Enhancing margarine oxidative stability, antioxidant retention, and sensory quality via tragacanth-chitosan hydrogel microencapsulation of supercritical CO₂-extracted green coffee

Margarine's susceptibility to oxidative deterioration was addressed by microencapsulating supercritical CO₂-extracted green coffee antioxidants (GCSE) in tragacanth-chitosan (TG-CS) hydrogels. Optimized extraction (70 °C, 30 MPa, 20 % ethanol) yielded GCSE with high phenolic content (36.35 mg GAE/g dw) and antioxidant activity (89.76 % DPPH, 91.79 % ABTS inhibition). Encapsulation at a 1:3 TG-CS ratio achieved 85.28 % efficiency, retaining 149.54 mg GAE/100 g phenolics. Characterization (SEM, FTIR, XRD) confirmed micro-scale particles (0.928 μm) with moderate stability (Zeta potential: -17.66 mV) and sustained release (67.33 % over 6 h). In margarine, encapsulated GCSE (T2) maintained oxidative stability (peroxide: 2.02 meq/kg; p-anisidine: 4.88 mMol/kg; acid value: 1.81 mg NaOH/g), comparable to synthetic TBHQ (T3), while the control (T4) deteriorated rapidly. T2 retained 59.48 % DPPH activity (vs. 51.06 % for free GCSE, T1) and matched T3's sensory quality (aroma, texture, color; p > 0.05). TG-CS microencapsulation offers a dual-functional, clean-label solution for lipid-based foods, enhancing shelf life without compromising natural efficacy.