However, few studies have focus on seed type or variety identification [10]. On selleckchem the other hand, digital image processing techniques offer a new option in order to obtain quick classification Inhibitors,Modulators,Libraries results [1,3,11�C14]. Inhibitors,Modulators,Libraries Nevertheless, the natural variability in seed appearance (regarding shape, colour Inhibitors,Modulators,Libraries and texture), as well as the existence of dust particles and uneven backgrounds still make the recognition of seeds a challenge for any machine vision system [3,15]. Therefore, alternative non-destructive and in situ techniques to identify and classify seed types and varieties need to be developed.The recent development of acoustic and digital analysis techniques offers innovative tools for an emergent number of industrial applications, especially in the food industry [16].

Ultrasound waves are widely used for the quality assessment of fruits, drinks and oils [16,18�C21]. However, sound waves have considerable advantages over ultrasound in terms of being able to assess large materials widths and being relatively inexpensive [17]. Sound waves are used to characterize Inhibitors,Modulators,Libraries the texture of nectarines, plums, and tomatoes by estimating the sound velocity through these materials [22,23]. Green et al. [24] have related the sound insulation characteristics with the physical properties of different forage types. Moreover, some studies have applied acoustic methods for assessing seeds. For instance, the analysis of the acoustic signal generated by the dynamic impact of seeds has been used to determine the seed moisture content [25,26] and to detect defects and seed damages [27�C29].1.2.

Acoustic PhenomenaAs a granular porous material, heaped seeds are a highly absorbing acoustic media [30,31]. The acoustic energy transmission in a porous media can be divided into structure-borne and air-borne transmission [32]. Hikling et al. [31,33] found that in heaped seeds, sound waves are principally air-borne transmitted, GSK-3 i.e., transmitted through the gas phase between seeds, since the transmission of sound through the solid seed matrix, i.e., structure-borne transmission, appears to be highly attenuated and almost nonexistent, presumably due to friction between seeds.When the air-borne sound wave comes into contact with heaped seeds, part of its energy is reflected, another fraction is transmitted through the medium and the rest is dissipated in form of heat due to thermo-viscous effects between seed particles (i.

e., absorption phenomenon) [34].The acoustic behaviour of a porous material is principally governed by the physical properties of the medium. Theoretical studies have shown that the main parameters that influence selleck chemicals llc the acoustic behaviour of porous media comprise porosity, air flow resistivity, tortuosity, viscous characteristic length and thermal characteristic length [32].