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Spectroscopic Techniques for Food Analysis
ANALYTICA CHIMICA ACTA ELSEVIER
Analytica
Chimica Acta 312 (1995) 351-352
Book Review Reginald H. Wilson (Ed.), Spectroscopic Techniques for Food Analysis, VCH, Weinheim, 1994 (ISBN l-56081-037-8). xv +246 pp. Price DM 165.00/f 66.00.
Spectroscopic techniques have been used for many years in research to quantify and characterise food products and food constituents. Their use has led to a better understanding of the behaviour of a range of molecules within complex, often fragile, systems under non-equilibrium conditions. Some of these techniques are now being used in industry, where they are transforming the very nature of industrial quality control. In recent years, several attempts have been made to produce a synthesis of these techniques either for neophytes or to help people in the field to keep abreast of recent changes. Not many have succeeded - most were either too superficial or too specialised and technical. As well, most of these books, being collections of separate chapters by specialists in each field, tended to lack overall structure and unity. The book edited by R.H. Wilson, however, almost entirely avoids these problems. It presents a clear but thorough overview of both the theoretical and practical aspects of the application of spectroscopic techniques to food analysis. Although the different chapters are written by recognized specialists, the fact that many of them work at the same Food Research Institute has obviously helped the editor to produce a coherent book without those faults commonly found in similar works. Most chapters start with a very general description of the spectroscopic technique and types of analytes and food products to which it can be applied. This is followed by a more detailed presenta0003.2670/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0003-2670(95)00323-l
tion of the theory of spectroscopy. Instrumental aspects are then considered - ranging from the different ways of producing and detecting the signals to problems of sample preparation and sample presentation. Most authors go on to specific applications either with precise details on the experimental procedure used or with reference to the primary article from which the procedure was drawn. The book starts with a short introductory chapter by P.S. Belton in which he classifies the various spectroscopies in terms of the excitation, selection and detection processes. He then outlines their main domains of application. In chapter 2, W.F. McClure demonstrates the interest of near-infrared (NIR) spectroscopy in the agro-food industry and shows the growing importance of signal treatment and chemometrics to extract the desired information from the signal. In chapter 3, R.H. Wilson and B.J. Goodfelllow explain why mid-infrared spectroscopy although it has been used in chemical analysis for a very long time, is only just now starting to encroach on the NIR technique. They discuss problems associated with sample presentation for solids and liquids, and the use of ATR, diffuse reflectance and photoacoustic detection to overcome them. They finish off with suggestions as to the probable directions in which MIR will evolve and recommendations on the criteria to use when choosing an instrument for food analysis. Because of the wide range of conceptually different methods covered by the single term of nuclear magnetic resonance, it is understandable why chapter 4 is the longest in the book. I.J. Colquhoun and B.J. Goodfellow cover all aspects of NMR spectroscopy, time-domain NMR and NMR imaging. The chapter includes more than 200 references.
352
Book Reuiew
The determination of metals in foods is treated by G.J. DeMenna in chapter 5. Atomic absorption and emission, X-ray fluorescence and ICP-mass spectrometry, ion chromatography and neutron activation are presented. Sample preparation, calibration and matrix effects are all discussed. The chapter concludes with detailed examples of metal determinations in a range of foodstuffs. Mass spectrometry is not yet very widely used in the analysis of food products. Until recently it was mainly used for the analysis of flavour volatiles. With the development of new ionisation techniques this situation is changing and MS now finds applications in the analysis of heat labile, non-volatile products. In chapter 6, F.A Mellon introduces both the different types of mass spectrometers and the various ionisation techniques available, including ICP-MS. The advantages of the various hyphenated techniques of sample separation and introduction (GC-MS, LC-MS, SFC-MS and CZE-MS) are also dis-
cussed. Once again the chapter concludes with examples of applications, including pyrolysis MS for the fingerprinting of analytes or food microorganisms. This chapter includes over 200 references. The final chapter, by W.J. Hurst, treats the use of UV-visible methods to determine organic and inorganic substances in food products. Although it is clear from this chapter that the range of applications is very wide, few details or references are given to help the reader. This book should be very useful for both students in food science, wishing to have an understanding of the different spectroscopic methods currently used to analyse foodstuffs, and the confirmed ‘engineer’ or researcher who would like to know which methods are applicable to a particular problem and need to be up to date on the latest developments in the field.
D.N. Rutledge
Analytica
Chimica Acta 312 (1995) 351-352
Book Review Reginald H. Wilson (Ed.), Spectroscopic Techniques for Food Analysis, VCH, Weinheim, 1994 (ISBN l-56081-037-8). xv +246 pp. Price DM 165.00/f 66.00.
Spectroscopic techniques have been used for many years in research to quantify and characterise food products and food constituents. Their use has led to a better understanding of the behaviour of a range of molecules within complex, often fragile, systems under non-equilibrium conditions. Some of these techniques are now being used in industry, where they are transforming the very nature of industrial quality control. In recent years, several attempts have been made to produce a synthesis of these techniques either for neophytes or to help people in the field to keep abreast of recent changes. Not many have succeeded - most were either too superficial or too specialised and technical. As well, most of these books, being collections of separate chapters by specialists in each field, tended to lack overall structure and unity. The book edited by R.H. Wilson, however, almost entirely avoids these problems. It presents a clear but thorough overview of both the theoretical and practical aspects of the application of spectroscopic techniques to food analysis. Although the different chapters are written by recognized specialists, the fact that many of them work at the same Food Research Institute has obviously helped the editor to produce a coherent book without those faults commonly found in similar works. Most chapters start with a very general description of the spectroscopic technique and types of analytes and food products to which it can be applied. This is followed by a more detailed presenta0003.2670/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0003-2670(95)00323-l
tion of the theory of spectroscopy. Instrumental aspects are then considered - ranging from the different ways of producing and detecting the signals to problems of sample preparation and sample presentation. Most authors go on to specific applications either with precise details on the experimental procedure used or with reference to the primary article from which the procedure was drawn. The book starts with a short introductory chapter by P.S. Belton in which he classifies the various spectroscopies in terms of the excitation, selection and detection processes. He then outlines their main domains of application. In chapter 2, W.F. McClure demonstrates the interest of near-infrared (NIR) spectroscopy in the agro-food industry and shows the growing importance of signal treatment and chemometrics to extract the desired information from the signal. In chapter 3, R.H. Wilson and B.J. Goodfelllow explain why mid-infrared spectroscopy although it has been used in chemical analysis for a very long time, is only just now starting to encroach on the NIR technique. They discuss problems associated with sample presentation for solids and liquids, and the use of ATR, diffuse reflectance and photoacoustic detection to overcome them. They finish off with suggestions as to the probable directions in which MIR will evolve and recommendations on the criteria to use when choosing an instrument for food analysis. Because of the wide range of conceptually different methods covered by the single term of nuclear magnetic resonance, it is understandable why chapter 4 is the longest in the book. I.J. Colquhoun and B.J. Goodfellow cover all aspects of NMR spectroscopy, time-domain NMR and NMR imaging. The chapter includes more than 200 references.
352
Book Reuiew
The determination of metals in foods is treated by G.J. DeMenna in chapter 5. Atomic absorption and emission, X-ray fluorescence and ICP-mass spectrometry, ion chromatography and neutron activation are presented. Sample preparation, calibration and matrix effects are all discussed. The chapter concludes with detailed examples of metal determinations in a range of foodstuffs. Mass spectrometry is not yet very widely used in the analysis of food products. Until recently it was mainly used for the analysis of flavour volatiles. With the development of new ionisation techniques this situation is changing and MS now finds applications in the analysis of heat labile, non-volatile products. In chapter 6, F.A Mellon introduces both the different types of mass spectrometers and the various ionisation techniques available, including ICP-MS. The advantages of the various hyphenated techniques of sample separation and introduction (GC-MS, LC-MS, SFC-MS and CZE-MS) are also dis-
cussed. Once again the chapter concludes with examples of applications, including pyrolysis MS for the fingerprinting of analytes or food microorganisms. This chapter includes over 200 references. The final chapter, by W.J. Hurst, treats the use of UV-visible methods to determine organic and inorganic substances in food products. Although it is clear from this chapter that the range of applications is very wide, few details or references are given to help the reader. This book should be very useful for both students in food science, wishing to have an understanding of the different spectroscopic methods currently used to analyse foodstuffs, and the confirmed ‘engineer’ or researcher who would like to know which methods are applicable to a particular problem and need to be up to date on the latest developments in the field.
D.N. Rutledge