Effects of pan-frying in margarine and olive oil on the fatty acid composition of cod and salmon

https://doi.org/10.1016/j.foodchem.2005.06.026Get rights and content

Abstract

Effects on the fatty acid composition of cod (Gadus morhua) and salmon fillets (Salmo salar) after pan-frying in margarine and olive oil were determined. The fatty acids of the margarine used were 55.5% saturated (SFA), 33.0% mono-unsaturated (MUFA) and 11.5% polyunsaturated (PUFA). The olive oil used contained 15.4% SFA, 76.1% MUFA and 8.5% PUFA. Using margarine or olive oil increased the SFA and MUFA percentages, respectively, in both species. For cod fillets (lean), pan-frying increased the fat content (0.55–4.15 g/100 g and 0.55–2.30 g/100 g before and after pan-frying, with margarine and olive oil, respectively), whereas, for salmon fillets (fat), it decreased (13.91 to 10.57 g/100 g and 15.35 to 12.95 g/100 g before and after pan-frying with margarine and olive oil, respectively). In conclusion, the culinary fat selection affects the total fatty acid content and composition of the prepared fish fillet.

Introduction

A regular consumption of fish (mainly fatty fish) is recommended in view of its high content of long chain omega-3 (n  3) PUFA, especially eicosapentaenoic acid (EPA, C20:5n  3) and docosahexaenoic acid (DHA, C22: 6n  3). No other food group is naturally as rich in n  3 PUFA as are fish and other seafood (Cunnane & Griffin, 2002). The regular consumption of these n  3 PUFA is considered to be important because of their role in the prevention of several degenerative diseases which are becoming more common in Western populations (including cardiovascular and inflammatory disorders, cancer and stroke) (Din et al., 2004, Kris-Etherton et al., 2003).

Several studies were undertaken to determine the effects of different cooking methods on the fatty acids of fish species, in particular deep fat-frying and oven-baking (Agren and Hanninen, 1993, Aro et al., 2000, Candela et al., 1997, Candela et al., 1998, Gall et al., 1983, Mai et al., 1978, Mustafa and Medeiros, 1985, Sanchez-Muniz et al., 1992). Yet, less information on the effect of pan-frying can be found. Only Agren and Hanninen, 1993, Al Saghir et al., 2004 and Mai et al. (1978) have studied the effects of pan-frying on the fatty acid profile of lake trout, white sucker, bluegill, rainbow trout, vendace, pike and salmon. Pan-frying is a frequently applied method and gives flavour characteristics to the food that are highly appreciated by the consumers.

The objective of the present study was to investigate the effect of pan-frying, with two different culinary fats, on the fatty acids of cod (Gadus morhua) and Atlantic salmon (Salmo salar). In Belgium, cod and salmon are the most eaten species of lean and fatty fish, respectively (Hoge Gezondheidsraad, 2004). Using these two species, in the same setting made it also possible to investigate the effect of the fat content on the compositional changes of fish fillets during processing. Candela et al., 1997, Candela et al., 1998 studied the effect of processing on these species, but only looked at the effects of deep-fat frying. In Belgium, pan-frying is another popular cooking method to prepare fish and fish derived foods. In this study more saturated margarine and an unsaturated vegetable oil were used for pan-frying. Comparing the use of culinary fats with different fatty acid profiles is relevant to investigate their influence on the fatty acid profile of the food after preparation. Moreover, in Belgian households, the use of saturated fats for pan-frying is being increasingly replaced by the use of more healthy unsaturated vegetable oils, especially olive oil.

Section snippets

Samples

Frozen fish fillets of cod and salmon with an identified origin were chosen as samples for this study, since the fat content and the fatty acid composition of fish can vary a lot with season, age and origin of the species (Bandarra et al., 1997, Hamre et al., 2003, Nettleton and Exler, 1992, Olsson et al., 2003). The fillets were bought in Belgian stores in September, 2003. The cod fillets originated from the northern part of the Atlantic Sea and were individually packed and had a mean weight

Pan frying in margarine

The fatty acid contents of cod and salmon before and after pan-frying in margarine are shown in Table 1, Table 2. The margarine used in this study was a saturated culinary fat. Of the total fatty acids, 55.5% were SFA, of which palmitic acid (C16:0) was present in the highest amounts. Another 33.0% of the total fatty acids were MUFA, with oleic acid (cis-C18:1n  9) as most abundant one. The percentage of PUFA was 11.4%, consisting mostly of linoleic acid (C18:2n  6). In this study, pan-frying in

Discussion

Pan-frying in margarine, as well as in olive oil, significantly increased the total fatty acid content in the case of cod fillets and resulted in a decreasing trend in the case of salmon fillets. Consequently, this study showed that the uptake of fatty acids from the culinary fat into the fried samples was inversely correlated with the total fatty acid content of the fish. Using margarine increased the percentage of SFA in both species, whereas, using olive oil increased the percentage of MUFA.

Conclusions

The effect of the pan-frying of fish fillets depends on the total fatty acid content of the fish and on the fatty acid profile of the culinary fat used. In lean fish, a significant increase in the amount of fatty acids was detected, leading to a fatty acid profile similar to the profile of the culinary fat used. In fatty fish, there was a trend for a decrease in the total fatty acid content. The alterations of the fatty acid profile of the fatty fish also changed the fatty acid profile in the

Acknowledgements

The authors gratefully acknowledge financial support from the Belgian Science Policy through the SPSD II project CP/02/56 and the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen).

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