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 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 such as 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 drinking 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.

“ozone is a powerful disinfectant that offers the benefits of effective microbial quality control of circulatory water”

An efficient and more environmentally-focussed alternative to chlorine, ozone is a powerful disinfectant that 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 of which we consume. That is why ozone is recommended 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 being increasingly in focus.

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 reducing both 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 detected

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 only 10 to 20 minutes before ozone breaks down to natural oxygen.

Whereas Chlorine causes 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.

Supporting the brewing processes

In the food and beverage industry, outstanding hygiene standards are paramount for both quality and food safety, as well as ensuring optimum performance of all equipment and processes.

Based in Yorkshire, Timothy Taylor’s is an independent, family-run brewery with 160 years’ experience, using the finest ingredients to brew the best possible beers. Landlord, a brewery favourite, has won more awards than any other beer.

Fermentation vessels are an essential component to any brewery, where the yeast converts the wort (malt extract and water) as it ferments into beer; the fermentation temperature defines a beers’ flavour. A common issue that can occur is the build-up of biofilm within the cooling jackets of the fermentation vessels, and at Taylors some date back to the 1960s. Biofilms most often consist of many species of bacteria, as well as fungi, algae, protozoa, debris, and corrosion products. Essentially, a biofilm may form on any surface exposed to bacteria and some amount of water. In the food and beverage industry, biofilm often impacts on industrial processes, but can also affect the thermal performance of some manufacturing equipment.

Loss of cooling efficiency and the consequential potential impact on product quality in this instance, could have costly implications, so when Timothy Taylor noticed the thermal performance of their cooling jackets deteriorating, they sought support from water equipment specialists and consultancy experts. In order to recommend a bespoke solution, a site survey was conducted and experts liaised directly with the brewers at Timothy Taylor to discuss the requirements of the brewery.

To treat the biofouling of the cooling circuit, an ozone unit with UV (V170) was recommended to provide direct chemical-free disinfection and return the cooling circuit to full efficiency.

Why ozone?

Ozone has been used for over 100 years as a method of disinfection in the brewing industry. It is a powerful oxidising agent produced in-situ, using only oxygen as its raw material.

“produced in-situ, ozone uses only oxygen as its raw material”

More frequently, companies are questioning the effects that traditional chemical sanitation methods (such as hypochlorite, peracetic acid (PAA) or hydrogen peroxide) have on their equipment condition, end product, and the environmental impact when waste water is drained.

A proven alternative, ozone is capable of destroying all bacteria, algae and biofilms with no risk of resistance build up or toxic residue. It removes the need for handling, storing and administrating harmful chemicals, while minimising water consumption.

Starting the improvement process

In October 2017, units were commissioned on Timothy Taylor’s brewery site in Keighley, keeping production downtime and disruption to a minimum. The UV unit was installed inline as part of the recirculation loop from the collection tank pump outlet.

Installed next to the collection tank and pump set, the ozone unit – along with ozone injection pump – was connected to the recirculation loop to deliver variable ozone concentrations to the system in line with flow. To control the ozone dose level, a dissolved ozone sensor was also fitted; this enabled accurate and precise ozone levels to be monitored and log the data.

Ozone units can be fitted into many applications. As the collection tank was situated in the humid cellar, the unit also required compressed air for the internal oxygen concentrator.

While the UV unit provides proven disinfection during normal operation, the ozone unit provides Cleaning in Process (CIP) to remove the buildup of biofilm and deep clean the system, as and when it is required. CIP cleanses the inside of the process equipment, reaching areas where physical cleaning is not possible.

Nick Berkovits, Second Brewer, at Timothy Taylor’s, commented: “It was great to see immediate results from the CIP which lead to dramatic thermal improvements in the months following commissioning.”

Remote monitoring

For continuous performance monitoring of the unit, a remote monitoring function was also installed, enabling the consultants and Timothy Taylor to monitor and log the unit’s performance. To fully integrate the equipment and to make it easier to use on a day-to-day basis, a Programmable Logic Controller (PLC) controls all functions of the ozone generator, and ozone injection pump, and the settings for the unit can be adjusted by the cabinet door mounted HMI.

Results as expected

Four months on, Nick further commented: “We’ve been very pleased with the result so far and I am keen to see the ongoing benefits of using both the ozone and UV units. Cleaning in situ has taken place every weekend since the equipment has been installed. This keeps our running costs down as the performance of our cooling jackets has improved. We refuse to compromise on quality, so with the support of this water treatment we can continue to brew our beers to the highest standard.”

With the food and beverage industry, sanitation and hygiene is one of the most important factors to consider, ensuring a safe product is being produced. For most organisations, sustainability and minimising energy consumption is now a huge focus – especially in this environmental and sustainable age.

By removing biofilm from the cooling jackets, the equipment returns to optimum thermal performance. As an added bonus, these non-chemical disinfection methods have immediate environmental benefits. With total biological control, ozone is easily monitored, safe and reliable.