Prolamin, an important storage protein of grains, is able to dissolve in aqueous ethanol because of its unique hydrophilic−hydrophobic property. The low allergenicity of prolamin makes it a good replacement of gluten to maintain textural properties of gluten-free food; the film-forming property makes it an excellent coating material for candy or nuts to extend shelf life and reduce flavor loss. However, the prolamin extraction process is not environment friendly with high energy and water consumption. The utilization of the switchable extractant will minimize the environmental impact of prolamin processing and get maximum utility out of the extractant and cut down energy and water consumption as well as simplify the extraction procedures. A switchable composite extractant (SCE) has been developed for a complete extraction of zein, which is the most abundant prolamin. By virtue of the solvent temperature-swing property, the SCE-simplified zein extraction increased the solvent usefulness and reduced the energy and water consumption. The electrophoretic patterns of the protein extracted by the SCE and aqueous ethanol showed the same main bands as the commercial counterpart. The extracted zein showed a similar protein recovery rate compared to aqueous ethanol (28.74% vs 29.38%) and a similar amino acid profile and solubility in aqueous ethanol (92.35% vs 92.06%) compared to the commercial counterpart with better tensile properties (4.38 MPa vs 2.68 MPa). The advantages of this new technique are numerous: (a) energy and water consumption was largely reduced; (b) procedures were simplified since no rectification of ethanol was needed; (c) potential harm of ethanol vapor to workers or industrial environment was minimized; and (d) no additional procedure was needed for the recycling of the SCE. This method minimizes the environmental impact of prolamin processing, optimizes the extractant, reduces the energy and water consumption, and simplifies the extraction procedures.

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As consumers’ interest in nature-sourced additives has increased, zein has been treated hydrothermally under alkaline conditions to prepare a nature-sourced emulsifier. The effects of mild hydrothermal–alkaline treatment with different temperatures or alkaline concentrations on the emulsifying properties of zein were investigated. The emulsification activity and stability index of zein hydrolysates increased by 39% and 164%, respectively. The optimal simple stabilized emulsion was uniform and stable against heat treatment up to 90 °C, sodium chloride up to 200 mmol/L, and pH values ranging from 6 to 9. Moreover, it presented excellent storage stability compared to commonly used food emulsifiers. The surface hydrophobicity caused the depolymerization of the tertiary structure of zein and the dissociation of subunits along with exposure of hydrophilic groups. The amino acid composition and circular dichroism results reveal that the treatment dissociated protein subunits and transformed α-helices into anti-parallel β-sheets and random coil. In conclusion, mild hydrothermal–alkaline treatment may well contribute to the extended functional properties of zein as a nature-sourced emulsifier.