Microbiology of Butter

Steve Flint

November 2014

NCDEA/Dairy Australia

Confocal Microscope Image of Butter

Microbiological Issues with Butter

Spoilage issues

Specification limits

Primary Causes:

Coliforms

E. Coli

Microbilogical Specifications for Butter

• Ref: 1995 – MOH, New Zealand

MARGARINE AND SALTED BUTTER

Aerobic plate count at 35C ( /g) n = 5 c = 2 m = 2.5 x 104 M = 2.5 x 105 Coagulase producing

staphylococcus ( /g)

Faecal coliform ( /g) n = 5

n = 5 c = 0

c = 2 m = 0

m = 50

M = 5 x 102 *Listeria monocytogenes ( /25 g) n = 5 c = 0 m = 0 Salmonella ( /25 g)

Yeasts and moulds ( /g) n = 5

n = 5 c = 0

c = 2 m = 0

m = 50

M = 5 x 102

Microbiological Specifications for Butter

Microorganism n c m M

APC/g 5 1 5 x 104

Coliforms 5 1 10 102

Psychrotrophs 5 1 10 102

Coag + Staph 5 0 102

ANZFA Standard 1.6.1, 2001

Micro Issues – The N0. 1 cause of

downgraded butter – general trends

• Primarily in Fritz plants

• Numerous small incidents of coliform

contamination

• Lypolytic contamination

• APC incidents

• Yeast and mould contamination

Micro Issues 2013/2014 Season

Micro. Issue

Coliforms

Yeast and Moulds

Lipolytics

Pseudomonas

Micro problems 2012/2013 season

• Pseudomonas issues – several sites

• Water and poor cleaning of water sytems

• Intermitted coliform issues

• Thermophiles in buttermilk

• Fat rework (Fritz plant)

• Fouling of cream concentrators (AMF plants)

Buttermilk Quality – biggest issue

2013/2014 • Thermophilies

• Anoxybacillus flavithermus & Geobacillus

stearothermophilus

• Specification limits and spoilage concerns

• Milk separation and cream holding (poor chilling)

• Thermalisation not always used

• B. cereus

• Psychrotroph, pathogen and spoiler

• Coliforms

• As predictor of butter quality

Problems caused by microorganisms in

butter • Exceed customer specifications

• Odours and taints - enzymatic

• Surface discolouration (yeast/moulds and

pseudomonads)

• Pathogen concerns

Pathogen Contamination

• Finland outbreak (1999)

• butter (100-1000 cfu/g Listeria monocytogenes)

• 18 affected, 4 deaths

• traced to manufacturing plant - several areas

• product recalled

• clean up costs

Butter/Cream products

Phase reversal

Salt addition

Moisture Removal

Acidification (Lactic butter)

Refrigeration

Butter and

Cream Products

Influence of product composition and

storage conditions

• Moisture: Small droplets (10 - 30 um) - restrict

bacterial growth

• Freezing / refrigerated storage -

Minimises most microbial growth

(Moulds can grow slowly <10°C)

• pH: The acidity of lactic butter -

(pH 4.5 - 5.2) inhibits many bacteria

• Salt: 2% salt (12.8% salt-in-moisture) - inhibits most

bacteria

(2 ÷15.9 x 100 = 12.8)

The effect of salt in butter

Effect of 0.3% Salt on Bacterial Growth in Butter

0 5 10 15 20 25 30

Storage Time (Days)

Major R.M (1983) Factors affecting bacterial

growth in butter

The effect of salt in butter

0 5 10 15 20 25 30

Storage Time (days)

growth in butter

The effect of storage temperature on

butter

Effect of 1.0 %Salt on Bacterial Growth in Butter

0 5 10 15 20 25 30

Storage Time (Days).

growth in butter

Effect of salt on bacterial growth in butter

0 5 10 15 20 25 30

Storage Time (days)

growth in butter

Bacterial growth in unsalted butter

Bacterial Growth in Unsalted Butter

0 5 10 15 20 25

Storage Time (Days)

/g 16C

growth in butter

The effect of freezing and thawing butter

Effect of Freezing/Thawing on the Microbiological

Stability of Butter

0 5 10 15 20

Storage Time (Days)

Frozen/Thawed

Chilled 4C

growth in butter

Control of microbial growth in butter -

summary • Salt concentration

• Moisture dispersion (10 ųm)

• Butter with 106 > 10 ųm – poor quality

• Butter with 105 or less >10 ųm – good quality

• Storage conditions

• Cool to < 6°C in 24 h

The source of microorganisms affecting

butter • Dirty plant and equipment

• Raw cream

• Water

• Personnel

• Air

Action of microorganisms on cream

• Acid production - eg lactic acid bacteria

• Enzyme production = off flavours/odours

- Lipases

- Proteases

- Phospholipases

Note pasteurisation/vacreation/flavourtech treatment does not destroy microbial enzymes

Typical source - Pseudomonads

The types of microorganisms found in NZ

butter

Microorganism Percentage of Isolates

Unsalted Butter Salted Butter

Bacillus 18 34

Pseudomonas 18 12

Coliforms 16 17

Vibrio 15 7

Acinetobacter 12 7

Yeast 11 2

Other 10 21

Lypolytic species – 55% of isolates (Pseudomonas, Bacillus,

Enterobacter, Yeast)

Proteolytic species – 20% of isolates (Pseudomonas, Bacillus,

Seratia)

Control strategies in manufacture

Control

Minimizing niches

Keeping out

Preventing growth

Destruction

Enclosed process

Clean environment

Quality ingredients

Personal hygiene

No cross- contamination

Suitable design, construction

Maintenance

Adequate cleaning

Cooling

Minimal storage

Chlorination

CIP/Sanitation

Fumigation

Pasteurisation

Vacreation

The Fritz manufacturing process

• Vacreation - 99% kill

• Crystallisation - microorganisms double

• Churning - 75% bacteria lost

• Working - moisture dispersion

• Packing - air exposure

• Cooling - critical (<6°C in 24 h)

HAZARDS: RAW MILK STORAGE

• Poor quality milk received

• Dirty silos

• Inadequate cooling (10 - 15°C)

• Long storage (>24h)

• OUTCOMES

• Contamination / Bacterial growth

• Fat damage (Psychrotrophs)

• Acid production

• Irreversible damage

HAZARDS: PASTEURISATION/ SEPARATION

• Heat-sensitive organisms destroyed

• Enzymes & breakdown products will survive

• Ideal thermophile growth temp (45 - 65°C)

• Long processing runs (>9h)

• Ineffective CIP

• OUTCOMES • Uncontrolled thermophile growth

• Contaminated cream stream

• Buttermilk / BMP contamination

HAZARDS: FAT RECOVERY

• Uncontrolled fat reprocessing

• Ineffective CIP

• Contaminated fat stream re-injected

• OUTCOMES

• Contaminated cream stream

• Cycle of thermophile contam. set up

• Buttermilk / BMP contamination

HAZARDS: VACREATION

• 103 - 105°C

• Bacterial spore survival

(psychrotrophic, mesophilic, thermophilic)

• OUTCOMES

• Thermophilic spores survive (major issue)

• Uncontrolled contamination cycle

• Buttermilk/BMP contamination

THERMAL DESTRUCTION

Heat Survival

Thermisation Pasteurisation Vacreation

63°C/15 s 72°C/15 s 103-105°C Microbacterium Bacillus Micrococcus Clostridium Streptococcus Enterococcus Alcaligenes Bacillus Clostridium

HAZARDS: CRYSTALLISATION

SILOS • Ineffective CIP of filters, lines & silos

• Cracks / pinholes in silos

• Cracks in agitator shafts, baffles etc

• Slow growth (9 - 15°C / 8 - 12h)

• OUTCOMES

• Crystallised cream contaminated

(jacket water, deposits, poor sanitation)

• Coliforms, APC, Pseudomonas

HAZARDS; BUTTERMAKING (a)

• Lines and cream balance tank

• Feed pump: Servicing, CIP, seals

• Churn screen: CIP

• Churn / Shute-Seal: Sanitation

• Shute / Separation section: Splash / Sanitation

• Separation section: Sprayballs / Sanitation

HAZARDS: BUTTERMAKING (b)

• Working Section

• Buttermilk injection (buttermilk quality, line, pump,

dosing point sanitation)

• Cracks in chilled water jacket

• Vacuum system / lamp housing

• OUTCOMES

• Recontamination of cream / butter stream

• (No “downstream” controls)

HAZARD: BUTTER SILO

• Insanitary design / construction / maintenance

e.g. Pressure plate: Poor fit

Teflon gasket: Crevices

Pump seals

• Ineffective CIP

OUTCOMES

• Deposits, poor sanitation

• Recontamination of butter stream

HAZARD: BULK PACKER

• Ineffective CIP

• Non-potable water used (splashing)

• Air exposure

• OUTCOMES

• Surface growth e.g. Pseudomonas

• Visual & sensory defects

HAZARD: PATTING MACHINES

• Ineffective CIP

• Breakdowns / human intrusion

• Air exposure

• OUTCOMES

(e.g. Coliforms, APC, Pseudomonas)

• Visual & sensory defects

HAZARD: BUTTER STORAGE

• Slow cooling (e.g. centre of pallet)

• OUTCOMES

• Continued bacterial growth

• Pseudomonas (surface), coliforms etc

• Sensory defects

The Ammix manufacturing process

• Cream treatment (Flavourtech)

• AMF

• Salt slurry

• Blending - growth of thermodurics at 40°C

• Pasteurisation - 99% reduction in bacteria

• SSHE cooling

• Pinworking

• Resting

• Packing

• Cooling

Ammix plant layout

Storage

Fraction

Storage

Vege Oil

Storage

Bags Cool storage

Robot Stacker

Metal Detector

Case Closer

Weight Check

Packing Heads

Pinworkers

G & A Cooling Barrels

Hopper

Mix Tanks

on load cells

Pasteuriser

PHE 75c

Cooling 42c Gaf Filter

PHE Product

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Thermophiles from; Pasteurisers, Separators,

Concentrators, B cereus spore survival

Aqueous

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Aqueous

Extended storage inadequately cooled, growth of B cereus

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Aqueous

Cracks in silo walls

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Aqueous

Insanitary lines and silos

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Aqueous

Residual moisture

Raw Materials

Cream &

B Serum

Storage

Fraction

Storage

Vege Oil

Storage

Hopper

Bags Anhydrous

Aqueous

Residual moisture

Contaminated ingredients

Product Mixing

Bags Cream

Storage

Preheater

Mix Tanks

Recycle, Remelt

Loop Spiroflow

Ingredients

Recycled product

• Thermophile growth in regen. section, • B cereus spore survival

Product Mixing

Bags Cream

Storage

Preheater

Mix Tanks

Recycle, Remelt

Loop Spiroflow

Ingredients

Recycled product

Direct addition - Packaging contamination

Thermophile growth in regen. section, • B cereus spore survival

Product Mixing

Bags Cream

Storage

Preheater

Mix Tanks

Recycle, Remelt

Loop Spiroflow

Ingredients

• Thermophile growth in regen. section, • B cereus spore survival Recycled

product

Cracked vessels

Product Mixing

Bags Cream

Storage

Preheater

Mix Tanks

Recycle, Remelt

Loop Spiroflow

Ingredients

Recycled product

Cracked vessels

Insanitary vessels

Product Mixing

Bags Cream

Storage

Preheater

Mix Tanks

Recycle, Remelt

Loop Spiroflow

Ingredients

Recycled product

Cracked vessels

Insanitary flexible coupling

Insanitary vessels

Heat Treatment & Filtration

Mix Tanks

Pasteuriser

Gaf Filter

Temperature fluctuations

Mix Tanks

Pasteuriser

Gaf Filter

Sensitive products not heated

Mix Tanks

Pasteuriser

Gaf Filter

Cracks/ pinholes

Mix Tanks

Pasteuriser

Gaf Filter

Cracks/ pinholes

Themophile growth- Regen. section

Mix Tanks

Pasteuriser

Gaf Filter

Cracks/ pinholes

Poor cleaning - Filter socks and housing

Mix Tanks

Pasteuriser

Gaf Filter

Cracks/ pinholes

Survival of thermodurics and bacterial spores

Poor cleaning - Filter socks and housing

SSHE, Pin Worker & Resting Tube

Packer

Resting Tube

Pin worker

Large volume - Poor CIP turbulence

Packer

Resting Tube

Pin worker

Large volume - Poor CIP turbulance

Blade attachment - Poor cleaning

Packer

Resting Tube

Pin worker

Pistons - Cleaning difficulties

Packer

Resting Tube

Pin worker

Pop-out CIP nozzles - Correct function

Pistons - Cleaning difficulties

Recycling

Mix Tanks

Recycle

Remelt

Spiroflow

Packer

Resting Tube

Insanitary recycling line

Recycling

Mix Tanks

Recycle

Remelt

Spiroflow

Packer

Resting Tube

Cracks/pinholes - cross-contamination

Recycling

Mix Tanks

Recycle

Remelt

Spiroflow

Packer

Resting Tube

Cracks/pinholes - cross-contamination

Extended recycle times-5% to 100% if packer stopped

Packing & Storage

Packer Cool Storage

Insanitary filling heads

Packing & Storage

Packer Cool Storage

Contaminated packaging materials

Packing & Storage

Packer Cool Storage

Aerial contamination eg yeasts and moulds

Packing & Storage

Packer Cool Storage

Condensation drips

Packing & Storage

Packer Cool Storage

Condensation drips

Slow cooling, bacterial growth

Sampling

What to Sample?

• Raw Materials

• Combined Ingredients

• Survivors After Heating

• Known Process Hazards

Sampling

Sampling Technique

• Document Methods to IANZ standard

• Train Samplers

• Use Clean Sterile Sampling Equipment

• Leave No Chemical Residues

• Do Not Contaminate Sample or Equipment

• Discard if Contaminated

• Label Samples Correctly

Sampling

Sample Storage

• Short Time (<1 Day) at Refrigeration Temps

• Minimise Micro. Changes

• Represent the Process / Product

• In-Process Testing in Manufacture?

• What Micro Failures can be Tested?

• Can Lab Supply Materials?

Sampling

Analyses

• To Reflect the Process e.g.

• APC30

• Coliforms

• Thermophiles

• Surface Spoilers, eg Yeasts, Acinetobacter

• B cereus

Sampling Points

Aqueous

Storage

Bags Cool storage

Pinworkers

Hopper

Mix Tanks

on load cells

Anhydrous

Storage

S Resting tube

Key factors affecting the micro quality of

butter

• Cream handling

• Fat recycling

• Water/buttermilk quality

• Cooling

Questions

Microbiology of Butter - Dairy Australia

Documents

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