Nondestructive detection of internal bruise and spraing disease symptoms in potatoes using magnetic resonance imaging

Magnetic resonance imaging (MRI) was applied to detect nonvisible internal bruise and spraing symptoms and to get insight on the chemical and anatomical causes of such defects. Cultivar Saturna with internal bruise and cultivar Estima with spraing symptoms were investigated by comparison of different MR images as proton density-, T1- and T2-weighted images and T2 maps. In all these types of MR images, it was possible to identify internal bruise and spraing spots in the potatoes, where these phenomena were present. When combining the information in the MR images, the interior of the internal bruise was characterised as being very dry (low signal in the proton-weighted image) with a small amount of highly mobile water in the shell around the bruise (high signal in T2-weighted image and high relaxation time in T2 map). The spraing spots were more diffuse; however, the dry interior and highly mobile water around the spraing dots were somewhat similar to the appearance of internal bruise but resembled more the appearance of human tumour tissue than bruise disorders in, for example, fruits. In conclusion, this study demonstrated that MRI can detect nonvisible internal bruise and spraing symptoms in potatoes, which has not been published before. MRI may, therefore, be an appropriate method for detecting and for studying developmental changes of such disorders and related disorders during postharvest storage in future experiments.