Solvent-Based Extraction of Pomegranate Seed Oil from Juice By-Products: Effects of Microwave-Assisted, Soxhlet, and Cold Methods on Quality and Oxidative Stability

Pomegranate juice production generates substantial seed residues, which can be valorized through extraction of PSO, rich in conjugated C18:3 isomers and bioactive minor constituents. This study compared three solvent-based extraction methods—MAE, Soxhlet extraction (SE), and cold solvent extraction (CSE)—for PSO recovery from juice-processing by-products. Oils were extracted using n-hexane and evaluated for yield, oxidative stability (using pressure differential scanning calorimetry), chemical quality parameters, fatty acid composition and derived nutritional indices, as well as bioactivity. Extraction method influenced oil performance: MAE combined the highest yield with the most favorable oxidative-stability metrics, SE showed intermediate results, and CSE provided lower yield but slightly better preservation of quality markers. All oils exhibited low hydrolytic degradation and limited oxidation progression, while fatty acid profiles remained largely unchanged, preserving the characteristic PSO pattern. Phenolic content and radical-scavenging capacity were moderately sensitive to extraction approach. Overall, differences in oxidative stability and bioactivity among methods were primarily driven by process conditions and minor-component retention rather than changes in major fatty acids, offering guidance for optimizing PSO recovery from juice-industry by-products.