a b s t r a c tThis review covers developments in non-invasive techniques for quality analysis and inspection of specialty crops, mainly fresh fruits and vegetables, over the past decade up to the year 2010. Presented and discussed in this review are advanced sensing technologies including computer vision, spectroscopy, X-rays, magnetic resonance, mechanical contact, chemical sensing, wireless sensor networks and radiofrequency identification sensors. The current status of different sensing systems is described in the context of commercial application. The review also discusses future research needs and potentials of these sensing technologies. Emphases are placed on those technologies that have been proven effective or have shown great potential for agro-food applications. Despite significant progress in the development of non-invasive techniques for quality assessment of fruits and vegetables, the pace for adoption of these technologies by the specialty crop industry has been slow.

Internal browning in pears (Pyrus communis L. cv. Blanquilla) has been studied by NMR and MRI in order to develop a non-destructive procedure for on-line disorder identification. For NMR relaxometry, disordered tissue shows higher transverse relaxation rates compared to sound tissue, especially at higher magnetic field strength and for long pulse spacing. Membrane alteration and therefore tissue disintegration, as well as water evaporation, appear to be the main causes of this response. Correlation between relaxation times and diffusion showed that the proton pools in disordered tissue are grouped into a smaller number of populations compared to sound tissue, also highlighting cell decompartmentation in disordered tissue. At a macroscopic level, fast low angle shot MR images, effective transverse relaxation-weighted (TR 11 ms and TE 3.7 ms) and proton density-weighted (TR 7.6 ms and TE 2.5 ms), were acquired for pears at a rate of 54 mm/s. Images have been discriminated for internal breakdown according to histogram characteristics. Up to 94 and 96% of pears, respectively, were correctly classified in the former and the latter type of images. In this study a minimum value of 12% of tissue affected by breakdown was always clearly identified.

Maintaining the quality of extra virgin olive oils (EVOOs) in the current globalised market is a key challenge for the olive oil manufacturers. To maintain the quality, one major factor is to resist its oxidation during processing and storage. Resisting the oxidation in EVOOs is a challenging task requiring control of different physical and chemical factors. However, rapid, real-time, and non-destructive monitoring the oxidation in EVOOs could support in maintaining its quality during storage. The present study utilises a novel right-angle fluorescence spectroscopy-based prototype for rapid monitoring of oxidation changes in three different EVOOs varieties (Arbequina, Picual, and Cornicabra) during storage. Furthermore, the effects of light exposure on oxidation of EVOOs were also studied. Two major changes in the fluorescence spectra of EVOO samples were mainly observed: a decrease in fluorescence emission intensity at 671 nm, and an increase in fluorescence intensities at 420, 440, 464, and 515 nm. These two changes were related to a decrease in chlorophyll content and parallel formation of oxidation products. The formation of oxidation products was found to have a linear relationship with the decrease in chlorophyll content. Out of the three, the Cornicabra variety showed the highest rate of oxidation changes. Furthermore, the EVOOs degraded rapidly when get exposed to light. In a fast and non-destructive manner, the fluorescence spectroscopy-based prototype successfully monitored the oxidation changes in the EVOOs. Keywords Extra virgin olive oil • Oxidation • Storage • Light exposure Abbreviations C0 2) Singlet oxygen (3 0 2) Triplet oxygen EU European Union EVOOs Extra virgin olive oils nm Nanometre UV-Vis Ultraviolet and visible VOOs Virgin olive oils Compliance with ethical standards Conflict of interest The authors declare no conflict of interest. Compliance with ethics requirements This article does not contain any studies with human and animal subjects.

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Magnetic resonance imaging was used to acquire images of the internal structure of mandarins for non-destructive seed identification. Two different types of fast MRI sequences were investigated: a gradient echo and a spiral-radial, with 484 ms acquisition time for the former compared to 240 ms for the latter. The radial-spiral option allows over-sampling of the central area of the k-space maintaining the contrast within the MRI images and so the feasibility of seed segmentation. Three segmentation techniques were applied for image post-processing: region-based, onedimension histogram variance, and two-dimension histogram variance, among which the latter procedure has been demonstrated to give the most promising results. Image features including perimeter, compactness, maximum distance to the gravity centre, and aspect ratio were employed in a linear discriminant function, by which seed identification of mandarins could be achieved with 100% accuracy using radial-spiral sequence and 98.7% accuracy with gradient echo images.