilizer (Indoor Purification Systems, Layton, UT)

All three products were tested according to product directions. They used low-bush blueberries as the produce. A water wash was also tested, using blueberries soaked in distilled water for one to two minutes. Here are the results:
  • Fit® washes got rid of roughly the same amount of microbes as distilled water. Both Fit® and distilled water reduced the level of residual pesticides compared to the unwashed samples.
  • Both ozone systems—the Ozone Water Purifier XT-301 and the J0-4 Multi-Functional Food Sterilizer—removed microbes from the blueberries. However, the distilled water wash was more effective than either of the ozone washes.
  • Because some produce washes are costly, we advise consumers to wash fresh fruits and vegetables with distilled water. Soak all produce for one to two minutes to reduce the risk of food-borne illness.

Clean Water

In the end, clean cold water (not more that 10 degrees colder than your produce, so you do not inadvertently draw contaminants in through the stem or blossom remnants) is very effective, especially if you are starting with organic produce.  If you want to go one step further, you could consider using distilled water because distilled or bottled water has been filtered and purified to remove contaminants.

Washing Techniques

Here are some different groups of produce and some recommendations for washing:
  • Leafy green vegetables. Separate and individually rinse the leaves of lettuce and other greens, discarding the outer leaves if torn and bruised. Leaves can be difficult to clean so immersing the leaves in a bowl of cold water for a few minutes helps loosen sand and dirt. Adding vinegar to the water (1/2 cup distilled white vinegar per 1 cup water), followed by a clean water rinse, has been shown to reduce bacterial contamination but may affect texture and taste. After washing, blot dry with paper towels or use a salad spinner to remove excess moisture. 
  • Apples, cucumbers and other firm produce. Wash well or peel to remove waxy preservative.
  • Root vegetables. You can peel potatoes, carrots, turnips and other root vegetables (though this removes the nutrient rich skin), or clean them well with a firm scrub brush under lukewarm running water.
  • Melons. The rough, netted surfaces of some types of melon provide an excellent environment for microorganisms that can be transferred to the interior surfaces during cutting. To minimize the risk of cross contamination, use a vegetable brush and wash melons thoroughly under running water before peeling or slicing. 
  • Hot peppers. When washing hot peppers, wear gloves and keep hands away from eyes and face.
  • Peaches, plums and other soft fruits. Wash under running water and dry with a paper towel.
  • Grapes, cherries and berries. Store unwashed until ready to use but separate and discard spoiled or moldy fruit before storing to prevent the spread of spoilage organisms. Wash gently under cool running water right before use. 
  • Mushrooms. Clean with a soft brush or wipe with a wet paper towel to remove dirt.
  • Herbs. Rinse by dipping and swishing in a bowl of cool water and dry with paper towels.


You should ideally start with organic produce.  This is an ideal though, as not all produce is readily available as organic, and, truthfully, organic is currently more expensive.  Secondly, good practices for cleanliness and appropriate washing techniques will help to ensure that your and your family will be eating the cleanest and safest produce possible.  It really does not take all that much effort, and you will develop techniques for multi-tasking such that it will not take much, if any more time to apply these best practices.  

All of us live busy lifestyles, and this is one more thing that we can hardly imagine performing ongoing research and study upon, but the alternative of outsourcing our health to various food suppliers in not an effective solution for sustained long term health.

Sidebar: Produce Wax

What Why are wax coatings used on fruits and vegetables? 

Many vegetables and fruits make their own natural waxy coating. After harvest, fresh produce may be washed to clean off dirt and soil - but such washing also removes the natural wax. Therefore, waxes are applied to some produce to replace the natural waxes that are lost.

Wax coatings help retain moisture to maintain quality and also visual appeal.  This may occur:
  • when produce is shipped from farm to market
  • while it is in the stores and restaurants
  • once it is in the home

Waxes also help inhibit mold growth, protect produce from bruising, prevent other physical damage and disease, and enhance appearance.  In fact, some produce produce their own natural protective wax coating.  Still, the bottom line is, do you want to ingest commercially applied wax with your produce?

How are waxes applied? 

Waxes are used only in tiny amounts to provide a microscopic coating surrounding the entire product. Each piece of waxed produce has only a drop or two of wax.
  • Coatings used on fruits and vegetables must meet FDA food additive regulations for safety. 
  • Produce shippers and supermarkets in the United States are required by federal law to label fresh fruits and vegetables that have been waxed so you will know whether the produce you buy is coated. Watch for signs that say: "Coated with food-grade vegetable-, petroleum-, beeswax-, or shellac- based wax or resin, to maintain freshness."
  • Although the FDA considers these coatings to be safe for consumption, many consumers prefer to remove them before using the produce. This has the additional benefit of removing the majority of micro-organisms that can cause food-borne illness and pesticides as discussed earlier.

Sidebar: Topical and Systemic Pesticides, Fungicides and Herbicides

Does washing conventional produce really remove its agrochemical residues?

The short answer is no, not entirely. According to the National Pesticide Information Center, washing produce reduces pesticide levels but doesn’t completely remove them. Some fruits and vegetables, for example, may have their residues sealed under a coating of shelf-life-extending wax. Others have soft or waxy skins that help chemicals stick to their surfaces.

A study done at the Connecticut Agricultural Experiment Station confirms that washing is only partially effective. Researchers looked at the residues of 12 different pesticides on foods and discovered that three types were unaffected by washing.

There’s also the issue of systemic pesticides; these are chemicals designed to be absorbed by plants to kill any bugs that eat them. These poisons are inside the produce itself and won’t be affected by washing. Tests conducted by the Pesticide Action Network found the problem to be common—74% of tested conventional lettuce and 70% of broccoli, for example, had internal residues. Systemics were also found inside treated potatoes, strawberries, sweet peppers, and collard greens.  This borders on the topic of genetically engineered systems such as those found on Bt Corn.

Now you’re probably wondering if those products sold specifically for washing produce can help. The answer is, only sometimes. A 2003 study examining the use of various non-toxic washing treatments on nectarines and found that three ingredients, ethanol, glycerol, and sodium lauryl sulfate (SLS), removed about half of the total residues. But other ingredients were no more effective than water. And you might not want SLS residue on your stone fruit. 

A similar 2010 study on cucumbers and strawberries found that acetic acid, the active component of vinegar, was also helpful. If you’re interested in using something other than water to clean your fruits and veggies, vinegar seems preferable to a produce washing product; you’re likely already eating vinegar and won’t have to question or research its ingredients.

Two American food crops, leafy greens and hot peppers, are of special concern for public health because residue tests conducted by the U.S. Department of Agriculture have found these foods laced with particularly toxic pesticides. Among the chemicals at issue are organophosphate and carbamate insecticides. These are no longer detected widely on other produce, either because of binding legal restrictions or voluntary phase-outs.

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