Evaluation of Rice Freshness Using Fluorescence
Date Issued
2010
Date
2010
Author(s)
Liao, Chung-Hsien
Abstract
The objective of this study was to apply fluorescence method for detection of the rice freshness by using spectrofluorometer and fluorescent sensing system. The paddy samples of different crop years were obtained from local district agricultural research and extension stations and farmers'' associations. The paddy was processed by laboratory huller and the milled white rice was stored in incubators at temperatures of 10℃, 25℃ and 35℃. The BTB-MR method and a commercial rice grain freshness tester were used to evaluate the pH value of group-kernel rice sample and single kernel rice sample respectively. The fluorescence responses of white rice samples were measured by Jasco FP-6300 Spectrofluorometer. The rice fluorescence spectra excited by a light source at 365 nm were obtained in the range between wavelength 400 nm and 600 nm. The results show that the variation of fluorescence intensity of different crop year rice flour sample is smaller than those of group-kernel sample. The rice fluorescence intensity is low at high moisture content. The rice fluorescence intensity is not affected by chalky kernel if the ratio of chalky kernel mixed in normal rice is less than 20%. The rice fluorescence intensity is not influenced by rice whiteness at the range between 34 and 40. The fluorescence intensity of stored rice at high temperature is higher than those stored at low temperature. The coefficient of determination (R2) of regression of fluorescence intensity attenuation against pH value was 0.57 for group-kernel rice. The fluorescence sensing system developed in this study is consisted of a high power UV LED and a digital color light sensor. The coefficient of determination (R2) of regression of fluorescence intensity against pH value was 0.22 for single kernel rice.
Subjects
rice
freshness
fluorescence
spectra
sensor
Type
thesis
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