Effects of cooking techniques on fatty acid and oxylipin content of farmed rainbow trout (Oncorhynchus mykiss)

Abstract

The aim of this study was to investigate the effect of various cooking techniques on the fatty acid and oxylipin content of farmed rainbow trout. Rainbow trout is an excellent source of long‐chain omega‐3 (n‐3) polyunsaturated fatty acids (PUFA) which have beneficial health effects. Fillets of 2‐year‐old farmed rainbow trout were baked, broiled, microwaved, or pan‐fried in corn (CO), canola (CaO), peanut (PO), or high oleic sunflower oil (HOSO). Fatty acids and oxidized lipids were extracted from these samples and their respective raw fillet samples. Fatty acid content was determined using gas chromatography and oxylipin content by mass spectroscopy. The values obtained from each cooking method were compared to those obtained from the respective raw fillets using paired t tests. PUFA content was not altered when samples were baked, broiled, microwaved, or pan‐fried in CO or CaO. Pan‐frying in PO reduced α‐linolenic acid (18:3n‐3), eicosadienoic acid (20:2n‐6), and dihomo‐γ‐linolenic acid (20:3n‐6), while pan‐frying in HOSO reduced 18:3n‐3, eicosapentaenoic acid (20:5n‐3), docosapentaenoic acid (22:5n‐3), docosahexaenoic acid (22:6n‐3), linoleic acid (18:2n‐6), 18:3n‐6, 20:2n‐6, 20:3n‐6, docosatrienoic acid (22:2n‐6), and adrenic acid (22:4n‐6) compared to raw fish. Cooking decreased the omega‐6 (n‐6) PUFA‐derived oxylipins, but caused no change in 20:5n‐3 or 22:6n‐3‐derived oxylipins of the fillets. In conclusion, pan‐frying was the only cooking method to alter the fatty acid content of the fillets, while observed changes in oxylipin content varied by cooking method. As the physiological impact of oxylipins is currently unknown, these results suggest that the cooking methods which optimize the consumption of n‐3 PUFA from rainbow trout are baking, broiling, microwaving, or pan‐frying in CO, CaO, or PO.

Nutritional characterization of freshwater mud eel (Monopterus cuchia) muscle cooked by different thermal processes

“…The ∑ω‐3PUFAs in raw FWME muscle was found 13.70%, which was reduced to 10.95%, 7.54%, 11.11%, and 11.11% in grilled, boiled, fried, and microwaved FWME muscles, respectively. Similar results of increasing the SFAs content and decreasing ∑ω‐3PUFAs in fish muscles due to various cooking treatments were reported (Flaskerud et al., 2017; Zhang et al., 2013). Eicosapentaenoic acid, considered as one of the most important fatty acids in fish oil, was found in very poor quantities in raw and cooked FWME muscles, ranging from 0.53% to 0.79%.…”

Profiling of Omega-Polyunsaturated Fatty Acids and Their Oxidized Products in Salmon after Different Cooking Methods

“…Although in this study, cooking oil was not used in the frying process, the reduction of PUFAs in pan-fried salmon may occur if cooking oil is added during frying. Flaskerud et al found that pan-frying trout in corn oil and canola oil had no effect on the level of PUFAs in the fish, but pan-frying with peanut oil and high oleic sunflower oil induced the reduction of EPA and of EPA and DHA, respectively [ 33 ]. This matched the findings from Gladyshev et al, who used sunflower oil to fry the salmon [ 13 ].…”

Effect of Core Temperature on the Oxidation of Lipids and Proteins During Steam Cooking of Large-Mouth Bass (Micropterus salmoides)

“…Lipids from the lyophilized sample (0.5 g) were extracted for 3 h using the chloroform-methanol method of Flaskerud et al [2017], and nitrogen was used to limit the exposure to oxygen. Then, the chloroform layer was separated and dried under nitrogen.…”