Study on variation of mineral contents in rice grains and the determination of production origin
Date Issued
2005
Date
2005
Author(s)
Chen, Tzu-Ying
DOI
zh-TW
Abstract
After entered the World Trade Organization (WTO), there have been more agricultural products imported from foreign countries to Taiwan. The products must possess particular characters, such as culture origin and nutrient content, so as to keep competitiveness and generate better profit. The aim of this study was to measure mineral contents of local rice grains, with which to establish a database of mineral contents for Taiwan cultivars. And use this database to understand the effect of environment on mineral contents of rice grains. Ultimately, the present study evaluated the feasibility of determining product origins by the mineral contents profiles.
In the current approach an ICP-AES (Inductively Coupled Plasma – Atom Emission Spectrometry) based protocol was developed to determine element contents including Zn, Mn, Fe, Ca, Cu, Mg, K, Se, Mo, B, Al, Sr and Ba in rice grains. Samples of different cultivars or grown under different temperatures and nitrogen rates were collected to determinant the effects of genotype or environment on mineral content of rice grains. In addition mineral contents for rice grains with different milling rates were also analyzed. To asses the possibility of differentiation of production origins, samples from local and foreign countries were also collected and the mineral content profiles were analyzed.
As revealed by our results in general, method of cultivation, such as the amount of nitrogen applications, temperature during grain-filling period, and milling degree may significantly affect the mineral content profile and Mg/K ratio which relates to the eating-quality of rice grains. For example, rice grains cultivated by organic farming had higher Mg/K ratio than by conventional farming. Application with medium nitrogen rate would increase Mg/K ratio of TK9, whereas application of high nitrogen would decrease the ratio. Moreover, high temperature during grain-filling period decreased Mg/K ratio of tested Japonica rice grains. Furthermore, results from milling degree showed that the distribution of mineral contents in rice grain is not even, and most of the mineral contents are concentrated in the bran or the surface of rice grains.
In the experiment of evaluation for production origin, samples of milled rice, brown rice, and milled rice of cultivar Koshihikari from local and foreign countries were collected to measure 13 elements of Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, Mo, Se, Sr, and Zn by ICP-AES. The mineral content profiles were further analyzed by utilizing the principle component analysis (PCA) and the discrimination analysis (LDA). The results showed that samples of different production origins could be differentiated by the statistic analysis.
Conclusively, the present results suggest that profile of mineral content of rice grains can be influenced by genetic background, culture environment and milling rate. The resultant mineral content profile of one sample can be used to differentiate its production origin by appropriate statistic analysis.
Subjects
水稻
礦物元素含量
產地
rice
mineral content
geographical origin
Type
thesis
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