Alginate–Pomegranate Peel Conjugates in Functional Ice Cream: Improved Rheological Stability, Meltdown Resistance, and Potential Anti-inflammatory Activity

This study addresses the circular valorisation of Punica granatum peels through eco-friendly ultrasound-assisted extraction, yielding a phenol-rich extract (BM, 32.78% yield). Qualitative LC-MS/MS characterization allowed the identification of main constituents, notably punicalin, punicalagin, gallocatechin, and ellagic acid, whereas target phenolic compounds were individually quantified via LC-MS/MS using reference standards. We hypothesized that the lipase-assisted incorporation of pomegranate polyphenols into alginate improves structural stability while preserving antioxidant and anti-inflammatory properties. BM and the resulting phenolic-enriched polymer PBM exhibited high total phenolic content (319.02 and 129.53 mg GAE g–1, respectively) and strong DPPH/ABTS radical scavenging activity (IC50 = 0.0159–0.0678 mg mL–1). When incorporated into artisanal ice cream as a dual-action agent (GPBM at 0.3% w/w phenolic-enriched polymer vs free extract GBM at 2.4% w/w), rheological analysis showed that PBM reinforces the matrix, shifting the G’ and G’’ transition region to higher temperatures (+5 °C) and accelerating structural recovery at −7 °C to 350 s (compared to >1,200 s for control ice cream GC). Melting kinetics revealed superior stability for GPBM, delaying initial drip time to 480 s (vs 300 s in GC and 120 s in GBM) and the 50% drip-through end point to 1,620 s (vs 1,080 s in GC), while achieving a near-complete meltdown (4.32% residual weight vs 50.50% at 6,000 s in GBM, where the 50% drip-through end point was not reached). Furthermore, both ingredients dose-dependently reduced nitric oxide production in LPS-stimulated RAW 264.7 macrophages. Overall, PBM shows promise as a candidate ingredient with combined rheological and in vitro bioactive potential for frozen dessert formulations.