磁振化學位移影像應用於番茄與香蕉內部物理化學性質之分析

Abstract

本研究主要是發展以化學位移影像技術偵測在後熟期間番茄內部之醣類與茄紅素以及香蕉內部之醣類變化。並發展一套演算法，首先將磁場不均勻度在化學位移影像上所產生之假影消除，並將番茄內部的醣類及茄紅素影像和香蕉內部之醣類影像顯現出來，比較其在後熟前後之差異性。實驗設定相同成像參數，取得在綠熟及紅熟時期的同顆番茄的化學位移影像，及經過乙烯催熟處理過後不同時間的香蕉進行比較。 首先比較在3T與7T兩不同磁場強度上的影像品質差異，在此選擇相同的水樣本峰值訊雜比(PSNR)、訊雜比(SNR)、及峰值之寬度(linewidth)以相同的實驗參數進行比較，可得到在7T上PSNR為3371、SNR為810、峰值寬度為0.214，其數值皆較在3T上所得為大。因為這些參數影響到化學位移影像之影像品質，因此可以知道在7T上所得之化學位移影像品質較佳。另外比較在不同醣類濃度下化學位移影像的訊號關係，可知醣類濃度與化學位移影像的醣類訊號成線性相關，因此番茄和香蕉之醣類影像可以此量化。 以化學位移影像及高效液相層析儀(HPLC)於番茄醣類與茄紅素的比較上，可發現番茄在後熟之後醣類含量會有些許的降低，而茄紅素含量會有增高的趨勢。另外比較香蕉內部的醣類變化，可發現當經過乙烯催熟處理過後，在前四天其果肉的醣類會有急速增加的現象，而果皮部分的醣類並沒有較大的變化。比較化學位移影像和HPLC的結果，可知道其實兩者有很大的一貫性，因此化學位移影像未來在應用於內部的生理分析會是一項很有用的工具。

This study developed an analytical method to detect the spatial changes of sugar and lycopene content in tomatoes and sugar content in bananas during ripening process by using CSI technique. An algorithm was developed to correct the image artifact due to field inhomogeneity, and thus to visualize the internal spatial distribution of sugar and lycopene content of the same tomatoes and sugar content of bananas before and after ripening. The experiments were performed to acquire tomato images with the same imaging parameters at mature green and red ripe stages and banana images on different days after ethylene treatment. The spatial distribution of sugar and lycopene content in tomatoes and sugar content in bananas were compared before and after ripening process. After comparing the maximum PSNR, SNR, and linewidth of water phantom in 3T and 7T CSI data with the same imaging parameters, we found the imaging indexes in 7T CSI -- the maximum PSNR 3371, the maximum SNR 810, and the maximum linewidth 0.214 ppm -- are almost twice those in 3T CSI. This demostrates that CSI image quality in 7T is better than in 3T. On the other hand, when comparing the concentration of sugar solutions and CSI intensity, we found that a linear relationship exists between them. Using the linear relationship, the sugar content of tomatoes and bananas was quantitatively analyzed. After comparing the sugar content and lycopene content in a tomato with CSI and HPLC analyses, the sugar content was found to have slightly decreased, and the lycopene content had increased after ripening process. We further compared the sugar content in bananas using CSI and HPLC analyses. The sugar content in the pulp quickly increased during the first 4 days after ethylene treatment, and there were little change in the peel. In this study, results from the CSI analyses of sugar and lycopene in tomato or banana fruits were consistent with that of the HPLC analyses. Therefore, the non-destructive CSI technique may become an efficient tool for physiological analyses in the future.