Aqueous Phase Extraction of Caper Seed Protein by Ohmic Heating‐Assisted Enzymatic Technique: Assessment of Physicochemical Characteristics and Techno‐Functional Properties of Extracts

ABSTRACT

Plant‐based proteins derived from underutilized seeds have attracted increasing interest due to their nutritional and techno‐functional potential. In this study, protein extraction from defatted Capparis ovata L. seeds was optimized using an integrated ohmic heating assisted enzymatic extraction (OHA‐EE) approach, while conventional alkaline extraction (CAE) was applied as a control. Process parameters were optimized using response surface methodology (RSM), identifying voltage and extraction time as the key factors affecting extraction efficiency. The optimum conditions were identified as 500 V and 100.7 min, with predicted values of 58.73% protein recovery and 88.40% total protein ratio. Experimental validation yielded 61.49% protein recovery and 90.16% total protein ratio, confirming the adequacy of the developed model. Compared with CAE, OHA‐EE significantly increased total soluble protein content (54.44 and 21.11 g protein/100 g powder, respectively), protein recovery (61.49% and 55.08%, respectively), and protein enrichment (1.48‐ and 1.32‐fold, respectively) of extracts. Amino acid profiling revealed higher concentrations of essential amino acids and hydrophilic residues in OHA‐EE proteins, contributing to improved solubility. OHA‐EE also enhanced water‐holding capacity (2.20 and 1.09 g water g ⁻¹ powder, respectively), oil‐binding capacity (2.91 and 1.55 g oil g ⁻¹ powder, respectively), and emulsion stability (523.35 and 187.31 min, respectively). Furthermore, improved protein solubility was observed under both acidic and alkaline conditions. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses confirmed extraction‐induced structural modifications and the formation of a more porous microstructure. Overall, the OHA‐EE method significantly improved protein recovery, structural characteristics, and techno‐functional performance. These findings demonstrate the potential of ohmic heating assisted enzymatic extraction for producing high‐quality plant protein powders and highlight the importance of comprehensive measurement and characterization in evaluating functional food ingredients.