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T₂ Map, Moisture Distribution, and Texture of Boiled Japanese Noodles Prepared from Different Types of Flour

¹Saitama Industrial Technology Center Northern Laboratory, 2-133 Suehiro, Kumagaya, Saitama 360-0031, Japan. ²Corresponding author. Phone: +81-48-521-0614. Fax: +81-48-525-6052. E-mail: tkojima@tech-lab.pref.saitama.jp ³National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan. ⁴Department of Chemistry, Faculty of Science, Saitama University, 255 Shimo-Okubo, Sakura-Ku, Saitama 338-8570, Japan.

Changes during boiling in the distribution of moisture in Japanese white salted noodles prepared from flour of different protein contents were investigated by magnetic resonance imaging. Changes in the moisture profiles of the noodles, which were obtained from spin-spin relaxation time (T₂) maps based on the correlation between moisture content (MC) and T² for each standard flour gel, showed an increase in MC with boiling time in all parts of noodles. The penetration of boiling water was faster in the noodles prepared from flour with low protein content than in those prepared from flour with high protein content. Relationships between the local MC and the texture parameters from cutting tests were investigated. The slope of force-displacement curve showed a high negative correlation with MC at 1 mm from surface of the noodles. There was also a negative correlation between MC and the force at each depth from the surface, except for the part closest to the surface, for samples taken after 16 and 24 min of boiling. This result proved that the MC is the primary factor determining the firmness of the noodles. The MC at the core, however, was not correlated with the peak force in this study.