Tailoring chickpea protein functionality for food applications through supercritical CO₂ processing

This study evaluates the use of supercritical CO₂ (SCCO₂) as a dual-purpose method for defatting and modulating the functional properties of chickpea protein. Two processing routes were investigated: 1) post-extraction SCCO₂ modification of protein obtained from full-fat flour (CP series), and 2) flour defatting followed by protein extract modification with SCCO₂ at different pressures (DFCP series). CP0 and DFCP0 refer to proteins from untreated and SCCO₂-defatted flours, respectively; CP75-800 and DFCP75-800 underwent additional SCCO₂ treatments at indicated pressures. SCCO₂ defatting at 850 bar and 65 °C reduced flour fat content by ∼79 % and yielded an 87.6 % pure protein extract (DFCP0) compared to ∼64 % in untreated CP0. Post-extraction SCCO₂ treatment further enhanced DFCP protein purity to >90 % at pressures ≥75 bar. Notably, solubility in DFCP75 reached 92.7 %, a 13 % improvement over the untreated DFCP0. SCCO₂ defatting prior to extraction efficiently improved protein gelling, lowering the minimum gelling concentration (MGC) from 20 wt% (CP0) to 10 wt% (DFCP0). Subsequent SCCO₂ treatment further reduced MGC to 8 wt% in DFCP75-DFCP300. CP samples treated at 500-800 bar exhibited the highest foaming capacity (126.7 %) and a 50 % increase in water-holding capacity. Structural analyses confirmed pressure-dependent changes in denaturation enthalpy, secondary structure, and aggregation. Principal component analysis revealed SCCO₂ pressure as a dominant factor, explaining 49 % and 47 % of the multivariate variation in CP and DFCP, respectively. These findings demonstrate that SCCO₂ processing is a powerful and tunable method for producing high-purity, functionally enhanced chickpea protein suitable for food applications.