The use of advanced instrumentation and sensors in the food industry has led to continuing improvement in food quality control, safety and process optimization. This book provides a very broad and detailed examination of these techniques, with each chapter prepared by a specialist in the technique and applications discussed. With the emphasis on practical applications, this presentation will be useful to food engineers, scientists and technical managers involved in the research, processing, safety and quality control of food products.

Contents

Preface

1. Instrumentation for Food Quality Assurance
   • Introduction: The Role of Quality Assurance in the Food Industry, On-Line, At-Line and Off-Line Instrumentation, Technology Transfer: Opportunities and Pitfalls
   • Challenging Conditions for Sensors: Complex and Variable Samples, Hostile Conditions and Stringent Hygiene Requirements, Non-Contact Techniques and Robotic Sampling and Conditioning
   • Interpreting the Readings: Measured Variables and Target Variables, Relationship between On-Lline and QC-Laboratory Methods, Data Processing Approaches, The Market ApproachNovel Sensors, Instrumentation as an Interdisciplinary Subject
   • Measurement Types: Target Variables, Instrumental Methods, Fringe Benefits
   • Appendix: Measurement Types
   
   
   

   Part I. In-line Measurement for the Control of Food Processing Operations

2. Principles of Colour Measurement for Food
   • Introduction
   • Colour Vision: Trichromatic Detection
   • Influence of Ambient Light and Food Structure: Adaptation, Appearance, Absorption and Scatter
   • Colour Description: The CIE System, Uniform Colour Space, Further Terminology
   • Instrumentation
   • Examples: Fresh Meat, Orange Juice
   
   
   
3. Colour Measurement of Foods by Colour Reflectance Instrumentation
   • Introduction: Food Colour and Quality
   • Color Measurement Principles: Brief Introduction: Tri- stimulus Colorimetry, Colour Scales and Colour Difference Formulae
   • Colour Measurement Methodology: Standardization of the Instrument, Selection, Preparation and Presentation of the Samples, Setting the Instrumental Variables, Determination of Colour Variables
   • Colour Measurement of Typical Food Materials
   • Conclusions
   
   
   
4. Sorting by Colour in the Food Industry
   • Introduction
   • What is a Sorting Machine?
   • Assessment of Food Particles for Colour Sorting: Spectrophotometry, Monochromatic Sorting, Bichromatic Sorting, Dual Monochromatic Sorting, Fluorescence Techniques, Near Infrared Techniques
   • The Optical Inspection Systems: Introduction, Illumination, Background and Aperture, Optical Filters, Detectors
   • Completing the Sorting System: Feed, Separation, Cleaning and Dust Extraction, Electronics Systems
   • Future Trends: Computer Vision Systems
   • Using a Colour Sorter
   
   
   
5. Compositional Analysis Using Near Infrared (NIR) Absorption Spectroscopy
   • Introduction
   • Theory of NIR Absorption Spectroscopy
   • Instrumentation: On-line NIR Instrumentation, Laboratory NIR Instrumentation, NIR Measurement Characteristics, Instrumentation and Installation in the Food Industry: Moisture Measurements in Foodstuffs, Multi-Component Analysis of Food Products, Quality Control for Food Packaging Materials
   • Practical Aspects of the Calibration of On-Line NIR Instruments: Calibration Methods, On-Line Installation and Sampling Procedures for Cross-Checking
   • Conclusion and What the Future Holds
   
   
   
6. Practical Aspects of Infrared Thermometry
   • Introduction
   • Radiation Thermometers: Collection, Detectors, Pro- cessing Electronics, Housing and Configurations, Line Scans and Thermal Imagers
   • Measurement Principles: The Black Body, Non-Black Target, Background Temperature, Emissivity, Examples
   • Miscellaneous Techniques: Enhancing Emissivity, Avoiding the Need to Know Emissivity, Inaccessible Targets
   
   
   
7. Microwave Measurements of Product Variables
   • Introduction
   • Advantages and Disadvantages of Microwave Techniques: Advantages, Disadvantages
   • Dielectric Properties and Their Parameters: Polarization, Dielectric Dispersion, Dielectric Dispersion of Water in Foodstuffs, Temperature Effects, Bulk Density, Conductivity
   • Methods for Measurement of Dielectric Properties: Attenuation Measurements, Resonant Methods, Reflective Measurements
   • Dielectric Properties and Measurements of Bulk Density and Composition: Density Measurement and Compensation in Moisture Measurement, Fat and Water, Sugar Solutions, Other Mixtures of Materials, Salt Concentration
   • Material Structure: Particle Shape and Distribution, Particle Size Apparatus for Microwave Measurement: Attenuation, Phase, Simultaneous Phase and Attenuation, Resonant Systems, Reflectance
   • Sensors: Horn Antennae, Stripline Sensors, Stripline Antennae, Open Ended Transmission Lines
   • Areas for Development
   • Appendix: Some Manufacturers of Microwave Moisture Measurement Instruments, List of Symbols
   
   
   
8. Ultrasound Propagation in Foods and Ambient Gases: Principles and Applications
   • Introduction
   • Overview of Ultrasound Applications: What is Measured?, Communication, Detection and Location, Level and Flow Rate Measurement, Non-Destructive Testing, Concentration Measurement, Passive Ultrasound Equipment: Acoustic Emission Monitoring, High-Power Ultrasound Equipment
   • Speed of Sound: Velocity of Propagation for Bulk Longitudinal Waves, Other Ultrasound Wave Types, Speed of Sound in Liquids, Speed of Sound in Solids
   • Acoustic Impedance: Definition, Implications for Velocity Measurement, Measuring Impedance instead of Velocity
   • Attenuation: Sources of Attenuation, Relaxation, Scattering
   • Conclusions
   • Appendix: Ultrasound Measurement Applications in and for the Food Industry, List of Symbols
   
   
   
9. Ultrasound Instrumentation in the Food Industry
   • Introduction
   • Low Frequency Techniques: Level Measurement by Echo Ranging, Beam-Break Detectors as Counters, Future Developments in Low-Frequency Instrumentation
   • High-Frequency Techniques: Flow Measurement Systems, Liquid Level Switches, Liquid Level Measurement Systems, Suspended Solids and Interface Detection Systems, Concentration Measurement Systems, Future Developments in High-Frequency Instrumentation
   • Contacts for Further Informtion
   
   
   

   Part II. Instrumental Techniques in the Quality Control Laboratory

10. Rheological Measurements
    • Introduction
    • Relevance of Rheological Properties of Foods: The Consumers Perception, The Requirements of the Processor
    • Basic Rheology
    • Measurement Systems: Capillary Viscometers, Rotary Viscometers
    • Rotary Viscometers: Concentric Cylinder Viscometers, Cone and Plate Viscometers, Other Rotary Viscometers
    • On-Line Measurement Systems
    • Instrument Selections
    • Appendix: List of Symbols
    
    
    
11. Modern Methods of Texture Measurement
    • Introduction
    • Current Methods of Texture Measurement: Sensory Texture Assessment, Instrumental Texture Measurement
    • Physiological Aspects of Chewing: Monitoring Human Subjects
    • Texture Measurement by Electromyography: Instrumentation and Measurement Procedure, Reproducibility, Data Interpretation
    • Future Developments in Texture Measurement
    • Conclusions
    
    
    
12. Water Activity and Its Measurement in Food
    • Definition
    • Significance of Water Activity: Effect on Food Quality, Effect on Food Stability, Legal Requirements
    • Water Activity Levels in Food and Their Control: Food of Animal Origin, Food of Vegetable Origin, Control of Water Activity Level, Example
    • Measuring the Water Activity Level: Background, Water Activity Level as a Function of Temperature, Influence of Equilibrium Periods and Sample Properties, Instrument Calibration
    • Measurement Technique: Manometric Method, Gravimetric Method, Psychrometric Method, Hygrometric Methods, Thermometric Technique
    • Conclusions
    
    
    
13. Instrumental Methods in the Chemical Quality Control Laboratory
    • Introduction
    • Versatile Instruments: Gas and Liquid Chromatography, Limitations of Gas and Liquid Chromatography, Supercritical Fluid Chromatography, Capillary Electrophoresis
    • The Trend towards Dedication: GLC System for the Analysis of Pesticides, HPLC System for the Assay of Ions and Sugars, Ion Chromatograph for Sulphite, Enzyme Electrode Analysers for Sugars and Alcohols
    • Dedicated Instruments
    • Dedicated Instruments for the Determination of Moisture, Ash and Fat: Moisture by Drying Methods, Moisture by Karl Fischer Titration, Ash by Combustion Methods, Fat by Solvent Extraction, System Based on the Karl Fischer Procedure, System Based on Oven Drying, Moisture Determination by Oven Drying and Ash by Combustion, Moisture by Microwave Drying and Fat by Solvent Extraction, Fat Determination by Solvent Extraction
    • Dedicated Instruments for Nitrogen Determination: For the Calculation of Protein and Meat Content: Nitrogen Determination by Acid Digestion, Nitrogen Determination by Combustion
    • Further Development of Instrumentation for Food Analytical Laboratories
    
    
    
14. Impedance Techniques for Microbial Assay
    • Nomenclature
    • Introduction
    • Rapid Microbial Methods: An Overview: Impedance as an Indicator of Microbial Load
    • Principles of Electrical Conductance Methods: Impedance and Its Component Variables, Cell Design and Geometry and Composition of Electrodes, Relationship between Test Cell Conductance and Bacterial Growth, Bacterial Number Resolution of Analysers, Temperature Control
    • Capacitance versus Conductance Measurement: Selection of Display Variable Early in the Growth Cycle, Mechanisms of Changes Observed Later in the Growth Cycle
    • Instrument Design: Method of Measurement, Multiplexed Cell Switching, Commercial Instrumentation
    • The Evaluation of Conductance Data: Bacterial Growth in Batch Culture, Determination of Inocula, Choice of Growth Media, Correlation with Conventional Microbiological Data
    • Future Possibilities
    
    
    
15. Impedance Microbiology in Food Quality Control
    • Introduction
    • Development of Protocols
    • Applications to the Detection of Micro-Organisms in Foods: Correlation Procedures, Total Counts, Selective Procedures, Shelf Life Prediction
    • Choice of Instrumentation
    • Future Developments
    
    
    

    Part III.New Sensors for Applications in the Food Industry

16. The Marker Concept: Frying Oil Monitor and Meat Freshness Sensor
    • Introduction to the Concept and Overview on Applications
    • A Novel in situ Monitor for Frying Oil: The Need for a New Probe, Development of the Probe Concept, Study to Assess Feasibility and Define Specifications, Characteristics of the New Probe, Protocol of the Trial with Prototype 1, Results of the Trial with the New Probe, Conclusions and Outlook
    • A Novel Knife-Type Probe for Meat Freshness: Development of the Probe Concept, Study to Assess Feasibility and Define Specifications, Characteristics of the New Probe, Trials with the New Probe, Conclusions and Outlook
    
    
    
17. Chemosensors, Biosensors and Immunosensors
    • Introduction: Chemical Sensor Types and Their Building Blocks, Recent Developments, Sensor Specifications for Food Applications
    • Chemically Sensitive Semiconductor Devices: Solid-State Sensors for pH, Acidity, Ions, Gases and Volatiles: Introduction to Novel pH Sensors, Alternative Approaches to pH Measurement, Microelectronic Chemical Sensors Based on the FET: Principles, Characteristics and Applications, Gas Sensing Semiconductor Devices
    • Conclusions
    • Amperometric, Potentiometric and Thermometric Biosensors: Introduction: Biosensor Types, Biosensors Based on Amperometric Indirect Dual-Membrane Enzyme Electrode (AIDMEE), Biosensors Based on the FET: the ENFET, the Enzyme Thermistor and Related Devices (ENTHERM)
    • Chemically Sensitive Optical and Acoustic Devices: Introduction, the Surface Plasmon Resonance (SPR) Device, the Total Internal Reflectance (TIR) Device, Fibre-Optic Probe (FOP) Devices, Piezocrystal Balance Devices, Surface Acoustic Wave (SAW) Devices
    • Applying Sensors: Introduction, Pattern Recognition by Multivariate Analysis or Neural Networks, Robotics and Flow Injection Analysis, Choice of Instrumentation Type

• A. Glossary: Terms in Instrumentation and Sensors Technology
• B: Ancillary Tables