Mechanisms of Docosahexaenoic and Eicosapentaenoic Acid Loss from Pacific Saury and Comparison of Their Retention Rates after Various Cooking Methods

Abstract

The docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents of Pacific saury (Cololabis saira), a fatty fish and staple of the Japanese diet, have been reported to decrease after cooking. This study compared the DHA and EPA contents remaining in saury after grilling, pan-frying or deep-frying to center temperatures of 75, 85, or 95 °C, and examined physical loss, lipid oxidation, and thermal degradation as mechanisms of DHA and EPA loss. Temperature changes inside the saury were monitored using thermocouples, while DHA and EPA contents, oxygen radical absorbance capacity, and measurements of lipid oxidation (that is, carbonyl value and thiobarbituric acid value) were determined chemically. Visualization of temperature distribution inside fish samples during cooking revealed large differences in heat transfer among cooking methods. True retention rates in grilled (DHA: 84 ± 15%; EPA: 87 ± 14%) and pan-fried samples (DHA: 85 ± 16%; EPA: 77 ± 17%) were significantly higher than deep-fried samples (DHA: 58 ± 17%; EPA: 51 ± 18%), but were not affected by final center temperatures despite differences in cooking times. Physical loss via cooking losses (grilling and pan-frying) or migration into frying oil (deep-frying) accounted for large quantities of DHA and EPA loss, while lipid oxidation and thermal degradation did not appear to be major mechanisms of loss. The antioxidant capacity of saury was not significantly affected by cooking treatments. The results of this study suggest that minimization of physical losses during cooking may increase DHA and EPA contents retained in cooked Pacific saury.

Linking Production and Consumption: The Role for Fish and Seafood in a Healthy and Sustainable Australian Diet

“…Cooking tends to reduce the relative moisture content of foods, thereby increasing concentration of some nutrients, but can also reduce the content of others. For example, greater cooking times and temperatures can increase lipid oxidation and lead to decreases in fat content [56,57]. The effects of smoking on nutrient content are also variable; heat and related moisture loss can lead to nutrient losses, while certain chemicals in smoke (depending on the method of smoking) can also promote nutrient retention through prevention of oxidation, thereby reducing oxidative changes to protein, fats and vitamins [58].…”

Dietary marine-derived long-chain monounsaturated fatty acids and cardiovascular disease risk: a mini review

“…Saury is one of the most highly enriched fish in LCMUFA and is widely consumed in Asia [22]. Herring, which is among the main commercial fish species in European countries, and Alaska pollock, which is the primary target for the fish industry in the United States, are also enriched in LCMUFA [23, 24].…”

Health Impacts of Omega-3 Fatty Acid Deficiency

“…For example, pan frying of freshwater fish caused a significant decrease in n-3 PUFA content, while the n-3 PUFA content of baked fish was similar to that of the raw fish (Schneedorferová et al 2015). A decrease in n-3 PUFA content was observed in Pacific saury, a pelagic fish, following pan frying, grilling, and deep frying, with the greatest loss observed after deep frying (42% loss) (Cheung et al 2016). The reduction in n-3 PUFA content was attributed to spillage of liquefied subdermal fat during grilling or leaching of fatty acids into the frying oil during deep-frying (Cheung et al 2016).…”

“…A decrease in n-3 PUFA content was observed in Pacific saury, a pelagic fish, following pan frying, grilling, and deep frying, with the greatest loss observed after deep frying (42% loss) (Cheung et al 2016). The reduction in n-3 PUFA content was attributed to spillage of liquefied subdermal fat during grilling or leaching of fatty acids into the frying oil during deep-frying (Cheung et al 2016). Lipid oxidation was also reported in grilled and pan-fried saury, and this may have contributed to the observed loss of fatty acid content.…”