Effect of Supercritical Fluid Extraction on the Reduction of Toxic Elements in Fish Oil Compared with Other Extraction Methods

Abstract

High-quality fish oil for human consumption requires low levels of toxic elements. The aim of this study was to compare different oil extraction methods to identify the most efficient method for extracting fish oil of high quality with the least contamination. The methods used in this study were Soxhlet extraction, enzymatic extraction, wet reduction, and supercritical fluid extraction. The results showed that toxic elements in fish oil could be reduced using supercritical C 0 2 at a modest temperature (60°C) and pressure (35 MPa) with little reduction in the oil yield. There were significant reductions in mercury (85 to 100%), cadmium (97 to 100%), and lead (100%) content of the fish oil extracted using the supercritical fluid extraction method. The fish oil extracted using conventional methods contained toxic elements at levels much higher than the accepted limits of 0.1 pg/g.

Valorization of mullet roe by‐products for the production of polyunsaturated fatty acids rich oils

“…On the other hand, the low oil recovery of PE has been attributed in the past for other fish by‐products to the high water content of the raw material. These studies (Hajeb et al, 2015; Rubio‐Rodríguez et al, 2012) showed higher extraction yields for moisture contents of fish by‐products lower than 20%. In the present case, the low temperature used for PE extraction has also contributed to the low yield.…”

Supercritical CO2 processing of omega-3 polyunsaturated fatty acids – Towards a biorefinery for fish waste valorization

“…Oils from sturgeon [46,47], common carp [48], striped weakfish [49], jumbo squid [38], sardine [50], orange roughy [38], yellow croaker [51], trout [52], salmon [38,53,54], sardine, and rendered fish meal [55] have been also obtained by SFE over the last decade (Table 1). Reported omega-3 PUFA contents in the extracted oil differ from 0.8 [38] up to 46 %wt [41], depending on the fatty acid profile of the original fish species and the fish part. Studies also showed that omega-3 PUFA content was not affected by the extraction method, since the fatty acid profile of scCO2-extracted fish oil was very similar to that obtained by Soxhlet extraction with hexane [37].…”

“…for Indian mackerel [41][42][43][44], and 67 g oil/100 g raw material (dry basis) for African catfish [45].…”

“…for mercury, 97-100% for cadmium, and 100 % for lead) were obtained by SFE (35 MPa, 60 ºC) compared to Soxhlet extraction with petroleum ether [41]. Inorganic or polar organometallic forms of heavy metals (e.g.…”

“…Inorganic or polar organometallic forms of heavy metals (e.g. arsenobetaine and most Cd and Pb forms) are not extracted by SFE due to the low polarity of scCO2 [38,41]. However, non-polar organometallic forms such as arsenolipids [62] or methylmercury [63] present higher lipophilicity and may be partially coextracted with fish oil during SFE; thus, its presence in the raw material and the final products should be monitored.…”