Upcycled Jojoba Protein as a Next-Generation Hydrocolloid: Advancing Emulsification, Gelation and Novel Applications for Sustainable Food Systems

Abstract

Transitioning to sustainable food systems requires innovative valorization of agro-industrial side streams into high-value functional ingredients. This study introduces jojoba (Simmondsia chinensis) oilcake, a largely underutilized oil extraction residue, as a promising source of upcycled protein with dual hydrocolloid functionality in emulsification and gelation. Protein was extracted using alkaline extraction and isoelectric precipitation, achieving a recovery of over 60% and ~70% purity. Mass balance analysis substantiated the valorization potential of the oilcake at 28% while confirming scalability. Osborne fractionation identified glutelin (61.7%) and albumin (34.6%) as predominant fractions, suggesting strong interfacial and gel-forming abilities of jojoba protein (JP). The pH-dependent physicochemical analysis indicated that solubility, secondary structure, surface hydrophobicity, and interfacial behavior of JP improved under neutral to alkaline conditions, with pH 7 demonstrating optimal performance. Comparative functional assays showed that JP had superior emulsifying ability (28.45 ± 0.55 m2/g) and comparable least gelation concentration (10%) to soy and pea proteins, with tunable functionality for heat-induced applications. The quantitative evaluation of intermolecular forces supported these findings, which identified hydrophobic interactions and covalent crosslinking (disulfide bonds) as major contributors to emulsification and gelation, respectively. Dynamic rheology further confirmed heat-induced, tunable viscoelastic networks in JP gels. To showcase the practical applicability, JP replaced conventional hydrocolloids in a millet milk–based custard system, effectively stabilizing the matrix and enhancing gel network formation, creaminess, and overall structural homogeneity. This proof-of-concept underscores the potential of JP in translating the structure–function attributes for the development of climate-smart innovative food products. These results imply that JP could be a multifunctional hydrocolloid, delivering structural and functional versatility in plant-based food formulations. In addition to functionality, jojoba offers distinct ecological benefits, such as minimal water and agrochemical supplies, adaptability to arid and marginal lands, and carbon sequestration ability. This makes jojoba a climate-resilient and resource-efficient protein source. Overall, the study positions jojoba protein as a next-generation, upcycled hydrocolloid in the evolving landscape of plant-based proteins and functional ingredients. The approach bridges innovative protein science with circular bioeconomy principles, presenting a transformative pathway toward resilient, resource-efficient, and sustainable food systems.