News

Mackerel processing in Icelandic waters

In the summer of 2008, mackerel samples were collected east of the country within Icelandic and Faroese jurisdiction and the sorting properties of the mackerel were assessed.

The samples were collected from three vessels, they were taken from a separator on deck as soon as the catch was pumped on board. 30 fish from each vessel were measured per week. The following factors were measured; total length, standard length, head length, bowl length, tails, width, height, circumference and weight in addition, the sex of fish was analyzed. The fish was decapitated and gutted on board the freezer vessels before it was frozen.

Mackerel_photo1

The smallest mackerel were 29 cm, but they did not reach 1% of the total number. The longest was mackerel, which was 35-39 cm. Mackerel that was 40 cm or longer was 20% of the total number of samples, the largest samples were 44 cm long and were 1% of the total number. Mackerel will be at most 60 cm long.

The smallest mackerel was about 250 grams but mackerel that weighed less than 300 grams was 4% of the total sample. The vast majority of samples ranged from 300 - 599 grams or 80% of the total, although the relative majority of samples were 400-499 grams or 31%. The heaviest samples were over 700 grams and the heaviest was 790 grams, the proportion of samples over 700 grams was 3%. When the sex division is examined, it can be seen that 65% of the samples were snagged and 35% spawned. 

Initial observations of the classification of mackerel from herring have been carried out using Style classifiers. In the Style classifiers, the sorting channels transport the raw material down to the conveyor belts and the dimension of the belts is adjustable, so that the smallest fish first falls onto the conveyor belts but the larger fish continues and later falls onto the conveyor belts which transport it further to processing. When the classifier was set solely to classify mackerel, the herring immediately fell onto a conveyor belt that transported herring and small mackerel in a train, which was then landed for smelting. When the classifier was set to classify both herring and mackerel, the dimension of the straps was smaller in the front half of the classifier but much larger in the back half, so the herring could be sorted from the mackerel, but this precludes the possibility of classifying the fish. The disadvantage of this method is that small mackerel slips with the herring and then has to be lost from the herring catch.

The largest exporters of frozen mackerel, along with roe and liver, are Norway and the United Kingdom, with a combined total of over 50% of world export value. Other countries that export mackerel to some extent are the Netherlands, Ireland, Mauritania, Canada, Germany, the United States and China. The buyers of these products are mostly Japanese, Russians and Chinese.

The largest market for frozen mackerel is in Japan, where 26% of the total market value is located. On the other hand, the Japanese do not buy mackerel from Icelanders, the reason being that the mackerel that enters Icelandic jurisdiction is in food and fats very quickly after spawning, which causes loosening in the fish muscle. The Japanese therefore buy autumn and winter-caught mackerel mostly from Norway and Britain, which is of higher and more equal quality.

When looking at markets for mackerel products, it is clear that markets in Japan and Eastern Europe are the most prosperous markets in terms of both volume and price. While mackerel is only caught during the summer in Icelandic jurisdiction, it is not possible to sell mackerel on the Japanese market, but markets in Eastern Europe show interest in summer-caught mackerel and buyers were willing to pay over 2500 usd / ton in the summer of 2008.

The project was funded by AVS.

Peer-reviewed articles

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
  • Color 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 labeling 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.

Link to book

Peer-reviewed articles

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
  • Color 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 labeling 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.

Link to book

Peer-reviewed articles

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

The focus in this article is on the relationship 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.

Link to article

Peer-reviewed articles

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

Quantitative descriptive analysis (QDA) was used to analyze 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 behavior 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 color, meaty texture, odor and flavor. 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.

Link to article

Peer-reviewed articles

Pleistocene genetic legacy suggests 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 analyzes 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.

Link to article

Peer-reviewed articles

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 microorganisms 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 bacterial decontamination. Two surface materials (plastic and stainless steel), water temperatures (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 characterized 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.

Link to article

Peer-reviewed articles

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.

Link to article

Peer-reviewed articles

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.

Link to article

Peer-reviewed articles

The effect of brining, modified atmosphere 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 below MA. The same synergistic effect did therefore not apply to brined loins as with unbrined ones.

Link to article

EN