Ripening of banana fruit monitored by water relaxation and diffusion 1H-NMR measurements

Water transverse relaxation times T2 and self-diffusion coefficients D have been measured on banana samples at different ripening stages. Relaxation data have been interpreted on the basis of a chemical and diffusive exchange model proposed by Belton and Hills [Mol. Phys. 61(4) (1987) 999] and Hills et al. [Mol. Phys. 67(4) (1989) 903]. According to that model the observed increase of T2 values of both cytoplasmatic and vacuolar water may be mainly attributed to the decrease of starch concentration during the ripening process. On the other hand, the observed water self-diffusion coefficient decrease is related to sugar accumulation as starch hydrolysis proceeds. At the early stages of ripening, the individual self-diffusion coefficient values of cytoplasmatic and vacuolar water differ from one another and have been calculated through the analysis of relaxation time-separated pulsed field gradient nuclear magnetic resonance experiments [J. Magn. Reson. A 112 (1995a) 237].