Differences in nuclear magnetic resonance images between chilled and non-chilled zucchini squash

Abstract

Nuclear magnetic resonance (NMR) imaging techniques provide a non-destructive method for detecting changes in the internal structure of zucchini squash ( Cucurbita pepo L., Ambassador) during exposure to chilling temperatures. Whole, freshly harvested zucchini squash were stored at either 2.5 (chilling) or 12.5°C (non-chilling). A 4.7 Tesla, 33 cm bore size, NMR imaging system was used to generate transverse images of the squash. Chilled squash produced an image with high signal intensity in the epidermal region. The T1 (spin-lattice relaxation time) weighted images, obtained by the inversion recovery technique, showed that cortex tissue of the chilled squash also had higher signal intensity than that of the non-chilled squash, indicating a shorter T1 relaxation time and a greater mobility of water in the chilled tissue. The T2 (spin-spin relaxation time) weighted images, obtained by the spin-echo technique, also showed higher intensity in the chilled squash than in the non-chilled samples, implying a longer T2 relaxation time for the chilled tissue. These results suggest that differences between chilled and non-chilled squash can be discerned non-destructivity by the intensity of the NMR images or the T1 and T2 relaxation times.