Flume washing is used to remove unwanted contaminants and maintain integrity for a wide variety of fresh produce after primary processes like cutting/slicing or dunk tank washing. Just as versatile, spray bars can assist flume washing or be used independently as a method of direct disinfectant application, such as in red meat microbial intervention treatments.
Flume and spray bars are a critical process in preventing cross-contamination and reducing microbial counts on produce surfaces. They are therefore widely used in food processing applications, including fresh cut produce and red meat processing, where a series of washes are used to clean produce and prevent cross-contamination.
Each sanitizer has its own unique advantages and drawbacks regarding cost, efficacy and disinfection by-products for each product being washed. The most common sanitizers in use are chlorine, chlorine dioxide and peracetic acid (PAA).
Chlorine is the most cost-efficient to dose at high concentrations in flumes. Although the weakest oxidiser of the three, chlorine will persist in wash waters for longer periods of time due to its reduced volatility.
Chlorine dioxide is significantly more expensive than chlorine, but much lower levels are required, typically 0 – 5 ppm. This increased reactivity makes it more effective against bio-film build-up and chlorine resistant pathogens.
Peracetic acid (PAA) is a more expensive sanitiser but it provides highly effective disinfection, even against chlorine resistant pathogens. In addition, it requires less complex dosing equipment than chlorine dioxide so can be overall most cost effective.
Direct spray applications, where the product is not rinsed further, will typically use peracetic acid as the breakdown products are either already food-grade (e.g. acetic acid) or generally regarded as safe (GRAS).
Other chemical disinfectants applied to produce surfaces may leave behind by-products harmful to health but are still useful where additional rinsing may take place before packaging or consumption. They may be preferred due to their lower cost compared to peracetic acid. The best disinfectant to use will therefore depend on the process being used, the produce being sprayed and whether it has regional approval.
In both flume and direct spray systems, minimum concentration limits must be maintained to satisfy legal or operational requirements regarding microbial safety. Maximum limits are implemented to prevent oxidative damage to produce or impact on employee safety.
Contamination through failure to control sanitiser concentrations in flume or spray water used in postharvest processing has been associated in multiple fresh produce outbreaks or food safety recalls.
Accurate onsite test results can be used to control sanitiser concentration and water quality at effective levels to ensure food safety, cost savings and reduced environmental impact.
Kemio delivers reliable on-site testing with the use of no glassware or chemicals which are not suitable in the manufacturing environment. Inclusive of testing for chlorine, peracetic acid, chlorine dioxide, and its disinfection by-product chlorite; Kemio gives you the flexibility needed to manage disinfection verification Find out more about how Kemio can improve safety, traceability and reliability, here.
The first thing to always consider when sampling from spray bars and flumes is ensuring it is both safe for the operator to do so and does not compromise produce or wash water quality. Never sample using glass vials or jars.
For flumes, if it is safe to sample directly from the flume this will provide the most representative sample. Look to sample downstream from where the chemical is being dosed to give time for it to disperse and reach a homogenous concentration. For longer flumes, multiple points should be tested to ensure the correct disinfectant residual is present even at the end of the line. If it is not safe to sample directly from the flume, water should be taken from a sampling port or run-off point on the line.
For spray bars, sampling from the nozzle itself will ensure that the concentration measured is exactly what is being applied to the produce. However, spray nozzles are often high up and the applied disinfectant may be applied at a high concentration and under pressure – so it is common to have sample ports built into pipework feeding spray bars for safety reasons.
When sampling from a port, rinse you sample container at least three times with water from the port – this removes contamination from the sample and ensures the water being tested hasn’t been sitting in the pipe.
Check standards are used to determine if an instrument is still within calibration.
Photometers work by sending light through the sample, check standards for these instruments are usually either Coloured Solutions or Neutral Density Filters (NDF). Both types have known and certified transmittance or absorbance values so they should give these values when read in a photometer. To make the checking process even simpler some instruments will convert these to a parameter such as chlorine and give the value mg/L. The ‘target’ value is on the certificate supplied with the set of Check Standards.
Kemio and sensor instrument check standards verify that the instrument correctly measures electric signals. As with electrochemical sensors in samples, the instrument applies a voltage to the check standard and measures the resulting current. Check standards include verified resistors, which produce a consistent electric current. Kemio validates the measured current internally. Sensor instruments display the corresponding concentration value, which is compared manually to target values on the certificate supplied with the set of check standards. Check standard kits come with four standards to test across the measurement range.
Palintest recommends that you dilute your sample with deionised water. The dilution factor can be set on the instrument allowing it to perform the calculation for you. This ensures that the sample remains within the target concentration and temperature range of the sensor being used.
Check your Kemio software version on your instrument by pressing Configuration > Settings > Details.
When scanning the QR code on your Kemio sensor box, Kemio checks to see if a new software version is available. If so, it will pop up a message asking you to download and install the latest software from the website.
The latest Kemio software can be found on the downloads tab of the Kemio product page here. We recommend that you check for updates every 3 months.