Lipid profiles of oil from trout (Oncorhynchus mykiss) heads,spines and viscera: Trout by-products as a possible source of omega-3 lipids?

Lipid profiles of fish oil extracted from trout heads, spines and viscera using supercritical carbon dioxide and Randall extraction with hexane were measured. The amount of unsaturated fatty acids (as a percentage of total fatty acids) was within the range of 72.6–75.3% in all the substrates. A significant presence of the most important omega-3 fatty acids was detected. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content in oil from spines, heads and viscera resulted to be 8.7% and 7.3%, 7.9% and 6.3%, and 6.4% and 6.0%, respectively. A low (≈3%), but worth noting, presence of lipids with omega-1 polyunsaturated fatty chains was observed in all the oils. Finally, significant differences were noticed in the relative amounts of triacylglycerides (TAG), diacylglycerides (DAG) and free fatty acids (FFA). Whereas oil from heads and spines was essentially composed of TAG (≈98%), in viscera oil the molar distribution ratio became TAG:DAG:FFA = 87:8:5.     

Stabilizing Smoked Salmon (Oncorhynchus gorbuscha) Tissue after Extraction of Oil

ABSTRACT: Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Discarded pink salmon (Oncorhynchus gorbuscha) tissues were preserved using a combination of smoke-processing and acidification with lactic acid bacteria (LAB). All samples were analyzed for moisture, protein, ash, and lipid contents. Bacterial cell counts, pH, and lactic acid concentrations were recorded as a measure of LAB viability. Neither raw nor smoked salmon were free from spoilage during 60 d of storage. Only fermented samples successfully stabilized below pH 4.7, while retaining lactic acid concentrations over 15 g/L during storage. When smoked, fermented salmon head tissues were dried, the pH of the resulting high-protein “cracker” was significantly lower than when crackers were prepared only from the smoked (but not fermented) salmon material. Both cracker varieties retained valuable polyunsaturated fatty acids. This research suggests that salmon-head tissues discarded after oil extraction represent a good source of protein and high-value fatty acids in a shelf-stable form. Practical Application: Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Material produced from salmon tissue discarded after oil extraction may represent a valuable resource for preparing high-protein crackers and other fish-based food products. In addition to providing a unique smoke-flavoring, the smoked, fermented fish material may also impart antioxidant factors thereby extending the shelf life of the product.     

Stability of encapsulated olive oil in the presence of caffeic acid

The aim of this study was to investigate the influence of microencapsulation and addition of the phenolic antioxidant caffeic acid (CA) on the storage stability of olive oil. Olive oil in the absence or presence of 300 ppm CA was encapsulated in 1.5% w/w sodium alginate shells. Encapsulated oil (with/without added CA) and unencapsulated oil were stored at 20 or 37 °C for 30 days and then subjected to stability and quality evaluation based on peroxide value (PV), p-anisidine value (p-AV), Totox value, free fatty acid (FFA), total extractable phenolic content (TEPC), and fatty acid composition. The CA addition increased the stability and TPC of the final oil product. Oxidation changes were generally slower in the encapsulated oil samples. Both encapsulation and addition of CA preserved unsaturated fatty acids (UFAs) including C18:1 (omega-9 FA), C18:2 (omega-6 FA) and C18:3 (omega-3 FA). We conclude that the current oil encapsulation method using alginate microspheres could be a feasible approach to increasing olive oil stability. The addition of CA to olive oil not only provides additional protection to the oil, but also improves the nutritional values of the final oil product in terms of elevated TEPC and desired UFAs.     

Effect of cooking method on the fatty acid profile of New Zealand King Salmon (Oncorhynchus tshawytscha)

Farmed New Zealand King Salmon (Oncorhynchus tshawytscha) was prepared according to common consumer techniques; raw, poached, steamed, microwaved, pan fried (no added oil), oven baked (no added oil) and deep fried (in sunflower oil). The fatty acid profile was investigated to determine the optimal preparation techniques to achieve both optimal sensory and nutritional qualities, in particular the levels of long chain polyunsaturated omega-3 fatty acids. The modified Bligh and Dyer method was used for lipid extraction and the Hartman and Lago method for FAMES preparation. Fatty acid composition was determined by gas chromatography. There were moisture and lipid losses during cooking amongst the different methods. The fatty acid profile showed only minor differences between the methods apart from an increase in PUFA in the deep fried salmon due to linoleic acid uptake from the frying oil. In all the cooking methods the omega-3 fatty acids were well preserved. However, deep fried showed the lowest amounts of omega-3 fatty acids. As the results showed good preservation of omega-3 fatty acids regardless of cooking method, there may be possible “internal protection” of omega-3 fatty acids in King Salmon that warrants future research.     

Use of oregano extract and oregano essential oil as antioxidants in functional dairy beverage formulations

To increase health benefits, dairy beverages can be enriched with omega-3 fatty acids, although these fatty acids are susceptible to oxidation. The use of oregano extract (OE) and oregano essential oil (OEO) as antioxidants in dairy beverages enriched with 2 g/100 g linseed oil was studied. The OE contained 269 mg gallic acid equivalents per gram and was shown by the DPPH radical assay to have powerful antioxidant activity. During 10 days of storage under light or heat conditions, color, conjugated diene hydroperoxides, hexanal, propanal, and dissolved oxygen concentrations were evaluated in dairy beverages containing various concentrations of OE or OEO. It was found that OE was more efficient than OEO in preventing the formation of conjugated dienes, hexanal, and propanal as well as the depletion of oxygen induced by heat or light oxidation. The addition of OE or OEO did not affect dairy beverage physical stability during storage.     

Supercritical fluid extraction of fish oil from fish by-products: A comparison with other extraction methods

Fish and fish by-products are the main natural source of omega-3 polyunsaturated fatty acids, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), both of them with a great importance in the food and pharmaceutical industries. Comparing to conventional fish oil extraction processes such as cold extraction, wet reduction or enzymatic extraction, supercritical fluid extraction with carbon dioxide under moderate conditions (25 MPa and 313 K) may be useful for reducing fish oil oxidation, especially when fish oil is rich in omega-3 such as salmon oil, and the amount of certain impurities, such as some species of arsenic. Furthermore, taking profit of the advantages of supercritical carbon dioxide as extractive solvent, a coupled extraction-fractionation process is proposed as a way to remove free fatty acids and improve fish oil quality, alternatively to physical and chemical refining procedures.     

EVALUATION OF PROCESSING, PRESERVATION AND CHEMICAL AND FATTY ACID COMPOSITION OF NILE TILAPIA WASTE

In this experiment, the heads of Nile tilapia were used as a raw material to produce flour through cooking, grinding, drying and sieving processes. The flour obtained was stored for 90 days in a refrigerator and shelf time was monitored by chemical methods (acid number [AN] and thiobarbituric acid [TBA] test), fatty acid composition and microbiological methods. The proximate composition was: moisture (6.01%), ash (19.38%), proteins (38.41%) and total lipids (35.46%). Thirty-six fatty acids were found in the lipidic fraction. The predominant ones were 16:0, 18:1n-9 and 18:2n-6. The fatty acids of the series n-3, 18:3n-3 (alpha-linolenic acid), 18:2n-6 (linolenic acid), 20:5n-3 (eicosapentaenoic acid) and 22:6n-3 (docosahexaenoic acid) were found in smaller proportion. No changes were detected in the flour stored for 90 days as to polyunsaturated fatty acids and microbiological analysis. The AN remained constant up to 60 days of storage and TBA values increased throughout the 90-day storage.

PRACTICAL APPLICATIONS

Waste Nile tilapia heads are not commonly used in human feeding and, therefore, are discarded. In this experiment, Nile tilapia heads were used as a raw material to produce tilapia flour; it was stored in a refrigerator and the shelf time was monitored for 3 months by chemical and microbiological methods. The flour is a caloric food, has high lipid content with omega-3 fatty acids, minerals, proteins and can be used as human feeding.     

Stabilizing Oils from Smoked Pink Salmon (Oncorhynchus gorbuscha)

ABSTRACT:  Smoking of meats and fish is one of the earliest preservation technologies developed by humans. In this study, the smoking process was evaluated as a method for reducing oxidation of pink salmon ( Oncorhynchus gorbuscha ) oils and also maintaining the quality of oil in aged fish prior to oil extraction. Salmon heads that were subjected to high temperatures (95 °C) during smoking unexpectedly produced oils with fewer products of oxidation than their unprocessed counterparts, as measured by peroxide value (PV), thiobarbituric acid reactive substances (TBARS), and fatty acids (FA). Higher temperatures and longer smoking times resulted in correspondingly lower quantities of oxidative products in the oils. Fatty acid methyl ester (FAME) analysis of smoke-processed oils confirmed that polyunsaturated fatty acids (PUFA) were not being destroyed. Smoke-processing also imparted antioxidant potential to the extracted oils. Even when antioxidants, such as ethoxyquin or butylated hydroxytoluene, were added to raw oils, the smoke-processed oils still maintained lower levels of oxidation after 14 d of storage. However, decreased antioxidant capacity of smoke-processed oils was noted when they were heated above 75 °C. Vitamin studies supported the antioxidant results, with smoke-processed oils displaying higher levels of α-tocopherol than raw oils. Results suggest that smoking salmon prior to oil extraction can protect valuable PUFA-rich oils from oxidation. Improved preservation methods for marine oils may extend their usefulness when added as a supplement to enhance levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in foods.     

Amino acid and fatty acid compositions and nutritional quality of muscle in the pomfret, Pampus punctatissimus

The pomfret, Pampus punctatissimus, is an important fisheries resource in China, but little is known about its amino acid and fatty acid compositions. Pomfret muscle contained 18.6% crude protein and 4.95% crude fat. Pomfret protein has a well-balanced amino acid composition, with high amounts of glutamic acid (114 mg/g), lysine (82.8 mg/g), leucine (76.7 mg/g), and aspartic acid (76.0 mg/g). Twenty two fatty acids were found in pomfret oil and saturated fatty acids were the most abundant (48.3%). Palmitic acid (16:0) was the dominant fatty acid, followed by oleic acid (18:1), DHA (22:6n-3), myristic acid (14:0) and stearic acid (18:0), with percentages of 30.5, 26.3, 12.2, 7.37 and 6.86, respectively. The ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) was 8.04; thus, pomfret muscle is rich in n-3 PUFA.     

Simultaneous rice bran oil stabilization and extraction using sub-critical water medium

Sub-critical water technique was used for simultaneous inactivation of lipase enzyme existing in rice bran and extraction of its oil in order to obtain the stabilized edible rice bran oil. Sub-critical water treatment was carried out in the temperature range between 120 and 240 °C for 10 and/or 20 min residence time in a batch reactor. The quality of the extracted oil was evaluated with respect to its total free fatty acids concentration over a 12 week period, and compared with the oil obtained by conventional extraction methods. Without sub-critical water treatment, the concentration of total free fatty acids in the rice bran significantly increased from 5.6% to 36.0%. In contrast, no increase was observed in the total free fatty acids concentration in the samples treated by sub-critical water. Experimental evidence showed that total free fatty acids concentration increased somewhat in the oils treated by conventional methods. Considering no change was observed in total free fatty acid concentration in the treated oils by sub-critical water, it was found that sub-critical water not only could efficiently extract oil from rice bran in a short residence time but also completely stabilized the extracted oil. Oil extraction yields generally increased with increases in sub-critical water treatment temperature and residence time. The highest extraction yield of oil was 249 (mg/g dry matter) obtained at 240 °C and 10 min residence time. Oil extraction by sub-critical water could be conducted in a very short residence time (10 and/or 20 min). Also, the kinetics of free fatty acids formation in untreated rice bran was investigated and developed which successfully describes the concentration of total free fatty acids in the course of rice bran storage.     

Effect of Fish and Oil Nature on Frying Process and Nutritional Product Quality

ABSTRACT: The modifications on a lean fish (cod—Gadus morhua) and a fatty fish (farmed salmon—Salmo salar) after the application of pan-frying using 2 types of oil with different lipid profile (extra virgin olive oil and sunflower oil) was the aim of this study. Fat content and total energetic value increased significantly after the frying process only in the lean fish, without relevant changes in the fatty fish. Extra virgin olive oil led to a higher fat absorption rate than sunflower oil in both fish. Frying hardly affected the lipid profile of farmed salmon regardless the oil used, however it drastically changed in fried cod compared to raw cod. Omega-6/omega-3 ratio increased from 0.08 in raw cod to 1.01 and 6.63 in fried cod with olive oil and sunflower oil, respectively. In farmed salmon, the omega-6/omega-3 ratio was 0.38 (raw), and 0.39 to 0.58 in fried salmon. The amount of EPA + DHA slightly decreased with frying in salmon, and increased in cod. The type of oil has more influence in the nutritional fish quality for the lean fish compared to that of the fatty fish. The use of extra virgin olive oil was efficient to avoid a significant increase of the lipid oxidation intensity during frying in cod but not in salmon. Practical Application: Food modifies its composition and nutritional value with the application of cooking technologies. As most food table composition tables are based on raw food products, this article contributes with interesting data on pan-fried fish composition, which may improve the approach to achieve a real intake of healthy nutrients as omega 3 fatty acids.     

Antioxidative effects of some phenolic compounds and carotenoids on refined hazelnut oil

Phenolic compounds (gallic acid, ellagic acid and quercetin) and carotenoids (β-carotene and retinol) were used to evaluate effects of antioxidant on refined hazelnut oil. Peroxide value (PV), free fatty acid (FFA), iodine value (IV) and color analysis were made on hazelnut oil 120 days stored in the 40 °C, light and airy condition. In oil sample PV were found at range of 78.1–621.5 (meqO₂/kg oil) in the end 120 days. Antioxidant effectiveness in hazelnut oil at the half of the storage period (60th day) was in the order: Quercetin > β-carotene = gallic acid > ellagic acid. Antioxidative effectiveness was not observed in retinol treatment. However, FFA and IVs were determined in the range of 0.65–0.86 (% as oleic acid) and 68–85, respectively, at final storage.     

Fatty acid compositions of fish oil extracted from different parts of Indian mackerel (Rastrelliger kanagurta) using various techniques of supercritical CO2 extraction

Fatty acid compositions of fish oil extracted from different parts of Indian mackerel (Rastrelliger kanagurta) using various techniques of supercritical carbon dioxide (SC-CO₂) at optimised conditions (35 MPa, 60 °C, 2 ml/min) were analysed and compared to the results of Soxhlet extraction. The amount of polyunsaturated fatty acids (PUFA) recovered (as a percentage of total extracted fatty acids) were within the ranges of 73.24–74.68% in the skin, 68.36–69.37% in the flesh, 56.20–57.3% in the viscera and 61.21–62.09% in the heads. The greatest amount of the ω-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were found in fish skin followed by flesh, heads and viscera. The greatest amounts of EPA (9–12%) and DHA (10–14%) were obtained using the soaking and pressure swing techniques. The pressure swing and soaking techniques are the most effective techniques for extracting the ω-3 family of fatty acids from fish samples.     

Production and bioavailability of calcium and magnesium salts of omega-3 fatty acids

In order to provide an alternative to traditional liquid fish oil gelatin capsules, we developed a solid, powdered form of omega-3 fish oil concentrate by forming calcium- and magnesium-fatty acid salts. These salts were produced using a concentrated fish oil ethyl ester that contained in excess of 60% omega-3 fatty acids. The bioavailability of these omega-3 salts was compared with that of fish oil ethyl ester in mice. Animals were given 8 mg of omega-3 fatty acid ethyl ester concentrate (control), calcium- or magnesium-omega-3 salts daily for three weeks. The omega-3 salt products resulted in omega-3 fatty acid content in serum and red blood cell membranes comparable to that produced by the ethyl ester supplementation. In addition, fecal excretion of omega-3 fatty acids was not increased by the presence of calcium or magnesium. In fact, there was a tendency for less omega-3 fatty acids to be excreted.     

Production and refinement of oil from carp (Cyprinus carpio) viscera

Carp viscera oil can be obtained by both ensilage and fishmeal processes. This study examined the refinement of carp (Cyprinus carpio) oils obtained by both processes, and compared crude, neutralised, bleached, winterised and deodorised oils’ characteristics and lipid profiles. Refined oils obtained by the two processes did not present significant difference (p > 0.05) for Lovibond colour, free fatty acids, and thiobarbituric acid values. The major fatty acids identified in the carp crude, bleached and refined oils were oleic, palmitic, palmitoleic, linoleic and linolenic, constituting approximately 69.6% of the total fatty acids of the oils. The n − 3/n − 6 ratio was approximately 1.05 for refined oil. Therefore, carp viscera refined oil can be considered a rich source of essential fatty acids of the n − 3 and n − 6 series.     

Purifying salmon oil using adsorption,neutralization, and a combined neutralization and adsorption process

The performance of activated earth and/or chitosan as an adsorbent to remove free fatty acids (FFA) and peroxides from the unpurified salmon oil was evaluated. The unpurified salmon oil was purified using three methods included activated earth adsorption process, neutralization process, and combined neutralization and activated earth adsorption processes. The purified salmon oil samples were evaluated for free fatty acids (FFA), peroxide values (PV), minerals, color, tocopherols, moisture content, insoluble impurities, and water activity. Neither chitosan nor the activated earth adsorption process was effective in removing FFA from the salmon oil. Neutralized oil had a higher intraparticular diffusion coefficient than the unpurified salmon oil for adsorbing peroxides. FFA of unpurified salmon oil was 3.5% and was significantly reduced (P < 0.05) to 0.12% by neutralization. No significant reduction of tocopherols content of the oil was observed in any of the three purification processes. After the adsorption processes, PV of neutralized oil had decreased from 4.75 to 2.90 mmol/kg. All three purification processes increased the lightness (L^∗) and decreased the redness (a^∗) and reduced mineral, insoluble impurities, moisture content, and water activity of the salmon oil. This study demonstrated that the combined process was more effective in reducing FFA, peroxides, and moisture content than either the activated earth adsorption or neutralization purification process alone.     

Compositional characteristics and nutritional quality of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab (Eriocheir sinensis) was analyzed for proximate composition, minerals, amino acids and fatty acid composition, and also evaluated for nutritional quality. The yields of crab meat and edible viscera were 24.2% and 9.2%, respectively. The crab meat contained 18.9% crude protein. About 80% of the protein resided in the crab meat portion, while about 90% of the fat was in the viscera. Chinese mitten crab was an excellent source of minerals, particularly zinc, iron, copper and phosphorus. The crab protein contained high amounts of glutamic acid (151 mg/g), aspartic acid (99 mg/g), arginine (99 mg/g), lysine (81 mg/g) and leucine (77 mg/g), and it was a high quality protein with well-balanced essential amino acid compositions. Twenty six fatty acids were found in the crab oil. The monounsaturated fatty acids were predominant with a percentage of 49.8. Oleic acid (18:1) was the dominant fatty acid, followed by palmitoleic acid (16:1), palmitic acid (16:0) and linoleic acid (18:2n − 6); and the percentages were 31.0, 14.3, 14.2 and 11.9, respectively. The ratio of n − 6/n − 3 polyunsaturated fatty acids (PUFAs) was 2.2, and this is a n − 3 PUFA-rich food. In short, the results showed that Chinese mitten crab is a nutritious food.     

Deodorisation process variables for croaker (M. furnieri) oil

Fish oil is the major food source of the long-chain omega-3 polyunsaturated fatty acids. Deodorisation represents a critical step of the refining process since it involves high temperature that could induce degradation reactions which affect oil integrity and quality. The present study evaluated the effect of the deodorisation variables (temperature, time and steam) on the croaker (Micropogonias furnieri) oil refining process. The evaluated parameters were Lovibond color (LC), free fatty acids (FFA), peroxide (PV), Iodine (IV) and Saponification (SV) values. The best deodorisation conditions were at 220 °C, 60 min and 5% of steam (based in oil mass), resulting in oil with LC of 0.4 red and 30 yellow, FFA of 0.09%, PV of 0.53 meq/kg. IV and SV were not significantly affected. The obtained fish oil presented high quality and oxidative stability, as well as EPA and DHA contents of approximately 12% of total fatty acids.     

Development of refined cuttlefish (<Emphasis Type="Italic">Todarodes pacificus</Emphasis>) oil and its use as functional ingredients

Cuttlefish (Todarodes pacificus) viscera were tried to extract bioactive oil containing high amount of ω-3 fatty acids. Cuttlefish oil (CFO) was extracted from the viscera, refined, and evaluated. The tried effective extracting condition was 9 h hot steam extraction. Raw CFO contained high ω-3 fatty acids (FA); 21.4% docosahexaenoic acid (DHA), 11.3% eicosapentaenoic acid (EPA). The raw CFO was refined by acetone fractionation at the optimum conditions (−30°C, 8 h). One advantage of the fractionated CFO was high amounts of DHA (28.6%) and EPA (14.7%). Also, another advantage of the refined CFO was its stability during 92-day storage period at 50°C. This was seen by measuring the acid values (AV<1.0) and peroxide values (POV<2.1) throughout the storage period. In conclusion, the refined CFO containing ω-3 FA (>43%) has potential as a good functional ingredient.