Determination of Selenium in Tofu by Hydride Generation-Atomic Absorption Spectrometry and the Relationship between Selenium Content and Soybean Origin

Abstract

Selenium, an essential trace element, affects disease prevention and health promotion activity, particularly controlling the occurrence and metastasis of cancer. We measured the selenium content in processed soybean food by hydride generation-atomic absorption spectrometry. Measurement conditions were validated by analysis of the standard reference material, rice flour NIST-SRM 1568 a. When the actual measurement value, 38.2±1.7 μg/100 g, was compared to the certified value for standard reference, 38.0±4.0 μg/100 g, we concluded that measurement conditions were reasonable. When we measured the selenium content in 41 different varieties of tofu, we found that the selenium content in tofu made from domestic soybeans was lower than those in tofu made from Canadian and American soybeans. We found similar results from the measurement of the selenium content in kinako. The selenium content of baked kinako made from American soybeans was higher than that of powder made from Japanese soybeans. We concluded that selenium content measurement in processed soybean foods can be used to distinguish domestic products from foreign products.