Multianalytical Characterization of Elderberry (Sambucus nigra L.) Pulp-Enriched Kefir Ice Cream: From Structure to Aroma and Sensory Quality

The development of functional frozen dairy products enriched with natural bioactive ingredients has attracted increasing interest. Elderberry (Sambucus nigra L.) is an anthocyanin-rich fruit with potential as a natural functional and coloring ingredient in dairy products. This study investigated the effects of incorporating 3%, 6%, and 9% elderberry pulp into kefir ice cream on its physicochemical, antioxidant, thermal, microstructural, volatile, and sensory properties. The study provides an integrated evaluation of elderberry-enriched kefir ice cream by combining physicochemical and antioxidant characterization with DSC, SEM, HS-SPME-GC/MS, and sensory analyses. Elderberry supplementation significantly decreased pH, increased redness, and enhanced total phenolic content and ferric reducing antioxidant power, which reached 694.16 mg GAE/100 g DM and 49.70 µmol TE/100 g DM, respectively, in EP9 (p < 0.05). Formulations containing elderberry pulp also showed significant differences in overrun, density, melting behaviour, and thermal properties (p < 0.05). Differential scanning calorimetry indicated lower melting enthalpy values in the elderberry-containing formulations, while scanning electron microscopy revealed modifications in porous microstructure. HS-SPME-GC/MS analysis tentatively identified 25 volatile compounds, with ketones representing the predominant volatile group and elderberry supplementation modifying the relative abundance of selected volatile compounds. Sensory evaluation showed improved appearance, flavor, texture, and overall acceptability compared with the kefir control (p < 0.05). Overall, formulations containing 6% and 9% elderberry pulp provided a favorable balance between technological quality, functional potential, and sensory acceptability, suggesting a practical formulation range for the development of naturally colored, functional kefir-based frozen dairy products.