In the realm of food safety and industrial disinfection, both hypochlorous acid (HOCl) and peracetic acid (PAA) have gained prominence. While both are effective oxidizing agents used for disinfection, they have distinct characteristics that make them suitable for different applications. Let’s explore the key differences between these two disinfectants.

Chemical Composition and Stability

Hypochlorous acid (HOCl) is a weak acid that forms when chlorine dissolves in water. It’s the same compound our white blood cells produce to fight infections. In electrolyzed water systems, HOCl is generated on-site through the electrolysis of salt water.

Peracetic acid (PAA), also known as peroxyacetic acid, is an organic compound that is typically produced by reacting acetic acid with hydrogen peroxide.

HOCl is generally more stable than PAA, especially at lower concentrations. PAA can decompose over time into acetic acid and hydrogen peroxide, which can affect its long-term storage and efficacy.

Efficacy and Speed of Action

Both HOCl and PAA are broad-spectrum disinfectants, effective against bacteria, viruses, and fungi. However, they have different strengths:

  • HOCl acts more rapidly, often achieving significant pathogen reduction within seconds of contact. Its neutral charge allows it to penetrate microbial cell walls easily.
  • PAA, while also fast-acting, typically requires slightly longer contact times than HOCl for equivalent disinfection.

HOCl is particularly effective against biofilms, which are often challenging to eliminate in food processing environments. PAA, while also effective against biofilms, may require higher concentrations or longer contact times.

Safety and Handling

HOCl, especially when generated through electrolyzed water systems, is generally safer to handle:

  • It’s non-irritating to skin and eyes at typical use concentrations.
  • It doesn’t produce harmful fumes.
  • It breaks down into simple salt and water, leaving no harmful residues.

PAA, while an effective disinfectant, requires more careful handling:

  • It has a strong, vinegar-like odor that can be irritating.
  • At higher concentrations, it can be corrosive to skin and mucous membranes.
  • Proper personal protective equipment (PPE) is crucial when handling concentrated PAA solutions.

Environmental Impact

HOCl has a lower environmental impact:

  • It quickly breaks down into harmless components (salt and water).
  • It can be produced on-site, reducing transportation and storage requirements.
  • At typical use concentrations, it doesn’t harm aquatic ecosystems.

PAA, while biodegradable, has some environmental considerations:

  • It breaks down into acetic acid and hydrogen peroxide, which can affect pH levels in water systems.
  • Its production process is more resource-intensive compared to on-site generation of HOCl.

Applications in Food Safety

Both HOCl and PAA are widely used in food safety applications, but they have different strengths:

  • HOCl is excellent for general surface disinfection, product washing, and water treatment. It’s particularly useful in situations requiring rapid action and frequent application.
  • PAA is often preferred for CIP (Clean-In-Place) systems in food processing equipment due to its effectiveness at removing mineral deposits and its stability in the presence of organic matter.

While both hypochlorous acid (HOCl) and peracetic acid (PAA) are effective disinfectants, HOCl offers advantages in terms of safety, environmental impact, and ease of use, especially when generated through electrolyzed water systems. PAA remains valuable for specific applications, particularly where its ability to remove mineral deposits is beneficial. However, recent research suggests that HOCl may be equally or more effective at removing contaminants in the clean-in-place (CIP) process. This area of research focuses on electrolyzed water and its separation capabilities through the processes of nanobubbles, electroflocculation, and electroflotation.

 

 

 

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