January 2021


In the UK, the Health and Safety Executive (HSE) definition of a biocidal product is one ‘which controls harmful or unwanted organisms through chemical or biological means’. Common examples are disinfectants, wood preservatives and insect repellents. In a food context, this refers to a class of, often chemical products, with activity that leads them to kill bacterial, viral or yeasts and moulds, which may cause, either a health concern to consumers or have a significant impact on product quality or shelf life. In this document, we will mainly focus on aspects related to food safety.

When we consider the moral and legal duty of any business, of whatever size or shape, producing food for sale to the consumer the fact that this food is safe and wholesome should be the first thing that comes to mind.  By food, in this article, we turn to the legal definition going right back to the Food Safety Act, 1990, ‘food means any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans’.

Part of this maintenance, of the safety of food throughout any business, is the control of contaminants that may have a deleterious effect on the consumer, such as chemical residues, unintended or undeclared allergenic ingredients, physical contaminants or pathogenic micro-organisms.  In this information statement, we shall consider the techniques available to control the last of these, namely pathogens.

Biocidal products form an essential element of any well developed and implemented food safety management system, where the control of microorganisms is of concern.  The aim of this statement is to proceed from first principles, through usage scenarios, and the legislative aspects to the perceived future, in particular regarding chemical biocides.

The use of disinfectants in food operations is well established for the control of contaminants, such as bacteria, yeasts, moulds, and more recently viruses, with the SARS-CoV-2 viral pandemic commencing at the end of 2019.


CASE STUDY - SARS-CoV-2 viral pandemic


The role of fomite transmission, in terms of inanimate surface cross-transfer of viral particles from an infected individual to another (traditionally referred to as ‘secondary vehicles’), was quickly identified as a potential spread mechanism, by researchers around the globe, with a commensurate increased cleaning and disinfection frequency for common touch-points, such as handrails, touch screens etc.

A report from Australian researches, published in October 2020, concluded that whilst previous studies had found recoverable virus up to 72 hours after inoculation onto a surface, their study had found that infectious SARS-CoV-2 viral particles were recoverable from surfaces, such as stainless steel, glass, polymer and paper banknotes and vinyl, was possible after a period of 28 days at 20° C, and 50% relative humidity. When the temperature was reduced to 7°C, the calculated infective survival rate (Z value 13.62°C) was estimated to be 64 days, which has implications for the food processing industry, where environmental temperatures will be around that, in order to maintain product integrity.  This makes the process of effective cleaning and subsequent disinfection is vitally important for the control of contaminants. A feature of this study, however, was the large number of viral particles used in the inoculum which may be considered higher than would be found to be expelled from an infected individual, that said the importance of cleaning and disinfection cannot be overstated.

Disinfection Prerequisite

Only items or surfaces that have been thoroughly cleaned of organic debris can be adequately disinfected.

Whilst this statement may seem obvious, in practice, on many occasions dirty or contaminated items, utensils or food contact surfaces are simply exposed to a solution of disinfectant, resulting in poor microbial decontamination and pathogen survival. Figure 1 demonstrates occlusion for solutions, and where a surface defect, however small, can shield bacteria from disinfectant contact. As a simple rule, if the disinfectant, of whatever type, cannot reach the bacteria, it cannot kill it or achieve effective decontamination.

Figure 1: Occlusion (Ref. 4)

Methods of Disinfection

Biocidal products are employed to achieve disinfection throughout the food (including dairy) and beverage sectors and form the backbone of the chemical methods for achieving this method of control, however other methods may also be employed:

  • Thermal: for example, steam or very high temperature water
  • Mechanical: high pressure being one example
  • Physical: for example, UV-C, employing ultraviolet frequencies to trigger the generation of free radicals in cells, leading to their death.

When considering chemical biocides, we look to classify them by their mode of action on the microorganism:

  • Oxidising - all organic material is oxidised leading to rapid, complete and effective destruction of all cells and most cellular material
  • Non-oxidising - the product enters the cell either, through translocation or osmotic pressure, following a build-up on the exterior of the cell wall. Once inside the cell, the reproductive processes may be disrupted, as well as the interference with the mitochondria which effectively closes down the energy production capability of the organism, leading to death.

Oxidising Biocides

Common oxidising products, in use in food and beverage scenarios, are solutions of sodium hypochlorite (bleach), peracetic acid, hydrogen peroxide, chlorine dioxide and hypochlorous acid.  Whilst highly effective against a wide spectrum of microorganisms (including spores, yeasts and moulds) many of these compounds should be used with care, due to their corrosivity (particularly against soft metals), risk of taint due to odour, and their rapid degradation, especially in the presence of UV e.g. in sunlight, the exception is stabilised ionic silver hydrogen peroxide which is odourless, tasteless and of low corrosivity so can be used widely.  This latter compound is, however, expensive and has yet to find a place in general disinfection use. Oxidising biocides will often be employed in CIP (clean-in-place) in dairy and beverage processing operations where low cost, low foaming and lack of operative contact is considered a benefit, however it may be followed with a fresh water rinse to reduce the risk of taint, or chemical residue contamination.

Dosing of oxidising disinfectants into in-use concentrations should be undertaken with care. Where manual dosing (not recommended) is employed, then suitable measuring jugs and personal protective equipment (PPE) must be employed, automatic dosing can be achieved either through a diaphragm pump (Figure 2) or a suitable volumetric dosing unit, such as a Dosatron (Figure 3). Care should be taken with the latter, as not all units are suitable for dispensing oxidising disinfectants, and either a PVDF (polyvinylidene difluoride) construction or suitable bypass unit should also be used, to avoid damage to the unit which will lead to poor concentration control or complete failure.

Figure 2 Figure 3

Oxidising disinfectants do, however, suffer from an additional disadvantage in that they can quickly degrade or be consumed by physical debris, resulting in dosing at a higher concentration at the point of entry to that which is needed to actually achieve biocidal efficacy at the point of use.  This is particularly true of chlorine dioxide and non-stabilised hydrogen peroxide, where the efficacy can be reduced very quickly leading to bacterial survival, particularly in cases where a biofilm has been allowed to establish and mature.  When using a sodium hypochlorite solution, one must also consider the ageing effect whereby chlorate ions can be formed during storage, which can be considered a contaminant for food. Correct cleaning of containment vessels and frequent replenishment of solutions, as opposed to simply topping up, can assist in reducing this risk. Further mitigation practices can be found in the Food Biocides Industry Group (FBIG) guidance documents, for multicomponent foods, soft drinks and fruit juices, fresh and prepared produce and provisions (cured meat, butter, dried milk products) etc.

In situ, generation of disinfectant solutions has also become popular in recent times, with solutions of hypochlorous acid frequently employed in this field.  A brine solution (NaCl) is exposed to an electrolysis process, generating a weak sodium hydroxide solution at one electrode and hypochlorous acid at the other. This effect can also be achieved through dissolving sodium hypochlorite in water and slightly acidifying, using citric acid. This is commonly employed in salad and vegetable washing or decontamination,  and to maintain washwater hygiene.  Traditional chemistry wisdom dictates that sodium hypochlorite (NaClO) and acid are not to be mixed, and indeed this is generally true where conditions are not tightly controlled.  However, in this scenario the acid used (citric) is relatively weak and the pH is nudged to 6–6.5, where the dissolution of NaClO is into hypochlorous acid, and not fully dissolute into Cl2 (readily lost as chlorine gas).

Non-oxidising Disinfectants

This class of products has formed the foundation of open plant disinfection processes for many years, as a result of their relative effectiveness, lower cost, low toxicity and corrosion profile.  The general mode of action is achieved by the positively charged disinfectant compound binding to the negatively charged bacterial cell wall, and effectively dissolving the phospholipid layer, resulting in the cell’s death. Other modes of action include the disruption of the mitochondria, as well as the cytoplasmic layer.

Commonly used actives are: quaternary ammonium compounds [e.g.  didecyldimethylammonium chloride (DDAC), benzalkonium chloride (BAC)], alkyl amine and biguanides. Unintended consequences of pesticide residue legislation have curtailed the application and usability of two of these actives, which we will return to later.

Dosing can be relatively easily achieved with many of these products being used at a 1-2% v/v (volume concentration) dose rate, often via venturi blocks (Figure 4) or a standard Dosatron (Figure 5).  Once again, manual dosing is not recommended due to the inconsistencies in concentration that will be achieved.

Figure 4 Figure 5

Relative Efficacy of Biocidal Actives

When choosing a disinfectant product to be utilised, consideration must not only be given to the material the contact surface is constructed from, but also the target microbiological contaminant of concern, as different biocidal actives have different efficacies against classes of bacteria, fungi, yeasts and moulds, or spores.  The relative resilience can be best visualised in the accompanying graphic (Figure 6) which illustrates the susceptibility of different classes from enveloped virus (such as SARS-CoV-2) at the ‘weakest’ end, to prions at the ‘most resilient’ end.

Figure 6: Resilience to biocides

 Ref: - McDonell, G.E. Antisepsis, Disinfection, and Sterilization: Types, Action, and Resistance; 2nd ed.; American Society for Microbiology Press: Washington DC, 2017

Each formulator will incorporate, a mixture of a biocidal active and additional components, such as surfactants and other adjuncts, into their blend, which will enhance the efficacy of the solution, by providing a physical action on bacterial populations.  Table 1 below, provides an illustrative example of the generic efficacies of the commercially available formulations, typically used in food and beverage operations.

Table 1: Comparison of relative biocidal active efficacy



Biocidal Type

Typical Concentration

Typical pH

Recommended Contact Time (minutes)

Type of Micro-organism










Gram +ve







Chlorine compounds

50 – 500ppm (available chlorine)

8 – 10

5 – 15







Hydrogen peroxide

100 – 1000 ppm

4 – 5

5- 15







Peracetic acid

50 – 20 ppm

4- 6

5- 15








10 – 100 ppm

2 – 4

5 -15









7 – 12

10 – 15









7 – 12

10 – 15









4 – 6

10 – 15









5 – 8

1 – 5









5 – 8

1 -5







***   Effective

**     Moderately effective

*       Partially effective

Ref: Campden BRI. Cleaning and disinfection of food factories - a practical guide, Second Edition: 2020 (Guideline G55)

As this table clearly demonstrates, when selecting a disinfectant product, consideration should be given not only to the material of construction of the food contact surface under treatment, but critically to the anticipated target contamination, or microorganism involved.  The adage ’know thy enemy’ is certainly true in the realm of disinfectant biocidal active selection.

Treated Articles

For such surface treatment, a coating is applied to or incorporated into, the material of construction of the equipment, utensils or surfaces, to restrict the growth or achieve microbial destruction.  Commonly used substances are silver (the most widely used as a surface coating), copper and titanium dioxide.  For example, silver ions disrupt the cellular division process, as well as inactivating the bacterial mitochondria, leading to cell death (Figure 7, courtesy of Addmaster).

When considering treated articles, one should bear in mind that no current real-world test exists to demonstrate or quantify the long-term effectiveness of such systems or treatments.  Care should be taken, in particular, with any coating applied which is water-based as this may be easily removed during routine cleaning operations thereby removing the effectiveness.

Figure 7


Physical Methods

When considering physical methods for reducing microorganisms, the most commonly used method, at least in processing scenarios, is the application of heat.  Whether this is cooking, pasteurisation, HTST (high-temperature, short-time), UHT (ultra-high temperature) or canning processes, the thermal destruction of pathogens and spoilage organisms is well understood and applied, however in food contact surface disinfection this technique is not widely used, mainly due to the possible damage to the surface, or the health and safety risk that would be posed to the operative undertaking the decontamination procedure.  The exception to this is the use of steam, in particular dry steam, in electrically sensitive equipment, or hard-to-reach areas of processing machinery, and in CIP systems where a final rinse water temperature of around 80OC is often employed, Of course, in this latter application, the operative is never in direct contact with the solution, thereby reducing the risks.

Other physical methods of bacterial decontamination have yet to be commercialised and remain at the  development stage, however these methods show promise, with various research being undertaken to quantify applicability (although mainly focussed on food product studies rather than food contact surfaces):

  • Cold Plasma: this technology may lend itself in time to food contact surface decontamination, in particular conveyor belts and other flat surfaces have been considered, where ’shadowing’ is not an inherent problem as the energised plasma can only decontaminate where it touches.
  • UV-C: as with cold plasma, UV-C has been demonstrated to be highly effective at microorganism decontamination on surfaces where shadowing is not a feature.  Items such as conveyor belts could benefit from this technology, in particular in dry manufacturing scenarios, or areas where water usage is to be avoided, for example, sandwich operations where Listeria species could thrive in the presence of water.
  • HPP (High Pressure Processing) and PEF (Pulsed Electric Field): whilst both of these have been demonstrated to provide good decontamination characteristics in foods, their application to food contact surfaces is difficult to conceive at this point in time. HPP is ineffective on bacterial spores, used in isolation, and its effect is very organism group dependent.
Application of Chemical Disinfectants

In the majority of food and beverage operations, biocidal (disinfectant) solutions are applied via spraying, soaking or wiping, with some sites undertaking an aerial decontamination, either as a mist or a fog.  Whatever the application method the key points to be considered are: Correct in-use concentration

  • Storage of both the neat concentrate and the diluted solution.  Correct storage of dilute solutions is essential as long-term holding, or simply ‘topping up’ dilute solutions can result in an overall reduction in efficacy, due to degradation or possible microbial contamination
  • Effective coverage of the surface, ensuring that all contact surfaces are suitably covered
  • Ensuring the correct contact time, as recommended by the formulator.
  • Removal of all traces of detergent solution, as the surfactant used may be incompatible with the disinfectant solution, resulting in the inactivation of the biocidal capabilities.


a) Spray application:

This is arguably the most common open plant disinfection method in use throughout the food sector for both change-over, daily and deep cleaning hygiene activities.  Application involves filling a spray device with a solution, typically 1-1.5% v/v, depending on the formulated product chosen, with the disinfectant being applied to all food contact and associated surfaces by the operative.  Figure 8 shows some commonly used application equipment.

Figure 8: Typical Spray Applications

(left to right: pump-up sprayer; trigger spray; lance)


b) Soak application:

Small, easily removed parts, conveyor belts and other items may be immersed in a vessel containing a solution of disinfectant, for a period of time.  This has the advantage of permitting the solution to contact all submerged parts and penetrate into the crevices within the fabric of the equipment, as well as providing extended contact times.  However, caution should be exercised to ensure that all surfaces requiring disinfection are fully submerged and that only items previously cleaned thoroughly are placed into the soak vessels, to avoid disinfectant occlusion or inactivation.


c) Biocidal wipes:

Such wipes are a convenient way of applying a prediluted solution of disinfectant to a surface, often whilst achieving a simple cleaning activity simultaneously, and are commonly used in changeover cleaning, for electrically sensitive equipment, and where light spillages have occurred.  The disadvantage is that the reliance of a wipe to both clean and disinfect (commonly known as sanitising) can lead to an unsatisfactory result, due to the problems of occlusion discussed earlier.  Wipes containers are also often left open with their lids removed, leading to the impregnated liquid evaporating, taking any effective biocidal activity with it and leaving behind only a plain, dry cloth.

d) Fogging or misting:

This is sometimes referred to as ’whole room disinfection’ and has been the subject of a guidance document produced by Campden BRI, for example. This technique involves saturation of the atmosphere of a food processing environment with a solution of disinfectant, in droplets small enough to remain airborne for a period of time before settling on surfaces.  The benefit is it can achieve contact with any bacteria suspended or residing on high level, horizontal surfaces, however the technique has limited penetrative potential, hence will have limited biocidal effect on vertical, downward facing surfaces or within equipment internal voids (at harbourage points). 

Fogging or misting should be regarded as a very useful additional stage following an effective cleaning and disinfection regime, and not as a replacement for the application of biocidal products to food contact surfaces.   Any surface or environment to be treated with a fog or vaporised disinfectant solution must always be cleaned effectively first, to avoid the occlusion issues mentioned earlier in this document.

Disinfectant Rinsing

The debate surrounding the need to rinse any disinfectant residue from food contact surfaces, following a suitable contact time, often focusses on the potential for chemical contamination of the subsequent food, and in many countries rinsing is a common practice that may even be required by law, as is the case in Denmark.  However, for many years in the UK, this has not been common practice for the majority of the industry, unless a tainting biocidal product, such as sodium hypochlorite, had been employed.  With the advent of approved organic products, such as through schemes administered by the Soil Association, rinsing has become commonplace in order to comply with the requirement that products must not be exposed to chemical residue. Developments in ionic silver stabilised hydrogen peroxide (Huwa-San), has led to this product being acknowledged as complying with that requirement, without the need for a rinse step.

For much of the processed food industry, a non-rinse disinfectant product remains preferable, to act as both an ongoing microbiological hurdle, and to avoid additional application of water during rinsing, that may encourage bacterial growth and spread as well as cross-contamination from floors and drains, throughout droplet spread transmission.  Those disinfectant formulations which make non-rinse claims are required to undergo both toxicological and taint test evaluations, to ensure that at the recommended in-use concentrations, the risk of contamination is low to none.  Previously the majority of non-oxidising disinfectant use was based on QAC compounds (DDAC and/or BAC), however as will be described later, the enforcement of legislation intended to control pesticide residues led to this compound requiring rinsing or switching to an alternative active substance, such as the alkylamine compounds which do not, at the time of writing, have a maximum residue level (MRL) applied.

Disinfectant Tolerance

Much discussion, often misunderstood, has taken place surrounding the ability of microorganisms, particularly bacteria, to become tolerant or resistant to the commonly used active substances employed in food hygiene.  Whilst there is significant evidence to show that sub-lethal concentrations [minimum inhibitory concentrations (MIC)] of the pure active substance, for example, DDAC or BAC, can show tolerance by some species of bacteria, when trained in a laboratory by growing in gradually increasing, but sub-MIC amounts of the active component] there is little evidence to support the argument that a properly formulated and applied disinfectant product, based on the biocidal active substance suffers in the same way This is primarily due to the inclusion, within the formulation, of other constituents that have a detrimental effect on the survivability of the bacteria concerned – for example, surfactants which weaken the bacterial cell wall, enabling the biocide to more effectively complete its mission. Further details can be found in the GFSI paper referenced at the end of this statement. 

Where bacterial populations have been demonstrated to survive cleaning and disinfection regimes, this is more commonly a result of:

  • Poor cleaning practices leaving debris on surfaces resulting in occlusion
  • Detergent residue remaining following an ineffective rinse stage, which inactivates the disinfectant
  • Application of a 1% v/v solution onto a wet surface, leading to dilution to sub-lethal concentrations whereby there is simply not enough biocide to deal with any bacteria present.

It is worth noting that there is little to no documented evidence of bacterial resilience to oxidising disinfectants, although some studies in the US have suggested that Listeria monocytogenes may be rendered viable, but non-culturable, when exposed to a chlorine solution. More research is underway to confirm this. It is worth noting that Listeria, in particular, hides in the rough surfaces of poor welds.

Legislative Framework

When we consider the moral and legal duty of any business, of whatever size or shape, producing food for sale to the consumer, the fact that this food is safe and wholesome should be the first thing that comes to mind. In terms of food, we can turn to the legal definition going right back to the UK Food Safety Act, 1990: ‘food means any substance or product, whether processed, partially processed or unprocessed, intended to be, or reasonably expected to be ingested by humans’.

The need to control pathogens is simple. If these microorganisms, whether viral, bacterial or fungal, are not contained then the final consumer is at risk of suffering from illness, with potential life-altering effects, or in extreme cases death.  In 2015, the World Health Authority concluded that 5,000 people per annum, in the European region, lost their lives as a result of contaminated food, with 14% being amongst the under 5 years age group.

Reviewing both legislation and retailer codes of practice, there is a clear identification that cleaning and disinfection is a prerequisite for the production of safe food, as well as a clear legal requirement that ’food contact surfaces must be cleaned and, where necessary, disinfected’ Reference: EU 852/2004 on the hygiene of foodstuffs’

For many years, one of the leading disinfectant classes utilised was based on Quaternary Ammonium Compounds (QAC or Quats) as this class ticked all the above boxes and was generally recognised as safe by many of those involved in policing the safe production of food.  This disinfectant is also especially useful in the fight against Listeria monocytogenes, an organism of particular concern to the UK’s ready to eat (RTE) food sector and a growing cause of food poisoning cases and fatalities in Europe and wider afield. More data on EFSA and European Centre for Disease Prevention and Control (ECDC) websites. The largest recorded outbreak worldwide occurred in South Africa in 2018 involving this organism, with a reported 1,060 cases and 216 deaths.  Other liquid disinfectant products routinely employed include alkyl amine, hydrogen peroxide, alcohol and peracetic acid along, with some lesser used compounds such as biguanide.

The legislative framework surrounding chemical biocides has been changing for many years with the implementation of the Biocidal Product Regulations (formerly Directive), across the EU which has required the registration of the active biocidal compounds (Article 95) meaning that only those listed articles can be legally used in the EU.  The regulations are now progressing through the classes of actives requiring formulators, to register and submit dossiers containing scientific data relating to the product as used by food and beverage and other processors. We are only focusing on Product Type 4 (Food and Feed) here as there are 22 product types, in total. 

This legislation has big implications for the future availability of disinfectant products, as research into new active substances has mostly ground to a halt due to the costs of generating the efficacy, stability and toxicity data, as well as the dossier writing, submission and evaluation costs.  For formulators, the submission of a dossier for products depends on the active substance, or substances, it contains but also requires efficacy, stability in the pack as sold, toxicity and usage data, with the product entering a ‘market freeze’, once the dossier is submitted, which means practically that changes cannot be made.  For many of these reasons the current range of disinfectant products from all of the suppliers is under review to assess if the original active is supported, if the product is suitable for support through the Biocidal Products Regulation (BPR), and finally whether there is a commercial justification to commit thousands of pounds to any given product.  In practical terms, some of the products used throughout the industry may very well just disappear if their cost of support is not commercially viable, and the development of new disinfectant formulations will be severely restricted, as those formulations created after dossier submission date will require possibly two years of assessment, prior to be being placed on the market for sale.

A further complication is the application of Regulation (EU) 396/2005 on plant protection products (PPP) to the world of food processing.  Readers may recall the earlier statement that one of the most widely used disinfectant classes were the Quat based formulations due to their efficacy, wide action and acceptable cost in use.  The use of this product formulation type has dropped in recent years due to the application of the aforementioned PPP regulations, to products such as sandwiches, ready meals and other processed foods, despite the efficacy of this product type against low temperature pathogens such as Listeria species.  The MRL of 0.1 mg/kg, set for food commodities under these regulations, has no legal provision that residues may have arisen from biocide use rather than from PPP use.  This has led to the widespread reduction in the use of QAC based products, with many high risk/high care food manufacturers switching to alternative classes, such as peracetic acid (PAA) or alkylamine, despite these being higher in cost, with some restrictions in the handling or compatibility with food manufacturing equipment.

This application of the PPP regulations to processed foods has been hotly debated and has led to questions being posed to the specialist committee of the Food Standards Agency (FSA) that considers and provides guidance on microbiological food safety issues. In 2018, the Advisory Committee for the Microbiological Safety of Food (ACMSF) committed to establishing a working party to evaluate the risks and report back to enable the scientific case for the application of legislation to the use of this disinfectant class.

During 2018, a further debate began at European level surrounding the levels of the contaminant chlorate permitted in food, again based on the application of PPP legislation.  Chlorate interferes with the absorption of iodine, particularly in babies and young adults, and was a widely used pesticide in previous years.  However its presence in food is rarely from this source, but rather from the fact that this compound is the result of the breakdown and ageing of sodium hypochlorite solutions, commonly used in salad or vegetable washing and processing, as well as in irrigation water, used during growing to restrict bacterial contamination. Recently in the UK, the FBIG, with representation from SOFHT (Society of Food Hygiene and Technology), British Association of Chemical Specialities (BACS) and various trade associations [all chaired by Chilled Food Association (CFA)], successfully lobbied for new chlorate MRLs legislation to recognise the requirement for Food Business Operators (FBO) to assure microbiological food safety and hygiene legislation [EU Commission Regulation 2020/749], along with the associated HSE guidelines. The onus is now on the food producer to demonstrate that any chlorate residues arose from legitimate sources i.e. biocide use, or chlorinated drinking-water inputs.  Provided this is done, and good practice followed in the use of biocides, then pesticide MRLs are not enforced.

Testing of Biocidal Efficacy and Concentrations in Use

Current biocidal testing protocols involve exposing known concentrations of bacteria to the formulation under examination and assessing the level of microbial reduction.  For example, the basic entry level test would be BS EN 1276 whereby bacteria are suspended in planktonic form in a solution of the disinfectant formulation, and the level of reduction is measured.  A more stringent test is BS EN 13697 whereby bacteria are dried onto stainless steel coupons and the disinfectant under test is sprayed onto the surface. This test is more rigorous due to the nature of the disinfectant only having one plane of attack to the bacterial cells, as well as the bacteria undergoing slower metabolic processes, once desiccated onto a surface.

For viruses, yeasts, moulds and certain specific pathogens or spores, different Euronorms exist which set out specific time, temperature, concentration and other test parameters, such as atmospheric gases present.

Testing is undertaken in specialist laboratories and should always be conducted against ISO methods to ensure validity and reproducibility, enabling the results to be relied upon.

In-use scenarios require the users to assure themselves that the concentration deployed to food contact surfaces is sufficient and that recommended by the formulation manufacturer.  Commonly this is achieved through the use of titration testing, either using laboratory equipment or more commonly with dropper test bottles, whereby a defined colour change is used to calculate the concentration of product present, using a conversion factor determined by the product itself. 

A simpler but cruder assessment may be undertaken using test strips, which reveal a colour change depending on the concentration of product present.  These results can be variable and should only be relied upon as an indicator of the concentration range present.  In all instances, the concentration present should be documented and recorded as part of the food safety management system, whereupon the information can be recalled, should the need for a due diligence defence be required.

Where concern is centred around a particular pathogen, many laboratories may offer a service whereby a suitable surrogate is utilised to avoid having to expose operations and equipment to unnecessary contaminants.  For example during the SARS-CoV-2 pandemic, the bacteriophage F6  (phi 6) was identified as a suitable surrogate which could be handled without risk and ‘added’ to a surface, prior to a cleaning and disinfection regime, thereby enabling the process to be fully validated as suitable to remove the organism.

Training in the Application and Use of Disinfectant Formulations

Arguably, one of the weakest links in the cleaning and disinfection of food and beverage producing operations is the operatives involved in those processes, specifically their training, awareness and diligence.  This is not to denigrate those personnel involved, or employed in this vital link in the food safety chain, but rather is to highlight the vital role that effective training in the use of disinfectant formulations, the need for effective disinfection and the possible pitfalls that can affect this operation and can befall these teams.

In general, many hygiene team members work unsociable hours (often at night or weekends) and their role in maintaining, and assuring, the safe production of food can often be overlooked, or taken for granted.  The same can be said for those involved in product changeover or interim cleaning, where the break in production can be regarded as a disruption in the smooth flow of product, through the operation and out to the end consumer.  Nothing could be further from the truth as these activities are vital to the safety of the consumer and the reputation and integrity of the producing operation.

Aspects include the following:

  • importance of the correct concentration of product
  • role that a wet surface may have on the dilution of the applied product to sublethal concentrations, thereby allowing bacterial survival
  • possibility of detergent residue inactivating the applied disinfectant, through incompatibility of the surfactant systems utilised in either product.  The need for thorough rinsing comes into play here
  • importance of thorough coverage of disinfectant and the role that the stipulated contact time has to play in product efficacy

As an example of where a lack of understanding and awareness can have tragic consequences, in 1995 a butcher’s shop in the Scottish border town of Wishaw was the source of an outbreak of E. coli O157 that resulted in the deaths of 21 people and poisoned over 500 more.  Whilst there were several contributory factors in this event, one of the issues noted in the Fatal Accident Enquiry (conducted by Graham L Cox QC based on the findings of Professor Hugh Pennington in his report) was that ‘What was being used was a biodegradable washing-up liquid for cleaning work surfaces. The description ‘biodegradable’ in the eyes of Barrs’ senior staff was synonymous with ‘bactericidal’. The liquid in use was green in colour. There is no doubt about that. Mr Barr thought that about five years before the outbreak he had changed his supplier on the recommendation of a former employee who said that he could get a cleaning agent with the same properties but at a more attractive price’. This fundamental lack of understanding, and awareness, was most likely compounded by the fact that E. coli has been demonstrated to not only survive but thrive in a neutral detergent, rendering any cleaning activity as bactericidally ineffective, and allowing bacterial survival on surfaces which went on to contaminate cooked meats with tragic consequences.

Hygiene Validation and Verification

This is outside of the scope of this briefing statement however consideration must be given to the potential interactions between the validation or verification testing employed, and any potential interaction with the biocide present in the disinfectant formulation.  As an example, the use of an oxidising disinfectant may bleach out the colour of a test strip or dropper method if not neutralised, or an allergen lateral flow device may be damaged leading to a false-negative if the antibody is exposed to an oxidising agent.

In all instance, discussions with both the test kit manufacturer and the disinfectant formulator is advised to ensure that the testing results are valid, accurate and reproducible.

The Future of Biocides

With the changes brought about by the BPR outlined earlier, little research and development is now taking place to bring new liquid disinfectants to the marketplace, and indeed there is concern that further implementation of MRL’s on active substances in foods may further reduce the choices of food, and beverage manufacturers. Commercialisation of some of the physical methods described earlier may assist with fulfilling the needs of sections of the industry, however it is advisable that processors engage with their hygiene support company, and the wider industry stakeholders to ensure that effective microbiological control can be maintained to ensure consumer safety.



A chemical designed to kill organisms through chemical or biological means


A chemical designed to kill microorganisms through chemical or biological means


The process of applying a disinfectant to surfaces with the intent of reducing the microbiological flora to safe levels, typically for food production


A chemical capable of being decomposed by bacteria, or other living organisms, and thereby avoiding pollution


A process for rendering the target surface sterile and free from any living microorganisms or their spores


A chemical designed to alter or remove organic material from a surface


A chemical which contains properties of both a detergent and disinfectant, commonly used for single-stage or light duty cleaning


The application of a disinfectant as a fog to fill a void or workspace


The application of a disinfectant as a gas or vapour to fill a void of workspace

Non-rinse disinfectant

A disinfectant formulation designed to be safe for leaving in place once applied, typically to a food contact or production surface.

Organic approved foods

A food or beverage product produced under conditions approved under a third-party organic management scheme e.g. Soil Association.  Typically, no chemical residue is permitted to be present or remain on surfaces, over which organic approved foods are handled conveyed or produced.  At the time of writing, only ionic-silver stabilised hydrogen peroxide is agreed as meeting these criteria

Triangle taint test

Triangle testing is one of the most commonly used sensory discrimination test methods. It is used to determine whether the consumer can detect if an external factor e.g. potential taint, has had an effect on a product

BS EN 1276

The European standard for the bactericidal activity of chemical disinfectants, as proof of effective infection control against harmful microorganisms such as MRSA, Salmonella, E. coli, flu virus (H1N1) and Pseudomonas aeruginosa

BS EN 13697

A suspension test used to evaluate bactericidal activity of chemical disinfectants. The BS EN 13697 standard tests bactericidal performance on a nonporous surface and includes harmful micro-organisms such as MRSA, Salmonella, E. coli, flu virus (H1N1) and Pseudomonas aeruginosa.

BS EN 14476

The European standard for viricidal efficacy includes both enveloped and non-enveloped viruses

Biocidal Product Regulations

The Biocidal Products Regulation [BPR, Regulation (EU) 528/2012] concerns placement on the market and use of biocidal products, to protect humans, animals, materials or articles against harmful organisms, like pests or bacteria, by the action of the active substances contained in the biocidal product. This regulation aims to improve the functioning of the biocidal products market in the EU, while ensuring a high level of protection for humans and the environment

  1. GFSI chemicals in food hygiene working group paper: Relationship of Sanitizers, Disinfectants, and Cleaning Agents with Antimicrobial Resistance May 2019 Journal of food protection 82(5):889-902 DOI: 10.4315/0362-028X.JFP-18-373 JA DONAGHY, B Jagadeesan, K Goodburn, M-C Quentin
  2. Riddell, S; Goldie, S; Hill, A; Eagles, D. The effect of temperature on persistence of SARS-CoV-2 on common surfaces. Virology Journal. 2020
  3. Sprenger, R. Hygiene for Management (19th edition). 2017
  4. Campden BRI. Cleaning and disinfection of food factories - a practical guide, Second Edition: 2020 (Guideline G55)
  5. Gorbalenya, A.E.; Baker, S.C.; Baric, R.S.; de Groot, R.J.; Drosten, C.; Gulyaeva, A.A.; Haagmans, B.L.; Lauber, C.; Leontovich, A.M.; Neuman, B.W.; et al. The species severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2. Nat. Microbiol. 2020, 5
  6. McDonell, G.E. Antisepsis, Disinfection, and Sterilization: Types, Action, and Resistance; 2nd ed.; American Society for Microbiology Press: Washington DC, 2017
  7. Rabenau, H.F.; Rapp, I.; Steinmann, J. Can vaccinia virus be replaced by MVA virus for testing virucidal activity of chemical disinfectants? BMC Infect. Dis. 2010, 10
  8. Becker, B.; Brill, F.H.H.; Todt, D.; Steinmann, E.; Lenz, J.; Paulmann, D.; Bischoff, B.; Steinmann, J. Virucidal efficacy of peracetic acid for instrument disinfection. Antimicrob. Resist. Infect. Control 2017, 6, 1–6
  9. European Centre for Disease Prevention and Control, Interim guidance for environmental cleaning in non-healthcare facilities exposed to SARS-CoV-2. 2020, 1–3
  10. Chin, A.W.H.; Chu, J.T.S.; Perera, M.R.A.; Hui, K.P.Y.; Yen, H.-L.; Chan, M.C.W.; Peiris, M.; Poon, L.L.M. Stability of SARS-CoV-2 in different environmental conditions. The Lancet Microbe 2020, 5247, 2004973
  11. Shirai, J.; Kanno, T.; Tsuchiya, Y.; Mitsubayashi, S.; Seki, R. Effects of Chlorine, Iodine, and Quaternary Ammonium Compound Disinfectants on Several Exotic Disease Viruses. J. Vet. Med. Sci. 2000, 62, 85–92
  12. Kampf, G. Efficacy of ethanol against viruses in hand disinfection. J. Hosp. Infect. 2018, 98, 331–338.
  13. Ministerio de Sanidad Documento técnico Prevención y control de la infección en el manejo de pacientes con COVID-19. 2020, 1–14
  14. Documents relating to the mitigation of biocidal MRL’s can be found at the Chilled Food Association website ( these include: -
    1. Multi-component Foods.
    2. Dairy products.
    3. Fresh produce.

Institute of Food Science & Technology has authorised the publication of the following Information Statement on Biocides.

This updated Information Statement has been prepared by Peter Littleton FIFST, peer-reviewed by professional members of IFST and approved by the IFST Scientific Committee. 

This information statement is dated January 2021. 

The Institute takes every possible care in compiling, preparing and issuing the information contained in IFST Information Statements, but can accept no liability whatsoever in connection with them. Nothing in them should be construed as absolving anyone from complying with legal requirements. They are provided for general information and guidance and to express expert professional interpretation and opinion, on important food-related issues.