Characterization of Lipids and Their Oxidation Products in Baked or Fried Breaded Shrimp Products

Abstract

Baking and frying are two common food preparation methods, but there is limited knowledge about the lipid oxidation events that occur in food products prepared in these ways. Two commercially available breaded shrimp products were examined using gas chromatography, for changes in cholesterol, phytosterols, and fatty acids as a result of baking and deep frying after separation into breading and shrimp components. Additionally, changes in oil quality factors were determined for the cooking oils used to prepare the fried products. Sterol concentrations changed in both shrimp products due to degradation. Oxidation products of cholesterol and fatty acids were found in the shrimp portions of both the baked and fried samples as well as the oils used for frying using gas chromatography in tandem with mass spectroscopy. Phytosterol oxides were detected in the frying oils, but not in the baked or fried shrimp products. The frying oils showed some oxidative losses of phytosterols. This work demonstrated that measurable lipid oxidation occurred, even over the short time periods needed to prepare these products. This may have implications for human health effects.Keywords: Shrimp, frying, oxidation, fatty acids, sterols.Thermal processing of foods typically induces changes that make products more appealing for consumption and improves nutrient availability and food safety. Baking or roasting involves exposure of products to high temperatures in air, often on metal surfaces. Deep frying relies on the use of an oil medium to transfer heat to the food product. This process also involves exposure of the food and its lipid components to air and metal surfaces from processing equipment. The oxidation of fatty acids and sterols is a free radical process [1]. The exposure of these compounds to conditions of high heat, air and light and often in the presence of metal ions as catalysts can result in the breakdown of unsaturated carbon-carbon bonds found in these compounds, accelerating lipid oxidation.The oxides of cholesterol produced in food products have been studied and discussed for almost two decades and have been reviewed [1,2]. Shrimp in particular have been the subject of recent studies on cholesterol oxidation products [3,4]. Investigations into the types of products formed and their effects on biological systems have shown that cholesterol oxides (COPS) are cytotoxic and mutagenic and have been implicated in the onset of arteriosclerosis and coronary heart disease in humans [5,6]. The structural similarity of plant sterols or phytosterols to cholesterol (Fig. 1) would indicate that similar types of oxidation products could be formed when phytosterol containing foods are subjected to the oxidizing conditions of many food processing operations. In the past, the main focus was on the oxidation of cholesterol from lard, tallow and meat containing products [7]. To date, there have been fewer studies published on phytosterol oxidation products (POPS). Work done with model systems and synthesized compounds showed that PO...

Ratio of Malondialdehyde to Hydroperoxides and Color Change as an Index of Thermal Oxidation of Linoleic Acid and Linolenic Acid

“…; Maskan ; Dean et al . ). Figure shows color changes observed for thermally oxidized LA and LNA in the model system.…”

“…Change in the color of oils is used as an indicator to show the quality of oil or fat (Takeoka et al 1997), as oil darkening can be attributed to the formation of brown pigments, resulting from a combination of oxidation and polymerization (Takeoka et al 1997;Maskan 2003;Dean et al 2009). Figure 1 shows color changes observed for thermally oxidized LA and LNA in the model system.…”

Impact of Air Frying on Cholesterol and Fatty Acids Oxidation in Sardines: Protective Effects of Aromatic Herbs

“…There are no studies on the formation of cholesterol oxides in fish treated thermally using an air fryer. However, the increase of COPs after heating has been reported in other studies of fish and fish products in different types of thermal processes such as boiling, steaming, and baking (Hong and others 1996); pan‐frying with oil (Echarte and others ); frying (Al‐Saghir and others ); microwave, frying, grilling, and roasting (Astiasarán and others ); grilling (Saldanha and Bragagnolo ; Saldanha and Bragagnolo ); baking and frying (Dean and others ); and baking in electric or steam‐convection ovens (Freitas and others ). Large levels of COPs are formed when the food is subjected to direct heat (Morgan and Armstrong ).…”

Analytical Strategies to Analyze the Oxidation Products of Phytosterols, and Formulation-Based Approaches to Reduce Their Generation

“…Similarly, POPs were purified from vegetable oils; however, diethyl ether was used for washing and acetone for elution [ 43 , 49 , 53 ]. Whereas the discussed procedures employ a single-step SPE, two-step SPE has been reported for the enrichment of POPs from vegetable oils and food products [ 51 , 52 , 54 ]. Using a silica cartridge, POPs were enriched from deep-fried potato chips by performing the procedure twice [ 54 ].…”