Fabrication and Characterization of Cereal Protein Based Delivery Systems for Nutraceuticals

Cereal proteins are one kind of the ideal biomaterials to develop delivery systems of bioactives due to the low toxicity, high biocompatibility/biodegradability, cost effectiveness, and versatile functionalities. The present research was focused on developing delivery systems of bioactives using cereal proteins with respect to formulation aspects and fabrication methods. In the first part of this study, protein from proso millet was extracted by two methods and then used to encapsulate curcumin. Subsequently, to further evaluate the delivery potential, protein from proso millet was compared with maize protein at a laboratory scale, which has been recognized as an excellent delivery material. For both studies, the fabrication parameters were systematically studied and the influence of encapsulation on functionalities and stabilities of nutraceuticals were investigated. In the next, a novel method was developed to prepare zein nanoparticles by the combination of thermal treatment at 70 ℃ and antisolvent process, leading to smaller size and more homogenous distribution. Polysaccharide, i.e., gum arabic and sodium alginate, were employed as a secondary layer to further improve the physicochemical properties of zein nanoparticles. To avoid the use of organic solvents like ethanol, a pH-cycle and low-energy method was developed to emulsify alkaline-dissolved eugenol by utilizing the pH-dependent solubility properties of zein and self-assembly properties of sodium caseinate (NaCas). The nanoemulsions showed extraordinary storage stability up to 30 days and retained good redispersibility after spray-/freeze-drying. Then, this self-assembly method was applied to prepare the antioxidant film by incorporating curcumin and zein to NaCas-based film. The addition of zein could significantly constrain moisture transfer and improve the tensile strength of NaCas-based film. Subsequently, the mechanism, i.e., conformational changes and interactions between zein and NaCas that play an important role during the pH-cycle process, was studied by fluorescence spectroscopy and other techniques including Raman spectroscopy and surface tension, etc. Finally, the pH-cycle method was firstly employed to investigate the delivery potential of protein from brewers’ spent grain by encapsulating curcumin