應用螢光光譜及螢光影像評估稻米之新鮮度

Abstract

本研究的目的是以螢光光譜與影像評估不同期別稻米的新鮮度。稻穀樣本從不同農會取得。實驗稻穀經過碾米過程得到糙米與白米樣本。稻穀、糙米與白米的螢光光譜反應是使用Jasco FP-6300螢光光譜儀進行量測。在激發光以365nm波長照射後，進行光譜掃描，其掃描範圍在400nm到600nm之間，即可獲得光譜反應資訊。分析螢光光譜之結果顯示，較舊白米樣本相對於較新樣本，有較強的螢光反應，且白米螢光強度高於相同期別之稻穀與糙米。在化學分析上，本研究使用BTB-MR法量測稻米之酸鹼度。在螢光峰值與酸鹼度之迴歸決定係數(R2)為0.72。以此方法辨別稻米新鮮度具有可行性。 在影像方法中，量測系統是由4組UV-A汞燈與灰階式數位型CCD感測器所組成。本系統為實驗室基本型且設計架設於暗室內，測試不同期別稻米樣本相關影像反應。結果顯示相同期別之白米樣本螢光影像強度高於稻穀與糙米樣本。變異數分析結果指出2007年第一期和第二期的白米螢光影像強度具有顯著的差異。應用螢光影像判別白米新鮮度具有可行性。

The objective of this project was to evaluate freshness of rice in different crop years using fluorescence spectrum and image. The paddy samples were obtained from different farmer’s associations. The experimental paddy was milled to obtain brown rice and white rice. The fluorescence responses of paddy rice, brown rice, and white rice were measured with Jasco FP-6300 Spectrofluorometer. The fluorescence responses were detected at wavelength in the range 400 nm to 600 nm after excitation at 365nm. The result shows that the aged white rice has stronger fluorescence response as compared to fresh sample. The white rice has strongest fluorescence response as compared to brown rice and paddy rice of the same crop year. In chemical analysis, this study used BTB-MR method to detect the pH value of rice. The coefficient of determination (R2) between the fluorescence peaks and pH value is 0.72.This result indicates that it is feasible to adopt fluorescence spectra to measure rice freshness. The fluorescence imaging system consists of four UV-A Hg lamps and a digital monochrome camera. The system is laboratory-based and is designed to be performed inside the darkened box. The fluorescence imaging system was tested for detecting rice in different crop year with respect to image response. The result shows that the white rice has strongest fluorescence image intensity as compared to brown rice and paddy rice in the same crop year. The significant difference in white rice fluorescence image intensity was found between the first and second crop of 2007. It is also feasible to adopt fluorescence imaging system to evaluate rice freshness.