Soluble starch/whey protein isolate complex-stabilized high internal phase emulsion: Interaction and stability

The complexes of soluble starch and whey protein isolate (WPI) were prepared and used to stabilize high internal phase emulsion (HIPE). Ultraviolet absorption and fluorescence analyses confirmed that the starch/WPI complexes were formed. These complexes were formed by hydrophobic interaction. Through appearance, micro-morphology, particle size, and rheological properties analyses, it was found that stable HIPE could be prepared by the starch/WPI complex when the addition of starch reached 7.5%. In addition, β-carotene in the WPI-stabilized HIPE was completely degraded after 72 h of ultraviolet irradiation, while β-carotene in the starch/WPI complex-stabilized HIPE still had a retention rate of 17.95%. Finally, the stability of the starch/WPI complex-stabilized HIPE was explored. The starch/WPI complex-stabilized HIPE was more stable in acidic environments, but the possible exception was the pI of the WPI. Particularly, this HIPE was stable at high ionic strengths. These results suggested that starch was able to improve the emulsifying ability of WPI.