From Waste to Wealth: Valorizing Pomegranate Seeds into Bioactive Oil by Microwave and Soxhlet Extraction

The growing global interest in utilizing plant-derived by-products as sources of functional ingredients stems from their environmental, economic, and health benefits, stimulating the development of innovative extraction methods. Pomegranate (Punica granatum L.), valued for its high nutritional value and richness in bioactive compounds, generates significant amounts of processing waste, mainly in the form of peels and seeds, which may pose environmental challenges. Approximately 50% of the pomegranate fruit is discarded during juice production, underscoring the importance of effective valorization strategies. One promising approach is the extraction of pomegranate seed oil (PSO), which enables the conversion of waste into a high-value raw material.
The aim of this study was to compare the physicochemical properties of PSO obtained using microwave-assisted extraction and Soxhlet extraction. The degree of hydrolysis was evaluated using the acid value, while the peroxide value was used to determine the content of primary oxidation products, in accordance with AOCS methods. Oxidative stability was assessed using pressure differential scanning calorimetry (PDSC), and the fatty acid profile was determined by gas chromatography (GC).
The results demonstrated that microwave-assisted extraction was more efficient than the Soxhlet method. The extracted PSO contained over 85% polyunsaturated fatty acids (PUFAs), including approximately 70% punicic acid, which is characteristic of this oil. Despite the low oxidative stability attributed to the high PUFA content, the oils showed good hydrolytic stability, with acid and peroxide values meeting the requirements specified in the Codex Alimentarius.
Overall, PSO serves as a valuable reservoir of bioactive compounds, particularly polyunsaturated fatty acids, and holds significant potential as a functional ingredient in food and nutraceutical formulations; however, further investigation is necessary to address its limited oxidative stability.