NCDEA/Dairy Australia
Effective Methods of
Cleaning and Sanitation
Steve Flint
15th May 2013
Food Hygiene Regulations
(Cover manufacture and service of food)
• All food contact surfaces and utensils must be
cleaned with detergent & bactericidal solution
• Premises required to be maintained in a clean &
hygienic condition
Reference: Practical Sanitation in the Food Industry,
1994. Maddox, I.S. Gordon & Breach Science Publishers
Outline of Presentation
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Defining the ideal cleaning programme
Cleaning basics
Manual and CIP systems
How much is too much
Sanitation – importance, options, how it works
Electroactivated water as an alternative
A good cleaning programme is a form of quality
assurance
Cleaning is an essential component of Good
Manufacturing Practice (GMP)
Ideal cleaning programme
• Two stages
• Cleaning = Removes at soil and at least 99% of
microorganisms
• Sanitation – Reduces microorganisms to 0.0001% of the
initial count
Types of cleaning
• Environmental
• Personal hygiene
• Manual cleaning
• Clean in place
Objectives of cleaning
• To recover product
• Remove soil
• Enable sanitation
• Prepare surfaces for further processing
Cleaning methods
• Wet
• Dry
Definition of a clean surface
• Visibly clean
• No odour
• White swab test
• Meets microbiological specifications
Types of Soil
• Organic – requires alkaline detergents
• Inorganic – requires acid detergents
Fat removal
• Easily removed with >50°C water
(melting range 50-60°C)
• Ideal flush temperature 50-55°C as this
avoids baking on proteins
• Detergents aid removal by emulsifying fats
and hold in suspension so it does not redeposit
Protein removal
• More difficult - especially if dried / burnt on
• Requires pre-softening (i.e. mechanical action
from high pressure water) and in extreme
cases scrubbing with a scouring agent
• Detergents break down proteins long protein
strands into smaller soluble sections
Detergents
• Detergent = a chemical that assists the cleaning
process when added to water
• Choice depends upon
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the type of contamination to be removed
the equipment to be cleaned
application method (soak, manual clean, foam)
contact time
• Industrial formulations are usually a mix of several compounds.
Cleaning (soil removal)
• Separation of soil from surface depends upon
• Mechanical action (Kinetic energy – eg flow – 1.5 m/s,
scrubbing)
• Chemical action (enzymatic, hydrolysis)
• Surfactants (lower surface tension)
Effective soil removal depends on
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Plant design
Water quality
Age and type of soil
Cleaning sequence
Cleaning concentration)
Time of exposure
Mechanical action (kinetic energy)
Temperature (10°C increase = 2 x increase in cleaning efficiency
between 50 – 80°C)
Factors affecting cleaning.
Conc Time
KE
Temp
Importance of water quality
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Potable
Free of microorganisms
Clear
Colourless
Non corrosive
Free of minerals (soft)
Chlorinated (0.2 – 0.5 ppm FAC)
Requirements of the ideal cleaning
compound
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Efficient
Safe
Non damaging – non corrosive
Does not leave residues that affect flavour
Easily rinsed
Types of cleaners
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Soaps
Alkaline detergents
Acid cleaners
Synthetic detergents (cationic wetting agents)
Enzymatic cleaners
Detergent auxiliaries (Sodium tripolyphosphates – combined
with Mg and Ca salts to prevent scale)
Detergent formulation
• Alkaline (alkali + surfactant + poly-PO4)
• Medium – sodium metasilicate, pH 10-10.5
• Heavy duty – sodium hydroxide, ph 12-13.
Corrosive and dangerous to personnel
• Acid (acid + surfactant)
• pH ~ 3. Remove mineral or alkali-insoluble deposit
e.g. “milk stone”
• Milk industry uses alkali followed by acid to
ensure complete clean
Detergent Application Methods
• Scrubbing brush & bucket
• Wasteful of detergent, labour intensive, difficult to
control
• Brushes must be cleaned & sanitized after use
• High pressure sprays
• Use with alkaline or acid detergent, provides
mechanical energy, manual scrubbing may also be
necessary
• Detergent usage high, liquid has short contact time
with surface. Lowers labour costs
Detergent application methods
• Low pressure sprays
• Less mechanical energy, but less wastage, rinse off
with high pressure water spray
• Manual scrubbing may still be required
• Foam cleaning (using a foaming unit)
• Foam adheres to surfaces, allowing contact time as
foam collapses
• Reduced labour cost, reduced wastage, easy to see
coverage
Foam cleaners
Foam cleaning
Foam coverage
Preliminary (roughdown) important
Dry foam - ineffective
Example of good foam coverage
Clean in place systems
• Advantages
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Cheap (low labour input)
Automated
Safe (strong detergents can be used)
No plant disassembly needed
Consistent and monitored
• Single use and re-use systems
Monitoring a CIP system
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Solution strength
Turbidity
Temp
Flow rate
Visual inspection
Micro tests (swabs and rinse)
Samples of first product processed
Two cleaning issues
• Optimum strength
• Chemical reuse
Optimum solution strength
Cleaning time (min)
Effect of NaOH concentration on cleaning time for whey
protein deposits (50°C 0.175 m/s) (Bird and Bartlett 1995)
60
50
40
30
20
10
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Sodium hydroxide concentration (%)
1
2
Effect of re-using sodium hydroxide on Spore
attachment
(Seal 2009)
Sanitisers
• Reduce pathogenic and food spoilage microorgansisms to safe acceptable levels
• Sanitisers do not penetrate soil therefore cleaning is as
an essential pre-requisite
Requirements of the ideal sanitiser
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Effective in low concentrations
Chemically stable
Readily soluble
Non toxic to humans
No odour
Colourless
Non corrosive
Broad spectrum
Cheap
How sanitisers work
• Inhibit microbial growth
• Prevent spore formation or other bacterial activity
• Kill micro-organisms
More specifically • Oxidation of cell components (eg Halogens)
• Formation of protein complexes (inhibit enzyme
activity)
• Hydrolysis of cell components
• Interfere with membrane permeability
Factors influencing sanitiser efficacy
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Types of micro-organisms
Any soil present
Water hardness
Time of exposure
Temperature
Concentration
Time
Temp.
Conc.
Resistance to sanitisers
Most
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Spores
Mycobacteria
Viruses
Fungi
Vegetative bacteria
Least
Efficacy of different sanitisers
Monitoring effectiveness of sanitisers
• Titration
• Microbiological tests
• Conductivity
• ATP assays
Most common sanitisers
• Chlorine-based: hypochlorite, chloramine,
chlorine dioxide
• Quaternary ammonium compounds
• Iodine-based: iodophor
• Peroxide based:
• Hot water - steam
Chlorine sanitisers
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Destroy bacterial capsules
Oxidation of cell cytoplasm
Form toxic radicals
Alter cell permeability
Precipitate bacterial protein
Prevent enzyme activity
Chlorine sanitisers
H+
HOCL + H+ + Cl-
Cl2 + H2O
OH
Most antibacterial
effect at pH 5-6
More about chlorine compounds
• Spores more resistant than vegetative cells
Spores = 1000 ppm FAC
Vegetative cells = 200 ppm FAC
• Inactivated by organic material
• Inactivated by light
• Activity deteriorates with time
Iodophor
• Iodine loosely bound to a detergent with an acid base
(Phosphoric acid)
• Attacks proteins and lipids
• Effective in acid conditions
• Corrosive
• Stains
• Colour not indicator of activity
• 25-50 ppm recommended concentration
Quaterinary ammonium compounds
(eg Cetrimide)
• Denature proteins
• Affect cell permeability
• Affect metabolic reactions in bacterial cells
QAC’s continued
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Highly stable
Safe
Non corrosive
High surface activity (foam)
Most effective on Gram positive bacteria
Activity reduced in hard water
Do not kill spores
Less affected by organic matter
Use 200-400 ppm
Peracetic acid/Hydrogen peroxide
• Oxidise cell components
• Effective at low concentrations (100 -500 ppm)
• Broad spectrum – bacteria and viruses
• Mildly corrosive
Fumigation
• Occasionally necessary to decontaminate large
area, e.g. chiller
• Gaseous sanitizer
• Atomise liquid sanitizer eg QAC
• Ethylene oxide in carrier gas
Fumigation Procedure
• Defrost and remove all product
• Clean using suitable detergent
• Steam out room – temperature >18oC and RH >
85% required
• Fumigate
• Seal room and leave fans running. Place warning
signs. Leave 24 hours
• Open and disperse fumes.
Troubleshooting – cleaning failures
• Wrong detergent used
• Chemicals not used according to manufacturer’s
instructions
• Poor control & supervision of cleaning procedure
• Build-up of microbial resistance to sanitizer –
change sanitizer type
Alternative system – Electrolysed Oxidising
Water
• Cleaning and sanitising solutions
• Catholyte
• ORP -800 mV
• pH 11.0
• NaOH 0.1%
• Anolyte
• ORP +1000 mV
• pH 2.5
• FAC 500 ppm
• Produced from NaCl
• 0.8% NaCl
• 20-35A 10V
Benefits
• Convenient
• Cheap
• Safe
• Enhanced efficacy claims (fresh solution)
Potential applications for EAW
• Replacing NaOH with Catholyte for cleaning
• Replacing traditional sanitisers with Anolyte (mixed
oxidant) to control bacteria
Effect of catholyte on biofilm removal
1.2
B. cereus 25
OD 540 nm
1
B. cereus 26
0.8
Ps. fluorescens
0.6
S. aureus
0.4
E. coli
0.2
B. subtilis
0
0
1
2.5 5
10 20 40 80
Catholyte (%)
Catholyte for biofilm removal
• Effective at concentrations of >10% (equivalent to
0.01% NaOH)
• Some variation between different bacteria
• Current NaOH use (1.5%) probably excessive
• Current hypochlorite (200 ppm) use probably
excessive
Sanitiser efficacy – bacteria and fungi
Test micro-organism
Minimum concentration for total kill of planktonic cells
Anolyte (%)
NO MILK
Sodium hypochlorite
(pH 6.7) (ppm)
+2%milk
NO MILK
+2% milk
B. Cereus (25)
40
40
125
60
S. thermophilus (H)
20
40
30
30
Ps. fluorescens (KW19)
40
40
125
125
S. aureus (M8K9)
40
40
30
30
E. coli (ATCC 25922)
20
40
30
30
B. subtilis (84)
40
40
125
125
Geobacillus (AM)
80
80
250
125
A. flavithermus (CM)
80
80
125
125
Cladosporium sp
40
80
125
250
Penicillium sp
40
>80
60
250
Minimum Effective Concentrations
20% Anolyte = 100 ppm FAC
30 ppm NaOCl = 23 ppm FAC
Sanitiser efficacy – bacteria and fungi
Test micro-organism
Minimum concentration for total kill –
Biofilm Cells
Anolyte (%)
Sodium hypochlorite
(pH 6.7)
B.cereus (25)
80
125
S. thermophilus (H)
80
125
Ps. fluorescens
(KW19)
>80
250
S. aureus (M8K9)
>80
250
E. coli (ATCC 25922)
>80
125
B. subtilis (84)
>80
125
Kinetic trials – 5% concentration of Anolyte
Log10 counts/mL
7
6
B.subtilis
5
E.coli
4
Ps.fluorescens
3
B.cereus
2
S.aureus
1
0
start
15
30
45
Time (seconds)
60
Sanitiser efficacy – bacteria and fungi
• Anolyte sanitation
• Efficacy less than sodium hypochlorite – based on FAC
levels.
• Minimal effect of organics
• Biofilm inactivation needs higher concentration than
planktonic cells
• Sanitiser activity is rapid - 15 sec
Potential applications for EAW
• Replacing NaOH with Catholye for cleaning
• Replacing hypochlorite sanitisers with Anolyte to
control bacteria
Summary & conclusions
• Catholyte is effective in removing biofilm
• Current strength of NaOH used to clean food plants
may be excessive for bioflim removal
• Anolyte efficacy against bacteria and fungi is less than
sodium hypochlorite based on the FAC
Summary
• Cleaning programmes are an essential part of a
successful food industry
• Cleaning and sanitation are separate distinct and
equally important activities in a cleaning programme
• Cleaning programmes will vary depending on what is
to be cleaned.
Questions