Flume and Spray Bar

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.

Where or why would I use a flume and spray bar?

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.

What are the most common sanitisers to use for flume-wash water?

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.

What are the most common sanitisers to use for direct spray disinfection?

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.

What control procedures do I need for flume and spray bar?

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.

Where should I take my sample from for flume and spray bars?

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.