The internal quality of agricultural products is an important attribute that is
considered by consumers when buying them. Grading agricultural products according
to their internal quality, is an effective way to make the best use of the products, and
thus improve the overall value. In recent years, several nondestructive, intelligent
sensing techniques have been studied extensively for detecting the internal quality of
agricultural products, including Vis/NIR spectroscopy, multi-/hyper-spectral imaging,
nuclear magnetic resonance and imaging, X-ray and computed tomography, electrical
nose and acoustic technique. In this chapter, the working principle of each technique is
provided, and corresponding applications in the agricultural domain are reviewed to
provide overall understanding of these techniques. The challenges and perspectives of
these techniques are also analyzed.
