Effect of a polyphenol–vacuum packaging on lipid deterioration during an 18-month frozen storage of Coho Salmon (Oncorhynchus kisutch)

10 páginas, 3 tablas, 2 figuras.-- The final publication is available at www.springerlink.comA packaging system combining a polyphenolrich film and vacuum (PPRF–VP) was applied to farmed coho salmon (Oncorhynchus kisutch) muscle for an 18- month storage (−18 °C). For it, two different concentrations of polyphenol compounds (namely, p-coumaric and ferulic acids) obtained from a barley husk extract were applied (PPRF–VP conditions) and compared to vacuum packaging without polyphenol presence (vacuum control; VP condition) and to packaging in the absence of vacuum and polyphenols (control; CP condition). The study was addressed to lipid hydrolysis and oxidation development and to lipid changes related to nutritional value. Both PPRF–VP conditions provided an inhibitory effect (p< 0.05) on conjugated diene and fluorescent compound formation in frozen salmon. Compared to CP condition, vacuum packaging (PPRF–VP and VP conditions) led to lower (p<0.05) peroxide and anisidine values and to an inhibitory effect (p<0.05) on α- and γ-tocopherol losses. No effect (p>0.05) of polyphenol presence and vacuum packaging could be inferred on free fatty acid formation (hydrolysis development) and on polyunsaturated fatty acid retention (polyene index assessment). A low rancid odour development was observed in all kinds of fish samples, this being lower (p<0.05) in fish kept under vacuum (PPRF–VP and VP) conditions.Peer reviewe

Quality assessment of sardines during storage by measurement of fluorescent compounds

5 páginas, 2 figuras, 5 tablasSardine alterations during chilled storage (0°C) were investigated by measuring the fluorescence ratio between two excitation/emission maxima (393/463 nm, 327/415 nm) and compared with common quality indices. Sardines were also maintained at 15°C to accelerate all reactions occurring at 0°C. Other quality indices (total volatile base-nitrogen, free fatty acids, formation of conjugated dienes, and thiobarbituric acid values) were determined and the use of the fluorescence ratio (fluorescence shift, δF) was analyzed. A high correlation was found between the δF and the total volatile base-nitrogen (r = 0.93, at 0°C; r = 0.92, at 15°C).Xunta de Galicia (Project XUGA 402 01B93).Peer reviewe

Differential lipid damage in various muscle zones of frozen hake (Merluccius merluccius)

5 páginas, 5 tablas, 1 figura.-- The final publication is available at www.springerlink.comA comparison of the lipid damage produced in different hake zones was carried out during frozen storage at –11 and –18 7C. Three light muscle zones and the dark muscle were considered. Lipid oxidation [conjugated dienes; thiobarbituric acid index (TBA-i); fluorescence formation] and hydrolysis (free fatty acids, FFA) were determined. The most predominant lipid damage in all zones was hydrolysis, at the end of storage reaching values of about 40% (for the light muscle zones) and 12% (for the dark muscle) of the total lipids at –11 7C. Significant (P~0.05) correlation value (rp0.67–0.85) relationships between the frozen storage time and the FFA content were obtained for the four muscle zones at both temperatures. A comparison of the regression lines slopes in the different zones showed that a lower (P~0.05) lipolitic activity was produced in the dark muscle compared to the three light zones at both temperatures. A low lipid oxidation development was produced in the three light muscle parts, so that no significant differences between them could be assessed. However, the dark muscle showed a higher oxidation development (TBA-i and fluorescence formation) as a result of a higher lipid content and the presence of prooxidant constituents.European Community, Research Projects FAIR-CT95–1111 and AIR 3-CT94–1921.Peer reviewe

The presence of bioactive compounds in European eel (Anguilla anguilla) skin: a comparative study with edible tissue

The presence of bioactive compounds in European eel (Anguilla anguilla) skin was studied. Proximate and lipid class compositions and analysis of the fatty acid (FA) profile (individual FAs; FA groups, i.e., saturated, monounsaturated, and polyunsaturated; FA ratios, i.e., polyunsaturated/saturated, ω3/ω6) were determined and compared to the composition of the eel muscle. As a result, higher (p 0.05) between both tissues could be detected for triacylglycerol and FA group (saturated, monounsaturated, and polyunsaturated) values and for the polyunsaturated/saturated FA ratio. It is concluded that European eel skin, a by-product resulting from commercial processing, can be considered a valuable source for the food and pharmaceutical industries by providing value-added constituents such as proteins, lipids, ω3 FAs, phospholipids, and α-tocopherol

Quality enhancement of chilled fish by including alga Bifurcaria bifurcata extract in the icing medium

9 páginas, 4 tablasBifurcaria bifurcata is a widely extended brown macroalga, whose antimicrobial and antioxidant properties have previously been described. In this study, ethanolic extracts of B. bifurcata were included in the icing medium employed for the chilled storage of megrim (Lepidorhombus whiffiagonis). For it, two different concentrations of this brown macroalga extract (0.67 and 2.50 g lyophilized alga L−1 aqueous solution; B-1 and B-2 batches, respectively) were tested for a 14-day storage. The effect of the alga extract was compared with a counterpart batch stored in traditional ice prepared only from water (B-0 batch). Significant (p < 0.05) inhibitions of microbial activity (aerobes, psychrotrophs, lipolytic bacteria, proteolytic bacteria and Enterobacteriaceae) as well as of pH and trimethylamine formation were observed as a result of the incorporation of the alga extract in the icing medium, being this effect especially relevant in the B-2 batch. Concerning lipid damage development, a significantly (p < 0.05) lower formation of free fatty acids (lipid hydrolysis development) and of fluorescent compounds (tertiary lipid oxidation development) in samples corresponding to both alga-including batches could also be observed; this inhibitory effect was more intense in fish belonging to the B-2 batch. The icing medium proposed in this work constitutes a promising strategy in order to apply algae extracts to enhance fish quality retention during the different steps of storage and commercialization of marine speciesThis work was supported by the Consejo Superior de Investigaciones Científicas (CSIC; Spain) through the project PIE 201370E001Peer reviewe

Effect of advanced chilling methods on lipid damage during sardine (Sardina pilchardus) storage

7 páginas, 2 figuras, 4 tablasSlurry ice is a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature. Its effect on lipid damage (hydrolysis and oxidation) was evaluated during the chilled storage of a fatty fish species, sardine (Sardina pilchardus). Slurry ice treatment was checked alone and in combination with ozone and compared to traditional flake icing during a 22-day storage. Different lipid damage indices (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescent compounds, FR) were checked and compared to sensory assessment and nucleotide degradation (K value). According to lipid hydrolysis (FFA) and oxidation (PV and FR) developments, slurry ice showed an inhibitory effect (p 0.05) from slurry ice alone when considering lipid hydrolysis, nucleotide degradation and some lipid oxidation indices (PV and FR), although a higher (p <0.05) TBA-i was observed at day 22 of storage when compared to flake ice and slurry ice treatments. However, a lower (p <0.05) fluorescence development was observed for fish treated under ozonised slurry ice when compared to traditionally iced fish. Sensory assessment showed a higher shelf life for fish samples treated under ozonised slurry ice than for their counterparts under slurry ice (15 d versus 12 d), while flake icing led to a far shorter shelf life (5 d). According to sensory and biochemical (lipid matter and nucleotide) analysis, slurry ice has proved to be a promising technology for damage inhibition and quality retention in a fatty fish species such as sardine. Ozonised slurry ice was also shown to be useful, since a longer shelf life was obtained in the present experiment and a pro-oxidant effect of ozone on sardine lipids was not provedThis work was supported by the Secretaría Xeral de I1D fromthe Xunta de Galicia (Galicia, Spain) (Project PGIDIT02RMA18E).Peer reviewe

Sensory and physical changes in chilled farmed coho salmon (Oncorhynchus kisutch): Effect of previous optimized hydrostatic high-pressure conditions

11 páginas, 2 figuras, 4 tablas.-- The final publication is available at www.springerlink.comThe effect of a previous hydrostatic high-pressure (HHP) treatment on sensory and physical quality of chilled coho salmon (Oncorhynchus kisutch) was investigated. As a first stage, a 22 factorial design based on the response surface methodology was used for optimization of HHP conditions; for it, the effects on color uniformity, white spots appearance, elasticity, and hardness were analyzed. In a second stage, optimized HHP conditions (135 MPa for 30 s, 170 MPa for 30 s, and 200 MPa for 30 s; treatments T-1, T-2, and T-3, respectively) were applied as previous treatment to chilling, being sampling carried out on salmon muscle at days 0, 6, 10, 15, and 20. A marked effect on sensory and physical parameters was detected after HHP treatment and throughout the chilled storage. According to odor (rancid, putrid), texture (elasticity, gaping, firmness), and color (L* value) attributes, fish corresponding to T-1 condition was shown to have better-maintained quality throughout the chilled storage than fish belonging to T-2 and T-3 conditions; additionally, a quality enhancement (putrid odor, cohesivity, gaping) was found when compared with control samples. In agreement to the preliminary optimization study, it is concluded that T-1 condition can provide the most effective HHP pre-treatment to better maintain sensory and physical properties when salmon muscle is to be commercialized as a fresh product. Results obtained for the quality evolution of chilled fish attest the importance of establishing a judicious selection of previous HHP treatment parameters to minimize undesirable changes related to sensory and physical characteristicsThis work was supported by the Universidad de Chile (Chile)-Consejo Superior de Investigaciones Científicas (Spain) program (Project 2006 CL 0034) and the FONDECYT program (Chile; project number: 1080626)Peer reviewe

On-board quality preservation of megrim (Lepidorhombus whiffiagonis) by a novel ozonised-slurry ice system

6 páginas, 3 tablas.-- The final publication is available at www.springerlink.comThe use of a combined ozonised-slurry ice system was investigated as a new refrigeration system for the on-board storage of megrim (Lepidorhombus whiffiagonis), a fish species that is usually stored aboard fishing vessels for 1 to 2 weeks. The time elapsed between the catch and unloading at the harbour affects its quality and commercial value directly. Microbiological, chemical and sensory analyses were carried out in megrim after 2 weeks of onboard storage in ozonised slurry ice, slurry ice or flake ice, and for an additional period of 6 days. Sensory analyses revealed that megrim specimens stored in ozonised slurry ice (oSI600 batch) maintained A quality even after 20 days of storage, while counterpart batches stored in flake ice showed B quality at unloading, after 14 days of on-board storage. Storage in ozonised slurry ice (oSI600 batch) also led to significantly (p<0.05) lower counts of aerobic mesophiles, psychrotrophic bacteria, Enterobacteriaceae and proteolytic microorganisms in megrim muscle as compared with flake ice. Biochemical analyses revealed that the use of ozonised-slurry ice or slurry ice alone slowed down the formation of total volatile base-nitrogen (TVBN) and trimethylamine-nitrogen (TMA-N) in comparison with storage in flake ice, also allowing a better control of pH. Lipid hydrolysis and oxidation events also occurred at a lower rate in the ozonised-slurry ice and slurry ice batches than in the flake ice batch. The present study demonstrates that the combination of slurry ice and ozone for the on-board storage of megrim is advisable, thus improving the quality and extending the shelf life of this fish species.This work was supported through a project grant by the Secretar´ıa Xeral de I+D from the Xunta de Galicia (Project PGIDIT04TAL015E).Peer reviewe

Effect of jumbo squid (Dosidicus gigas) skin extract on the microbial activity in chilled mackerel (Scomber scombrus)

6 páginas, 4 tablas, 2 figurasDuring the industrial processing of jumbo squid (Dosidicus gigas), large amounts of by-products containing biological active compounds are generated. In this study, aqueous solutions including acetic acid-ethanol extracts of jumbo squid skin (JSS) were tested at three different concentrations as icing media. The effects of the JSS extracts on the quality evolution of chilled mackerel (Scomber scombrus) were monitored. A significant inhibition (p < 0.05) of microbial activity was determined in the fish batch corresponding to the icing condition including the highest JSS concentration. Additionally, fish specimens corresponding to batches including any of the JSS concentrations tested showed lower (p < 0.05) proteolytic counts and pH values than control mackerel. Sensory analysis revealed a marked shelf life extension in chilled mackerel stored in ice including the highest JSS concentration; specimens from such batch were found to be still acceptable after 13 days of storage, while all other mackerel batches were rejectable. The marked microbial activity inhibition observed could be explained on the basis of the presence in ice of lipophilic compounds obtained by acetic acid-ethanol extraction of JSSThis work was supported by the CONACYT-Mexico grant 154046 and the Consejo Superior de Investigaciones Científicas (CSIC) through Research Project PIE 201370E001Peer reviewe

Lipid Oxidation Inhibition in Frozen Farmed Salmon (Oncorhynchus kisutch ): Effect of Packaging

3 pages, 1 table.Coho salmon (Oncorhynchus kisutch) has recently attracted a great interest as a farmed product. This research focuses on its commercialisation as a frozen product. For it, an advanced storage technology combining vacuum and a polyphenolic rich-film was applied for a 9-months storage period (–18°C). The study was addressed to lipid hydrolysis and oxidation changes and to endogenous antioxidant content in salmon muscle. No effect of packaging conditions could be observed on free fatty acid formation. However, vacuum packaging conditions provided a partial inhibition of primary (peroxide) and secondary (anisidine value) lipid oxidation development; this inhibitory effect was accompanied by a lower tocopherol isomers loss. The employment of a film including polyphenolic compounds led to a partial inhibition of α-tocopherol breakdown and to a lower secondary (anisidine value) and tertiary (fluorescent compound formation) lipid oxidation development. A partial inhibitory effect on lipid oxidation development is concluded for the employment of a polyphenolic compound rich-film packaging when applied to farmed coho salmon.This research was carried out in the frame of the Project No. 2006 CL 0034 (2007–2008), granted by the U. Chile-CSIC Cooperation Program. Coho salmon fish was provided by Aquachile SA (Puerto Montt, Chile).Peer reviewe