Measurement of Fruit Quality using Nuclear Magnetic Resonance.

摘要

The quality of fruit is a primary concern for both the fruit industry and consumer. The objectives of this study were to explore the potential of magnetic resonance techniques in the measurement of various quality attributes of fruit, including tomato and pomegranate. The quality attributes investigated consisted of quantitative and qualitative properties related to the chemical, physical, or physiochemical properties of fruit. The fruit samples were tested using different magnetic resonance techniques, including MRI, 1D and 2D NMR relaxometry, to characterize the environment of water in fruit tissue.;In this research, a set of MR images with different contrast origins were acquired from each fruit to characterize water properties in the fruit tissue. Multivariate modeling methods, Partial Least Square Discriminant Analysis (PLS-DA), Principle Component Analysis (PCA) and Partial Least Square (PLS), were used to build models for quality attributes of fruit based on the MR images, and to determine the optimum MR images for quality assessment. The maturity of tomato, the presence of internal fungal infection, the pH, titratable acidity, and soluble solids/acidity ratio of pomegranate were successfully measured or identified using multivariate models based on MR images. T2 weighted and diffusion weighted images proved to be the most important MR image types for assessment of the fruit quality attributes studied.;Moreover, the MR imaging technique was able to resolve the internal structure of the fruit, and made it possible to measure the properties of a specific part of the tissue in the fruit. MRI was used to characterize the red layer and pericarp of processing tomato and to explore the correlation between the pericarp properties and peelability of tomato. The layered structure of pericarp can be visualized in a T2 weighted image. MRI demonstrated potential as a nondestructive method to characterize tomato pericarp and evaluate the peelability of processing tomatoes.;The 1D and 2D NMR relaxometry method quantified the physiological changes in fruit at the subcellular level. The change in the 1D and 2D NMR spectrum of pomegranate suggested that alternation in the water environment and water redistribution occurred in both fungal infected and controlled atmosphere stored arils.