nondestructive testing of food...

Nondestructive Testingof Food Quality

EDITORS

Joseph Irudayaraj �Christoph Reh

The IFT Press series reflects the mission of the Institute of Food Technologists – advancingthe science and technology of food through the exchange of knowledge. Developed inpartnership with Wiley-Blackwell, IFT Press books serve as leading edge handbooks forindustrial application and reference and as essential texts for academic programs. Craftedthrough rigorous peer review and meticulous research, IFT Press publications representthe latest, most significant resources available to food scientists and related agricultureprofessionals worldwide.

IFT Book Communications Committee

Dennis R. HeldmanJoseph H. HotchkissRuth M. PatrickTerri D. BoylstonMarianne H. GilletteWilliam C. HainesMark BarrettJasmine KuanKaren Nachay

IFT Press Editorial Advisory Board

Malcolm C. BourneFergus M. ClydesdaleDietrich KnorrTheodore P. LabuzaThomas J. MontvilleS. Suzanne NielsenMartin R. OkosMichael W. ParizaBarbara J. PetersenDavid S. ReidSam SaguyHerbert StoneKenneth R. Swartzel


EDITORS

Joseph Irudayaraj �Christoph Reh

Joseph Irudayaraj, PhD, is an associate professor of Agricultural and Biological Engineering atPurdue University, West Lafayette, IN. With over 15 years of research and teaching experience inbiological and food engineering, Dr. Irudayaraj has been a faculty member at the University ofSaskatchewan, Utah State University, and Penn State. His current role at Purdue is to develop microand nanosensors for food, health, and environmental applications.

Christoph Reh, PhD, is a research scientist at Nestle Research Center, Lausanne, Switzerlandworking on scientific projects for innovative beverage concepts. Prior to his appointment he wasinvolved for more than 10 years in process analytics including non-destructive testing for factoryapplication and physico-chemical characterization of foods.

C© 2008 Blackwell Publishing and the Institute of Food TechnologistsAll rights reservedChapter 7 copyright is held by Malvern Instruments, Ltd.

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First edition, 2008

Library of Congress Cataloging-in-Publication Data

Nondestructive testing of food quality / edited by Joseph Irudayaraj and Christoph Reh. – 1st ed.p. cm. – (IFT Press series)

Includes bibliographical references.ISBN-13: 978-0-8138-2885-5 (alk. paper)ISBN-10: 0-8138-2885-6 (alk. paper)1. Food–Quality. 2. Food industry and trade–Quality control. 3. Food adulteration and inspection.

I. Irudayaraj, Joseph, 1961– II. Reh, Christoph. III. Series.

TP372.5.N66 2008664′.117–dc22

2007023792

The last digit is the print number: 9 8 7 6 5 4 3 2 1

Titles in the IFT Press series

� Accelerating New Food Product Design and Development (Jacqueline H.P. Beckley,Elizabeth J. Topp, M. Michele Foley, J.C. Huang and Witoon Prinyawiwatkul)

� Biofilms in the Food Environment (Hans P. Blaschek, Hua Wang, and Meredith E.Agle)

� Calorimetry and Food Process Design (Gonul Kaletunc)� Food Ingredients for the Global Market (Yao-Wen Huang and Claire L. Kruger)� Food Irradiation Research and Technology (Christopher H. Sommers and Xuetong

Fan)� Food Risk and Crisis Communication (Anthony O. Flood and Christine M. Bruhn)� Foodborne Pathogens in the Food Processing Environment: Sources, Detection and

Control (Sadhana Ravishankar and Vijay K. Juneja)� High Pressure Processing of Foods (Christopher J. Doona, C. Patrick Dunne, and

Florence E. Feeherry)� Hydrocolloids in Food Processing (Thomas R. Laaman)� Microbiology and Technology of Fermented Foods (Robert W. Hutkins)� Multivariate and Probabilistic Analyses of Sensory Science Problems (Jean-Francois

Meullenet, Rui Xiong, and Chris Findlay� Nonthermal Processing Technologies for Food (Howard Q. Zhang, Gustavo V.

Barbosa-Canovas, V.M. Balasubramaniam, Editors; C. Patrick Dunne, Daniel F.Farkas, James T.C. Yuan, Associate Editors)

� Nutraceuticals, Glycemic Health and Diabetes (Vijai K. Pasupuleti and James W.Anderson)

� Packaging for Nonthermal Processing of Food (J. H. Han)� Preharvest and Postharvest Food Safety: Contemporary Issues and Future Directions

(Ross C. Beier, Suresh D. Pillai, and Timothy D. Phillips, Editors; Richard L. Ziprin,Associate Editor)

� Processing and Nutrition of Fats and Oils (Ernesto M. Hernandez, Monjur Hossen,and Afaf Kamal-Eldin)

� Regulation of Functional Foods and Nutraceuticals: A Global Perspective (Clare M.Hasler)

� Sensory and Consumer Research in Food Product Design and Development (HowardR. Moskowitz, Jacqueline H. Beckley, and Anna V.A. Resurreccion)

� Thermal Processing of Foods: Control and Automation (K.P. Sandeep)� Water Activity in Foods: Fundamentals and Applications (Gustavo V. Barbosa-

Canovas, Anthony J. Fontana Jr., Shelly J. Schmidt, and Theodore P. Labuza)� Whey Processing, Functionality and Health Benefits (Charles I. Onwulata and Peter

J. Huth)

Contents

Contributors ixPreface xiii

Chapter 1. An Overview of Nondestructive Sensor Technologyin Practice: The User’s View 1Christoph Reh

Chapter 2. The Influence of Reference Methods on theCalibration of Indirect Methods 33Heinz-Dieter Isengard

Chapter 3. Ultrasound: New Tools for Product Improvement 45Ibrahim Gulseren and John N. Coupland

Chapter 4. Use of Near Infrared Spectroscopy in the FoodIndustry 67Andreas Niemoller and Dagmar Behmer

Chapter 5. Application of Mid-infrared Spectroscopy to FoodProcessing Systems 119Colette C. Fagan and Colm P. O’Donnell

Chapter 6. Applications of Raman Spectroscopy forFood Quality Measurement 143Ramazan Kizil and Joseph Irudayaraj

Chapter 7. Particle Sizing in the Food and Beverage Industry 165Darrell Bancarz, Deborah Huck, Michael Kaszuba,David Pugh, and Stephen Ward-Smith

vii

viii Contents

Chapter 8. Online Image Analysis of Particulate Materials 197Peter Schirg

Chapter 9. Recent Advances in Nondestructive Testing withNuclear Magnetic Resonance 211Michael J. McCarthy and Young Jin Choi

Chapter 10. Electronic Nose Applications in the Food Industry 237Parameswarakumar Mallikarjunan

Chapter 11. Biosensors: A Theoretical Approach toUnderstanding Practical Systems 283Yegermal Atalay, Pieter Verboven,Steven Vermeir, and Jeroen Lammertyn

Chapter 12. Techniques Based on the Measurement ofElectrical Permittivity 321Malcolm Byars

Index 339

Contributors

Yegermal Atalay (11)Division Mechatronics, Biostatistics and Sensors, Department ofBiosystems, Katholieke Universiteit Leuven, Willem de Croylaan 42,B-3001 Leuven, Belgium

Darrell Bancarz (7)Malvern Instruments Ltd., Grovewood Road, Enigma Business Park,Malvern, Worcestershire, WR14 1XZ, United Kingdom

Dagmar Behmer (4)Bruker Optik GmbH, Rudolf-Plank-Str. 27, 76275 Ettlingen, Germany

Malcolm Byars (12)Process Tomography Ltd., 86, Water Lane, Wilmslow, Cheshire, SK95BB, United Kingdom

Young Jin Choi (9)Department of Food Science and Biotechnology, San 56-1, Sillim-dong,Gwanak-gu, Seoul 151-742, Republic of Korea

John Coupland (3)Department of Food Science, 103 Borland Lab, The Pennsylvania StateUniversity, University Park, PA 16802, USA

Colette Fagan (5)Biosystems Engineering, UCD School of Agriculture, Food Scienceand Veterinary Medicine, Earlsfort Terrace, Dublin 2, Ireland

ix

x Contributors

Ibrahim Gulseren (3)Department of Food Science, 103 Borland Lab, The Pennsylvania StateUniversity, University Park, PA 16802, USA

Deborah Huck (7)Malvern Instruments Ltd., Grovewood Road, Enigma Business Park,Malvern, Worcestershire, WR14 1XZ, United Kingdom

Joseph Irudayaraj (6)225 S. University Street, Purdue University, West Lafayette, IN 47907,USA

Heinz–Dieter Isengard (2)University of Hohenheim, Institute of Food Science and Biotechnology,Garbenstr. 25, D-Stuttgart, Germany

Michael Kaszuba (7)Malvern Instruments Ltd., Grovewood Road, Enigma Business Park,Malvern, Worcestershire, WR14 1XZ, United Kingdom

Ramazan Kizil (6)Istanbul Technical University, Chemical Engineering Department,Maslak, 34469 Istanbul, Turkey

Jeroen Lammertyn (11)Division Mechatronics, Biostatistics and Sensors, Department ofBiosystems, Katholieke Universiteit Leuven, Willem de Croylaan 42,B-3001 Leuven, Belgium

Parameswarakumar Mallikarjunan (10)312 Seitz Hall, Virginia Tech, Blacksburg, VA 24061, USA

Michael J. McCarthy (9)Department of Food Science and Technology, University of California–Davis, Davis, CA 95616-8598, USA

Andreas Niemoeller (4)Bruker Optik GmbH, Rudolf-Plank-Str. 27, 76275 Ettlingen, Germany

Contributors xi

Colm O’Donnel (5)Biosystems Engineering, UCD School of Agriculture, Food Scienceand Veterinary Medicine, Earlsfort Terrace, Dublin 2, Ireland

David Pugh (7)Malvern Instruments Ltd., Grovewood Road, Enigma Business Park,Malvern, Worcestershire, WR14 1XZ, United Kingdom

Christoph Reh (1)Nestle research Center, Vers-Chez-les-Blanc, CH-1000 Lausanne,Switzerland

Peter Schirg (8)PS Prozesstechnik GmbH, Novartis Areal, K-970.1, CH-4002 Basel,Switzerland

Pieter Verboven (11)Division Mechatronics, Biostatistics and Sensors, Department ofBiosystems, Katholieke Universiteit Leuven, Willem de Croylaan 42,B-3001 Leuven, Belgium

Steven Vermeir (11)Division Mechatronics, Biostatistics and Sensors, Department ofBiosystems, Katholieke Universiteit Leuven, Willem de Croylaan 42,B-3001 Leuven, Belgium

Stephen Ward-Smith (7)Malvern Instruments Ltd., Grovewood Road, Enigma Business Park,Malvern, Worcestershire, WR14 1XZ, United Kingdom

Preface

During the last few years, nondestructive testing of food quality hasdrawn increasing attention by the food industry and research institutions.Based on the overwhelming need and the motivation provided by thesuccess of the past Institute of Food Technologists (IFT) symposia onfood quality testing and measurements, we brought together scientistsand engineers from academia and industry to provide their perspectiveson nondestructive testing methods.

When preparing the book we realized the opportunity that nonde-structive testing has provided to food science and food technology. Onone hand, the food industry is now able to automate a large number ofproduction control analyses, allowing the reduction of analytical costs,improving processes, and increasing product quality to meet the qual-ity standards and regulations as well as customer satisfaction. Becauseof nondestructive testing methods, it is now possible to follow foodproducts during processing without disturbing the product as a resultof sampling requirements. The improvements were made possible bydevelopments in related technology areas such as computing, opticaldevices, and miniaturization. The rapid development of CCD opticalchips combined with a huge drop in price is a simple example that willattest to this fact.

We hope that this book will help people become aware of the dif-ferent technologies available and increase the impact of nondestructivetesting of food in production and research. We leave the readers withthe advice that a holistic approach considering process, product, peo-ple, and method will always give the best application for nondestructivetesting.

We are very thankful to all of our authors from academia and industryfor giving us their precious time and providing us several interestingperspectives and valuable insights.

xiii

Chapter 1

An Overview of Nondestructive Sensor

Technology in Practice: The User’s View

Christoph Reh

Introduction

This introductory chapter describes the area where nondestructive foodtesting is relevant and why it is considered to be an area of increasedinterest. This chapter should give an idea of the main drivers of this areaof analytics and illustrate the limitations users will face when they willdevelop new applications. The requirements of a factory applicationare different from those of the use of nondestructive instrumentationin the field, on the farm, in a warehouse, in the supermarket, in centrallaboratories, or even for specific research purposes. The underlyingargument of this chapter is that the understanding of the operation ofthe applied sensor is important to validate the application. Often thesimple use of nondestructive instruments lets the user believe that theanalysis performed is relevant and valid. However, in reality, it mightnot be so.

Why Do We Need Nondestructive Testing to IncreaseFood Quality?

The success of nondestructive instrumentation in the food industry isdriven by several considerations. Despite the often significant invest-ment, more and more installations are beneficial to the operator becauseof their good implementation. This can only be achieved when the target

1

2 Nondestructive Testing of Food Quality

environment is well analyzed to fit the desired equipment in the opti-mum manner into plant operations. The planning phase is probably mostimportant since the implications of people, instrumentation, methodol-ogy, required material, environment, and management are identified andtranslated into specifications. Success can be planned, and many diffi-culties can be avoided if the final installation is well understood fromthe start.

The underlying drivers for using nondestructive instruments areeither cost reduction or improved operations. During the evaluationphase, often only direct cost reductions and investments are consid-ered. Because investments are often significant, the benefits are notalways completely seen at the start of the project. The principal advan-tages of online applications are reduction of the analysis time, reduc-tion of the cost of analysis, shortening of the release time, and, as aconsequence, lowering of production costs. Additionally, operators canimprove their process understanding, control of the process, and, asa consequence, the first time quality as a result of improved productconsistency.

Nondestructive testing equipment can be widely used throughout thefood industry. The following areas are the most relevant:

1. Raw material control in the field or at the factory reception2. Process control either online or off-line after sampling3. Rapid analysis of intermediate or final products in the laboratory4. Product development and storage testing5. Research

Raw Material

Raw material is of great importance for the food industry. To keep thestock in the warehouse, ingredients are often delivered just-in-time.This requires very rapid release procedures forcing companies to applyrapid nondestructive testing widely. Other drivers of this trend are theincreased consumer demand for fresh products. This results in much ofthe industry shortening the chain between the farm and the consumer.Wherever time can be cut out of the supply chain, the consumer willbenefit. Another aspect is the relatively narrow specifications of rawmaterials required for more and more products. An integral part of non-destructive testing at raw material reception often ensures compliance

An Overview of Nondestructive Sensor Technology in Practice 3

Figure 1.1. Online near infrared analyzer Corona to perform compositional analysisin food production (Carl Zeiss GmbH, Jena).

with specifications set. The procedure leads in consequence to reducedproduct losses that are a result of more narrowly controlled specifica-tions. In the longer term, an improvement of the consumer-perceivedproduct quality is observed. Raw material control is therefore evenextended into agricultural production. Ingredients can be oriented fortheir optimum use based on their on-site quality assessment.

Process Control

Process control can be done either online or off-line. Under online anal-ysis, we normally understand that no human sampling is involved inthe measurement process. We further differentiate direct and bypasssolutions. In a direct measurement, the instrument does not affect theprocess, and the product is directly placed in the process line, a stor-age tank, or a mixing operation. Figure 1.1 is a typical installationof an online analyzer in direct measurement showing a diode-arraynear infrared spectrometer type Corona from Carl Zeiss GmbH (Jena,Germany). A bypass instrument is placed in a bypass loop to which theproduct is diverted in order to perform the measurement. The prod-uct is then returned to the line after measurement. This is applied


when the measurement instrument requires much defined measurementconditions, which cannot be achieved directly in the process. Exam-ples are requirements for a specific distance between a transmitter andreceiver, the collection of sufficient product, or the compaction of theproduct. In some cases, the product is discarded, which is uncharacteris-tic of nondestructive testing. Nevertheless, these applications might stillbe very beneficial because they have significant advantages in terms ofreduction of the use of chemicals, reduction of the influence of humans,and very short measurement times. The reduction or elimination of theuse of chemicals is a strong driver for using indirect nondestructive tech-niques. To avoid any risk, chemicals are often banned in areas wherethey come into contact with the food.

The alternative to online analysis is the measurement either off-line,at-line, or near-line. In all of these applications, a sampling procedurefrom the process line toward the instrument is required. The instru-ment can be either located next to the line, in a production labora-tory, or in a central laboratory. The sampling procedure is in all casesa risk for the quality of the analytical result. Operator influence isconsidered to be a major source of error. Another influence can bethe physical modifications a product undergoes before it is measured.On the other hand, it is often easier to install an off-line nondestruc-tive installation because normally a standard instrument setup can beused.

Final Products

The rapid analysis of intermediate or final products in the laboratory isfrom a measurement point of view very similar to off-line analysis. Themotivation for this type of application is to increase the efficiency ofthe analysis required for the release of these products. This is especiallyadvantageous if a large number of samples need to be screened. Typicaldrivers are also cost reductions because of reduced cost of analysis andthe reduction of chemicals used in the laboratory.

Product Development

For product development and storage testing, nondestructive testing canbe an advantage because of the ability to follow the properties of onesingle product over time. The majority of traditional analyses in the food


industry are based on destructive procedures, and it is not always certainthat all products are exactly the same. By following a single product,the evolution can often be established more precisely.

Research

The interest of research groups to apply nondestructive analysis is simi-lar to the one mentioned for product development. The ability to followone single product during a process or during its shelf life gives a hugeadvantage compared to traditional testing procedures. Even more, itgives the ability to follow changes, which could not be detected usingtraditional approaches. The development of the area of nondestructiveanalysis for food research is principally driven by the improved resolu-tion of sensors and the mathematical capabilities of today’s computers.In the case of food, this allows researchers to follow processes such asdrying, cooking, baking, crystallization, homogenization, gellification,or agglomeration.

Changes in the Food Industry and Consequencesfor the Use of Sensors

The food industry is undergoing a significant process of consolidation.This typically results in an increase in the size of the production facilityallowing the operator better use of the installation. It is obvious thatreal-time online analysis or rapid near-line analysis based on nonde-structive techniques leads to clear benefits for the operator. One of theobserved trends is the increased automation of production. This allowsan increased use of online instrumentation and especially of nondestruc-tive instruments.

The following list gives some of the advantages:

� Improved product quality� Less downtime between production cycles� Reduction of waste� Increase of capacity� Improved operational security� Better use of energy and resources� Shorter holding time of raw materials and finished products


A large number of production facilities are still labor intensive witha low level of automation. There is a strong tendency to reduce thehuman influence on the product by having more continuous or automatedbatch processes. This is only possible if the lot sizes are sufficiently bigto generate an economical advantage. Another driver is the increaseddemand for traceability of the production. With an automated processand integrated sensors for measuring key attributes, the product qualityat any point in time can be mapped. More and more, products receive atime coding, which often can be traced back to the data collected duringproduction.

On the other hand, not all product parameters can be measured auto-matically. Whereas the principal chemical composition and some phys-ical product aspects can be measured by nondestructive instruments,the sensory characterization of the product still requires human test-ing. Despite massive efforts to develope electronic noses or electronictongues, only very few applications are used industrially for productrelease. It is more common to use the available measurement capa-bilities to optimize the process and to keep the process conditions inan operating range where the required sensory parameters are deliv-ered. The products are controlled for their key sensory aspects by apanel of experienced people for release purposes. This procedure isunlikely to be changed in the coming years because minor compo-nents or modifications can lead to significant changes in the product.It should be pointed out that contrary to the chemical and pharma-ceutical industries, food products are generally less defined regardingtheir chemical composition. The majority of the raw agricultural prod-ucts have quite a wide specification. Additionally, not all processesin the food industry are understood in detail. This is especially truefor all aspects related to aroma and taste of food because of the verycomplex chemistry occurring during processing. Additionally, if theproduct at the time of production is not yet in physical and chemi-cal equilibrium, it does not provide the characteristics the consumerperceives.

What Are the Central Elements of Successful Use?

The successful use of nondestructive instrumentation relies on a com-plete understanding of the environment. The nondestructive technology


and its technical capabilities are only one piece. The following elementsare of central importance:

1. Staff2. Instrumentation3. Method4. Consumables5. Place of installation6. Management

Involving the Right Staff

Staff with adequate training is often key to installing a nondestructivetesting instrumentation. This is normally not an issue for an academicapplication where the instrument is often a central part of the research.When used in an industrial environment, this issue becomes more criti-cal. Often management considers nondestructive testing equipment eas-ier to use and, therefore, assumes that normal factory staff should beeasily able to install and operate the application. This assumption isespecially incorrect for the period between the selection of the equip-ment and its installation. It might be true for the operational phaseas long as the staff is well trained to perform the maintenance of theinstrument.

To develop correct specifications, to define adequate methods, and tofind the correct location, a global understanding of the task is required.The most difficult applications are normally online applications becausethe process defines quite a number of parameters affecting the measure-ment. Often it is best to bring together a team covering production,engineering, quality assurance, and product development to correctlyplan and install the equipment. After training of the operational staff,outside help will be required on an occasional basis.

Specifying the Instrumentation

The specification process is crucial for the success of any large invest-ment in analytical equipment, and this is especially true for non-destructive testing installations. As already mentioned, it would be


preferable to run this process with a team of people with differentexpertise.

The specification process is very well described by Bedson (1996).This paper gives guidance on how to perform equipment validation forany analytical instrument. In practice, it is very difficult to give generaladvice for the installation process covering a large number of differenttechnologies because the critical points can vary from one technologyto another. It is therefore extremely useful to consider the introductionof a nondestructive application as a process with a generic structure.Bedson (1996) developed guidance for the equipment qualification pro-cess, including the following four stages:

1. Design qualification2. Installation qualification3. Operational qualification4. Performance qualification

Design Qualification

Design qualification covers all tasks related to planning and selectingthe application, including development of the specifications leading toselection of the supplier. The choice to develop an application shouldstart from a clearly defined need for a certain measurement. The designqualification should lead to the development of instrument specifica-tions, which will be the basis of the relationship with the instrumentsupplier. These specifications strongly depend on where the instrumentwill be deployed. For process control, an optimum performance withina relatively small range of variation of the targeted parameter might betargeted. For a research application, one will choose an instrument withhigh flexibility regarding its range of application. Apart from purelyinstrument-related specifications, one should also define the require-ments related to staff, methods, installation, and consumables.

Installation Qualification

The next step of the process is installation qualification covering all ofthe procedures related to installation of the equipment in its place of use.One of the most time-consuming exercises can be calibration, especiallywhen process parameters are measured indirectly with techniques such


as near infrared spectroscopy, refractometry, microwave absorption, orsimilar techniques. To calibrate correctly the choice of a well-adaptedreference method is often critical. Other issues in this context are refer-ence laboratory performance, sampling procedures, and generation ofa sample set covering the calibration range required. In a productionenvironment, the variation in concentration of one naturally occurringingredient can be quite small. Sometimes the range needs to be extendedto develop a stable calibration. In other cases, physicochemical changesoriginating from the production process can affect either the referenceanalysis or the nondestructive technique. These are some of the prob-lems which should be explored by the team during either installation oroperational qualification.

Operational Qualification

Operational qualification is required for the instrument to operate underdefined conditions. This step is usually less critical when the two earliersteps have been performed well. It is obvious that a better specificationof an application will lead to fewer surprises at this stage. It is importantto accurately document all actions that have been performed. The betterthe documentation, the easier required actions can be identified.

Performance Qualification

The final step of the described process is performance qualificationwhere one has to demonstrate that the installation performs accordingto the specifications set at the beginning of the process. For processequipment, the focus of this validation process is assessment of theprecision, accuracy, and robustness of the instrumental setup.

It should be pointed out that the qualification process does not stopafter the four qualification steps have been completed. Instruments willhave to undergo requalification after any significant change such as:

� Change of place of installation� Modification of the instrument or the operating software� Replacement of parts� Maintenance� Modification of product or process


The degree of this requalification is strongly dependent on the type ofequipment and the gravity of the change. Based on experience, duringthe qualification process, a protocol should be established for the mostcommon changes. Changes related to the equipment often can be esti-mated based on validation studies. This can be best illustrated for theplace of installation. Presentation of the food product to the equipmentis often the most critical parameter for the overall performance of theequipment. During installation and calibration, aspects such as the dis-tance of the sensor to the product, aperture of a measurement window,or angle of measurement are often assessed and documented. Thesedata are very helpful to define the critical parameters for requalifica-tion. In the case of maintenance, repair, or upgrade, requalification ismainly targeted toward assessing the equal functioning of the new com-ponent. For most of these changes, the equipment supplier normally pro-vides a testing procedure. It is important to ensure the presence of thesetests during design qualification because it limits the time required forrequalification.

Because measurement equipment is normally maintained by the qual-ity assurance department, changes in the product or process are oftenoverlooked or their influence on the measurement is underestimated.Compositional changes due to recipe adaptations or even natural varia-tions of raw materials can cause differences in the results. Other sourcesof difference can be changing operating conditions of ovens, mixers,homogenizers, and other processing devices. The effect of homoge-nization of milk on the measurement of fat and solid-non-fat (SNF) bymid-infrared spectroscopy is widely known and studied. This examplewill be discussed in more detail later in this chapter. For the reliable com-position analysis of powders by near infrared spectroscopy, particle sizeis a critical parameter. Particle size distributions of powders often varyas a result of the operating conditions of mills, spray dryers, or agglom-erators. This influence can be limited either by including the variationof the particle size in the calibration model or by better controlling theoperating conditions of the process unit. In reality, an approach takingboth factors into account will probably be chosen. This illustrates thatdue to the introduction of nondestructive measurement, variation of theprocess and, as a consequence, of the product, can be detected and fixed.This leads then to an improved definition of the product and productionwith higher consistency.


Defining the Method

Definition of the method is complementary to instrument specificationand focuses more on the operational aspects of the application. Thiswork should be done just after a first decision has been determined onwhat technology will be applied for the testing procedure. It might bethat the required method procedures are part of the final decision ofwhat technology will be applied.

Defining the method is the outcome of the equipment qualificationprocess mentioned under instrument specification. It is very importantto translate all of the knowledge collected into an actionable method.The individual steps need to be well defined and documented to ensurelong-term application by the operator. Operator training must includegenerating alertness to the critical points of any nondestructive testingapplication.

Ensuring the Supply of Consumables

The permanent availability of consumables is probably the easiest pointto achieve. The importance of this point is the operational availability ofnondestructive testing instrumentation. Especially in the case of onlineapplications, an outage can lead to significant losses in production. Thispoint is especially relevant in countries or regions where after-salessupport from the supplier is limited or slow. Apart from a service guar-antee from the equipment supplier, it is often advantageous to performsome of the maintenance in-house with your own staff. In this context,the availability of all consumables required for the normal operation ofthe application should be kept in stock. This could even include equip-ment parts in order to be able to perform any repairs that have a higherrisk of happening. Training of the operator for these tasks needs to beadditionally considered.

Identifying the Place of Installation

The place of installation refers to technical and operational parame-ters. The technical parameters are driven by the technology used for the


nondestructive testing procedure. Almost all technologies have techni-cal limitations in order to achieve an optimal result. These limitationswill be covered in more detail in the chapters on major technologies usedin the food industry. At this point it should be mentioned that in the caseof nondestructive testing, normally the measurement setup should beadapted to the product and, in the case of production control, to theprocess line. Therefore, nondestructive instruments are often used aftersample preparation. Sample preparation is applied when the outcomeof the testing procedure can be improved by optimizing sample presen-tation to the equipment. It might be, therefore, important to decide ifsample preparation might lead to a better result.

To clarify the technical impact of the place of installation on thequality of the measurement, thorough knowledge of both aspects isrequired. Sample presentation of the measurement technology needs tobe adapted to produce reliable and actionable results. The instrumentsetup needs to base its result on a representative sample. Parameterssuch as sample volume or measurement time are very important in thiscontext.

The operational aspects are most often more important than the tech-nical aspects because the economical advantage is principally drivenby optimization of the operation. It is of key importance to measure orcontrol in order to be able to correct. But it is of limited use to measurea parameter that can no longer be changed when the result of the testingprocedure comes available. There might be an advantage to automatinga testing procedure used for product release. Nevertheless the gain indetermining a process parameter, which can be used for process control,will lead to important savings for the operator.

Getting Management Support

Management support is the ultimate requirement for successful instal-lation of nondestructive instruments. Automated analysis of productquality control often requires a change in mind-set. It goes along withsignificant changes on the production floor and in the factory labo-ratory. This affects the day-to-day work of the staff involved in thespecific area and can completely change the way product quality isapproached. As a consequence of improved product quality monitoring,more proactive intervention in the production process will be required,

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