Ultrasound‐ and Microwave‐Assisted Extractions Facilitate Oil Recovery from Gilthead Seabream (Sparus aurata) By‐Products and Enhance Fish Oil Quality Parameters

Abstract

AbstractThis research aimed to analyze ultrasound (UAE) and microwave‐assisted extraction (MAE) as novel technologies for utilizing gilthead seabream (Sparus aurata) by‐products to produce high‐quality fish oil for human consumption. The impacts of extraction parameters, namely, temperature, time, solvent‐to‐solid ratio, and their interactions on the extraction yield, are investigated using response surface methodology (RSM), and a central composite rotatable design. The optimized conditions are 15.47 mL g−1 of solvent‐to‐solid ratio, 38 min, and 42 °C for UAE and 15.84 mL g−1 of solvent‐to‐solid ratio, 18 min, and 40 °C for MAE. Under optimal conditions, the maximum extraction yields are 38.40 and 36.70% (g/g) for UAE and MAE, respectively. Both UAE and MAE have significantly higher mass transfer rates (61.70 and 121.58 g h−1, respectively) than Soxhlet extraction (10.78 g h−1). The fatty acid composition, physicochemical, and oxidation analyses of fish oils confirm the suitability of both UAE and MAE for the recovery of high‐quality oils from fish processing by‐products. The valorized oils mainly include unsaturated fatty acids (≈75%) and are rich in oleic acid. Furthermore, scanning electron microscopy analysis reveals that the key driving force for fast oil extraction is the structural degradation of fish by‐products caused by ultrasound and microwave.Practical Applications: Due to environmental and economic viewpoints, the validation of fish oil from fish industry by‐products has become a popular research topic recently. Alternative recovery techniques such as ultrasound‐ (UAE) and microwave‐assisted extraction (MAE) protocols may have additional benefits in producing functional oils. Interactive effects of process parameters determine the success of the extraction technique; therefore optimization is a critical approach when applying the extraction protocols. This study shows that UAE and MAE techniques significantly enhanced oil extraction rate from gilthead seabream (Sparus aurota) by‐products at lower temperatures and by using lower amounts of solvent. UVA and MAE increase oxidative stability and do not change the fatty acid composition. Hence, the by‐product of the gilthead seabream can be a sustainable and food‐grade fish oil source and UAE and MAE can be a good alternative to the conventional (Soxhlet) extraction by providing high yield and quality oil.