Status and future of magnetic resonance imaging sensors for in-line assessment and sorting of fruit

Nuclear magnetic resonance spectroscopy and magnetic resonance imaging (MRI) have been demonstrated to measure an extensive range of fruit quality parameters including composition, maturity and defects. These measurements have been demonstrated to be effective on many types of fruit, for a range of attributes. Additionally, multiple quality factors can be measured simultaneously, rapidly, non-destructively and non-invasively on each fruit. With recent breakthroughs in magnet technology NMR/MRI systems of sufficient field homogeneity can be made for sorting fruit at 10 to 12 fruit s^-1. Results from both an alpha and a beta prototype for sorting citrus fruit based on internal defects (for example, seeds in seedless citrus and dryness) have demonstrated sorting speeds that are consistent with integration into commercial fruit packing operations. The potential and existing challenges to commercial implementation of NMR/MRI sensors are described.