I. Introduction to Peracetic Acid (PAA)
Peracetic acid (PAA), or peroxyacetic acid (C2H4O3), is a crucial biocide for hygiene in the agri-food industry. This colorless to pale yellow liquid with a pungent odor is an aqueous solution in equilibrium with acetic acid (CH3COOH), hydrogen peroxide (H2O2), and water.
Key Physico-Chemical Properties
- Potent Oxidizer: Higher potential than chlorine/chlorine dioxide.
- pH: Acidic, around 2.8 (for traditional PAA).
- Miscibility: Water, alcohol, ether.
- Variability: Melting point (-11°C to < -30°C), flash point (>40°C), and auto-ignition (approx. 200°C) vary with concentration. Explosion risk at 110°C.
- Corrosivity (traditional): Attacks most common metals and some plastics. Stérile C formulations are non-corrosive.
Sterilizing Mechanism of Action
PAA acts by oxidation, destroying cell membranes, proteins, and genetic material (DNA/RNA) of microorganisms. Its non-specific action minimizes the risk of microbial resistance.
II. Applications of PAA
PAA is a versatile disinfectant used throughout the agri-food industry.
🌍 Surfaces and Equipment (CIP/OSP)
Widely used for Clean-In-Place (CIP) and Open Surface Cleaning (OSC) systems, particularly by foaming. Typical concentrations: 93-500 ppm for food contact surfaces (60s min).
📦 Packaging Treatment
Disinfection of cartons, bottles. Rapid decomposition into safe products, minimizing residues and often without rinsing.
🍎 Food Product Disinfection
Used on fruits, vegetables, meats, eggs. Effective against pathogens. Up to 500 ppm in wash water. Does not impart odor/flavor.
💧 Water Management
Disinfection of recirculated wash water, wastewater treatment, cooling water. Controls biofilms and decomposes organic matter.
🏭 Specific Uses (Dairy, Brewery)
Clean-In-Place (CIP) in dairy, brewery, cheese processing plants, pasteurizers. Also in commercial greenhouses.
III. Advantages and Challenges of PAA
🌟 Key Advantages
- Broad-Spectrum Biocidal Efficacy: Active against bacteria (Gram+/Gram-), spores, yeasts, molds, viruses. Effective against *S. aureus, E. coli, Salmonella, Bacillus subtilis*.
- Rapid Action & Efficacy at Low Temperature: Fast results (full spectrum in 5 min for bacteria/fungi, 10 min for spores at 0.26%). Energy savings.
- Favorable Environmental Profile: Degrades into acetic acid, water, oxygen. Biodegradable, no known DBP.
- Absence of Harmful Residues & No Rinsing (often): Simplifies processes, saves water.
- Compatibility with Organic Matter: Remains effective even in the presence of soiling.
⚠️ Challenges and Disadvantages (Traditional PAA)
- Corrosivity: Can attack metals (aluminum, copper, brass) and some plastics. Stérile C is non-corrosive.
- Health/Safety Risks: Irritant (skin, eyes, respiratory tract), pungent odor. Stérile C is odorless and non-corrosive, reducing these risks.
- Stability of Diluted Solutions: Rapid decomposition (e.g., 50% in 24h). Stérile C (diluted powder) is stable for 10 days.
- Cost and Availability: Can be more expensive than some disinfectants.
- Limited Efficacy (Protozoa): Less effective against *Giardia, Cryptosporidium*.
Focus on Stérile C: A New Generation
"Stérile C" is an advanced PAA formulation that overcomes traditional disadvantages:
🛡️ Non-Corrosive
Protects equipment and extends its lifespan.
💧 Neutral pH
Safer to handle, does not damage pH-sensitive surfaces.
👃 Odorless
Improves operator comfort, ideal for food environments.
🌿 Enhanced Eco-Responsibility
Minimal environmental footprint, complete biodegradability.
⏳ Improved Stability
The Stérile C solution (dissolved powder) maintains its efficacy for 10 days.
These properties make Stérile C a preferred option for optimized, safe, and sustainable hygiene.
V. Comparison with Other Disinfectants
PAA (advanced formulations like Stérile C for corrosivity, odor, pH) stands out in several aspects.
Comparative Table of Key Disinfectants
| Characteristic | Peracetic Acid (PAA - Stérile C type) | Chlorine / Hypochlorite | Quaternary Ammonium Compounds (QAC) | Hydrogen Peroxide (H2O2) |
|---|---|---|---|---|
| Oxidation Potential | Very Strong | Strong | N/A | Moderate |
| Activity Spectrum | Broad (Bacteria, Spores, Yeasts, Molds, Viruses) | Good (Bacteria, some Viruses) | Good (Bacteria, some Viruses) | Limited (Gram+/- Bacteria, little on Spores, Yeasts, Molds) |
| Efficacy at low T° | Very Good | Limited | Good | Limited, especially > 60°C |
| Sensitivity to organic matter | Low | High (forms by-products) | Low | High |
| Residues / By-products | Non-toxic (acetic acid, water, oxygen) | Harmful (chloramines, THMs) | Can form hard residues, allergens | Non-toxic (water, oxygen) |
| Corrosivity (Metals) | Low/None (Stérile C) | High (liquid solutions) | Low | Low |
| Odor | Low/None (Stérile C) | Strong | Low | Low |
| pH | Neutral (Stérile C) | Variable (often alkaline) | N/A | Acidic or Neutral |
| Cost (relative) | Higher | Low | Low | Moderate |
| Rinsing required | Not necessary (some applications) | Generally necessary | Generally necessary | Generally necessary |
Note: PAA characteristics in this table reflect the improved properties of advanced formulations like Stérile C for corrosivity, odor, and pH.
Visual Overview of Biocidal Efficacy (Indicative Scale)
Comparison of perceived efficacy (5 = very effective, 1 = least effective). Based on general information from the report.
VI. Good Practices for Handling, Storage, and Disposal
Rigorous management is essential. Stérile C mitigates some risks, but general precautions remain.
Essential: resistant gloves (e.g., butyl), safety glasses, face shield, protective clothing. Respiratory protection (masks, ABEK-P3 filters) if vapors are present (especially traditional PAA). Risks are reduced with Stérile C (non-corrosive, odorless).
Handle in a well-ventilated area. Closed systems and local exhaust ventilation recommended for traditional PAA. Gas detectors for leaks. Less critical for irritating vapors with odorless Stérile C.
Intervention plans, regular training. Do not smoke, drink, eat. Avoid skin/eye contact, inhalation. Rinse thoroughly if contact occurs and consult a doctor. Applicable to all chemical products.
Vertical, well-ventilated, away from light/heat/ignition sources. Avoid contamination (heavy metals, alkalis). Concentrated PAA storage: 2-8°C or -20°C to 35°C. Stérile C may have less strict container requirements (non-corrosive).
Avoid release into the environment. Concentrated waste/large spills: approved collection point for hazardous waste. Harmless decomposition in diluted use (advantage of Stérile C).
VII. Regulation and Standards
European Regulatory Framework (Regulation (EU) No 528/2012)
The Biocidal Products Regulation (BPR) (EU) No 528/2012 harmonizes the authorization of biocides. PAA is approved for product types 1-6. Specific authorizations, such as for the "Airedale PAA product family" (EU 2023/1200), detail the conditions of use.
Table 2: Recommended Concentrations and Contact Times
| Application Area | PAA Concentration (ppm or % active) | Contact Time | Rinsing Required | Regulatory Context / Source |
|---|---|---|---|---|
| Equipment Disinfection (CIP) | 0.02% (bact./yeast) to 0.15% (bact./yeast/fungi/virus) 93-500 ppm (food contact surf.) | 15 min (general) 60 sec (food contact surf.) | No (some cases) Yes (dairies, final rinse potable water) | (EU) 2023/1200, General Rec. |
| Open Surface Disinfection (OSC) | 0.15% (bact./yeast/fungi/virus) | 15 minutes | No (some cases) | (EU) 2023/1200 |
| Fruit/Vegetable Wash Water | Max 500 mg/L (peas/beans) Max 500 ppm residual (fruits/veg.) | Not specified | Yes (peas/beans) | Anses (France), General Rec. |
| Spinach Cooling Water | Max 75 mg/L | Not specified | Yes (potable water) | Anses (France) |
VIII. Conclusion and Recommendations
PAA is a strategic disinfectant in the agri-food industry. Advanced formulations like Stérile C (non-corrosive, neutral pH, odorless, stable) optimize its use.
Recommendations for Optimal Use:
- Prioritize advanced formulations (Stérile C) to reduce risks and material constraints.
- Use precise dosing systems.
- Ensure adequate ventilation (less critical for odor/irritation with Stérile C).
- Apply PPE and train personnel.
- Respect storage conditions and waste management.
- Strictly follow regulations and ensure pre-cleaning.
PAA, especially with innovations like Stérile C, is key for safe, effective, and sustainable agri-food production.