Merki: Árstíðarbreytileiki

Skýrslur

Influence of seasonal variation and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

Útgefið:

01/12/2016

Höfundar:

Paulina E. Romotowska, Magnea G. Karlsdóttir, María Gudjónsdóttir, Hörður G. Kristinsson, Sigurjón Arason

Styrkt af:

AVS rannsóknasjóður í sjávarútvegi (R 040-12)

Influence of seasonal variation and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

Áhrif geymsluhitastigs (-18 °C vs. 25 °C) og veiðitíma (ágúst vs. september) á niðurbrot fitu í Atlantshafs makríl veiddum við Íslandsstrendur voru skoðuð í þessu verkefni. Stöðugleiki fitunnar var metinn með því að mæla fyrstastigs (PV) og annarsstigs myndefni þránunar (TBARS), fríar fitusýrur (FFA) auk fitusýrusamsetningu. Niðurstöðurnar sýna marktækan mun í fituniðurbroti með langvarandi geymslu, þar sem niðurbrotið var marktækt minna þegar geymt var við – 25 °C samanborið við -18 °C. Auk þessa var fiskur veiddur í september með hærri þránunargildi samanborið við fisk frá ágúst. Aftur á móti var ensímatískst fituniðurbrot meira í águst en september. Niðurstöðurnar gáfu einnig til kynna að magn ómega-3 fjölómettaðra fitusýra var nokkuð stöðugt út geymslutímann. Með öðrum orðum þá sýndu niðurstöðurnar að hitastig í frostgeymslu hafði mikil áhrif á fituniðurbrot en stöðugleikinn var háður því hvenær fiskurinn var veiddur.

Lipid deterioration of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters was studied, as affected by different frozen storage temperatures (-18 °C vs. -25 °C) and seasonal variation (August vs. September). The lipid stability was investigated by analyses of hydroperoxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acids, as well as changes in fatty acid composition. Results showed significant lipid deterioration with extended storage time, where the lower storage temperature showed significantly more protective effects. Furthermore, a higher lipid oxidation level was recorded for fish caught in September than in August, although lipid hydrolysis occurred to be greater for fish in August than in September. Moreover, results indicated a rather stable level of omega-3 fatty acid during the whole frozen storage period. The analysis indicated that both lipid oxidation and hydrolysis were affected by the frozen storage temperature and the stability differed with regards to season of catch.

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Skýrslur

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

Útgefið:

01/12/2015

Höfundar:

Paulina E. Romotowska, Magnea G. Karlsdóttir, María Guðjónsdóttir, Sigurjón Arason, Hörður G. Kristinsson

Styrkt af:

AVS rannsóknasjóður í sjávarútvegi (R 040-12)

Tengiliður

Sigurjón Arason

Yfirverkfræðingur

sigurjon.arason@matis.is

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

Á þeim tíma sem makríll er við íslandsstrendur er hann í miklu æti sem veldur því að hann snögg fitnar með þeim afleiðingum að holdið verður mjög viðkvæmt fyrir meðhöndlun. Í þessari rannsókn var makríll sem var veiddur sumarvertíðarnar 2012 og 2013 (júlí, ágúst, september) og frá mismunandi veiðisvæðum (austur, norðaustur, suður og suðaustur) skoðaður. Til þess að meta á hversu vel hráefnið hentar til vinnslu á hágæðaafurðum til manneldis, var makríllinn mældur m.t.t. vatns- og fituinnihalds, fitusýrusamsetningar, litar, þránunar og frírra fitusýra. Almennt var makríllinn sem safnað var sumarið 2012 af betri gæðum en makríll frá 2013. Niðurstöðurnar gáfu einnig til kynna breytileika á milli veiðimánaða m.t.t. fituinnihalds og framgang þránunar. Makríll sem var veiddur um miðbik vertíðarinnar hafði lægsta þránunargildið, sem gefur til kynna að sá makríll hentar best fyrir vinnslu á hágæðaafurðum til manneldis.

Atlantic mackerel (Scomber scombrus) appears in Icelandic waters during its heavy feeding period, resulting in variation in mackerel products quality. Fish caught at different season during the summers of 2012 and 2013 (July, August, September) and at different sites of the Icelandic fishing area (East, Northeast, South and Southeast) were analysed. Measurements of lipid and water content, fatty acid composition, colour changes, lipid hydroperoxide (PV), thiobarbituric reactive substances (TBARS) and free fatty acid (FFA) were studied with the aim of investigating whether this raw material was suitable for the production of high quality products for human consumption. In general, samples collected during the summer of 2012 showed a better condition than fish from 2013. The results indicated seasonal variation in lipid content and rancidity development. The lowest rancidity values were observed in the middle of the Icelandic catching season, indicating that this raw material was best suited for production of high quality products. Moreover, geographical variation of the mackerel catches had an impact on the saturation of the fatty acids, and appeared as follows: East > Southeast > Northeast > South.

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