Detection of water variation in rosebuds during hot-air drying by LF-NMR and MRI

AbstractThis study investigated drying kinetics and changes in water in rosebuds during hot air drying at 40, 50, 60, and 70 °C, using NMR and MRI technology to evaluate transverse relaxation times (T2), water status and distribution. Drying rate increased with temperature, with the Midilli model predicting the drying process of rosebuds more accurately than other mathematical models. Three water fractions with different T2 values were identified: T21 (0.1–2 ms), T22 (5–50 ms), and T23 (50–600 ms). Water status and distribution in rosebuds differed with a higher moisture content in receptacles than in petals. During drying, the total peak amplitude and T2 values in rosebuds declined (LF-NMR), with changes in internal water distribution shown by MRI. Moisture content was significantly correlated with LF-NMR parameters, especially ATotal/g. Therefore, the Midilli model described the drying of rosebuds, and LF-NMR and MRI technology can monitor changes in water status and distribution during drying.