Co-Processing Versus Infusion for Turmeric–Ginger Functionalization of Olive Oil: Effects on Quality, Bioactivity, and Storage Stability

This study compared co-processing during malaxation (TG_MAL) and post-extraction infusion (TG_INF) for the functionalization of olive oil with turmeric and ginger, using untreated extra virgin olive oil (U_EVOO) as a control. Three independent batches per treatment were monitored over 360 days for quality indices, color, apparent pigments, α-tocopherol, total phenolic content (TPC), antioxidant responses, in vitro digestive-enzyme inhibition, and sensory attributes. At T360, TG_MAL had the lowest peroxide value (9.79 meq O2 kg−1), compared with TG_INF (14.03) and U_EVOO (15.82), whereas TG_INF had the highest free acidity (1.04%). Both functionalized oils retained higher TPC than the control at T360 (379.65 and 384.65 versus 309.65 mg kg−1 for TG_MAL, TG_INF, and U_EVOO, respectively). Antioxidant responses were assay-dependent: functionalization did not consistently improve DPPH or ABTS scavenging, although lower apparent IC50 values were obtained in the β-carotene bleaching assay. TG_INF showed the lowest IC50 values for α-amylase, α-glucosidase, and pancreatic lipase at T360, indicating greater persistence of in vitro inhibitory activity. The two protocols also produced distinct color and sensory profiles. These findings demonstrate protocol-dependent trade-offs rather than a universally superior approach. Interpretation is limited by potential spice-derived spectral interference, different nominal spice dose bases, and the additional 30-day infusion period preceding the TG_INF storage baseline.