Zein-Polyglycerol Conjugates with Enhanced Water Solubility and Stabilization of High Oil Loading Emulsion.

Huang, Shuangshuang; He, Junbo; Han, Lijuan; Lin, Hong; Liu, Gang; Zhang, Weinong

To increase the water solubility of zein as a stabilizing agent for oil-in-water (O/W) emulsions, three zein-polyglycerol (Zein-PG) conjugates, Zein-PG-2, Zein-PG-6, and Zein-PG-10, were prepared by dehydration between zein and polyglycerol aldehydes obtained by NaIO4 oxidation of polyglycerol-2, -6, and -10, and characterized by free amine content, grafting degree, Fourier transform infrared spectroscopy, and fluorescence spectra. All conjugates dispersed in water as nanoparticles and were verified by transmission electron microscope. Conjugation with PG changed the isoelectric point of zein from 6.2-6.8 to 4.0. Zein-PG-6 and Zein-PG-10 showed strong stabilization on the O/W emulsions with 18-fold loading of soybean oil on the basis of conjugate mass, displaying high oil loading capacity. CLSM confirmed the O/W structure of emulsions and that the absorption of Zein-PG-10 on the oil droplet surface offered the driving force to be stable. The present Zein-PG conjugates thus produced an enticing resource for use as nanocarriers or bio-emulsifiers in food or pharmaceutical industries.