A Dedicated MRI for Food Science and Agriculture

Abstract

A dedicated magnetic resonance imaging (MRI) apparatus that is small, lightweight, and usable in an ordinary research room was devised for developmental research and quality estimation of foods and agricultural products. The thawing processes of frozen margarine and meats were traced, the distributions of oils in adipose tissue (fat) and water in muscle tissue for pork and beef were distinctively visualised, the oil-accumulating tissues in seeds and the sticky materials on surface of fermented soybeans (natto) were characterised, and the three-dimensional organisation of the fine vasculature in fruits was visualised by the apparatus. The proton-specified MRI was easy to operate and provided well depicted images of internal structures, the distribution and mobility of water and oils, and susceptibility differences inside materials, demonstrating that the devised machine is useful for food and agricultural research.Keywords: small dedicated magnetic resonance imaging (MRI), proton-specified apparatus, frozen margarine, frozen meats, natto, fruits *To whom correspondence should be addressed. E-mail: nobu@affrc.go.jp IntroductionMagnetic resonance imaging (MRI) non-destructively provides information on internal conditions for gross materials (McCarthy, 1994;Faust et al., 1997;Hills, 1998), and has been effectively used in food science and agricultural research. Unfortunately, however, it is not widely used because the machine is large, expensive, and difficult to operate.Small MRI apparatuses have been developed from the late 1990s for use in research rooms adjacent to material production sites. However, the image quality was unstable, and the apparatuses were usually specialised for specific objectives. These issues result from the low field permanent magnets used for the apparatuses. The field strength of permanent magnets is strongly affected by the ambient temperature (Haishi et al., 2001), and the inhomogeneity in a low magnetic field is difficult to regulate in the construction of the magnet (Constantinesco et al., 1997). In the present brief paper, we report a small, dedicated MRI apparatus devised and improved for use in developmental research and quality estimation of foods and agricultural products.The apparatus was constructed based on the system previously reported by Haishi et al. (2001), which was a small proton MRI spectrometer (MRTechnology Inc., Tsukuba, Japan) equipped with a 1.0 Tesla (T: unit indicating the magnitude of a magnet) permanent magnet with a 60-mm pole gap (Neomax Co., Ltd., Saga, Japan) and a solenoid detector with gradient circuits for imaging. The following were introduced to overcome the defects associated with common small MRI apparatuses and to make the apparatus usable for various materials employed in foods and agricultural products. The magnetic field used was stronger than a similar small MRI system using a 0.2 T permanent magnet (Constantinesco et al., 1997). A stronger magnetic field was advantageous for detecting weak signals and for obtaining good quality images with an ...

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