Promoting Food Safety
Wash water sanitisers
It is important to appreciate that the function of the sanitiser is not to sterilise the food. Instead the food is being washed in water and the water will therefore pick up a microbiological load from contamination present on the food. This microbial load in the wash water then needs to be managed and controlled to minimise the transfer of microbes from one food item to another. The sanitiser is a frontline tool in the control of this microbial load.
Below are some of the most common sanitisers used in the fresh produce industry.
Chlorine
Chlorine is widely used as a sanitiser in fresh produce washing due to its effectiveness, ease of use and relatively low cost. However, chlorine is strongly affected by pH, temperature and cleanliness of the water and therefore needs to be carefully monitored. More chlorine is required in dirty water because chlorine is de-activated by organic matter.
Chlorine Dioxide
The use of chlorine dioxide as a sanitiser is common in the fresh produce industry because of its efficacy. It is also less affected by pH and organic matter compared to chlorine. It also produces fewer disinfection byproducts.
Chlorine dioxide is easily and conveniently generated in situ by mixing relatively innocuous solutions of chlorite and acid. For this reason, it is important to also monitor levels of chlorites as it is also subject to limits on concentration.
The test method used for chlorine dioxide is quite critical as false positives can occur with DPD and Chlorophenol Red methods, whereas the Lissamine Green can suffer from false negatives especially at low temperatures.
Peroxyacetic Acid (PAA)
PAA is effective against a broad spectrum of microbes. It remains active when the organic load is high and is effective even at low temperatures. PAA may be approved for use in organic food production. It avoids the “bleach” smell associated with chlorine which can be a particular issue washing of equipment and containers in bottling of drinks.
Peroxyacetic acid can decomposes to acetic acid which can be utilised as a food source by some microbes It is also expensive and is not compatible with some materials so equipment and machinery used with PAA needs to be chosen carefully.
PAA can be irritating to eyes, skin and respiratory system. PPEis required especially if handling at high concentrations. peracetic acid can be hazardous to the health of workers, and therefore should be handled with care and monitored regularly.
Dosing of sanitisers
Over or under dosing of sanitisers can have severe impacts – underdosing can compromise product quality and safety, and overdosing can unnecessarily increase chemical costs. Read our article what is the best method for produce wash water to find out more about the effects of over and under dosing of sanitizers.
Continuing innovation with online dosing equipment means that producers do not have to manually add sanitizers to the wash systems, however the growth in online systems has not been supported by the techniques used for validating and calibrating those very same systems. Without effective calibration and validation, these systems may not support satisfactory QA and risk management procedures.