METHOD FOR DETECTING HOLLOW IN WATERMELON USING NUCLEAR MAGNETIC RESONANCE

PURPOSE: To detect hollows in watermelons at a high speed with accuracy without being affected by seeds by applying a first high-frequency magnetic field to the watermelons, then applying second and third high-frequency magnetic fields at a specified time interval, and processing nuclear magnetic resonance signals obtained from the watermelons. CONSTITUTION: A first non-selective 180-degree high-frequency magnetic field (RF) pulse A is applied to each watermelon for the excitation of protons in its seeds and flesh, then a second 90-degree RF pulse B is applied after Ti time, then a third 180-degree RF pulse C is applied after Te/2 time, so that a nuclear magnetic resonance signal is obtained Te time after the application of the pulse B. When the Ti time and the Te/2 time are set to the range of 400 to 600 milliseconds and that of 5 to 20 milliseconds (i.e., Te is 10 to 40 milliseconds), respectively, signals from the seeds and the flesh become equal in strength, and a spectrum from the watermelon that has seeds but no hollow has no defects at all, while defects are caused only in the spectrum from the watermelon that has hollows. Therefore, the presence of the hollows can be accurately detected without the influence of the seeds.