Extraction, Refining, and Quality Analysis of Fish Oil from Three Types of Squid Viscera

To explore the different extraction methods and traditional refining process of squid visceral fish oil and its quality changes, the deep-sea squid viscera from the Equator, Argentina, and the North Pacific were used as raw materials in this study. Firstly, different organic reagent extraction methods and compound methods were used to extract fish oil from Argentine squid viscera. The method with the highest oil yield and best quality was selected for refining three types of crude squid visceral oil. The sensory morphology, physicochemical indicators, fatty acid composition and volatile flavor compounds of three types of crude and refined squid visceral oils were analyzed. The results showed that the oil extraction method of the No.6 solvent assisted freeze-thaw was the best, with a yield of 12.90%, and the physical and chemical indexes of squid visceral oil after refining were significantly improved. The peroxide value, insoluble impurities, color difference value, acid value, moisture and volatiles, and anisidine values were significantly reduced (P<0.05), and the pH and decolorization rate were significantly increased (P<0.05). Except for insoluble impurities and moisture and volatiles, the remaining indicators met the standards of SC/T 3502-2016 for crude fish oil and refined fish oil. A total of 16 fatty acids were detected in three squid visceral oil, mainly oleic acid, palmitic acid, EPA, and DHA. The types of fatty acids remained unchanged and the content of polyunsaturated fatty acids increased after refining. Sixty-five volatile flavor substances were detected in squid visceral oil, including 12 essential flavor substances of squid visceral oil, mainly trans-2-cis-6-nonradial, which jointly offered squid visceral fish oil the odor characteristics. This research can be applied to the deep processing technology of deep-sea squid by-products, internal organs, product extraction, and high-value utilization of fish oil, which provides technical support and theoretical basis.