You are in the business of growing, harvesting and even packaging fresh produce; but are you using the safest product on the market, to clean fruit and vegetables?

Do you know what different methods are available?

Consumers are demanding organic alternatives to traditionally farmed produce and the natural progression for every fresh food producer should be to rid their crops of harmful chemicals to meet with these demands.

The chemicals currently used to clean and prolong the life of fruit and vegetables are posing a threat to human health and the environment. If there are safe, effective alternatives then farmers and growers need to consider them for their business

At the end of the day, consumer demand will always depict the success of every product and in a market worth 2.33bn; it makes sense for you, the farmers and growers, to know what post-harvest cleaning options are available.

What are the different methods for cleaning harvested crops?

  • Heat treatment
  • Irradiation
  • Sulfur Dioxide
  • Ozone
  • Chlorine
  • Electrolysed water

Do you know the risks involved with each of these post-harvest cleaning methods?

In this article we are going to look into each of these cleaning methods and give you information to allow you to make an informed decision.

It is worth bearing in mind that there is not a ‘one method suits all’ when it comes to post-harvest cleaning. The choice you make will be dependent on the type of crops you grow and whether or not growing your crops without risking human health and the environment, is a priority.

Post-harvest – what is used to clean fruit and vegetables before they reach the shops?

How effective is heat treatment (blanching) for cleaning fruit and vegetables?

No chemicals are used in this process

Blanching is a non-chemical method of ridding harvested fruit of bacteria and pests such as insects.

The fruit or vegetables can be immersed in hot water or ‘blasted’ with steam. The actual temperature and immersions time are dependent on the method you use (immersion or steam) and also the type of crop you are intending on washing.

The blanching parameters for each individual fruit or vegetable vary wildly which could be seen as a disadvantage.

Under blanching stimulates enzymatic actions and increases degradation rate, whereas over blanching causes loss of texture, colour, and flavour.

It has been reported that blanching by immersion in hot water runs the risk of the fruit or vegetable losing more vitamins and minerals and produces waste in the water. These waste products need more oxygen to allow it to be broken down and dissolved. When there is a large biological oxygen demand (BOD) in water, it results in lower dissolved oxygen levels for fish and aquatic life.

What is food irradiation?

Chemicals are used in this process

Irradiation is when food is has been exposed to radiation to eliminate bacteria and pathogens. According the foods standard agency, the food itself does not become radioactive.

“The law covering food irradiation states that irradiation can only be used where it is of benefit to the consumer. A company that wants to irradiate a food product has to be able to show that the benefits of irradiation outweigh any negative aspectsFSA

‘Outweigh any negative aspects’ this statement in the context of radiation worries me;

What are the negative aspects of food irradiation?

  • Irradiation damages the quality of food
  • Irradiation doesn’t kill all the bacteria in the food
  • This process can break down pesticides into new, potentially more dangerous chemicals - some of which have never been studied!
  • Irradiated foods lose 5%-80% of vitamins A, C, E, K or B complex
  • No one knows the health effects of a life-long diet that includes a large number of foods that can already be legally irradiated. The only study carried out was for the duration of 15 weeks only. This was done in China and the results of which are only available in Chinese.

You can read more about the negative effects of food irradiation here

How is sulphur dioxide used in post-harvest treatment of fruit?

Chemicals are used in this process

Have you ever been behind a car and smelt rotten eggs? This smell is caused by the hydrogen sulphide not being processed through the catalytic converter properly. The rotten egg smell is the result of the small sulphur content in the hydrogen sulphide.

Sulphur dioxide is used by some producers as a fungicide on grapes and is also used as a preservative on dried fruits.

This is not good news for humans or the environment; sulphur dioxide has been reported to aggravate the nose, lungs and throats and can exacerbate existing respiratory problems.

When sulphur dioxide combines with air and water, it creates sulphuric acid. Sulphuric acid, along with other gaseous compounds result in acid rain.

Acid rain has a devastating impact on forests, freshwater and soil. It kills insect and aquatic life-forms as well as causes damage to buildings and having impacts on human health. Due to the corrosive nature of the acids it damages both non-living things as well as living organisms.

Related content:  What is acid rain?

Can Ozone be used to treat post-harvest fruit and vegetables?

Chemicals are used in this process

Ozone was found to prevent the growth of yeast and mould during the storage of fruits way back in 1939.

Ozone is a sturdy biocide mainly because it kills bacteria, pathogens and fungi using oxidisation processes. Oxidation removes electron from a molecule. Taking away electrons disrupts the cellular structures of bacteria, rendering them harmless.

Ozone is a gas; it is highly efficient at killing bacteria, viruses, and protozoa and is almost always, generated on-site. It does not require transportation or storage of dangerous materials.

Because of its toxicity, this chemical needs to be consistently monitored.

As well as fruit and vegetable cleaning, Ozone has been used to treat drinking water; you can read more about Ozone (O3) in water treatments here

How is Chlorine used to clean fruit and vegetables?

Chemicals are used in this process

In the UK and EU fresh produce would normally be washed with chlorine; yes, the same chemical that some of you may use to clean your toilet.

With Chlorine disinfection come the formation of trihalomethanes THM’s (disinfection by-products). Disinfection by-products (DBPs) result from chemical reactions between organic and inorganic matter in water.

Although there are over 600 THM’s (disinfection by-products) 4 are of greater concern:

  • Chloroform (CHCl3)
  • Bromodichloromethane (CHCl2Br)
  • Dibromochloromethane ( CHClBr2)
  • Bromoform – (CHBr3)

It is the Chloroform that is of most concern; studies suggest links to cancer, and at high levels, reproductive effects.

Trihalomethanes (THM's) are only one group of many hundreds of possible disinfection by-products—the vast majority of which are not monitored—and it has not yet been clearly demonstrated which of these are the most plausible candidate for the cause of these health effects.

Items such as vegetables, fruit and chicken carcases are treated with Chlorine (CI) and along with the production of disinfection by-products, Chlorine is dangerous to the handler.

All though used in weaker doses that bottled, household chlorine, there are still some farmers, producers and packers that choose to clean their fruit and vegetables with chlorine even though it is toxic, unsafe and increasingly being banned by various governments.

Related content: hidden chemicals in supermarket fruit and vegetables 

Can fruit and vegetables be cleaned without chemicals?

No chemicals are used in this process

Short answer, yes

A safe method to rid crops of bacteria is by using electrolysed water.

Electrolysed water is produced by the electrolysis of ordinary tap water containing saline (salt). The electrolysis process produces two separate solutions from a double chambered cell. The positive chamber produces a solution containing a range of oxidisers and a small amount of hypochlorous acid. The negative chamber produces sodium hydroxide.

The resulting solution from the positive chamber is electrolysed water, an effective disinfectant.
Electrolyzed water is known globally by several different names:

  • EOW
  • ECA
  • Electrolyzed oxidizing water
  • Electro-activated water
  • Electro-chemically activated water solution
  • Electrolysed water (UK spelling)Electrolysed water looks and feels just like ordinary water, it is non-toxic and turns back to ordinary water over time. This means that it is safe to touch, consume and return to the environment.

Despite this, it is capable of extraordinary disinfection and is proven to effectively destroy pathogens, including:

  • MRSA
  • E-coli
  • Salmonella
  • Norovirus
  • Legionella
  • Listeria
  • Clostridium difficile

We recently wrote a blog ‘can post-harvest fruit and vegetables be cleaned without chemicals?' – you can read that here

What next?

It is concerning to think that the inorganic treatments highlighted are still used on our food today (2019). In some cases, there are instances where the processes or chemicals have not been fully tested to ensure they are safe.

Post-harvest washing that was once considered decontamination is now viewed as a high-risk cross-contamination point.

The chemicals used to clean and prolong the life of fruit and vegetables are posing a threat to human health and the environment. If there are safe, effective alternatives them farmers and growers need to consider them for their business

Related content: what is sustainable agriculture and why is it important?

Where can I buy an electrolysed water generator?

There are 3 companies where you can buy electrolysed water generators in the UK, one being our own company. We design and build the technology as do Aqualution, Envirolyte is solely a distributor.

Bridge Biotechnology 
Envirolyte UK (distributor only)

The electrolysed water produced by each manufacturers generator produces a very similar solution in that they are all safe, effective and sustainable.

You may still have some questions or doubts about something that appears to be a 'new' technology here are 5 reasons why an electrolysed water generator MAY NOT be suitable for you


There are a few links in this article, to save to looking for them we have listed them below:


What is wrong with food irradiation

What is acid rain?

Ozone as a food processing aid 

what is sustainable agriculture and why is it important?

Link to the food standards agency website

hidden chemicals in supermarket fruit and vegetables 

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