Sanitising food contact surfaces is essential but chemical sanitisers are not all created equally. Martin Stone from HACCP International provides a checklist of best practices and the pitfalls to avoid.
Sanitising food contact surfaces is an essential operation in food production where the control of microorganisms in the finished product is considered important. Chemical sanitising involves the destruction of micro-organisms on a surface through the use of chemicals.
Chemical sanitisers have their own pitfalls and are not all created equally – they should only be purchased from suppliers where performance and applied food safety has been verified. The HACCP International certification scheme provides this assurance to end users.
The first pitfall is not understanding that sanitising cannot be effectively achieved without the first step of ‘cleaning’. Cleaning is the removal of food residues and biofilms from a surface which present two barriers to sanitising; they provide a medium for
microorganisms to grow within and, they physically protect microorganisms from the kill effect of the sanitiser.
Ultimately, it is impossible to effectively sanitise an unclean surface. It is critical that all traces of soil and biofilms are removed in order to expose microorganisms to the sanitising agent and to remove potential for microorganism growth.
The following points deserve attention to achieve the best results for food safety and sanitiser performance.
Sanitiser storage or handling
Sanitisers, especially in concentrated form, may be toxic and have objectionable odours and flavours associated with them. Storage of these products in a location where drips and spills will not contaminate food or packaging is essential.
Cross contamination, that may occur through decanting and dilution, to food contact surfaces must be avoided. Dedicated, labelled containers for measuring and diluting must be provided (repurposed food containers should never be used). Staff handling these chemicals should be dressed in dedicated PPE.
Usage parameters and official directions
Sanitisers are designed to be used at specific concentrations and temperatures. Using sanitisers outside of their specified ranges can lead to reduced efficacy. Dispensing equipment must be routinely calibrated to ensure the correct concentration is being delivered.
Contact time
Sanitisers have a specific requirement for contact time in order to achieve a microbiological kill. Too short a contact time will reduce efficacy of the sanitiser. To achieve the correct contact time, the application format should be decided upon as discussed in the following point.
Application format
Sanitisers can be applied in numerous ways depending on the equipment being sanitised. Immersion (dipping), CIP, spraying and foaming onto a surface are common application methods that each have their own benefits and drawbacks.
These must be considered to ensure the most effective way of providing contact with all parts of the equipment for the desired contact time.
As a guide, immersion, provides excellent control of contact time and the ability to provide contact into all areas (including those hidden) of the equipment. Foaming can extend contact times, particularly on vertical surfaces. Spraying (and fogging) can provide excellent coverage on large expanses of product contact surfaces or the manufacturing environment.
Equipment coverage
Disassemble equipment to ensure contact with the chemical on surfaces paying particular attention to seals, inspection ports and penetration points on flat surfaces. Tight corners and fine gaps also should be eliminated by disassembling for effective sanitiser contact.
Seals within pipework must be inspected and disassembled at appropriate intervals. The undersides of equipment and areas within guards must always be considered as these can commonly escape sanitising and easily re-infect the food stream and sanitised surfaces.
Sanitising system
One of the benefits of chemical sanitisers is the ability to be used in the broader manufacturing environment thereby reducing the microbiological loads in the facility. Reduction of bacteria such as Listeria in certain food processing environments for example, can be a key element of the production of safe food.
The design of the environmental components such as drains can hinder the effectiveness of chemical sanitisers. For example, drainage systems are commonly designed not to run ‘full’, that is, pipes and causeways will only partially be filled under normal operating scenarios. Thus, in this example, achieving contact times and indeed contact at all with the entire surface of a drainage pipe may not be possible.
Line turbulence levels
In line turbulence is critical in ensuring appropriate cleaning via CIP of a pipework system. Appropriate levels of turbulence are delivered through in-pipe velocities of the cleaning chemicals. Laminar flows can result in incomplete cleaning and ineffective sanitation due to reduction of contact with remaining microorganisms.
Spray ball coverage
The delivery of chemical sanitisers via spray balls can be hindered where spray balls fail to deliver sanitising solution to all areas of the surface. This can occur due to poor spray ball design, shielding and running the system at less-than-optimal pressure. Shielding can occur when parts of the equipment form a physical barrier between the spray ball discharge and the target surfaces.
Pipework integrity
Dead legs are impossible to clean and sanitise and will result in microbiological contamination of food. Pipework that is not free draining can cross contaminate food with residual chemicals when the line is restarted.
Rinsing
Some sanitisers do not require rinsing from surfaces after use and some do. It is important to understand the characteristics of the chemicals being used in this regard. Errors have occurred when sanitiser type is alternated to avoid microbiological resistance. Rinsing of sanitisers from a surface must always involve the use of potable water.
Cross contamination risks removed
Once surfaces have been sanitised, great care must be taken to ensure these surfaces are not re-contaminated prior to the next scheduled use for food processing. Pests, human traffic, condensation and movements of food products have all been responsible for the recontamination of sanitised surfaces prior to scheduled use. Plant operators must consider these elements and have effective controls in place to avoid reinfection.
Sanitising is a critical part of the safe food process where ever a reduced microbiological load on equipment is important. By failing to consider and verify the potential pitfalls as outlined above, sanitising operations can fail, leading to increased microbiological loads, damage to product integrity and unsafe food.
This article first appeared in the June/July edition of Food & Drink Business.
