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Makrílvinnsla á Íslandsmiðum

Sumarið 2008 var makrílsýnum safnað austur af landinu innan íslenskrar og færeyskrar lögsögu og mat lagt á flokkunareiginleika makrílsins.

Sýnunum var safnað af þremur skipum, þau voru tekin úr skiljara uppá dekki um leið og aflanum var dælt um borð. 30 fiskar af hverju skipi voru mældir á viku.  Eftirfarandi þættir voru mældir; heildarlengd, staðallengd, hauslengd, bollengd, stirtla, breidd, hæð, ummál og þyngd auk þess var kyn fiska greint.  Fiskurinn var hausaður og slógdreginn um borð í frystiskipunum áður en hann var frystur.

Makrill_mynd1

Minnstu makrílarnir voru 29 cm en þeir náðu þó ekki 1% af heildarfjöldanum. Langmest var af makríl sem var 35-39 cm. Makríll sem var 40 cm eða lengri var 20% af heildarfjölda sýna, stærstu sýnin voru 44 cm að lengd og voru 1% af heildarfjöldanum. Makríll verður mest 60 cm langur.

Minnstu makrílarnir voru um 250 grömm en makrílar sem voru undir 300 grömmum voru 4% af heildarsýnafjöldanum. Langflest sýni voru á bilinu 300 – 599 grömm eða 80% af heildinni, þó voru hlutfallslega flest sýni 400-499 grömm eða 31%. Þyngstu sýnin voru yfir 700 grömm og var það þyngsta 790 grömm, hlutfall sýna yfir 700 grömm var 3%.  Þegar kynskiptingin er skoðuð  sést að 65% af sýnunum var hængur og 35% hrygna. 

Fyrstu athuganir á flokkun makríls frá síld hafa verið framkvæmdar með Style-flokkurum. Á Style-flokkurunum flytja flokkunarrásir hráefnið niður á færibönd og er vídd bandanna stillanleg, þannig dettur minnsti fiskurinn fyrstur niður á færibönd en stærri fiskurinn heldur áfram og dettur seinna niður á færibönd sem flytja hann áfram í vinnsluna. Þegar flokkarinn var stilltur eingöngu m.t.t. til að flokka makríl datt síldin strax niður á færiband sem flutti síld og smámakríl í lest, sem síðan var  landað til bræðslu.  Þegar flokkarinn var stilltur til að flokka bæði síld og makríl var vídd bandanna minni á fremri helmingi flokkarans en mun meiri á aftari helmingi hans, þannig tókst að flokka síldina frá makrílnum en það útilokar þó þann kost að stærðarflokka fiskinn. Gallinn við þessa aðferð er þó að smámakríll slæðist með síldinni og þá þarf að týna hann úr síldaraflanum.

Stærstu útflutningsríkin af frosnum makríl, ásamt hrognum og lifur, eru Noregur og Bretland, þau hafa samanlagt yfir 50% af útflutningsverðmæti í heiminum. Önnur lönd sem flytja út makríl í einhverjum mæli eru Holland, Írland, Máritanía, Kanada, Þýskaland, Bandaríkin og Kína. Kaupendur að þessum afurðum eru að stærstum hluta Japanir, Rússar og Kínverjar.

Stærsti markaðurinn fyrir frosinn makríl er í Japan en 26% af heildarverðmæti markaðarins eru þar. Hins vegar kaupa Japanir ekki makríl af Íslendingum, ástæðan er sú að makríllinn sem leitar inn í íslenska lögsögu er í æti og fitnar mjög hratt eftir hrygninguna en það veldur losi í fiskvöðvanum. Japanir kaupa því haust og vetrarveiddan makríl að mestu leyti af Norðmönnum og Bretum, sem er af meiri og jafnari gæðum.

Þegar markaðir fyrir makrílafurðir eru skoðaðir þykir ljóst að markaðir í Japan og Austur-Evrópu séu fengsælustu markaðirnir bæði hvað varðar magn og verð.  Á meðan makríll veiðist einungis á sumrin í íslenskri lögsögu er ekki hægt að selja makríl á Japans-markað en markaðir í Austur-Evrópu sýna sumarveiddum makríl áhuga og voru kaupendur tilbúnir að borga yfir 2500 usd/tonn sumarið 2008.

Verkefnið var styrkt af AVS.

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Sensory evaluation of seafood: methods. In: Fishery Products: Quality, Safety and Authenticity

Food quality and safety issues continue to dominate the press, with most food companies spending large amounts of money to ensure that the food quality and assessment procedures in place are adequate and produce good and safe food. This holds true for companies and laboratories responsible for the processing of fish into various products, those responsible for researching safe new products, and departments within other companies supporting these functions.

Fishery Products brings together details of all the major methodologies used to assess the quality of fishery products in the widest sense. Subject coverage of this important book includes chapters on assessment of authenticity, and several chapters on quality assessment using various methods, such as:

  • Texture measurement
  • Electronic nose and tongue
  • NMR
  • Colour measurement

This timely volume will serve as a vital tool for all those working in the processing of fishery and aquaculture products: including laboratory personnel working in regulatory bodies, food quality control personnel, food scientists, food technologists, nutritionists, seafood trade bodies, seafood labelling regulatory bodies, government food protection agencies and environmental health personnel. Libraries in research establishments and universities where food science, food technology, nutrition, aquaculture, fisheries and biological sciences are studied and taught should have copies of this important publication on their shelves.

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Sensory evaluation of seafood: general principles and guidelines. In: Fishery Products: Quality, Safety and Authenticity

Food quality and safety issues continue to dominate the press, with most food companies spending large amounts of money to ensure that the food quality and assessment procedures in place are adequate and produce good and safe food. This holds true for companies and laboratories responsible for the processing of fish into various products, those responsible for researching safe new products, and departments within other companies supporting these functions.

Fishery Products brings together details of all the major methodologies used to assess the quality of fishery products in the widest sense. Subject coverage of this important book includes chapters on assessment of authenticity, and several chapters on quality assessment using various methods, such as:

  • Texture measurement
  • Electronic nose and tongue
  • NMR
  • Colour measurement

This timely volume will serve as a vital tool for all those working in the processing of fishery and aquaculture products: including laboratory personnel working in regulatory bodies, food quality control personnel, food scientists, food technologists, nutritionists, seafood trade bodies, seafood labelling regulatory bodies, government food protection agencies and environmental health personnel. Libraries in research establishments and universities where food science, food technology, nutrition, aquaculture, fisheries and biological sciences are studied and taught should have copies of this important publication on their shelves.

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Consumer preference and description of salmon in four Northern Atlantic countries and association with sensory characteristics

The focus in this article is on the relation between consumer preference and objective description of the product profile of salmon. A consumer study of eight salmon products was carried out in Iceland, Denmark, the Netherlands, and Ireland. In addition, objective sensory profiling using a trained sensory panel was performed on the products, which varied according to storage method, storage time, origin, and species. For five out of eight samples, no significant differences in overall liking between the countries were found in the consumer study. However, the consumers gave the samples significantly different descriptions. There was a strong correspondence between the consumer descriptions and the sensory profile.

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Sensory characteristics of different cod products related to consumer preferences and attitudes

Quantitative descriptive analysis (QDA) was used to analyse the sensory quality of eight cod products, different with regard to origin (wild/farmed), storage time (short/extended) and storage method (fresh/frozen/packed in modified atmosphere). At the same time, 378 consumers in four European countries tasted and scored the cod products on a 9-point hedonic scale. In addition information on the consumers attitudes, motives/barriers and fish purchase behaviour was collected. The aim was to investigate how sensory quality corresponded to consumers liking of different cod products and to study the liking in terms of different consumer attitudes and demographics. The QDA discriminated well between the products. The farmed cod products were considerably different from wild cod, with more light and even colour, meaty texture, odour and flavour. Country differences were considerable with regard to fish consumption, attitudes and preferences of the eight cod products. However, it was demonstrated that within each country, different segments of consumers existed with different preferences, motives/barriers and demographic background. The results indicated various potential to increase fish consumption.

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Pleistocene genetic legacy suggest incipient species of Sebastes mentella in the Irminger Sea

To investigate a possible speciation event within the redfish (Sebastes mentella) complex in the Irminger Sea, we examined genetics, traditional morphology, geometric morphometrics and meristics of individuals sampled throughout the Sea. Tissue samples from 1901 fish were collected in 1995 and 1996 and from 1999 to 2002, and the fish were genotyped at nine microsatellite loci, two of which were developed for this study. Individual-based genetic analyses showed that two different gene pools exist in the Irminger Sea. Although these groups overlap extensively geographically, they segregate according to depth: those above and below 550 m. This signal of genotype distinction with depth was evident in both the earlier and later sampling. Historical imprints in the genetic data indicated that the redfish in the Irminger Sea are likely to represent a case of an incipient speciation event that began in allopatry during the Pleistocene glaciations followed by secondary contact. Although hybridization was observed between groups, an analysis of traditional and geometric morphometrics and of meristic variables suggested that restricted gene flow between the currently parapatric deep- and shallow-mesopelagic incipient species may be maintained by ecological isolation mechanisms.

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Decontamination Efficiency of Fish Bacterial Flora from Processing Surfaces

There are numerous parameters that can influence bacterial decontamination during washing of machinery and equipment in a food processing establishment. Incomplete de-contamination of bacteria will increase the risk of biofilm formation and consequently in-crease the risk of pathogen contamination or prevalence of other undesirable microorga-nisms such as spoilage bacteria in the processing line. The efficiency of a typical washing protocol has been determined by testing three critical parameters and their effects on bac-terial decontamination. Two surface materials (plastic and stainless steel), water tempera-tures (7 and 25 °C) and detergent concentrations (2 and 4 %) were used for this purpose in combination with two types of detergents. Biofilm was prepared on the surfaces with un-defined bacterial flora obtained from minced cod fillets. The bacterial flora of the biofilm was characterised by cultivation and molecular analysis of 16S rRNA genes. All different combinations of washing protocols tested were able to remove more than 99.9 % of the bacteria in the biofilm and reduce the cell number from 7 to 0 or 2 log units of bacte-ria/cm 2 . The results show that it is possible to use less diluted detergents than recommend-ed with comparable success, and it is easier to clean surface material made of stainless steel compared to polyethylene plastic.

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Total phenolic compounds, radical scavenging and metal chelation of extracts from Icelandic seaweeds

Screening of potential antioxidant activities of water and 70% acetone extracts from ten species of Icelandic seaweeds was performed using three antioxidant assays. Significant differences were observed both in total phenolic contents (TPC) and antioxidant activities of extracts from the various species evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. Acetone extracts from three Fucoid species had the highest TPC and consequently exhibited the strongest radical scavenging activities. High correlation was found between TPC of seaweed extracts and their scavenging capacity against DPPH and peroxyl radicals, indicating an important role of algal polyphenols as chain-breaking antioxidants. However, water extracts generally had higher ferrous ion-chelating activity than 70% acetone extracts and no correlation was found with their TPC, suggesting that other components such as polysaccharides, proteins or peptides in the extracts were more effective chelators of ferrous ions than phenolic compounds.

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Comparison of Campylobacter fla-SVR genotypes isolated from humans and poultry in three European regions

Aims: The genetic diversity of Campylobacter isolated from human infection and from poultry was assessed in strains originating in three different European regions in order to compare these two hosts and to investigate European regional differences.

Methods and Results: Randomly chosen isolates originated from Norway, Iceland and Basque Country in Spain were genotyped by sequencing of the short variable region (SVR) of flaA. A total of 293 strains were investigated, c. 100 per country with half originated from either host. The results indicate extensive diversity in both hosts and identified differences in the nature and distribution of genotypes between the countries. These differences could in part be related to geographical location, in that Campylobacter genotypes from Iceland and Norway were more similar to each other than either was to Basque Country.

Conclusions: Differences between the countries exceeded the observed differences between human and poultry isolates within a country.

Significance and Impact of the Study: Regional differences are extensive and should not be ignored when comparing genotyping data originating from different international studies.

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The effect of brining, modified atmospher packaging and superchilling on the shelf life of cod (Gadus morhua) loins

The aim of these experiments was to evaluate the effect of brining, modified atmosphere packaging (MAP), and superchilling on the quality changes of cod loins as measured by microbial, sensory, and chemical analysis. Unbrined and brined (2.5 ± 1.0% NaCl) cod loins were kept in styrofoam boxes (air) and under modified atmosphere (MA, CO2/O2/N2: 50/5/45) at 0, −2, and −3.6 °C. Samples were examined over a 4-wk period. Total viable psychrotrophic counts and counts of H2S-producing bacteria reached higher numbers in the air-packed brined fish at −2 and −3.6 °C than in comparable unbrined groups, being significantly different (P < 0.05) at the lower temperature. However, lower counts of these bacteria were obtained in the brined MAP fish than in comparable unbrined fish. Counts of Photobacterium phosphoreum increased most rapidly in air- and MA-packed loins kept at 0 °C. Lower counts were found at superchilled temperatures. According to sensory analysis the shelf life of unbrined air-packed loins was about 11 d at 0 °C and 14 to 15 d at −2 °C. The shelf life of MA-packed unbrined loins was about 14 to 15 d at 0 °C but 21 d at −2 °C. Thus, synergism of combined superchilling (−2 °C) and MA led to a considerable shelf life increase for unbrined loins despite the fact that processing and packaging took place 4 to 5 d post-catch. The shelf life of air-packed brined loins at −2 °C was 12 to 15 d but only 13 d under MA. The same synergistic effect did therefore not apply to brined loins as with unbrined ones.

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