‘Kill step’ validation of low-moisture extrusion


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In the USA, the Food and Drug Administration has had a zero tolerance policy for Salmonella since 2010, which is why various extrusion industries have experienced a dramatic increase in recalls over the past two years.

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‘Kill step’ validation of low-moisture extrusion

  1. 1. Digital Re-print -May | June 2013‘Kill step’ validation of low-moisture extrusionwww.gfmt.co.ukGrain & Feed MillingTechnology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies,the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis ofinformation published.©Copyright 2013 Perendale Publishers Ltd.All rights reserved.No part of this publication may be reproduced in any formor by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872
  2. 2. Innovations for a better world.Innovative extrusion processes without limits. Bühler is the global technologypartner for companies producing breakfast cereals, snack foods, or food in-gredients on a commercial scale. With its extensive extrusion know-how andits passion for customized solutions, Bühler is always in a position to generateadded value and success for any product idea. Bühler offers an integral range ofproducts and services for all process stages – from correct raw material handling,cooking and shaping through extrusion to drying of the extruded products. Andthis for all market segments – from breakfast cereals and snack foods to modifiedflours and starches, texturized proteins, or vitaminized rice. In short: extrusionprocesses without limits.extrusion@buhlergroup.com, www.buhlergroup.com/extrusion
  3. 3. In the USA, the Food and DrugAdministration has had a zero tolerancepolicy for Salmonella since 2010,which is why various extrusion industrieshave experienced a dramatic increase inrecalls over the past two years.In many of these recalls, Salmonella wasfound in the plant (commonly found in rawmaterials) and even though very few casesled to sickness, the manufacturer decided torecall all batches produced at that time. It’sbetter to be safe than sorry, but these recallsundermine consumer confidence, damagebrands and impact the entire industry.While every manufacturer strives forproducts that are 100 percent pathogenfree, applicable and validated scientific stud-ies to support properly designed extrusionfood safety systems weren’t possible…untilnow.Kill step validationTo mimic how products are contami-nated under real-world production facil-ity conditions, Extru-Tech built a BSL (Bio-Safety Level) 2 pilot plant outfitted with aproduction scale Extru-Tech E525 extrusionsystem. As a result, Extru-Tech now offersthe industry’s first scientific validation studyof a food/feed extrusion system that killsSalmonella at levels higher than normallyfound in most facilities.In an effort to target an industry with thehighest exposure, Extru-Tech chose to firstaddress specific issues within the pet foodindustry by tailoring their validation protocolto an adult canine specification. However,due to the equipment design duplicity, thissame architecture and protocol providescredibility to multiple extrusion markets.“Extru-tech is using actual equipmentthat you would find in most pet food plantsin a bio-hazard laboratory or a pilot plant,”says Dr Jim Marsden, regents distinguishedprofessor, Kansas State University. “Rawmaterials can be inoculated with Salmonellaor other pathogens and the effect of theextrusion process can be exactly quantified.This process is a breakthrough for the petfood industry.”Production scale vs traditionaltesting methodsFood/feed manufactur-ers have relied on tradi-tional lab studies based ontesting equipment rangingfrom beakers and pressurepots to table-top modelextruders. Most testinghas been completed on alab table at very low pro-duction rates of 30 g to a1 kg per hour - not exactlyreal world conditions.Typically for a pilotscale extrusion lab, theExtru-Tech model E325would be used. However,the smallest change, fromthe lab E325 (3.25 in‘Kill step’validation of low-moistureextrusionby Will Henry, research &development, Extru-Tech Inc., USAFigure: 3 E525 extrusion systemKey considerations used inthe studyFor the development stage of thisprocess, key operational parameterswere analyzed to scientifically validate atypical extruded pet food process.Equipment scale - productionratesImpartial and internal studies have prov-en the agnostic relationship betweenlaboratory scale equipment and pro-duction scale equipmentEquipment configuration - barrel screwstack-up, preconditioner paddle con-figurationImpartial and internal studies haveshown that even the slightest change inequipment setup will impact the proc-ess’s pathogenic efficacyFormulationImpartial and internal studies provideexcellent insight into the variationsinherent within individual ingredientcomponents and how they interactdifferently within a processing environ-ment (i.e. thermal energy efficiency,water absorption, energy of gelatiniza-tion)Product specificationParameters such as: size, shape, den-sity, cell structure, moisture and wateractivityImpartial and internal studies reflect thatspecific changes in product character-istics via process management, equip-ment configuration or formulation, willdirectly affect the efficiency of microbio-logical control.Figure 1: Collection of equipment architecture thatrepresent models for existing validationsGrain&feed millinG technoloGy22 | may - June 2013FEATURE
  4. 4. bore) to a production E525 (5.25 inbore), translates to a production rateof 200 to 600 pounds per hour for theE325 and upwards of 8,000 pounds perhour for the E525 (in terms of typicalpet food). The process data translationis cumbersome at best and filled withnon-linearity.With all this in consideration theBSL-2 pilot plant was outfitted witha E525 production scale extrudersystem and the equipment was config-ured for the production of an industrygeneric low-moisture dry-expandedpet food.Creating a dryinoculant testA significant pointof discovery is how araw material is con-taminated or inocu-lated in a factory.Various preemptivetrials, discovered thatmany of the read-ily available and sci-entific methods ofinoculation are nottruly representativeof a typical contami-nation event that ourclients deal with on adaily basis.For example, somestudies have developed thermal survivabilityprofiles (charts that show death of variousmicrobes against time or temperature).However, these data sets were created withthe microbes suspended in a largely aqueoussolution. If Salmonella is in a liquid, heat willtransfer quickly and kill it quickly. However,this is not a representation of what happensin a pet food plant and creates a false set ofoperational parameters that do not controlSalmonella.For pet food, food, and feed manu-facturers, Salmonella is usually introducedthrough dry ingredients. For this reason, wedeveloped a dry inoculant. A dry inoculantintroduced into the ingredient stream betterrepresents how the pathogens are usuallypresent within contaminated raw ingredients.The obvious pathogen choice was a3-serotype cocktail of Salmonella as it is themost opportunistic organism that is preva-lent in the pet food industry and the media.The selected industry generic pet food for-mula was charged with a tailored inoculantthat represents typical contamination eventsin the manufacturing process.Ultimately all three replications of thechallenge study resulted in a log reduction ofSalmonella that exceeded the 5-log reduc-tion requirement of a CCP allocation.Validation 101As any food safety auditor may tell you,the ability to correlate the assignment ofcritical control points (CCPs) to scientificallyvalidated proof of their effectiveness in thecontrol of targeted pathogens is ultimateconfirmation of effectiveness.“All food manufactures are requiredunder the Food Safety Modernization Act(FSMA) to develop written food safetyplans,” says Dr Marsden. “For example, ifSalmonella is a hazard that is reasonably likelyto occur in the process or product, then aseries of interventions are required and theymust be scientifically proven.”Validation is the process of demonstrat-ing that a food safety system (HACCP,CCPs, CLs) as designed can adequatelyFigure: 2 E925high capacityextrusionsystem (13 to15 t/hr petfood)Grain&feed millinG technoloGy may - June 2013 | 23Rota Val’s rotary and diverter valves are UK manufactured from our Wiltshire baseusing only high quality British castings.For more information please visit www.rotaval.co.uk or contact ourtechnical sales team on 01249 651138 & sales@rotaval.co.uk.A SOLID reputation for quality without compromise!Receive 5% discount on your first order when you quote MFJUN13.www.oj-hojtryk.dkDie and roll re-working machinesPellet Die re-working and unblockingO&J Højtryk A/SØrnevej 1, DK-6705Esbjerg ØCVR.: 73 66 86 11Phone: +45 75 14 22 55Fax: +45 82 28 91 41mail: info@oj-hojtryk.dkO&J_AD_QP_190x60.indd 1 11/02/2013 09:09FEATURE
  5. 5. control (5-log reduction) the identifiedhazards to produce a safe product. As theUnited States Department of Agricultureindicates there are two distinct elementsof validation:• The scientific justification ordocumented basis for the systemdesign requires scientific and technicaldocumentation that demonstratesthe designed process can control theidentified hazard. The practical andscientific demonstration must provethe system can perform as expected.This consists of keeping records todemonstrate the plan in operationand that the HACCP plan achievesexpectations.• Conducting multiple repetitions in areal-time processing environment usingfull- scale production equipment andactual production formulations thathave been inoculated with designatedhigh levels of specific (non-man made)microorganisms. The process also mustprove that high levels of microorganismsare reduced or killed through thelethality conditions of the CCP.“The best way to see how effective anintervention is against certain pathogens isto actually inoculate a food product withSalmonella,” says Dr Marsden. “We thenapply that intervention under conditionsthat ideally replicate a real-world food plantto measure the reductions associated withthat treatment. As a result, we know exactlyhow effective an intervention is in controllingspecific pathogens.”Basing a food safety system on impracticaldata is not safe! By selecting a sub-standardfood safety model, you forfeit all leverage tomitigate the risk of a food safety event.Validating your extrusion foodsafety systemUntil now, an extrusion kill step validationhas not been available in the food industry.Extru-Tech now offers scientific validationfocused on the extruded foods that exceedFSMA requirements.“Extru-tech is documenting the param-eters that are required to deactivateSalmonella in the extrusion process,” saysDr Marsden. “There are other productionsteps that follow where Salmonella couldre-contaminate the product. Extru-tech islooking at those additional steps to identifyinterventions that could be applied down-stream to prevent recontamination.”Study parametersPossible paths for validation of a typicalpet food process were reviewed inorder of preference and viability:Pilot plant - most accepted and least riskConfigure a pilot plant withrepresentative production-scaleequipment models and performa tailored challenge study withspecific formulations, equipmentconfiguration, product specificationsand targeted pathogensPros - correlation becomes moot,no riskCons – noneIn-plant surrogateSelect non-pathogenic surrogateand inoculate actual productionprocess flowPros - matched equipment andprocess modelCons - lack of applicable(correlation) challenge study dataIn-plant pathogenicInoculate actual production processflow with pathogenic microbePros - correlation becomes moot.Cons - risk of future events andliability thereofLaboratory validationSecure a BSL-2 laboratory toperform ‘bench-top validationPros - specific pathogen, surrogatecorrelation, tailored formulationCons - does not replicateequipment scale, configuration orthe manufacturing processScientific literature - least acceptedand most riskSearch for existing scientificdata that best represents yourmanufacturing modelPros - least costCons - difficult to find a singlestudy that will be even minimallyrepresentative of a pet foodextrusion processMore inforMation:Tel: +1 785 284 4133Website: www.extru-techinc.comNewsletter: http://eforms.kmpsgroup.com/wattpub/forms/extr_subscribe.htmFigure 4: Summary data of extrusion validation for all three repetitionsFigure 5: XX Extru-Tech Inc. pilot plant control system screenshotdepicting CCP verificationGrain&feed millinG technoloGy24 | may - June 2013FEATURE
  6. 6. www.gfmt.co.ukLINKS• See the full issue• Visit the GFMT website• Contact the GFMT Team• Subscribe to GFMTA subscription magazine for the global flour & feed milling industries - first published in 1891INCORPORATING PORTS, DISTRIBUTION AND FORMULATIONIn this issue:• Additivesfor flourstandardisationPart II:Additives other thanenzymes• High efficiencyelevatorbuckets:modern vstraditionaldesign• Feed focusPoultry• Assessingnutritional valuewith NIRMay-June2013• ‘Kill step’validation oflow-moistureextrusion• Adding value tofeed millingwith profit-oriented feedformulation• Pest controlacross the supplychainfirst published in 1891This digital Re-print is part of the May | June 2013 edition of Grain & FeedMilling Technology magazine. Content from the magazine is available to view free-of-charge, both as a fullonline magazine on our website, and as an archive of individual features onthe docstoc website.Please click here to view our other publications on www.docstoc.com.To purchase a paper copy of the magazine, or to subscribe to the paper edi-tion please contact our Circulation and Subscriptions Manager on the linkadove. INFORMATION FOR ADVERTISERS - CLICK HEREArticle reprintsAll Grain & Feed Milling Tecchnology feature articles can be re-printed as a 4 or 8 page booklets (thesehave been used as point of sale materials, promotional materials for shows and exhibitions etc).If you are interested in getting this article re-printed please contact the GFMT team for more informa-tion on - Tel: +44 1242 267707 - Email: jamest@gfmt.co.uk or visit www.gfmt.co.uk/reprints