title: Water dynamics of Ser-His-Glu-Cys-Asn powder and effects of moisture absorption on its chemical properties.
abstract: BACKGROUND
  This study has elucidated moisture dynamics in the soybean peptide, Ser-His-Glu-Cys-Asn (SHECN) powder by using dynamic vapor sorption (DVS) and nuclear magnetic resonance (NMR). We also tried to investigate the effects of moisture absorption on the biological activity and chemical properties of SHECN with some effective methods such as mid-infrared (MIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).
  
  
  RESULTS
  DVS results showed that the moisture absorption of SHECN could reach a maximum of 33%, and the SHECN powder after synthesis actually existed in a trihydrate state of SHECN.3H2O. Low-field NMR revealed that three water proportions including strong combined water, binding water and bulk water were involved in SHECN moisture absorption and absored water dominantly existed in the form of combined water. Magnetic resonance imaging (MRI) and MIR spectroscopy results indicated that moisture absorption could change the morphology and structure of SHECN. After moisture absorption at 50% and 75% relative humidity, 19 volatiles were identified by GC-MS analysis. Additionally, this study showed that a part of reductive groups in SHECN was oxidized and its antioxidant ability declined significantly (P < 0.05) after moisture absorption.
  
  
  CONCLUSIONS
  Water absorbed into SHECN powder can significantly change its microstructure and cause its activity to decrease. We must prevent SHECN from absorbing moisture during storage because the water can accelerate the oxidation of samples and promote microbial reactions. © 2016 Society of Chemical Industry.
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, People's Republic of China.
authors.forename: Songyi
authors.initials: S
authors.lastname: Lin
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, People's Republic of China.
authors.forename: Peiyu
authors.initials: P
authors.lastname: Xue
authors.affiliation: College of Food Science and Engineering, Jilin University, Changchun, People's Republic of China.
authors.forename: Shuailing
authors.initials: S
authors.lastname: Yang
authors.affiliation: College of Food Science and Engineering, Jilin University, Changchun, People's Republic of China.
authors.forename: Xingfang
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, People's Republic of China.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Dong
authors.affiliation: School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, People's Republic of China.|Department of Food, Nutrition and Packaging Sciences, Clemson University, Clemson, SC, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D008401:Gas Chromatography-Mass Spectrometry; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry*; D011208:Powders / Q000737:chemistry; D013025:Glycine max / Q000737:chemistry*; D014867:Water / Q000032:analysis*
chemical_list: D010455:Peptides; D011208:Powders; D014867:Water
keywords: GC-MS; LF-NMR; antioxidation; moisture absorption; soybean peptide; water dynamics