Murphy & Son Limited
Murphy & Son Limited
Alpine Street
Old Basford
Nottingham, NG6 0HQ

Tel: 0115 978 5494
Fax: 0115 924 4654
email: info@murphyandson.co.uk

 

Cleaning in the Brewery

by Ray Alton

Contents
Introduction
Formulation of Cleaning Materials
Properties of Detergent Constituents

 
Introduction

There are three basic standards of cleaning

i) Physically Clean - visually clean

ii) Chemically Clean - clean to a standard where anything coming into contact with the surface suffers no chemical contamination.

iii) Microbiologically Clean - clean and sterile so that there is no physical or micro-biological contamination.

 
This table outlines the standard required for various parts of the brewing process:
Process Plant Soil Type Cleaning Procedure Cleaning Criteria Chemicals
Milling Mills and Rollers Dust Manual Physically clean None
Mashing Mash Tun Particulate sugar, scale, tannin Manual or CIP Chemically clean Detergent
Boiling Copper Starch, sugar, hop residues, scale, tannins Manual or CIP Chemically clean Detergent
Cooling Para-flow Particulate protein scale Manual, CIP or both Micro-biologically clean Detergent & Sanitiser
Fermentation F.V.'s Yeast, Tannin, Sugar, Scale, Protein, Oxidation products Manual or CIP Micro-biologically clean Detergent & Sanitiser
Conditioning Closed Vessels Yeast, Protein, Scale CIP Micro-biologically clean Detergent & Sanitiser
Packaging Casks Yeast, Protein, Scale CIP Micro-biologically clean Detergent & Sanitiser
Cellar Beer lines Yeast, Protein, Scale CIP Micro-biologically clean Detergent & Sanitiser
 

The choice of cleaner employed will be dependent upon the nature of the deposits found in a particular environment and on the cleaning criteria. Generally speaking organic deposits such as proteins, gums, yeast, sugars and hop residues are most efficiently removed by caustic based cleaners, whilst inorganic scale is removed by acidic cleaners. The materials of construction of the plant are also critical, caustic soda based cleaners for example being aggressive to Aluminium.

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Formulation of Cleaning Materials

Organic Dissolving Power:
Caustic soda is very efficient at dissolving the typical organic soil created by wort, beer and yeast residues within brewing plant. Caustic Soda also possesses a degree of bactericidal properties, particularly when used in a hot CIP system. However because there are a number of other requirements of a well formulated detergent, the efficiency of caustic soda is greatly increased by the use of selected additives.

Sequestering Power:
Using Caustic Soda alone as a detergent can cause problems in areas of high water hardness. Under strongly alkaline conditions carbonate salts are precipitated from solution, which may result in a whitish film being left on the surface of plant after the cleaning cycle. The addition of Ethylene Diamine Tetra-acetic Acid (E.D.T.A.), Sodium Gluconate, or Sodium Hexametaphosphate (Calgon) to the formulation acts as an efficient sequesterant, helping to keep the carbonate in solution.

E.D.T.A. and Sodium Gluconate also dissolve Calcium in alkaline conditions, helping reduce the formation of beerstone in vessels. However where beerstone has already taken a strong hold, acidic cleaners based on sulphuric, nitric, phosphoric or sulphamic acids will be needed.

Wetting and Penetration:
In order to be effective, a detergent needs to wet the surface of the soil and to then penetrate the crevices by capiliary action. It is by this means that the detergent overcomes the adhesion of the soil to the surface of the plant. The incorporation of surfactants into detergent formulations best achieves this requirement.

Dispersion:
Having utilised the wetting and penetration properties of surfactants to loosen soil and the chemical dissolving power of the Caustic Soda, it is then necessary to break up the large particles so created. Surfactants again are very efficient in this respect, along with metasilicates and phosphates.

Suspension:
By breaking up the dispersed matter into smaller particles the soil is easier to maintain in suspension, reducing the risk of soil re-settling onto plant surfaces during the cleaning cycle. Once again surfactants, metasilicates and phosphates best achieve this objective.

Rinsability:
The purpose of cleaning is to remove deposits from the brewing vessels that may cause beer spoilage, either microbiologically, organoleptically or physically. However, by their very nature, the cleaning materials themselves are a potential hazard. Residues of cleaning materials left in the plant pose a serious problem to Brewers, and for that reason an essential property of a formulated detergent is that it is itself easily removed by rinsing after the C.I.P. cycle. Caustic again is poor in this respect, Wetting Agents giving the best rinsability. Metasilicates and phosphates are an improvement on Caustic alone, but do not match the performance of Wetting Agents.

The most effective cycle of cleaning is:
Pre-rinse – to remove loose material
Detergent wash – to chemically clean
Intermediate Rinse – to remove detergent
Disinfection – to microbiologically clean
Final Rinse.

Many brewers however use a combined sanitiser/detergent, usually a chlorinated caustic formulation, to clean and sanitise in one operation. A little of the sanitising effect of the chlorine is lost, but results are quite satisfactory.

Sterilisation:
Sterilisation of brewing plant and equipment is usually achieved by the use of chlorine in the form of Sodium hypochlorite or Sodium dichloroisocyanurate, or QAC's, Quaternary Ammonium Compounds.These very effective means of sterilisation suffer from one drawback - the need to rinse after use to avoid tainting the wort and beer. This is not ideal since water, whilst potable, is certainly not sterile. It is unlikely that rinse water would contain beer spoilage organisms, however it is becoming common practise to use a Terminal Sterilant such as Peracetic Acid, for the final rinse. Used to spray FV's, CT's, RB's, casks and bottles immediately prior to use, peracetic acid sterilises without the need for rinsing.

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Properties of Detergent Constituents
  Organic Dissolving Power Wetting / Penetration Dispersion Suspension Rinsability Sequestering Power Calcium Dissolving Power Bactericidal Properties
Caustic Soda V. Good Poor Poor Poor Poor None None Fair
Sodium Metasilicate Fair Fair Good Fair Fair None None Poor
Sodium Tripolyphosphate None Poor Fair Fair Poor Fair None None
Sodium Hexametaphosphate None None Fair Fair Fair Good Poor None
Surfactants None V. Good Good Good V. Good None None Poor
E.D.T.A. None None None None Fair V. Good Good Poor
Sodium Gluconate None None None None None V. Good Good None
 
References:

Malting and Brewing Science, Hough Briggs and Stevens
Detergents and Sterilants in the Brewery, Michael Barrett LRIC
Detergents and Sterilants, Michael Barrett LRIC
Detergents for CIP, C G Stillman
How Clean is Clean, Dr Christine Fleming