低场核磁共振技术快速检测鲜乳水分方法研究

Rapid Detection of Water Content in Fresh Milk by Low-Field Nuclear Magnetic Resonance

运用低场核磁共振技术研究鲜乳变质过程中水分的变化规律,选取反转恢复脉冲序列和Carr-PurcellMeiboom-Gill序列测定鲜乳样品在不同贮藏时间的弛豫参数,根据纵向弛豫时间T1、横向弛豫时间T2观测样品的水分含量,并通过T2反演数据的拟合结果得出自由水和结合水的变化趋势。研究表明,随着贮藏时间的延长直至鲜乳变质腐败,鲜乳中的总水分先减少后增加,其中自由水减少,结合水先减少后增加。结果表明,低场核磁共振技术可用于快速、有效地判定鲜乳的新鲜程度,并有助于在鲜乳贮运过程中品质的实时监控。

Low-field nuclear magnetic resonance(LF-NMR) was used to study the change of water content in fresh milk during the deterioration process. IR pulse sequence and carr-purcell-meiboom-gill(CPMG) pulse sequence were selected to determine relaxation parameters of fresh milk sample at different storage times. According to the collected relaxation time T1 and T2,the water content of milk samples could be observed. Furthermore,the changing trends of free water and bound water were concluded by fitting T2 inversion data. This research showed that the total water content of fresh milk decreased firstly and then increased with the extension of storage time,among which the free water decreased continuously,and the bound water decreased initially and subsequently increased. The experimental results demonstrated that LF-NMR could be applied to determine the freshness of milk rapidly and efficiently,which will be beneficial to monitor the quality of fresh milk in real time during transportation or storage.