Figure 4 : Schematic overview of the different chemometric approaches using VIS-NIR spectra . Courtesy : Cortes et al . ( 2019 )
Regardless of the type of instrument , the system consists of a sample holder , a light source , a detector ( to record the received light intensity ), and a computer ( to register and process the spectral information ). Its potential has been investigated in a wide range of applications . For example , a Vis-NIR spectrometer has been used to predict and detect internal physiological disorders such as jelly seeds and black flesh in mango , to predict defects in mandarin fruit and to predict rind pitting disorder in grapefruit .
Other Technologies
The concept of the e-nose can be used for detecting and identifying complex chemical mixtures that constitute aromas , odours , fragrances , formulations , spills and leaks . The common e-nose consists of an array of gas sensors , an analogue to digital ( A / D ) converter , and a computer that is equipped with a pattern recognition algorithm . While the e-nose mimics human olfaction , an e-tongue mimics the human tongue to detect food spoilage which requires
the specific activity of micro-organisms and enzymes . Like human receptors , the e-tongue system consists of multiple sensors with a different spectrum of reactions from one another . The information given by each sensor is complementary and the combination of all sensor results generates a unique fingerprint .
Acoustic emission ( AE ) is an important attribute of food texture which represents the firmness , crunchiness and crispiness that can be considered as signs of freshness . In the traditional way , the acoustic emissions are measured destructively such as using hand shaking and hitting the surface of the crop or agricultural product . By PA , the AE can be measured using sensors that transform the propagated elastic waves and speed of sound into valuable information . The general instrument set-up consists of a microphone probe , acoustic signal amplifier , an A / D converter , a personal computer , interference software and a few other devices to control the loading process and register the evaluation results .
Dielectric properties are another quality trait in agricultural products . The dielectric properties of a material can be determined through the
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