Lipid Oxidation In Fish Research Articles

Oxidative stability, volatile components and polycyclic aromatic hydrocarbons of cold-smoked sardine ( Sardina pilchardus) and dolphinfish ( Coryphaena hippurus)

Although a wide variety of compounds are deposited during the smoking process, much more attention has been given to phenols and polycyclic aromatic hydrocarbons (PAHs). However, even though phenols have an important role to play as food antioxidants, some PAHs have cytotoxic and mutagenic effects. In the present work, two fish species differing in composition (dolphinfish ( Coryphaena hippurus) and sardine ( Sardina pilchardus)) were salted and cold-smoked. Two different smoking treatments were selected in order to compare phenol content and muscle antioxidant activity employing the ferric reducing power (FRAP) method. Both smoking treatments increased fish lipid oxidation stability compared with the salted muscle. The characterization of the volatile components of the headspace of the more intensely processed smoked products was carried out by SPME/GC/MS, which revealed the presence of typical phenol and carbonyl derivatives, as well as some oxidation products and PAHs of low molecular weight. PAH composition was further investigated by extracting and identifying the PAHs by GC/MS. Neither benzo(a)pyerene nor other high molecular weight PAHs were detected, naphthalene and its derivatives being the most abundant compounds in the smoked products.

Ability of whey protein isolate and/or fish gelatin to inhibit physical separation and lipid oxidation in fish oil-in-water beverage emulsion

The effect of pH on the capability of whey protein isolate (WPI) and fish gelatin (FG), alone and in conjugation, to form and stabilize fish oil-in-water emulsions was examined. Using layer-by-layer interfacial deposition technique for WPI–FG conjugate, a total of 1% protein was used to prepare 10% fish oil emulsions. The droplets size distributions and electrical charge, surface protein concentration, flow and dynamic rheological properties and physiochemical stability of emulsions were characterize at two different pH of 3.4 and 6.8 which were selected based on the ranges of citrus and milk beverages pHs, respectively. Emulsions prepared with WPI–FG conjugate had superior physiochemical stability compare to the emulsions prepared with individual proteins. Higher rate of coalescence was associated with reduction in net charge and consequent decrease of the repulsion between coated oil droplets due to the proximity of pH to the isoelectric point of proteins. The noteworthy shear thinning viscosity, as an indication of flocculation onset, was associated with whey protein stabilized fish oil emulsion prepared at pH of 3.4 and gelatin stabilized fish oil emulsion made at pH of 6.8. At pH 3.4, it appeared that lower surface charge and higher surface area of WPI stabilized emulsions promoted lipid oxidation and production of hexanal.

Influence of emulsifier type on lipid oxidation in fish oil‐enriched light mayonnaise

AbstractThe oxidative stability of fish oil‐enriched light mayonnaise (40% oil) and the influence of two different emulsifiers, egg yolk and milk protein‐based emulsifier, were evaluated. Moreover, the effects of different fish oil concentrations (4, 10 and 14%) and storage temperatures (2 and 20°C) were investigated. As expected, the results showed that lipid oxidation increased with storage temperature, and at 20°C with increasing fish oil concentrations. On the basis of the findings in this study, a storage temperature of 20°C for 4 months cannot be recommended for light mayonnaise due to significant lipid oxidation even in mayonnaises without fish oil. However, enrichment of light mayonnaises with 4% fish oil without adding antioxidant did not result in increased oxidation when stored at 2°C, and thus seems feasible; however, this has to be confirmed by sensory analysis. Surprisingly, our hypothesis that substitution of egg yolk with a less iron‐containing emulsifier (milk protein‐based emulsifier) could increase the oxidative stability of fish oil‐enriched mayonnaises was not confirmed. These findings suggest that the initial quality of the emulsifiers was more important than its iron content in terms of lipid oxidation.

Measurement of malondialdehyde in fish: A comparison study between HPLC methods and the traditional spectrophotometric test

Alternative methods to the traditional spectrophotometric determination of the malondialdehyde-thiobarbituric acid (MDA-TBA) complex (method A) and to the overestimation of MDA levels in the TBA reaction have been develop for the evaluation of lipid oxidation in fish. In this study, two HPLC separation methods of the MDA-TBA (method B) and MDA-dinitrophenylhydrazine (MDA-DNPH) adduct (method C) were investigated and compared to the traditional spectrophotometric TBA test (method A) in samples of chilled fish (hake, sea bream and sardine). Detection limits were 0.16, 0.10 and 0.20 μM MDA and quantification limits were 0.23, 0.17 and 0.26 μM MDA, for methods A, B and C, respectively. Recovery of method B ranged between 100% and 108% and of method C between 90% and 112%. Method A presented low recovery levels (under 71%). Overall method performance followed the order HPLC method MDA-DNPH > HPLC method MDA-TBA > traditional spectrophotometric TBA test. Though showing a better accuracy and specificity, method C had, however, some disadvantages, a relatively high limit of detection (0.20 μM MDA) and a lower reproducibility at lower MDA contents in standards and samples. Nevertheless, these are not critical drawbacks for an application in routine fish analysis, given the high MDA concentrations in oxidised fish. The application of the modified HPLC methods in fish samples with different levels of MDA, showed that these methods are useful for the samples with low amounts of oxidation products, such as chilled hake as well as in samples with high levels of oxidation, like 15 days chilled stored sardine.

Hemoglobin-Mediated Lipid Oxidation and Compositional Characteristics of Washed Fish Mince Model Systems Made from Cod (Gadus morhua), Herring (Clupea harengus), and Salmon (Salmo salar) Muscle

The use of washed cod light muscle minces in mechanistic studies of hemoglobin (Hb)-mediated fish lipid oxidation has largely increased in the past 5 years. Although cod light muscle has a low level of intrinsic lipid oxidation catalysts, a prerequisite for a good oxidation model system, we believe it cannot fully mimic the oxidation kinetics taking place in other fish species being more susceptible to lipid oxidation. The aim of this study was to systematically investigate whether washed mince model systems useful in Hb-mediated oxidation studies could be prepared also from herring (Clupea harengus) and salmon (Salmo salar) light muscles. The kinetics of oxidation in the washed models was measured during ice storage (+/-Hb), and the results were related to compositional differences. Minces from cod, herring, and salmon light muscles were washed 3 times with 3 volumes of water and buffer. A 20 microM portion of Hb and 200 ppm streptomycin was then added, followed by adjustment of pH and moisture to 6.3 and 86%, respectively. Samples with or without Hb were then stored on ice, and oxidation was followed as peroxide value (PV), rancid odor, redness (a*) loss and yellowness (b*). Prior to storage, all minces and models were also analyzed for total lipids, fatty acids, alpha-tocopherol, proteins, Hb, Fe, Cu, and Zn. Hb-mediated lipid oxidation appeared within 2 days on ice in all models. Small differences in the oxidation rates ranked the models as herring > cod > salmon. These differences were ascribed to more preformed peroxides and trace elements in the herring model, and more antioxidants in the salmon model. Controls, without Hb, stayed stable in all cases except herring, where a very slight oxidation appeared, especially if the herring raw material had been prefrozen. In conclusion, fattier fish like dark muscle species and salmonoids are useful for making washed mince model systems and would be a better choice than cod if there is an interest in the oxidation kinetics of such species.

Effect of Lactobacillus cultures on microbiological, chemical and odour changes during storage of rainbow trout fillets

AbstractThe purpose of this study was to investigate the effect of applying two Lactobacillus protective cultures on microbiological, chemical and odour changes during storage of refrigerated vacuum‐packed rainbow trout (Oncorrynchus mykiss) fillets. Lactobacillus sakei CECT 4808 and Lb. curvatus CECT 904T were inoculated individually or in combination into rainbow trout fillets. The samples were vacuum‐packed and stored at 4 ± 0.5 °C and were assessed during a 20‐day storage period for microbiological (Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria (LAB), H2S‐producing bacteria, yeasts and moulds) and chemical (pH, total volatile basic nitrogen, lipid oxidation) parameters and off‐odour. Samples inoculated with Lb. sakei and with both strains had significantly (P≤0.05) lower counts of all microbiological spoilage indicator organisms (Enterobacteriaceae, Pseudomonas spp., H2S‐producing bacteria, yeasts and moulds) than those inoculated with Lb. curvatus or the controls. All chemical parameters examined and off‐odour scores were also significantly (P≤0.05) improved in the samples inoculated with Lb. sakei or with both strains compared with those inoculated with Lb. curvatus or the controls. Lb. sakei generally showed a better preservative effect (P≤0.05) than the combination of strains. Inoculation with Lb. sakei CECT 4808 could provide an additional hurdle to improve shelf‐life of refrigerated vacuum‐packaged trout fillets, as inoculation with this strain resulted in extension of shelf‐life by 5 days. Furthermore, this strain showed some antioxidative ability, which could retard lipid oxidation in fish. Copyright © 2006 Society of Chemical Industry

Inhibition of Hemoglobin- and Iron-Promoted Oxidation in Fish Microsomes by Natural Phenolics

Natural phenolic antioxidants have been tested in hake (Merluccious merluccious) microsomes as inhibitors of lipid oxidation promoted by fish muscle prooxidants: hemoglobin (Hb), enzymatic NADH-iron and nonenzymatic ascorbate-iron. The phenolics selected were as follows: (a) a grape phenolic extract (OW), (b) a fraction (IV) with isolated grape procyanidins with a medium-low degree of polymerization and galloylation percentage, (c) hydroxytyrosol obtained from olive oil byproducts, and (d) a synthetic phenolic antioxidant, propyl gallate. All compounds delayed lipid oxidation activated by Hb, enzymatic NADH-iron, and nonenzymatic ascorbate-iron, excluding hydroxytyrosol that was not an effective antioxidant on oxidation promoted by nonenzymatic iron. The relative antioxidant efficiency was independent of the prooxidant system, IV > propyl gallate > OW > hydroxytyrosol, and showed a positive correlation with their incorporation into microsomes (p < 0.05). The reducing capacity or ability for donating electrons and the chelating properties may also contribute to the antioxidant activity of phenolics, although these factors were less decisive than their affinity for incorporating into the microsomes. Conversely, the inhibition of Hb oxidation by phenolics and their polarity did not seem to play an important role on antioxidant mechanism. These results stressed the importance of incorporating the exogenous antioxidants into the membranes where are located key substances for fish lipid oxidation (highly unsaturated phospholipids, iron-reducing enzymes, and endogenous alpha-tocopherol).

Effects of lipid oxidation on fish lipids — amylopectin interactions

AbstractThe results of studies on fish lipid oxidation effects on lipid‐amylopectin starch interactions are presented. Particular attention is paid to fish lipid availability (extractability from the system) and fatty acid contributions to individual lipid groups after mixing‐provoked interaction and after a 30‐day storage at —18 °C. The study involved model systems containing fish lipids at different levels of oxidation, lipids containing an antioxidant (BHA), and gelatinised amylopectin starch in a 10% aqueous solution. The lipid to starch ratio was 1:1. The test systems were subjected to selective extraction. The extracts were assayed for lipid content, peroxide value, anisidine value, fluorescence, and fatty acid composition.Compared to fresh fish lipids, those lipids, which were oxidised to a higher extent were shown to be more amenable to complexing with amylopectin, but they were also more readily released during frozen storage. On the other hand, addition of BHA stabilised the lipid‐amylopectin starch interaction during storage at —18 °C.In the entire systems tested, polyunsaturated fatty acids, eicosapentaenoic and docosahexaenoic acids in particular, proved to be most susceptible to binding, up to 90% of the latter being complexed.

Effect of Packing Media on the Oxidation of Canned Tuna Lipids. Antioxidant Effectiveness of Extra Virgin Olive Oil

The effectiveness of packing media differing in the content of natural antioxidants has been tested on lipid oxidation occurring during tuna canning. Extra virgin olive oil, having a high content in natural polyphenols, and other filling media lacking phenols (refined olive oil, refined soybean oil, and brine) were selected. The three oils also showed different quantities of tocopherols, the highest amount being detected in refined soybean oil. Different rates of oxidation were observed among the four media after thermal processing and storage of tuna cans; extra virgin olive oil showed a potential antioxidant activity on fish lipids. The verified antioxidant ability may be attributed to the solubilization of hydrophilic phenols into the water−muscle interface. The phenolic composition from extra virgin olive oil studied by reversed-phase HPLC showed a marked change after fish processing, thus suggesting phenol decompositions and strong interactions between oil phenols and fish muscle components. The aqueous environment built by brine made fish lipids more prone to oxidation, presumably due to the accumulation of unsaturated fatty acids at the oil−water interface. Keywords: Antioxidants; fish lipid oxidation; canning; packing medium (extra virgin olive oil, refined olive oil, soybean oil, brine); phenols

Enhancing the antioxidant effect of α-tocopherol with rosemary in inhibiting catalyzed oxidation caused by Fe 2+ and hemoprotein

A mixture of α-tocopherol and rosemary extract (0·035% + 0·035%) was used to inhibit fish lipid oxidation catalyzed by Fe 2+ or hemoprotein. In a sardine oil model system, a mixture of α-tocopherol and rosemary extract showed a significantly stronger antioxidant effect, as it prolonged the induction period for 10 and 16 days longer than α-tocopherol alone and rosemary extract alone, respectively. In addition, the effective lifetime of α-tocopherol in samples treated with the α-tocopherol and rosemary extract mixture was 10 days longer than in samples with only α-tocopherol added even though the amount of added α-tocopherol in the latter case was twice that for the mixture. In fish dark muscle, the mixture of α-tocopherol and rosemary extract also showed a stronger anti-oxidant effect than either tocopherol or rosemary extract alone. Treatment of samples with this mixture also led to a lower rate of decomposition of highly unsaturated fatty acids, myoglobin and hemoglobin, and triglyceride compared to samples treated with tocopherol or rosemary extract alone.

Linoleate 13(S)-lipoxygenase in sardine skin

A novel lipoxygenase was found in sardine skin. It oxidized linoleic acid more efficiently than arachidonic acid or eicosapentaenoic acid. Esterified fatty acids such as methyl linoleate and trilinolein were also oxidized. 13(S)-Hydroperoxyoctadeca-9(Z),11(E)-dienoic acid was produced as the primary oxidation product from linoleic acid by both the crude extract of skin tissue and the active fraction after gel filtration. The enzyme had an optimum pH at 7.0 and was stable over the pH range 6-9. It may participate in the initiation of lipid oxidation in fish.

Study on the influence of freezing rate on lipid oxidation in fish (salmon) and chicken breast muscles

SummaryChicken breast and salmon muscle were frozen either slowly or rapidly at –25°C, and then stored at –5°C for up to 83 and 47 days respectively. At intervals samples were thawed and TBA values measured on either muscle distillate or centrifugal exudates. TBA values increased slightly but significantly with storage time, but freezing rate had no effect.

Radiation induced lipid oxidation in fish.

Oxidative rancidity in herring and redfish was studied as a function of the applied irradiation dose, the storage time and storage temperature and the packaging conditions.--Measurements of the TBA (thiobarbituric acid) value and the peroxide value were used to evaluate the degree of oxidation of lipids, and were related with sensory scores.--Especially for the fatty fish species (herring) irradiation accelerated lipid oxidation and induced oxidative rancidity. Irradiation of vacuum-packed herring fillets and subsequent storage at +2 degrees C seems to be an interesting process. For the experiments conducted on a semi-fatty fish (redfish), oxidative rancidity was never the limiting factor for organoleptic acceptability.