Abstract:

【Objective】 The water composition of Ginkgo biloba seeds plays an important role in its physiological metabolism and affects its quality. Information about moisture distribution and migration inG. biloba seeds during hot air drying can provide data to optimize drying and rapidly determine the water content during storage. 【Method】The Carr-Purcell-Meiboom-Gill decay signals were obtained during hot air drying of G. biloba seeds by low-field nuclear magnetic resonance (NMR) equipped with a 0.5 T permanent magnet and proton resonance frequency of 21 MHz at a temperature of 32℃. The transverse relaxation time (T₂) was calculated based on the decay signal data using the SIRT algorithm, which provides the position and area of each peak. NMR images were obtained by SE imaging sequence. 【Result】 The drying rate increased with an increase in the air temperature during hot air drying. For all states of water, T₂ followed a decreasing trend during drying. The states of water could be classified into three main categories: bound water (0.79-7.32 ms), weakly bound water (13.67-89.07 ms), and free water (109.70-1 072.27 ms). The moisture state ofG. biloba seeds changed, and free water and weakly bound water were gradually removed during hot air drying. Increased water content significantly correlated with stronger NMR signals and larger peak areas. This phenomenon can be described by this equation: y = 7 436.46 x + 153.32 (R²= 0.993). NMR imaging was used to visualize proton images at different stages in the light and dark. 【Conclusion】 There is a high correlation between moisture content and NMR relaxation peak value. The water content of G. biloba seeds can also be observed directly using a nuclear magnetic map.

Key words: ginkgo seed, moisture transformation, dry, low field-nuclear magnetic resonance, transverse relaxation time