Sustainable valorization of jojoba oilcake: Pressing method-dependent protein stability and functionality for food applications

Jojoba (Simmondsia chinensis) is known for its highly versatile oil, which has good therapeutic and cosmetic applications. The residual meal, rich in protein (26–29 %), is unexploited and limited for use in food systems due to the presence of anti-nutritional factors (mainly in the seed coat). This study attempts to upcycle jojoba oil cake to produce alternative proteins by investigating its extractability, and physicochemical, and functional characteristics. Three different extraction methods, namely, hot-pressed, dehulled and hot-pressed, and cold-pressed, were adopted. The results showed a significant impact of the pressing techniques on the properties of jojoba protein. Dehulling resulted in high purity (81.34 %) proteins with enhanced nutritional profile but had a negative effect on the stability (T_d: 76.9 °C) and functional properties. Hot pressing methods resulted in protein dissociation, denaturation (T_d: 79.9 °C), and disintegration, leading to the loss of structural integrity, which was evident from the SEM images. Conversely, the cold-pressed proteins exhibited high thermal stability (T_d: 87.4 °C), bioactivity (73.63 % DPPH free radical scavenging activity), and functional properties despite having comparatively lower purity (61.53 %). The supremacy is attributable to the structural integrity of the proteins, which is preserved due to minimal processing impact. Overall, the findings demonstrated that jojoba proteins derived from cold-pressed oil cake displayed remarkable functional properties, suggesting their potential as a valuable functional ingredient. This enhances the circular bioeconomy through the use of agro-industrial residues in the food industry, resulting in waste reduction and promoting sustainability.