Standards and Best Practices for Cleaning in Brewing
Effective cleaning is fundamental to brewing quality beer. There are three basic standards of cleanliness in the brewing industry:
Physically Clean: Visually clean, with all visible soil or residue removed.
Chemically Clean: Free from chemical residues, ensuring anything that comes into contact with the surface is not contaminated.
Microbiologically Clean: Sterile, with no physical or microbial contamination remaining.
Cleaning Standards Across the Brewing Process
Different parts of the brewing process require different cleaning standards, depending on the equipment, soil types, and risks of contamination. Here’s an overview:
Milling
- Plant: Mills and Rollers
- Soil Type: Dust
- Cleaning Procedure: Manual
- Cleaning Criteria: Physically clean
- Chemicals: None
Mashing
- Plant: Mash Tun
- Soil Type: Particulate sugar, scale, tannin
- Cleaning Procedure: Manual or CIP
- Cleaning Criteria: Chemically clean
- Chemicals: Detergent
Boiling
- Plant: Kettle/Copper
- Soil Type: Starch, sugar, hop residues, scale, tannins
- Cleaning Procedure: Manual or CIP
- Cleaning Criteria: Chemically clean
- Chemicals: Detergent
Cooling
- Plant: Para-flow Heat Exchanger
- Soil Type: Particulate protein, scale
- Cleaning Procedure: Manual, CIP, or both
- Cleaning Criteria: Microbiologically clean
- Chemicals: Detergent & Sanitiser
Fermentation
- Plant: Fermentation Vessels
- Soil Type: Yeast, tannin, sugar, scale, protein, oxidation products
- Cleaning Procedure: Manual or CIP
- Cleaning Criteria: Microbiologically clean
- Chemicals: Detergent & Sanitiser
Conditioning
- Plant: Closed Vessels
- Soil Type: Yeast, protein, scale
- Cleaning Procedure: CIP
- Cleaning Criteria: Microbiologically clean
- Chemicals: Detergent & Sanitiser
Packaging
- Plant: Casks
- Soil Type: Yeast, protein, scale
- Cleaning Procedure: CIP
- Cleaning Criteria: Microbiologically clean
- Chemicals: Detergent & Sanitiser
Cellar
- Plant: Beer Lines
- Soil Type: Yeast, protein, scale
- Cleaning Procedure: CIP
- Cleaning Criteria: Microbiologically clean
- Chemicals: Detergent & Sanitiser
The choice of cleaning agent depends on the nature of the deposits and the cleaning criteria. Organic soils (proteins, yeast, sugars, hop residues) are best removed by caustic-based cleaners, while inorganic scale is addressed with acidic cleaners. It’s important to consider the plant’s materials—caustic soda, for example, can damage aluminium surfaces.
Key Properties of Cleaning Materials
- Organic Dissolving Power: Caustic soda is highly effective at dissolving organic residues and offers some bactericidal action, especially when hot. Additives can further boost its performance.
- Sequestering Power: In hard water areas, caustic soda alone may leave carbonate residues. Adding agents like EDTA, sodium gluconate, or sodium hexametaphosphate helps keep minerals dissolved and prevents beerstone formation.
- Wetting and Penetration: Surfactants allow detergents to wet and penetrate soils, breaking their adhesion to plant surfaces.
- Dispersion and Suspension: Surfactants, metasilicates, and phosphates help break up and suspend soil particles, preventing re-deposition during cleaning.
- Rinsability: Cleaning chemicals must be easy to rinse off to avoid contaminating the final product. Wetting agents provide superior rinsability over caustic alone.
The Cleaning Cycle
The most effective cleaning involves the following steps:
- Pre-rinse: Removes loose materials
- Detergent Wash: Achieves chemical cleanliness
- Intermediate Rinse: Removes detergent
- Disinfection: Achieves microbiological cleanliness
- Final Rinse
Many brewers use combined sanitiser/detergent products, such as chlorinated caustic solutions, for convenience. While this may slightly reduce the sanitising effect, it usually provides satisfactory results.
Sterilisation in Brewing
Sterilisation is typically achieved using chlorine-based products or quaternary ammonium compounds (QACs). These require thorough rinsing, as residues can taint beer. Increasingly, brewers use terminal sterilants like peracetic acid for a final, rinse-free sterilisation step—ideal for vessels, casks, and bottles just before use.
Properties of Common Detergent Constituents
- Caustic Soda: Excellent for dissolving organic materials, some bactericidal effect, but poor rinsability and sequestering power.
- Sodium Metasilicate: Fair cleaning and rinsing abilities, but limited bactericidal effect.
- Sodium Tripolyphosphate & Hexametaphosphate: Help with dispersion and sequestering, but limited cleaning power.
- Surfactants: Excellent for wetting, dispersion, and rinsability, but not bactericidal.
- EDTA & Sodium Gluconate: Great for sequestering and dissolving calcium, helping prevent beerstone.
In summary, effective cleaning in brewing is about matching the right standards and chemicals to each stage of production, ensuring quality and safety in every batch.