Zein‐Based Adhesives: Sustainable Extraction and Application in Bioadhesive Technologies

Zein, a hydrophobic protein derived from corn, presents significant potential as a sustainable bioadhesive alternative to conventional petroleum‐based adhesives. This study explores a sustainable method for extracting and purifying zein from corn gluten meal (CGM), followed by a comparative analysis of raw, purified, and commercial zein. The samples were characterized by thermal (thermogravimetric analysis [TGA] and differential scanning calorimetry [DSC]), spectroscopic (Fourier transform infrared spectroscopy [FTIR] and ultraviolet–visible [UV–Vis] spectroscopy), and morphological (hot‐stage optical microscopy) analyses. Raw zein was extracted using aqueous ethanol and purified by anti‐solvent dialysis to remove impurities, including carotenoids. For adhesive formulation, raw zein was combined with sodium dodecyl sulfate (SDS) and cast into films, which were then modified by immersion in FeCl 3 or CaCl 2 solutions. The resulting zein‐based adhesives (Zein/SDS/Fe and Zein/SDS/Ca) were tested on various substrates (polypropylene, glass, wood, and cardboard) through shear tests. The adhesives demonstrated competitive bonding performance, particularly Zein/SDS/Fe formulation on wood substrate, confirming their potential for practical applications. In addition, the material exhibits characteristics that may contribute to sustainability and cost‐effectiveness, including the use of a renewable agroindustrial byproduct as feedstock, a high extraction yield (~90%), a simple and potentially scalable processing route, ethanol recovery and reuse, and relatively mild processing conditions.