Considerations for

validating

extrusion systems

Presentation to the

GMA Science Forum April 4, 2012 V2

David Anderson Food Safety Manager

Del Monte Foods Company

Pittsburgh PA

Discussion points

A. Equipment configurations

B. Microbial death in LMF

C. Process validation options

D. Considerations

E. Validation guidance

F. References

A. Equipment

configurations

PreConditioner

Extruder Further processing (e.g., coating, bulk storage,

packaging)

Dryer Cooler

Equipment Configuration

Heating steps have the potential to demonstrate the desired pathogen reduction

Prevent recontamination in transfer and storage

Typical PreConditioner

Dry ingredient addition

Liquid ingredient addition

Steam

Colors

Divert gate

PreConditioner

Extruder

TID

• Functions • Mixes food components

• Brings to a required temperature and

percent moisture

• Devices • Temp. Indicating Device (TID)

• Divert gate before the Extruder to

reject low-temperature product

• Residence time • Depends on RPM, paddle config.,

PreConditioner symmetry

• Temperature • Results from steam injection

Typical

0-5 psig pressure

175-205°F temperature

20-25% moisture

Typical Extruder

• Functions • Add additional components

• Time at pressure and temperature convert

the product to desired characteristics

• Devices • Temp. Indicating Device (TID)

• Possible divert valve after the Extruder

• Residence time • Depends on RPM, screw configuration,

divert valve position

• Temperature • Results from steam injection,

shear/friction

• Cooling may be applied

PreConditioner

Extruder

TID

Steam

Colors

Coolants

Divert valve (“Back-pressure valve”)

Typical

15-30 sec. retention

300-600 psig pressure

230-270°F temperature

20-28% moisture

Dryer

• Functions • Remove moisture from the product

• Devices • Temp. Indicating Device (TID)

• Residence time • Depends on belt speed

• Single pass

or multi-pass with product tumbles

• Temperature • Heated air

Single-pass

Multi-pass

TID

TID

Operation

Pre-

Conditioner Extruder

Drying

Oven

Enrobe

/Coat

Baking

Oven Cool

Surge/Store

/Package

1. X X X X X X

2. X X X X

3. X X X X

4. X X X

5. X X X X

6. X X

7. X X

• Many configurations possible

• Validation is specific to the equipment

X - the operation is present - heating step

Variations on a process theme…

B. Microbial death

in Low-moisture foods

Impact of the Food Matrix

• Increased Salmonella resistance occurs with

increased solids, lower moisture/aw

• Reduced Salmonella resistance can come from

bacteriocins and other additives (Doyle et. al, 2000)

• If testing the impact of the food matrix, use a

qualified microbiology laboratory.

Useful references:

• Thermal Death Time study methods (e.g. NFPA, 1978

or Stumbo, 1973) or published articles for Low-moisture

food TDTs

• “Parameters for Determining Inoculated Pack/Challenge

Study Protocols.” (NACMCF, 2010 - J. Food Prot. 73:140-202)

Heat resistance in Dry Animal Feeds

z = 19.82 F°

* The processor may determine resistance relative to aw.

*

Micro tests: LMF Surrogates

Reported surrogate microorganisms for Salmonella spp.

Surrogate Example Food Reference

B. stearothermophilus spores,

B. stearothermophilus 12980

Animal feed,

Poultry feed

Okelo et al, 2006

Okelo et al, 2008

Enterococcus faecium

NRRL B-2354* Almonds

ABC, 2007b

Pantoea agglomerans

SPS2F1 Dry roast almonds ABC, 2007d

Pediococcus spp. and

Pediococcus acidilactici

“Saga 200” and “Biosource”

Ground, formed beef

jerky Borowski et al, 2009.

Pediococcus spp. Whole-muscle

turkey jerky Williams et al, 2010

Do not use pathogens in a food process environment.

C. Methods to validate

the process

Codex (CAC/GL 69-2008) and Scott (2005):

• Use scientifically valid data

• Conduct experiments (microbiological tests, and

measures of the system & product)

• Use mathematical modeling 10 (T – Tref)/z

Σ [( )Δt]/D

Methods to validate processes

Validation steps:

• Confirm in-plant product and process similarity to

those in the source document.

• Measure the delivered process to confirm that it

meets the required process conditions.

• Process temperature, residence time, product

temperature.

• Justify in the Validation Report.

• Implement minimum product/process conditions.

• Monitor during production, keep records, verify.

1. The scientific source describes a thermal process schedule

Validation steps:

• If conducting TDTs, use approved methods.

• Confirm in-plant product and process similarity to

those in the TDT study.

• Measure the delivered process to confirm minimum

conditions. Consider slowest-heating zones.

• e.g., process/product temperature, residence time.

• Model pathogen reduction.

• Justify in the Validation Report.

• Implement minimum product/process conditions.

• Monitor during production, keep records, verify.

2. Use time/temperature and TDT data to model microbial reduction

Validation steps:

• Select the test organism.

• Conduct in-plant studies with surrogates…

• Record product and process conditions

• Or conduct lab studies w/ surrogates/pathogens.

• Record product and process conditions

• Conduct plant tests to justify scale-up to plant conditions.

• Justify in the Validation Report.

• Implement minimum product/process conditions.

• Monitor during production, keep records, verify.

3. Conducts count-reduction or end-point micro. studies

Validation tests

• Tests of the production process • Temperature mapping; heat transfer distribution

• Retention time

• Other required process conditions

(e.g., relative humidity)

• Tests of product • Heat penetration studies

• Analyses (e.g., moisture/aw, preservative level)

Validation tests

Uniformity of

temperature;

of heat transfer

Rate of

product

heating

Product

retention

time

Product

moisture

PreConditioner • Temperature Indicating

Device (TID) measurements

• Insert additional TIDs

during validation testing

• Analyte in test

product

(e.g., salty, dye)

• Product

measurement

• Calculation Extruder

Drying Oven •Temperature

mapping

• Heat transfer

distribution

• Heat

penetration

test

• Analyte in test

product

(e.g., salty, dye)

• Physical

marking of

test product

• Product

measurement Baking Oven

Wireless datalogger examples

DataTrace MPIIITM

and MadgeTech

Temperature

dataloggers, with protective

insulation for high

temperatures.

Scorpion Data Logging System

for ovens (Temperature, air

velocity, heat flux, humidity).

Manufacturer Web address

DataTrace MPIII TM (Mesa Labs) www.mesalabs.com

Dickson www.dicksondata.com

Ecklund Harrison www.ecklund-harrison.com

Ellab Tracksense® Pro www.ellab.com

MadgeTech, Inc. www.madgetech.com

Omega Engineering www.omega.com

Scorpion Systems www.readingbakery.com

Super M.O.L.E.® www.ecd.com

TechniCAL, Inc. www.tcal.com

ThermoLog TM www.c-p-e.be

TMI www.tmi-orion.com

Examples of equipment suppliers

(Not an endorsement of any supplier. Exclusions are unintended.)

B. Considerations

Process Equipment…

Pre-

Conditioner

• In-process product temp. may be difficult to measure

• Justify the retention time at temperature,

especially if heating is not uniform

• Consider retention time (fastest-moving particle)

Extruder

• In-process product temp. may be difficult to measure

• Justify the retention time at temperature,

especially if heating is not uniform

• Consider retention time (fastest-moving product)

• External cooling may be applied

Drying Oven

Baking Oven

• Bed depth may be critical for heating

• Air flow is affected by baffle position; and

maintaining dryer pans free of blocked perforations

• Consider measured process temperature differences

from product temperatures

0

10

20

30

40

50

60

0 100 200 300 400

Time (Seconds)

Rec

ov

ere

d a

na

lyte

(%

)

75% of rated capacity 100% 160%

Preconditioner Retention Time

vis. Operating Capacity Setting

Preconditioner Retention Time

vis. Wall Clearance

0

10

20

30

40

50

60

0 100 200 300 400

Time (Seconds)

Rec

ov

ere

d a

na

lyte

(%

)

Normal wall clearance 4x normal wall clearance

% retracted Product temp. (°C)

0.0% 140

33.3% 139

50.0% 138

66.7% 135

83.3% 122

100.0% 104

0% retracted

100% retracted

Temperature probe inserted into the extruder barrel.

View from near the die end (cross section).

From Extru-Technician online magazine.

(Henry, and Rokey, 2010 and Krebs, 2012)

Extruder temp. probe - distortion

Effect of retraction:

Extruder: temperature probe

Helpful practices: • Insert deeply for most accurate readings.

• Sheathe probes to protect from wear.

• Insulate the sensor where it passes through

the extruder wall.

• Use duplicate sensors.

• Regularly replace sensors that wear.

• Locate probes near the die,

and in other locations if possible.

• Calibrate probes; keep records of calibration.

Calibration and Maintenance

• Keep calibration records

• Consider a Change Management program:

Pre-Conditioner & Extruder

• Paddle/screw wear → retention time.

• Paddle/screw replacement → revalidation?

Ovens

• Burner fouling → reduced heat. Uniformity?

• Dryer pan fouling → reduced air flow.

D. Process controls,

Monitoring,

Verification

Process controls to consider

Pre-

Conditioner

• Min. time: Paddle configuration and RPM

• Min. temperature

• Max. flow rate: dry components

• Min. flow rate: liquid components

Extruder

• Min. time: screw configuration and RPM

• Min. temperature

• Min. pressure, shear

Drying Oven

Baking Oven

• Min. time: belt speed; consider product tumbles

• Min. temperature

• Max. bed depth

• Min. air flow

• Baffle settings, dryer pans free of blockage

• Min. product initial temperature upon entry

Monitoring, records, review

Lessons from conventional canning…

• Monitor Critical Control Points

at sufficient frequency to ensure control

• Record observations

• Respond to process deviations

• Product disposition

• Process improvement following a deviation

• Verify that the system is working

• Record review

• Audits of the system

E. Validation guidance

F. Final thoughts

G. References

Validation guidance

• Guideline for the Validation of Food Safety Control

Measures (CAC/GL 69-2008) (Codex)

• ICMSF Microorganisms in Foods 8:

Use of Data for Assessing Process Control and

Product Acceptance (ICMSF, 2011)

• Validating the Reduction of Salmonella and Other

Pathogens in Heat Processed Low-Moisture

Foods. (Anderson and Lucore, April 2012)

http://community.pmmi.org/Alliance/Home/

Final thoughts…

• Validation activities provide the scientific data to

support pathogen control measures.

• Monitoring and verification in the plant can show

compliance to validated limits.

• A Management of Change program may be vital

• Challenges exist for validating extrusion and

related processes

- D-value increases with lower moisture/aw

- Product temperatures and retention time must be

justified through testing and controlled in-process

References

ABC (Almond Board of California), 2007a. Considerations for Proprietary

Processes for Almond Pasteurization and Treatment, v1.0, April 13, 2007.

Almond Board of California, Modesto, CA. www.almondboard.com

ABC, 2007b. Guidelines for Process Validation Using Enterococcus faecium

NRRL B-2354, v1.2, October 2007. Almond Board of California, Modesto,

CA. www.almondboard.com

ABC, 2007c. Guidelines for Validation of Blanching Processes, v1.0, April 13,

2007. Almond Board of California, Modesto, CA. www.almondboard.com

ABC, 2007d. Guidelines for Validation of Dry Roasting Processes, October 2007.

Almond Board of California, Modesto, CA. www.almondboard.com

ABC, 2007e. Guidelines for Validation of Oil Roasting Processes, v1.0, April 13,

2007. Almond Board of California, Modesto, CA. www.almondboard.com

ABC, 2007f. Guidelines for Validation of Propylene Oxide Pasteurization, v3.0,

October 1, 2008. Almond Board of California, Modesto, CA.

www.almondboard.com

ABC, 2007g. Guidelines for Validation of Propylene Oxide Treatment for In-shell

Almonds, v2.0, October 1, 2008. Almond Board of California, Modesto, CA.

www.almondboard.com

References

ABC, 2007h. Pasteurization Treatments. December 2007. Almond Board of

California, Modesto, CA. www.almondboard.com

Anderson, D. G. and L. A. Lucore. 2012. Validating the Reduction of Salmonella

and Other Pathogens in Heat Processed Low-Moisture Foods. Alliance for

Innovation & Operational Excellence, Alexandria, VA. Published online at

http://community.pmmi.org/Alliance/Home/. Accessed [scheduled for April,

2012].

Borowski, A.G., S.C. Ingham, and B.H. Ingham, 2009. Validation of ground-and

formed beef jerky processes using commercial lactic acid bacteria starter

cultures as pathogen surrogates. Journal of Food Protection 72: 1234-1247

Codex (Codex Alimentarius Commission), 2008. Guideline for the Validation of

Food Safety Control Measures (CAC/GL 69-2008). Joint FAO/WHO Food

Standards Program, FAO, Rome, Italy. www.codexalimentarius.net

Doyle, M. E. and Alejandro S. Mazzotta, 2000. Review of Studies on the Thermal

Resistance of Salmonellae. J. Food Prot. 63:779–795.

References

ICMSF (International Commission on Microbiological Specifications for Foods),

2011. Microorganisms in Foods 8: Use of Data for Assessing Process

Control and Product Acceptance. Katherine M. J. Swanson, ed. chair. New

York: Springer Science+Business Media, LLC.

Henry, W. and G. Rokey. 2010. Safety First. Extru-Technician online

newsletter, January 2012. Extru-Tech, Inc., Sabetha, KS.

www.extru-techinc.com. Accessed March 18, 2012.

Krebs, R. S.. 2012. Art of validation: The challenge of correlating published

validated science to a specific processing unit. The Extru-Technician online

newsletter, January 2012. Extru-Tech, Inc., Sabetha, KS.

www.extru-techinc.com . Accessed March 18, 2012.

References

NFPA (National Food Processors Association). 1978. Laboratory Manual for Food

Canners and Processors, Volume 1, 3rd edition. "Thermal Death Times", Pp.

166-203. Westport, CN: AVI Publishing Co., Inc.

NACMCF (National Advisory Committee on Microbiological Criteria for Foods),

2006. Requisite Scientific Parameters for Establishing the Equivalence of

Alternative Methods of Pasteurization. J. Food Prot. 69:1190-1216.

NACMCF. 2010. Parameters for Determining Inoculated Pack/Challenge Study

Protocols. J. Food Prot. 73:140-202.

Okelo, P. O., S. W. Joseph, D. D. Wagner, F. W. Wheaton, L. W. Douglass, and L.

E. Carr, 2008. Improvements in Reduction of Feed Contamination: An

Alternative Monitor of Bacterial Killing During Feed Extrusion. Journal Applied

Poultry Research 17: 219-228.

Okelo, P. O., D.D. Wagner, L.E. Carr, F.W. Wheaton, L.W. Douglass, S.W.

Joseph. 2006. Optimization of extrusion conditions for elimination of mesophilic

bacteria during thermal processing of animal feed mash. Animal Feed Science

and Technology 129:116-137.

References

Scott, V. N.. 2005. How does industry validate elements of HACCP plans? Food

Control. 16:497-503.

Stumbo, C.R.. 1973. Thermobacteriology in Food Processing, 2nd edition. “Death

of Bacteria Subjected to Moist Heat” and “Thermal Resistance of Bacteria”, Pp.

70-120. Orlando, FL: Academic Press, Inc.

Williams, P., W. M. Leong, B. H. Ingham, S. C. Ingham, 2010. Lethality of Small-

Scale Commercial Dehydrator and Smokehouse/Oven Drying Processes

Against Escherichia coli O157:H7-, Salmonella spp.-, Listeria monocytogenes-,

and Staphylococcus aureus-inoculated Turkey Jerky and the Ability of a Lactic

Acid Bacterium to Serve as a Pathogen Surrogate. Poster presented at the

annual meeting of the Institute of Food Technologists. Chicago, IL. July 2010.

Thank You David Anderson Food Safety Manager

Del Monte Foods Company

Pittsburgh PA