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

Do meals contain a relevant amount of oxylipins? LC-MS-based analysis of oxidized fatty acids in food

Several oxylipins are potent lipid mediators and are discussed to be absorbed after oral intake. However, information about their concentrations in oils and processed foods are scarce. Here, we analyzed the concentrations of mono-, di- and multihydroxy- as well as epoxy-PUFA in virgin and refined oils as well as in different foods/meals. Oil refining causes hydrolysis of epoxy-PUFA and thus high dihydroxy-PUFA concentrations (e.g. 15,16-DiHODE 290 µg/g in refined vs. 15 µg/g in virgin rapeseed oil), making the epoxy-to-diol ratio a potential marker for refined oils. Low oxylipin levels were found in foods with high amounts of saturated fatty acids such as Hamburger patties (around 30 µg/g). High concentrations (up to 1200 µg/g, 80 mg per serving) and high oxylipin/precursor-PUFA ratios were found in fried falafel and processed foods such as vegetarian sausage/fish fingers. Our study provides first insights in the oxylipin concentrations of our daily food, indicating a relevant intake.

Characterization of Volatile Flavor Compounds and Aroma Active Components in Button Mushroom (Agaricus bisporus) across Various Cooking Methods

To investigate the impact of various cooking methods on the volatile aroma compounds of button mushroom, gas chromatography-mass spectrometry (GC-MS) and electronic nose (E-nose) were utilized for aroma analysis. The results indicated that the E-nose was able to effectively distinguish between the samples prepared using different cooking methods. In the raw, steamed, boiled and baked samples, 37, 23, 33 and 35 volatiles were detected, respectively. The roasting process significantly contributed to the production of flavor compounds, giving button mushroom its distinctive flavor. Sixteen differential aromas were identified based on the p-value and VIP value. Additionally, the cluster analysis of differential aroma substances revealed a stronger odor similarity between the steamed and raw groups, consistent with the results of the OPLS-DA analysis of overall aroma components. Seven key aromas were identified through OAV analysis and omission experiments. In addition, 1-octen-3-one was identified as the main aroma component of cooked button mushroom. The findings of the study can be valuable for enhancing the flavor of cooked button mushroom.

The Effects of Omega 3 and Omega 6 Fatty Acids on Glucose Metabolism: An Updated Review

Massive changes have occurred in our diet. A growing consumption of vegetal oils rich in omega-6 (ω-6) and a depletion of omega-3 (ω-3) fatty acids (FAs) in our food has led to an imbalance between ω-3 and ω-6. In particular, eicosapentaenoic (EPA)/arachidonic acid (AA) ratio seems to be an indicator of this derangement, whose reduction is associated to the development of metabolic diseases, such as diabetes mellitus. Our aim was therefore to investigate the literature on the effects of ω-3 and ω-6 FAs on glucose metabolism. We discussed emerging evidence from pre-clinical studies and from clinical trials. Notably, conflicting results emerged. Source of ω-3, sample size, ethnicity, study duration and food cooking method may be responsible for the lack of univocal results. High EPA/AA ratio seems to be a promising indicator of better glycemic control and reduced inflammation. On the other hand, linoleic acid (LA) appears to be also associated to a minor incidence of type 2 diabetes mellitus, although it is still not clear if the outcome is related to a reduced production of AA or to its intrinsic effect. More data derived from multicenter, prospective randomized clinical trials are needed.

Review on retention of long-chain omega-3 polyunsaturated fatty acids (EPA and DHA) in fish as affected by cooking methods

Fatty acids are essential building blocks for the structural components of the cells, tissues, organs, and certain biologically active substances synthesis. Omega-3 polyunsaturated fatty acids are long-chain fatty acids essential for several biological functions including oxidative stress reduction and cardiovascular safety. Diet rich in omega-3 fatty acids is well acknowledged as beneficial to one's health and well-being. For the development of balanced diets, the nutrient content of raw and cooked foods is crucial. However, cooking method, animal age, and carcass characteristics might affect nutrient retention during cooking, and these factors are often unique to specific countries. This review thus provides a general overview of several cooking effects on long-chain omega-3 retention in fish. It can be concluded that the DHA and EPA's true retention values are correlated to the impact of different cooking treatments.

The effect of the cooking method on rainbow trout (Oncorhynchus mykiss) fillets

Fish is nutritious seafood and contains protein with high biological value and essential nutrients for the human body. In Iran, the fish Oncorhynchus mykiss is locally known as Ghezelala and is a commercial fish species. Different methods were used to process the fish: boiling, frying in sunflower oil and grilling. This research investigated on effect of various cooking methods on proximate pH and cooking loss of fresh fish (Oncorhynchus mykiss). The highest and lowest values for protein were found in fish processed using grilling (18.51%) and frying (16.52%), respectively (p <0.05) compared to the fresh sample (18.20%). The fat content of the fried sample showed significantly highest (5.16%) (p <0.05), while the lowest fat content was found for the boiled sample (20.57%) compared to the fresh fat (24.36%) (p <0.05). Comparing the loss percentage of samples in different cooking methods showed that the boiled sample had the lowest value (25.46%) and the fried sample with the highest value (45.02%) (p <0.05). pH value in the boiled sample was the highest (6.74%), while the grilled sample had the lowest (6.63) compared to the fresh sample (6.54). The highest energy value was found for the fried sample (578.48 kcal/100g), and the lowest was for the boiled sample (269.29 kcal/100g). The results suggest that the boiled and grilled fish found higher nutritional quality due to the relatively high protein content, the most needed nutrients. The results also showed that all cooking methods did not significantly affect in mineral content of the fresh fish.

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

This paper reports the effects of four popular cooking methods viz. grilling, boiling, frying, and microwaving on the proximate and nutritional compositions of freshwater mud eel (FWME) muscle. The moisture content of raw FWME muscle was 74.45%, which was similar in boiled products but lower in grilled, fried, and microwaved products (p ≤ .05). The protein content in raw and cooked FWME muscles varied between 14.49% and 21.28%. There were found 20 different fatty acids in FWME muscle of which palmitic acid was the most abundant one with an amount of 26.51%-29.70% in raw and cooked FWME muscles. FWME muscle contained a substantial amount of ω-3 polyunsaturated fatty acids, ranging from 7.54% to 13.7%. However, the thermal effects during cooking decreased the ω-3 polyunsaturated fatty acid contents. There were seven essential and eight nonessential amino acids available in FWME muscle; among the essential amino acids, lysine content was the highest. Raw and cooked FWME were very rich in calcium, between 794.52 mg/100 g and 883.24 mg/100 g muscle. Among the studied heavy metals, Pb content was the highest. However, all the heavy metal contents were within acceptable limits determined by health risk assessment, that is, target hazard quotient and target cancer risk.

Quantitation of Oxylipins in Fish and Algae Oil Supplements Using Optimized Hydrolysis Procedures and Ultra-High Performance Liquid Chromatography Coupled to Tandem Mass-Spectrometry

Fish and algae oil supplements are enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are precursors to oxidized fatty acids, known as oxylipins. Here, we optimized a base hydrolysis method for measuring oxylipins in oil with ultrahigh-performance liquid chromatography coupled to tandem mass-spectrometry (UPLC-MS/MS) and quantified them in fish and algae oil supplements. Hydrolysis of 2 μL of oil with sodium carbonate resulted in greater oxylipin concentrations and minimal matrix effects, compared to higher oil volumes (10, 20, and 30 μL). Oxylipin yield was higher when oil was hydrolyzed in methanol containing 0.1% acetic acid and 0.1% butylated hydroxytoluene, compared to no methanol, and using sodium hydroxide versus sodium carbonate. Oxylipins extracted from 2 μL of oil using sodium hydroxide in solvent showed that EPA-derived oxylipins were most abundant in fish oil (84-87%), whereas DHA-oxylipins were abundant in algae oil (83%). This study shows that fish and algae oils are direct sources of EPA- and DHA-derived oxylipins.

Limited Antioxidant Effect of Rosemary in Lipid Oxidation of Pan-Fried Salmon

Consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) rich fatty fish is known to provide an array of health benefits. However, high temperature in food preparation, such as pan-frying, potentially degrades eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) of the n-3 PUFAs by heat oxidation. The addition of antioxidant condiments, and herbs in particular, may retard PUFA peroxidation and preserve EPA and DHA during pan-frying. In this study, different types of antioxidant condiments (sage, rosemary, black peppercorn, thyme, basil, and garlic) were tested for antioxidant capacity, and the condiment with the highest capacity was selected for its effect on lipid oxidation of salmon. The changes in fatty acids and lipid peroxidation of salmon, during pan-frying with the selected condiment (olive oil infused with rosemary, RO_(infused)), were compared with salmon prepared in extra virgin olive oil, olive oil, or without oil. The total saturated fatty acid was found to be less in pan fried salmon with RO_(infused). None of the oil type conserved EPA- and DHA-content in salmon. However, RO_(infused) lowered lipid peroxidation by lessening hydroperoxide and 4-HNE formation, but not the other related products (HDHA, HETE, isoprostanes). Our observation indicates that the antioxidant capacity of RO_(infused), when it is incorporated with food, becomes limited.

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

Consumption of food containing n-3 PUFAs, namely EPA and DHA, are known to benefit health and protect against chronic diseases. Both are richly found in marine-based food such as fatty fish and seafood that are commonly cooked prior to consumption. However, the elevated temperature during cooking potentially degrades the EPA and DHA through oxidation. To understand the changes during different cooking methods, lipid profiles of raw, boiled, pan-fried and baked salmon were determined by LC-MS/MS. Our results showed that pan-frying and baking elevated the concentration of peroxides in salmon, whereas only pan-frying increased the MDA concentration, indicating it to be the most severe procedure to cause oxidation among the cooking methods. Pan-frying augmented oxidized products of n-3 and n-6 PUFAs, while only those of n-3 PUFA were elevated in baked salmon. Notably, pan-frying and baking increased bioactive oxidized n-3 PUFA products, in particular F-_4t-neuroprostanes derived from DHA. The results of this study provided a new insight into the application of heat and its effect on PUFAs and the release of its oxidized products in salmon.

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

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.