ABSTRACT
Further Reading .................................................................................................... 157 3.2 Monitoring and Mapping of Fresh Fruit and Vegetable
Using VIS Spectroscopy............................................................................ 157 3.2.1 Product Pigment Contents, Spectral Signature,
and Spectral Indices ........................................................................ 157 3.2.2 Spectroscopy in the VIS Wavelength Range.................................. 160 3.2.3 Mapping Technique, GPS Technique, and Data Management ...... 170
3.2.3.1 Design of the Portable Spectrophotometer Equipment ...... 170 3.2.3.2 Fruit Analyses Using the Portable Spectrophotometer
Equipment with Probe for Light Interaction ..................... 174 3.2.3.3 GPS Technique .................................................................. 175 3.2.3.4 Data Management.............................................................. 175
3.2.4 Application Examples ..................................................................... 175 3.2.4.1 Apple Fruit......................................................................... 175 3.2.4.2 Sweet Cherry ..................................................................... 181 3.2.4.3 Carrot Root ........................................................................ 181 3.2.4.4 Potato Tuber ...................................................................... 184
3.2.5 Mapping of Spectral Indices of Apple Fruit Development in Orchard ................................................................. 185 3.2.5.1 Fruit Maturity in Dependence on Geographical Site ........ 185 3.2.5.2 Effect of Fruit Yield per Tree on Maturity Progress......... 186 3.2.5.3 Effect of Climatic Condition on Maturity Progress .......... 186 3.2.5.4 Mapping............................................................................. 187
3.2.6 Conclusions ..................................................................................... 189 References ............................................................................................................. 191 3.3 Near-Infrared Spectroscopy ....................................................................... 192
3.3.1 Introduction ..................................................................................... 192 3.3.1.1 Setting the Task ................................................................. 192 3.3.1.2 Going Further .................................................................... 194
3.3.2 Factors for Success.......................................................................... 195 3.3.2.1 Attribute ............................................................................. 195 3.3.2.2 Sample ............................................................................... 196 3.3.2.3 Instrument .......................................................................... 198
3.3.3 Spectroscopy and Chemometrics Theory ....................................... 207 3.3.3.1 Data Preprocessing ............................................................ 207 3.3.3.2 Spectroscopy of Water ...................................................... 209 3.3.3.3 Sugar in Water................................................................... 212 3.3.3.4 Calibration Based on Multivariate Regression.................. 214 3.3.3.5 Chemometric Terms .......................................................... 215 3.3.3.6 Chemometrics: Calibration Techniques............................. 217 3.3.3.7 Chemometrics: PLSR Wavelength Selection .................... 219
3.3.4 Application in Food ........................................................................ 222 3.3.4.1 Fresh Fruit ......................................................................... 222 3.3.4.2 Grains and Grain Products ................................................ 225
3.3.5 On-Line Quality Monitoring ........................................................... 229 3.3.5.1 Definition ........................................................................... 229 3.3.5.2 Issues ................................................................................. 229 3.3.5.3 Examples............................................................................ 229
Acknowledgment .................................................................................................. 234 References ............................................................................................................. 234 3.4 Network of NIRS Instruments ................................................................... 239
3.4.1 Need for Calibration Transfer ......................................................... 239 3.4.2 Strategies to Remedy the Situation ................................................. 240
3.4.2.1 On the Level of the Predicted Results............................... 241 3.4.2.2 On the Spectral Level ........................................................ 242 3.4.2.3 In the Calibration Model ................................................... 243 3.4.2.4 Advantages and Disadvantages ......................................... 245
3.4.3 Examples ......................................................................................... 246 3.4.3.1 Grain Analysis Based on Filter Instrument ....................... 246 3.4.3.2 FOSS Infratec Grain Network ........................................... 246 3.4.3.3 VDLUFA Forage Maize Network..................................... 247
References ............................................................................................................. 248
3.1.1.1 Basics
Optical radiation is defined as emission in the spectral range from 100 nm up to 1000 mm (Figure 3.1.1). It includes the ultraviolet (UV) radiation from 100 up to 380 nm, the visible (VIS) region from 380 till 780 nm, and the infrared (IR) radiation with longer wavelength than 780 nm. The range from 780 nm up to 2.5 mm is called near-infrared (NIR) region, the region from 2.5 to 25 mm is the mid-infrared (MIR) region, and the range above is the far-infrared (FIR) region.
