Evaluation of Electrolyzed Water as a Low-Cost, Organic Method to Reduce Contamination in Indoor Production of Gourmet Mushrooms

"Organic mushroom production is particularly susceptible to attack by fungal and bacterial diseases and by fly infestations. These pests cause reductions in yield, quality and shelf life of the crop and seriously affect the economic viability of organic mushroom production." David Beyer, Professor of Plant Pathology at Penn State University.

Mushrooms grow in a warm, humid environment which is also an ideal environment for numerous contaminants. The nutrient-rich grow blocks contain sawdust and grain, ideal hosts for competing molds and fungi. Clean blocks, free from contamination, are essential to high-yields, salable crops, and profitable production. Focus for addressing contamination issues has been at the stage of making the sawdust blocks. The next stage is keeping them free of contamination during the fruiting process. Preventing contamination is important because once a contaminant colonizes and sporulates on a grow block, it is difficult to completely eliminate the contaminant from the growing room. Contamination also reduces yields as the contaminant competes for resources.

As with all crops, the limitations imposed by organic standards reduce the options for preventative and curative treatments. Small-scale producers are further limited by their budget, so a low-tech, reliable, and inexpensive solution is ideal.

There is a movement in the Northeast to incorporate mushrooms into diversified vegetable farms. In order to do this successfully, farmers need affordable solutions to common challenges. Contamination is one of those challenges.

Research into contamination has focused on the pasteurization of grow medium prior to inoculation. Numerous studies explore steam, hot water, and cold pasteurization techniques. That is essential, but once clean grow blocks are open to the fresh air to induce fruit body production, they are susceptible to contamination. Finding a solution to contamination during production would be unique. In this experiment we will test the preventative treatment of exposed surfaces of grow blocks with a daily application of Electrolyzed Water (EW).

Electrolyzed water, also known as electrolyzed oxidizing water, is an OMRI-approved sanitizer approved for food contact. Electrolyzed water is generated on-site with a specially designed device that applies an electrical current to a solution of table salt, water, and vinegar (vinegar is optional, depending on desired solution.) According to OMRI “The resulting solution can be acidic, neutral or basic depending on the design of the specific generating device, and it contains an equilibrium of hypochlorous acid and hypochlorite ions. It is the presence of hypochlorous acid and hypochlorite ions that gives electrolyzed water solutions many of their sanitizing properties.”

In the article Electrolyzed Water as a Novel Sanitizer in the Food Industry: Current Trends and Future Perspectives Rahman discusses the chemistry of electrolyzed water and the numerous, diverse studies, all with favorable results. According to Rahman, “The application of EW is a sustainable and green concept and has several advantages over traditional cleaning systems including cost effectiveness, ease of application, effective disinfection, on-the-spot production, and safety for human beings and the environment. These features make it an appropriate sanitizing and cleaning system for use in… food processing environments.”

Examples of EW in agricultural applications:

- Foliar application on bedding plants to work as a fungicide in a greenhouse setting. Fungal diseases were reduced and plants were unharmed by the use of Electrolyzed Water.

- Reduction in E.Coli on sprouts

Examples of EW in mushroom production:

- Ding et al reported reduced bacterial loads from the application of Low Concentration Electrolyzed Water on oyster mushrooms.

- In 2003 Chikthimmah reported the findings of research to reduce contamination in mushrooms by irrigating with acidic electrolyzed water. This research reached a positive conclusion with the added benefit of an extended shelf life.

While the research to date has indicated Electrolyzed Water will yield favorable results, the application of it has been hindered by complexity and cost. In the aforementioned article by Rahman, it is stated “With recent technological advances, EW has gained popularity. Owing to these advantages, better equipment for producing EW is now available and EW has become a promising nonthermal disinfectant.”

In the past, low cost equipment yielded unpredictable results. If too much salt was added, the result was a solution with residual salt that damaged the mushrooms. If the concentration of a buffer was too low or non-existent, sodium hypochlorite (bleach) was produced, which would be equally damaging to the mushrooms.

More reliable devices created two streams (acidic electrolyzed water and basic electrolyzed water) and cost ten thousand dollars or more, meaning they were out of the price range of small producers.

Recently, new technology has been introduced that combines the two outputs into one product with both hypochlorous acid (disinfectant) and sodium hydroxide (cleaner.) This technology is reliable and affordable.

This proposal is to study the equipment that produces one stream (with hypochlorous acid and sodium hydroxide) to determine if this is an affordable, appropriately sized machine that provides a solution to reduce contamination for small-scale mushroom producers

CITATION LIST

What are common contaminants of the mushroom culture? Retrieved from http://en.psilosophy.info/what_are_common_contaminants_of_the_mushroom_culture.html

LaJeunesse, Sara (2017, December 6). Researchers Receive $950,000 to Develop Pest Controls for Organic Mushrooms. Retrieved from

https://news.psu.edu/story/497109/2017/12/06/research/researchers-receive-950000-develop-pest-controls-organic-mushrooms

Electrolyzed Water. Retrieved from https://www.omri.org/electrolyzed-water

Electrolyzed Water as a Novel Sanitizer in the Food Industry: Current Trends and Future Perspectives. Retrieved from https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12200

Evaluation of acidic electrolyzed water for phytotoxic symptoms on foliage and flowers of bedding plants

Page Crop Protection Volume 22, Issue 1 , February 2003, Pages 73-77 J. W. Buck, M. W. van Iersel, R. D. Oetting and Y.C. Hung

Sharma, R. R., and A. Demirci. 2003. Treatment of E. coli O157:H7 inoculated alfalfa seeds and sprouts with electrolyzed oxidizing water. Intl. J. Food Microbiol. 86:231-237

Ding, Tian & Rahman, S.M.E. & Oh, Deog-Hwan. (2011). Inhibitory effects of low concentration electrolyzed water and other sanitizers against foodborne pathogens on oyster mushroom. Food Control. 22. 318-322. 10.1016/j.foodcont.2010.07.030.

Chikthimmah, N., McMillen, J., Demirci, A., LaBorde, L. F., and Beelman, R. B. 2003. Electrolyzed oxidized water irrigation to reduce bacterial populations on fresh mushrooms. Abstracts of IFT Annual Meeting, Chicago, IL. Abstract No. 18922. http://ift.confex.com/ift/2003/techprogram/paper_18922.htm