Effect of Extraction Method on the Yield and Quality of Mullet Roe Oil

Abstract

Striped mullet (Mugil cephalus) roe is used for the production of high nutritional and added‐value delicacies. Its lipid fraction is rich in polyunsaturated fatty acids (PUFA) and bioactive compounds. This study examines scalable oil extraction methods for mullet roe oil extraction. Namely, solvent extraction (SE) using ethanol in two different temperatures, supercritical fluid extraction (SFE) using CO2‐ethanol mixture (SFE‐E) in two different temperatures, expeller oil press (EP) extraction, expeller oil press combined with ethanol extraction (EP‐SE) and wet reduction (WR) are examined. The methods are evaluated with regard to the oil yield and recovery, the oil oxidation and the composition in fatty acids, and polar compounds and unsaponifiable matter. EP‐SE and SE provide the highest oil recovery for tested extraction temperatures (76% and 65% respectively), followed by SFE‐E (46%) and EP (36%). Extracted oils present high PUFA content (28.5–33.9%). The type of extraction process and the process variables affect oil oxidation as well as the concentration of polar compounds and unsaponifiable matter. In terms of oxidation levels, 85% of the extracted oil samples were within the limits set by the Codex Alimentarius Commission. The potential of the examined methods for industrial mullet roe oil production is discussed. Practical applications: Oil rich in polyunsaturated fatty acids was extracted from stripped mullet roe. The work proposes several scalable extraction methods using mild conditions which could be applied to obtain edible and high nutritional value mullet roe oil with high recovery reaching up to 76%. The same methods could be employed also for mullet roe by‐products. The obtained results improve the knowledge regarding the potential of roe valorization for oil extraction as well as the effect of the extraction method on the oil yield, main composition features and the quality characteristics of oil extracted by mullet roe. This research could offer new opportunities for the food industry for fish roe valorization for high nutritional quality oil production.

Oil from Mullet Roe Byproducts: Effect of Oil Extraction Method on Human Erythrocytes and Platelets

“…Overall, enzymatic extraction resulted in much higher concentrations of secondary oxidation products and the expeller press provided the best results in terms of all oxidation indices. The effect of non-enzymatic processes on mullet roe oil quality has recently been examined in detail by Kalogianni et al [ 9 ] and Georgiou et al [ 8 ], highlighting that process factors have an impact on oil quality in terms of oxidation.…”

“…Although avgotaracho and its associated products are frequently consumed, nothing is known about their toxicity or that of their oil extracts. Regarding the methods of oil extraction, traditional techniques for fish-oil extraction, which mainly involve wet rendering or solvent extraction, can involve heating and/or the use of organic solvents [ 6 , 8 ]. The former causes heat-labile compounds to oxidize and degrade, whereas the latter is hazardous to human health and the environment.…”

“…These techniques include pH-shift processing, enzymatic hydrolysis, subcritical water extraction, fermentation, supercritical fluid extraction with carbon dioxide (SFE–CO 2 ), ultrasound extraction, and microwave extraction [ 10 ]. Kalogianni et al and Georgiou et al applied physical methods as well as organic solvent extraction in order to produce food-grade mullet roe oil from avgotaracho production waste [ 8 , 9 ]. An expeller press and ethanol extraction methods were selected as the methods, providing good recovery and oil-quality characteristics.…”

“…To the best of the authors’ knowledge, there is no previous study that examines the biological effects of mullet roe oil or mullet roe oil byproducts. For the extraction, a physical extraction method and a solvent extraction method—namely, expeller press extraction and ethanol extraction—were selected according to our previous work as methods that could provide a good extraction yield and good oil-quality characteristics as determined by chemical analysis [ 8 , 9 ]. In addition, enzymatic extraction, which is often used for the production of oils from fish byproducts [ 11 , 12 ], was used for comparison.…”

“…Expeller oil press extraction (EP)T = 50 • C; centrifuging at 4132× g for 15 min[8,9] Solvent extraction (SE-25) T = 25• C for 2 h two times with ethanol; evaporation at 37 • C and 5 mbar [8,9] Enzymatic extraction (alcalase) (EE) 300 g; enzyme inactivation at 90 • C for 10 min with Alcalase ® 1%; incubation for 35 min at 55 • C; enzyme inactivation for 10 min at 90 • C; cooling at 25 • C; centrifuging at 8000 rpm for 15 min at 25 • C [14] Enzymatic extraction (protease) (EE) 300 g; enzyme inactivation at 90 • C for 10 min with Protease ® 1%; incubation for 35 min at 55 • C; enzyme inactivation for 10 min at 90 • C; cooling at 25 • C; centrifuging at 8000 rpm for 15 min at 25 • C [14]…”