利用低场核磁共振(low-field nuclear magnetic resonance, LF-NMR)技术研究了冻融后松茸水分的存在形式及相对含量，比较了冻融次数对解冻损失率、色泽和硬度等品质指标的影响，利用多层自旋回波(multi-slice spin echo, MSE)序列获得样品质子密度成像，进而分析冻融过程松茸内部水分的变化。结果表明，松茸中存在结合水、不易流动水和自由水，对应的横向弛豫时间分别为T21(0.01～10 ms)、T22(10～100 ms)和T23(100～1 000 ms)。冻融过程中松茸不易流动水、结合水、自由水相对含量分别为88.7%～92.2%、6.2%～9.8%、0.7%～1.9%，随着冻融次数增加，自由水和不易流动水含量不断下降，结合水含量先增加后减少；松茸解冻损失率增大，亮度L值、红度a*值和黄度b*值逐渐降低，硬度先下降后上升，松茸品质下降。MRI结果表明，冻融5次后，菌柄失水较菌伞严重，菌柄部分区域已无自由水存在。相关性分析表明，冻融次数与T22、T23、a*、b*和解冻损失率极显著相关(p<0.01)。T22、T23与a*值、b*值和解冻损失率显著相关(p<0.05)。因此，应用LF-NMR对松茸水分状态及组分含量的测定可以作为考察松茸品质的指标。

The moisture state and content of Tricholoma matsutake after freeze-thaw were analyzed by low-field nuclear magnetic resonance (LF-NMR) technology. The effects of freeze-thaw cycles on the thawing loss rate, color and hardness were compared. To learn the effect of the freeze-thaw process on Tricholoma matsutake moisture distribution, during the experiment period, the proton density weighted images of the sample were obtained with multi-slice spin echo (MSE) pulse sequence. The results showed that the water states in Tricholoma matsutake included free water, immobilized water and bound water, which were T21 (0.01-10 ms), T22 (10-100 ms), T23 (100-1 000 ms), respectively. With the increasing of freeze-thaw cycles, the free water content and immobilized water content was decreased gradually, bound water content was increase slightly and then decreased; The thawing loss rate increased, L values (lightness), a*(redness) and b*(yellowness) values decreased, hardness decreased first and then increased, causing a decline in quality. MRI results showed that water loss of stipe was more serious than that of pileus, some areas of stipe hardly existed free water after 5 cycles of freeze-thaw. The correlation analysis showed that the times of freeze-thaw had a significant correlation (p<0.01) with T22, T23, a*(redness), b*(yellowness) and thawing loss rates. The T22 and T22 had a significant correlation (p<0.05) with thawing loss rates, a*(redness) and b*(yellowness). Therefore, application of using LF-NMR in the determination of water content and composition of Tricholoma matsutake could be used as reference indexes for the quality control.