Santiago P. Aubourg

Influence of storage time and temperature on lipid deterioration during cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) frozen storage

Lean fish deterioration during frozen storage (−30 and −10 °C) for up to 1 year was studied by the assessment of lipid changes. Comparison between a formaldehyde (FA)-forming species (cod) and a non-FA-forming one (haddock) was carried out. Lipid damages were measured on the basis of free fatty acids (FFA), peroxide value (PV), thiobarbituric acid index (TBA-i) and fluorescent compounds. In both species at −30 °C, most lipid damage indices showed significant correlations with the storage time. However, at −10 °C, only the FFA and fluorescence detections provided significant correlations with the storage time. Comparison between the fish species showed higher lipid oxidation (PV and TBA-i) and hydrolysis (FFA content) in haddock than in cod at −10 °C; however, a higher fluorescence development was observed in cod at the same temperature. At −30 °C, little differences in lipid damage indices were detected between the two species. © 1999 Society of Chemical Industry

Proton nuclear magnetic resonance rapid and structure-specific determination ofω-3 polyunsaturated fatty acids in fish lipids

Based on proton nuclear magnetic resonance (1H-NMR) spectroscopy, a rapid and structure-specific method for the determination of ω-3 polyunsaturated fatty acids (PUFAs) in fish lipids is presented. The different chemical shift observed for the methyl resonance of ω-3 PUFAs (δ=0.95 ppm) with respect to the methyl resonance of all other fatty acids (δ=0.86 ppm) has provided the possibility of proposing a new and rapid method for the determination of ω-3 PUFA content. Twenty-four fish lipid samples (raw, cooked and canned albacore tuna) produced results that showed good agreement between1H-NMR analysis and gas chromatographic determination. Raw and cooked samples showed significantly higher levels of ω-3 PUFA than canned tuna.

Fluorescence study of the pro-oxidant effect of free fatty acids on marine lipids

The free fatty acid (FFA) effect on the oxidative stability of marine lipids was studied by fluorescence assessment. Under different reaction conditions, including time, temperature and FFA content and type (different chain lengths and unsaturation degrees), FFAs were made to interact in model systems with a commercial marine oil (cod liver oil) and two different fish (hake and pout) white muscles. Fluorescence assessment showed a pro-oxidant effect of all types of FFA, which increased with time, temperature and FFA content in the reaction mixtures. At 30 °C a higher degree of oxidation was obtained in systems including the shorter-chain-length fatty acids (lauric and myristic) compared to systems including the longest ones (arachidic and stearic). At the same temperature an increasing pro-oxidant effect was also observed with increasing degree of fatty acid unsaturation (stearic < oleic < linoleic < linolenic). When a lower temperature (−10 °C) was tested, a differential pro-oxidant effect among fatty acids (chain length and unsaturation degree) was not observed. © 2001 Society of Chemical Industry

Lipid damage detection during the frozen storage of an underutilized fish species

Lipid damage was studied on an underutilized fish species (blue whiting, Micromesistius poutassou). Blue whiting fillets were frozen at −40°C and stored at −30 and −10°C up to 1 year. Primary and secondary lipid oxidation products, interaction compounds and lipid hydrolysis were studied on the fish white muscle. At −30°C most of the lipid damage indices tested (free fatty acids, peroxide value, conjugated dienes, thiobarbituric acid index and fluorescence detection) showed a significant (p<0.05) correlation with the storage time. However, as the fish damage increased (−10°C condition) only the free fatty acids and fluorescence detections provided satisfactory correlations with the storage time (r2=0.94 and r2=0.92, respectively), while reliability of the remaining indices decreased in order to assess lipid damage and fish deteriorative changes.

Composition of phospholipids of white muscle of six tuna species

A comparative study of the phospholipids of white muscle of six of the comercially utilized tuna species, including quantitative analyses of phospholipid classes and studies of the acyl composition of the major components. Plasmalogen compounds also were identified and quantified. Choline and ethanolamine glycerophospholipids were the most abundant classes in all the samples, as well as the only molecules containing plasmalogens (16∶0, 18∶0, and 18∶1 alkenyl ether chains). The patterns of fatty acid distribution within each of the phospholipid classes showed general similarities in the species analyzed. However, ratios between certain saturated and polyunsaturated fatty acids in different phospholipid classes showed remarkable diffences. The high content of n−3 polyunsaturated fatty acids in the principal phospholipids, such as the plasmalogens, and taking into account the fatty acids possible importance in human nutrition, indicates that the white muscle of tuna species may be a potentially important dietary item.

Review: Loss of Quality during the Manufacture of Canned Fish Products:

From the moment the fish is caught till it arrives at the consumer as a canned product, raw matter is submitted to a variety of industrial steps. Thus, a storage process (namely, chilling or freezing) is needed for holding the raw material to be canned; a cooking step is normally employed for reducing moisture and inactivating endogenous enzyme activity; a rigorous thermal treatment (sterilization) is undertaken to inactivate micro-organisms; and a proper canned storage is necessary to guarantee good palatability of the product. As a result, labile and essential nutrients (proteins, vitamins, lipids, minerals) present in the raw fish are exposed to different processing conditions that can reduce the nutritional and sensory values of the final product. In the present work, detrimental changes produced in each of the steps involved in the manufacture of canned products are mentioned. This review is focused on nutritional and sensory losses in species commonly employed for canning preparation, and special attention is given to research concerning the effect of varying conditions of previous processing (chilling, freezing and frozen storage and cooking) on the quality of the final canned product. New and current technological strategies are recommended to increase the shelf life of previously stored material and to retain sensory and nutritional quality in the final canned product.

A comparison between conventional and fluorescence detection methods of cooking-induced damage to tuna fish lipids

ZusammenfassungLipidschäden während des Abkochens von zwei Thunfisch-Arten (Thunnus obesus undTh. thynnus) wurden untersucht. Fluorescenzmeßungen in verschiedenen Wellenlängenbereichen wurden mit anderen Methoden verglichen, die zur Bestimmung von Lipidschäden gebraucht werden. Als Ergebnis der Wärmebehandlung wurde eine Fluorescenzverschiebung zu höheren Wellenlängenmaxima offenbar; gleichzeitig zeigten die Qualitätskriterien eine verstärkte Lipidschädigung (Carbonylbildung und Bräunungsentwicklung sowie Zunahme von freien Fettsäuren). Die Fluorescenzverhältnisse zwischen 393/460 nm und 327/415 nm (Maxima) zeigten weniger Abhängigkeit von den Proben als andere Lipidschädenmessungen.AbstractThe damage to tuna fish lipids induced by cooking was investigated in theThunnus obesus andTh. thynnus varieties, using conventional and fluorescence detection methods, and the results were compared. As a consequence of thermal processing, the peaks at longer wavelengths increased, which correlated with other conventional indices of lipid damage (i.e. carbonyl compound formation, browning and increases in the free fatty acid content). A special significance was given to the fluorescence ratio between the maxima of the excitation emission data at 393/460 nm and 327/415 nm; increases in this ratio as a result of cooking were less dependent on the samples than were other conventional methods of measuring lipid damage.

Oxidative Stability of Spray-Dried Microencapsulated Fish Oils with Different Wall Materials

Multilayer microencapsulation of fish oil was evaluated by using fish gelatin (treated with or without microbial transglutaminase [MTGase]), chitosan, and maltodextrin for its ability to control lipid oxidation. This study showed that a mixture containing gelatin and maltodextrin obtained the highest percentage of core release. The oxidative stability of the formulated mixtures and the bulk oils was investigated during a period of 60 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products, and p-anisidine (p-AV) and thiobarbituric acid reactive sub-stances (TBARS) was used to analyze secondary oxidation compounds. Observation of oxidation products showed that combinations of gelatin and maltodextrin made by adding MTGase and a mixture of gelatin and chitosan were able to increase the oxidative stability, and increases in PV and p-AV and TBARS were found for all oils.

13C nuclear magnetic resonance monitoring of free fatty acid release after fish thermal processing

Abstract13C Nuclear magnetic resonance spectroscopy was applied to the study of lipid hydrolysis occurring during industrial canning of tuna (Thunnus alalunga). An increase in the free fatty acid (FFA) level was observed after cooking and sterilization, and a different FFA pattern was found when storage of the frozen raw material and thermal steps (cooking and can sterilization) were compared. Lipolysis in raw muscle occurs preferentially in thesn-1 andsn-3 acyl positions of triacylglycerols, with a consequent cleavage of saturated and monounsaturated fatty acids. After thermal processing, an increase of docosahexaenoic acid (DHA) was found in the FFA fraction, as well as a relative decrease of the peak intensity of DHA in thesn-2 position of triacylglycerols. This finding indicates a different mechanism of FFA release during the frozen storage and thermal processing of raw fish.

Changes in free amino acids content in albacore (Thunnus alalunga) muscle during thermal processing

ZusammenfassungDie Wirkung des Kochens und Sterilisierens bei verschiedenen Temperaturen auf den Gehalt an freien Aminosäuren (FAA) im Thunfischmuskel (Thunnus alalunga) wurde während der Herstellung von Thunfischkonserven untersucht. Die freien Aminosäuren wurden mito-Phtalaldehyd derivatisiert, auf einer C-18-Kolonne mit HPLC abgetrennt und durch Fluorescenz und UV-Detektoren nachgewiesen. Nach dem Kochen war der Verlust an FAA nicht signifikant, jedoch in dem bei 110° und 115 °C sterilisierten Endprodukt ergaben sich signifikante Verluste bezogen auf das Ausgangsmaterial, aber nicht auf das bei 118 °C erhitzte; alle Erhitzungstemperaturen führen zu demselben letalen F-Wert. Der Zeiteinfluß der Erhitzung bei 115 °C wurde bei 60 und 100 min bewertet. Signifikante Verluste sind bei beiden Dosenkonserven aufgetreten (≈25%) und zwischen diesen und dem Rohfisch ( ≈12% und ≈34%) bei einer Erhitzungszeit von 60 und 100 min). Die Bestimmung des FAA-Gehalts in Thunfischkonserven kann für den Nachweis der Einwandfreiheit des thermischen Prozesses sehr nützlich sein.SummaryThe effects of cooking and sterilization at several temperatures on the free amino acids (FAA) content in albacore (Thunnus alalunga) muscle were studied during the processing of canned tuna. FAAs were derivatized witho-phtalaldehyde, separated on a C18 column by HPLC and detected by both fluorescence and ultra-violet detectors. After cooking the loss of FAAs was not significant. However, in the final product sterilized at 115 °C and 110 °C (throughout the whole process) there were significant losses with regard to the start material, but not at 118 °C (all temperatures leading to the same lethal F-value). The influence of the thermal process time at 115 °C was evaluated for 60 and 100 min. Significant losses were found between both canned products (≈25%) and between the raw fish and the final product (≈12% and ≈34%, process time 60 and 100 min, respectively). The determination of the content of FAA present in canned albacore may be a useful indication of the severity of the thermal processing.