NEGLECTED SICILIAN BLACK CHICKPEA LANDRACES: FROM FLOUR CHARACTERIZATION TO GELLING AND EMULSIFYING PROPERTIES OF THE ULTRASOUND-EXTRACTED PROTEINS

Sicilian black chickpea (Cicer arietinum L.) landraces represent a valuable agrobiodiversity resource for sustainable plant-based proteins. In this study, two distinct morphological ecotypes were selected and investigated: smooth (SBC) and rough (RBC). Despite their nutritional value, these pigmented legumes have been historically neglected due to factors such as their dark appearance and extended cooking times. A highly effective strategy to recover and valorize these landraces is the extraction of their proteins to formulate novel plant-based ingredients. However, utilizing conventional alkaline methods for this purpose can result in suboptimal recovery rates. An effective method to enhance extraction yield and modulate protein structure is ultrasound-assisted extraction (UAE), a green technology based on acoustic cavitation. In this context, the objective of the present work is first to comprehensively characterize the physicochemical properties of the native flours from both ecotypes, and then to investigate the effect of UAE on the structural, gelling, and emulsifying properties of their protein isolates. A comparative study of the native flours revealed that the rough ecotype is rich in soluble carbohydrates (raffinose family oligosaccharides) and exhibits superior hydration and swelling capacity, whereas the smooth ecotype contains slightly higher protein and fiber fractions. Subsequently, UAE was evaluated for protein recovery. Results showed that ultrasonication significantly improved the extraction yield up to 71% compared to conventional extraction, without inducing extensive polypeptide degradation. Structural analyses (FTIR, DSC, intrinsic fluorescence) demonstrated that acoustic cavitation promoted a partial structural unfolding, reduced aggregation, and increased surface hydrophobicity. The final part of the study focused on the functional application of these ultrasound-extracted proteins. The structural modifications enhanced their colloidal competence, allowing the formation of strong, highly water-retentive viscoelastic gels upon thermal treatment. Furthermore, the extracted proteins successfully stabilized oil-in-water emulsions, maintaining physical stability against coalescence over 10 days of storage due to strong electrostatic repulsions (zeta-potential ~ -30 mV). In conclusion, UAE effectively tailors the functionality of black chickpea proteins without extensive chemical modifications, demonstrating the versatility of these neglected landraces as sustainable ingredients for the stabilization of both structured gel networks and complex emulsion systems