Moisture absorbed into the powder of Met-Pro-Asp-Ala-His-Leu (MPDAHL)-a novel egg albumen antioxidant peptide-profoundly affects its properties. In this study, we elucidated water dynamics in MPDAHL using DVS, DSC, and low-field 1 H NMR. Based on the DVS data, we found that MPDAHL sorption kinetics obey a parallel exponential model. DSC results indicated that both water and heating could change the microstructure of MPDAHL. The T2 parameters of NMR reflected the different phases of moisture absorption revealed that there were 4 categories of water with different states or mobility in the MPDAHL during the moisture absorption process. The fastest fraction T2b mainly dominated the hygroscopicity of MPDAHL and the absorbed water significantly changed the proton distribution and structure of MPDAHL. Thus, this study shows that DVS, DSC, and low-field 1 H NMR are effective methods for monitoring water mobility and distribution in synthetic peptides. It can be used to improve the quality assurance of functional peptides.
Keywords: differential scanning calorimetry; dynamic vapor sorption; egg albumen peptide; low-field nuclear magnetic resonance; water dynamics.
© 2016 Institute of Food Technologists®.