An apple packing facility in the Pacific Northwest sought our help to reduce their chemical usage while minimizing risks associated with food safety bacteria and decay-causing mold.
The packing line has a dual-flume system, with the flumes in series called the T-Dump and the Treatment Tank. The apples are transferred from storage bins into the T-Dump flume water tank, which is the most heavily fouled water in the facility due to the dirt and debris present on the bins and fruit. A large volume recirculation pump creates sufficient flow to float the apples along the T-dump flume to an elevator, where they are lifted out and dropped back down into a second flume, called the Treatment Tank. The Treatment Tank water stays considerably cleaner than that in the T-Dump, but can still contain a significant loading of bacteria and decay microorganisms.
Due to a 2014 listeriosis outbreak that was linked to consumption of carameled apples, there has been an increased effort to develop best practices to minimize the presence of food safety pathogens in apple packing water systems. The chemical treatment programs employed at this packing facility are consistent with most other apple packing facilities in the Northwest. The T-Dump flume was treated with citric acid and peroxyacetic acid (PAA), for the purpose of providing a strongly acidic medium for de-scaling hardness from apples while relying on the antimicrobial activity of PAA for microorganism control. The Treatment Tank was treated with chlorine (Sodium Hypochlorite, NaOCl) and a buffering acid to maintain the pH around 7.0, and was typically heated to about 90oF in order to warm the skin of the apples to properly accept a wax coating.
Despite treatment of the T-Dump flume with 80 ppm of PAA, the measured levels of total aerobic bacteria and total fungi (molds/yeasts) were in the range of 103-107 cfu/mL, each. These results indicated very poor microbial control of bacteria and fungi within the treated T-Dump flume water system.
HydroFLOW water conditioners are environmentally friendly devices that have been distributed throughout the world for many years, but only recently entered the U.S. market. Over twenty years ago, Hydropath Holdings, located in the U.K., invented a process that treats fluids by inducing a robust yet harmless signal of 150kHz throughout plumbing systems made of any material. The pipe, and/or the fluid inside of it, acts as a conduit which allows the signal to propagate. The induction of the signal prevents scale and biofilm from accumulating inside plumbing systems and gradually removes existing deposits. This preventative action significantly reduces energy, chemical, water and maintenance costs which extends the service life of equipment and pipes.
We installed the HydroFLOW unit onto the 6" recirculation pipe that carries the T-Dump flume water from the back of the flume to the front where the new bins of apples are introduced with two primary objectives: 1) to determine the benefit of the Hydropath signal in the presence of the normal treatment dose of chemicals, and 2) to determine the minimum chemical dosage required, in the presence of the Hydropath signal, to maintain equal or better microbiological control as compared to the use of chemicals alone
Once the Hydropath signal was initiated there was a dramatic decrease in both bacteria and fungi in the tank (18-35ppm decreased to 14ppm)
The HydroFLOW water conditioner was moved to the Treatment Tank to determine the effect on chlorine usage and performance. In the week prior to initiating the Hydropath signal, the microbiological testing under conditions of 40-50 ppm of Total Chlorine at a pH of 6.7 showed no measureable bacteria or fungi in the water system (non-detect). Once the HydroFLOW signal was initiated, the chlorine dose was reduced. Interestingly, even with dosages as low as 10 ppm Total Chlorine, the microbial results remained at non-detect. Also, the Free Chlorine and Total Chlorine levels were exactly the same. However once the HydroFLOW was turned off, and the Total Chlorine was left at 10 ppm the Free Chlorine level dropped to less than half that of the Total Chlorine, and microbial counts became detectable (ranging from 101 to 103 cfu/mL).
As a side-benefit, the cleaning and sanitation personnel reported that the debris accumulated on the side walls of the flumes was significantly lighter and easier to clean when the HydroFLOW unit was in operation than under the normal operation of chemical treatment.
The results of this study have demonstrated the dramatic benefit of Hydropath’s eco-friendly technology for enhancing the ability of sanitizers to control bacteria and fungi in apple flume water systems reducing the Minimum Inhibitory Concentration (MIC). Similar benefits have been observed in cooling water systems, pools, and other industrial water applications.