Development of a μTAS for Evaluating Rice Freshness

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  • QIU Xiaoli
    Graduate School of Life and Environmental Sciences, University of Tsukuba
  • SASSA Fumihiro
    Graduate School of Pure and Applied Sciences, University of Tsukuba
  • ITOH Daisuke
    Graduate School of Pure and Applied Sciences, University of Tsukuba
  • LI Yanjie
    Graduate School of Life and Environmental Sciences, University of Tsukuba
  • SUZUKI Hiroaki
    Graduate School of Pure and Applied Sciences, University of Tsukuba
  • SATAKE Takaaki
    Graduate School of Life and Environmental Sciences, University of Tsukuba

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  • 米の鮮度計測用μTASの開発

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Abstract

Rice lipids are easily hydrolyzed to free fatty acids by lipase during storage, in this study, Micro Total Analysis Systems (μTAS) was developed for detection of fat acidity to evaluate rice freshness. It attained microtitration on a microchip with a main working area of W (11 mm) × L (45 mm). The device was constructed using glass and polydimethylsiloxane (PDMS) plates with flow channels, two injection ports, a volume regulation cell (collection of small plugs), and a Φ4.0 mm reaction cell. The small plugs with different volumes are formed by injecting the KOH solution and air to the microchannel simultaneously using microsyringe pumps. As the accumulating of small plugs in the volume regulation cell, large plugs with uniform volume are formed, then, uniform large plug was ejected into the reaction cell and mixed with the extracted rice sample solution, color change of phenolphthalein, which was added into extracted rice solution as a pH indicator, was occurred with the increasing of volume of uniform large plugs. Approximately 2 minutes were required for one detection for the fabricated μTAS. To verify the performance of device, different varieties of brown and milled rice grains harvested between 2005 and 2010 were used for freshness evaluation. Moreover, to verify fat acidity using μTAS, a conventional neutralization titration method for evaluation freshness was used. According to the results, a good correlation (R2 = 0.980–0.984) was observed between the fat acidity determined using μTAS and that determined by the conventional method for brown and milled rice grains. Therefore, μTAS developed can be used for evaluating rice freshness.

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