Original article: Characterisation of water species revealed in the drying operation of Todarodes pacificus Steenstrup using water proton NMR analysis |
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Authors: | Yasuyuki Konishi Masayoshi Kobayashi Kou‐ichi Miura |
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Affiliation: | 1. Hokkaido Industrial Technology Center, 379 Kikyo‐cho, Hakodate, Hokkaido 041‐0801, Japan;2. Advanced Technology Institute of Northern Resources, 2‐2‐8‐6 Tonden, Kita‐ku, Sapporo, Hokkaido 002‐0852, Japan;3. Department of Biotechnology and Environmental Chemistry, Kitami Institute of Technology, 165 Koen‐cho, Kitami, Hokkaido 090‐8507, Japan |
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Abstract: | For the discrimination of water molecules during the squid‐drying process, the water distribution was characterised by water proton NMR and moisture diffusivity (De) analysis methods as a function of the water content (W0). The proton NMR spectrum showed three peaks indicating three different species (species‐A, ‐B, and ‐C) distributed in the squid muscle, each of which had a characteristic behaviour of the relaxation time (T2) as a function of the W0. The 1/T2 of species‐A was drastically varied at W0 = 120%‐d.b., indicating two further categories, i.e., species‐A1 and ‐A2. Species‐A1 is available at W0 > 120%‐d.b. and was characterised as having De = 5.1 × 10?10 m2 s?1, activation energy of moisture diffusivity (ED) = 17 kJ mol?1, and relaxation rate 1/T2 = 74 s?1, as evaluated by the proton NMR spectrum without depending on W0. Species‐A2 is available at W0 < 120%‐d.b., indicating a distribution of De = 4.8 × 10?10–1.7 × 10?10 m2 s?1, ED = 25–35 kJ mol?1 and 1/T2 = 1.8 × 103–1.5 × 102 s?1 with increasing W0. Species‐A1 and ‐A2 were assigned as weakly restricted water and strongly restricted water, respectively. |
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Keywords: | Activation energy of diffusivity correlation time effective moisture diffusivity reproducibility of the water species water species‐A1 and ‐A2 |
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