Dynamics of water mobility and distribution in soybean antioxidant peptide powders monitored by LF-NMR.

In this study, we aimed to elucidate the characteristics of water mobility and distribution in soybean antioxidant peptide powders (SAPPs) using low-field nuclear magnetic resonance (LF-NMR). SAPPs of three different molecular weights (MWs) were exposed to a room temperature environment with a relative humidity of 45%, and the dynamics of water mobility and distribution were monitored by LF-NMR. Results revealed that there were four transverse relaxation time fractions in SAPPs. The major (over 90%) fraction was bound water, and the distribution of water in samples with different MWs was different. The moisture absorption capacity of SAPPs with MWs of less than 1 kDa was the strongest, and all T2 fractions/water population contents in SAPPs with MWs of 1-3 kDa were the lowest. This study provided an effective real-time monitoring method for water mobility and distribution in SAPPs and may have applications for promoting peptides quality assurance.