Destruction of hydrogen bonding and electrostatic interaction in soy hull polysaccharide: Effect on emulsion stability

Hydrogen bonding and electrostatic interactions play an important role in the microstructure of soy hull polysaccharide (SHPA) and the stability of corresponding emulsions. In this study, urea and NaCl were added in the preparation of samples, which could destroy these two noncovalent interactions, and they were labeled as SHPAU and SHPA-N, respectively. The results show that more hydrogen bonding was generated along with the electrostatic shielding effect, which led to longer and branched polysaccharide chains of SHPA-N. However, the chain of SHPA-U was rough and fragmentary, which may be attributed to hydrogen bonding and protein regions destroyed by urea. Furthermore, the addition of NaCl and urea led to lower interfacial pressure, and the adsorption kinetics at the oil/water interface were significantly changed. In addition, all emulsions had a liquidlike structure, and both SHPA-N and SHPA-U emulsions had a bimodal size distribution. The relaxation time and line width of the 1H NMR analysis decreased with the addition of NaCl and urea, indicating the decreasing interaction between SHPA-N/SHPA-U and oil molecules. These phenomena were related to the coalescence and flocculation in these two emulsions. After 24 h of storage, the stability of the SHPA-N emulsion was superior to the others; this may be due to its higher viscosity. This study laid the foundation for further research on the mechanism of polysaccharide O/W emulsions stabilized by SHPA and other polysaccharides.