Seasonal chemical-physical changes of PGI Pachino cherry tomatoes detected by magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI) has been used to study the variations of internal structure and chemical-physical characteristics of cherry tomatoes (Lycopersicon esculentum cv. Shiren), one the most economically valuable horticultural crops, in different harvesting seasons. In particular, the study focused on PGI (Protected Geographical Indication) Pachino cherry tomatoes, characterised by taste and nutritional value, notably in the winter production, amounting about 500 ton/year. Spin-spin and spin-lattice relaxation times, T₂ and T₁ respectively, determined on whole fruit, provided useful data highlighting variations among samples according to the season (winter, spring and summer). MRI images evidenced differences among cellular tissues such as pericarp and endocarp, through variations of: (1) T₂ and T₁ measures and water tumbling and diffusion motion, (2) thicknesses of different morphological zones, (3) qualitative characteristics of the tissue covering placental cavities where seeds are contained. Results of variance analysis (ANOVA) showed that physical parameters, as the transverse and longitudinal relaxation times, T₂ and T₁, measured in the morphological tissues of vegetables are excellent variables highlighting their differences in different seasons. This innovative non-destructive technique in food science has great potential in fruit quality assessment.