Thinking Beyond Chemicals for Sustainable Fresh Produce Sanitation

Growing consumer awareness and increasingly stringent regulatory demands have resulted in renewed emphasis on the quality of water and selection of disinfectants used for the washing and preparation of vegetables, salads and other fresh produce.

Microorganisms can contaminate salads, fruits and vegetables from any number of sources; fertilisers used for growth, water used for irrigation, use of pesticides as well as bacteria from animals can all impact the cleanliness of the fresh produce. Therefore, before being placed onto the market, fruits and vegetables must be thoroughly and suitably washed to reduce the health risks of contamination from bacteria, such as E.coli.

The consequences of not adhering to food safety standards are severe. Foodborne illnesses are a concern for any producer, wholesaler or retailer – as well as consumers. In 2016, a national outbreak of E.coli 0157 caused 161 cases of illness in Britain, with two fatalities. Following an investigation undertaken by Public Health England (PHE) and working with Food Standards Agency (FSA) and Local Authority Environmental Health, mixed salad leaves were identified as the likely cause of the outbreak.

Maintaining high food safety standards is fundamental for producers, and SOCOTEC understands that choosing the safest and most effective sanitation method is crucial to meeting this objective.

Sanitising salads

Traditionally, chlorine was used to wash fresh fruit, vegetable and salad products to kill microorganisms and remove pesticides. Even today, chlorine is heavily relied upon for sanitation purposes but not without its disadvantages. Chlorine’s limited effect in destroying microorganisms on the fruit and vegetable surface means that high dosages of chlorine are required. Not only does this mean there is residual surface contamination on the washed products, increasing environmental concern around the levels of chlorine in discharged waters has resulted in restricted use.

The use of chlorine in processing organic produce of salads, fruits and fresh vegetables is banned in the EU and most countries. While the use of chlorine at high levels in processing non-organic fresh produce is still permitted, there are many reasons why food manufacturers should look for alternative products and processes for cleaning and disinfection and avoid the use of chlorine. Some EU countries have already taken this in step - permitting only drink quality water for this process.

Clean without chemicals

Traditionally, the treatment process would include adding an absorbent material to help encourage the dirt particles to clump together and settle to the bottom of the water tank, as well as a disinfectant (often chlorine) to destroy the remaining microorganisms and bacteria.

An efficient and more environmentally-focussed alternative to chlorine, Ozone is a powerful disinfectant which offers the benefits of effective microbial quality control of circulatory water, without the need for halogen-based chemical biocides or disinfectants.

Ozone gas treats the water using a process called Ozonation. With Generally Regarded As Safe (GRAS) status, granted by the United States Food and Drug Administration (FDA), ozone can be used for all food products without restriction (excluding milk which has its own specific regulations).

Tests have shown that Ozone controlled at 2 mg/ltr in the wash water can achieve a greater than 99% reduction in surface microbial populations, equal to or better than that achieved with chlorine at levels of up to 50 mg/ltr. Ozone is particularly effective against E. Coli, the food pathogen of most concern in the produce industry (C*T for 99% de-activation, 0.02 for ozone against 0.4-0.75 for chlorine dioxide).

As well as sanitation, the aesthetics and taste of produce is fundamental to food as a product in which we consume. That is why SOCOTEC recommends Ozone as a tried, tested and examined method that does not affect the quality, colour or surface texture of salads, fruit or vegetables. In fact, Ozone can also eliminate the undesirable flavour produced by bacteria and does not pose a risk of hazardous by-products, as is the case for Chlorine.

Many benefits of sustainable production

For the food industry, sanitation is the most important factor. But, like any organisation, sustainability and energy efficiency are also high priorities with corporate responsibility an increasing focus in this modern day.

Processing fresh produce naturally lends itself to high water consumption, through cleaning, sanitising, manufacturing and processing operations such as refrigerating. Because of the associated water footprint in food production, evaluating water consumption and seizing the opportunity to reduce water usage - where possible - can support the food production industry in both reducing costs and the environmental pressure on water resources.

In a bid to minimise water consumption, organisations can reuse and recycle water but it is important to ensure the water subject to reuse is of high-enough quality. In food production, wash water quality can be compromised as a result of the soils and other contaminants on the fresh produce. After washing the fruits and vegetables, the contaminated wash water requires treatment to bring the water back up to drinking water quality – or higher.

Not only can Ozone treat water without the use of traditional halogenated chemicals, Ozone can also support any organisations’ objective to minimise water consumption. Because the ozone gas is produced ‘in situ’ within the Ozone unit, Ozone refreshes and sanitises the water without contamination – an ideal water treatment option for reuse and recycling. Better yet, using Ozone treats water to a degree of purity and freshness that is unachievable by any other means. 

High quality water is a valuable resource which must be used considerately and maintained to ensure high quality outputs and for effective business performance. With growing demand on water use, it is speculated that high quality water will eventually become even harder to come by. It is the purity and lack of residual contamination that makes Ozone the ideal choice for organic food processing.

No toxins

In the modern world, where convenience is key and ‘ready-to-eat’ produce is a sought-after option, consumers are relying on food producers and their washing processes to meet food and safety standards.

Therefore, when using ozone, there are no residual compounds or toxins left on the product - or in the rinse water. This is because Ozone has a short half-life, lasting onto 10 to 20 minutes before ozone breaks down to natural oxygen.

Whereas Chlorine caused environmental concern when discharged, Ozone’s lack of residual contamination means that Ozone-treated wash water can be discharged to the environment or used for other applications without additional treatment or decontamination.

While Chlorine and other chemical compounds may seem like the easier option, investing in long-term solutions can support sanitation objectives, as well as meet other business goals in reducing operating costs and minimising the overall impact on the environment through reduced water usage and cleaner waste water discharge.

SOCOTEC provides a range of water treatment services - including using ozone as a disinfectant. Click here or call us on 0845 603 2112 to be put through to someone who can support you.

Read our FAQs on Ozone here.

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