Year: 2017

News

It is better to smoke whole mackerel products

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Benjamin Aidoo is defending his master's thesis in environmental and resource sciences at the University of Iceland. Benjamin's thesis is entitled "The effect of different smoking methods on the formation of polyaromatic hydrocarbon compounds (PAH) and the physicochemical quality of smoked mackerel products"

Further location

  • Matís
  • Vínlandsleið 12
  • 113 Reykjavík
  • June 8, 2017 at 14
  • Meeting room 312

Effects of different smoking methods on the formation of polycyclic aromatic hydrocarbons (PAHs) and physicochemical quality in smoked Atlantic mackerel products

Effects of different smoking methods on the formation of polyaromatic hydrocarbon compounds (PAHs) and the physicochemical quality of smoked mackerel products

The effects of different smoking methods and temperatures on the formation of polyaromatic hydrocarbons (PAHs) in smoked mackerel were studied. The effects of different smoking methods, storage temperatures and packaging materials on the stability of hot smoked mackerel products were also investigated, by observing their physical and chemical properties. The study showed that the formation of PAHs was above the desired level if cell smoking was used on mackerel fillets. However, PAHs were found to be below the limit if the mackerel was smoked whole or in a Bradley smoke oven. However, the temperature obtained in the Bradley smoke oven was not high enough to ensure the stability of the products in terms of degradation by microorganisms, oxidation or enzymes through storage in the refrigerator. The formation of free fatty acids and oxidative derivatives was generally higher in fillets than in whole fish. The formation of TVB-N could also be slowed down if the fillets were stored under vacuum instead of air packaging. It is therefore recommended that mackerel be smoked whole in a cabin smoke oven, and stored in a refrigerator under a ventilated container to ensure maximum quality.

Supervisors

  • María Guðjónsdóttir, University of Iceland
  • Sigurjón Arason, Matís, University of Iceland

Everyone welcome! 

Reports

Overview of available methods for thawing seafood / Solutions available for thawing seafood

Published:

01/06/2017

Authors:

Sigurður Örn Ragnarsson, Jónas R. Viðarsson

Supported by:

The Norwegian Research Council (Project number 233709 / E50)

Overview of available methods for thawing seafood / Solutions available for thawing seafood

There is a constant demand for quality raw materials that can be used for producing seafood products for high paying markets in Europe and elsewhere in the world. Suppliers of demersal fish species in the North Atlantic are now meeting this demand by freezing the mainstay of their catches, in order to be able to have available supplies all year around. This is partly done because of seasonal fluctuations in catches, which are harmful from a marking point of view. The fact that all these raw materials are now frozen demands that methods used for freezing and thawing can guarantee that quality of the raw material is maintained. There are a number of methods available to thaw fish. The most common ones involve delivering heat to the product through the surface, as with conduction or convection. These methods include water and air-based systems. More novel methods are constantly on the rise, all with the aim of making the process of thawing quicker and capable of delivering better products to the consumer. These procedures are however, often costly and involve specialized workforce to control the process. All in all, it depends greatly on what kind of conditions a company is operating under regarding which thawing methods should be chosen. This report identifies the most common methods available and provides information on their main pros and cons.

There is a constant demand from fish processing plants around the world for good raw materials from the North Atlantic for the production of products for demanding markets. To meet this demand and in view of the large seasonal fluctuations in catches of certain fish species, companies have decided to freeze the raw material for later use. This requires good methods for freezing the raw material, but it is no less important that the thawing of the raw material is good. There are many methods for thawing fish and other seafood. It has been most common to use heat transfer through surfaces with heat transfer or thermal conductivity. These methods are mostly based on the use of water or air as a medium for thawing. Newer methods exist that try to make the process faster and thus deliver a better product to consumers. However, these methods are often costly and involve a great deal of staff specialization. After all, it matters what kind of business it is and how the companies' situation is at any given time when thawing methods and technical solutions are chosen. This report identifies all the major thawing methods and the technical solutions available on the market today, as well as outlining their main advantages and disadvantages.

View report

News

Knowledge develops the fishing industry

Cooperation on research and development in the fisheries sector is part of Iceland's development cooperation. In this way, the aim is to utilize Icelanders' expertise in the field where Icelanders are at the forefront, so that, among other things, improved food security can be promoted on the basis of sustainable resource utilization. Such co-operation has recently revealed results that strengthen the arguments for the importance of good and disciplined work methods in the production of fish fillets.

In the recent month of May came out article in the Journal of Food Engineering on the effects of ambient temperatures and pending raw material processing. The article is based on a study conducted in collaboration with Icelanders' emphasis in development cooperation, where it is planned to utilize Icelanders' expertise in the field of fish processing. The study was carried out jointly by private companies and public bodies, and such co-operation is part of Iceland's contribution to meeting the world's goals.

A Chinese student United Nations University School of Fisheries (UNU-FTP), Mu Gang, worked on the research under the guidance of Icelandic instructors during his study stay in Iceland. Mu Gang's instructors were dr. Kristín Anna Þórarinsdóttir at Marel, Ásbjörn Jónsson and Arnljótur Bjarki Bergsson at Matís and the research was carried out at Matís.

The article provides results that strengthen the argument for the importance of good and disciplined work methods in the production of fish fillets. Purposeful cooling plays a key role in preserving quality. As important as it is to minimize the damage to the fish from fishing to consumption, it is also important to reduce any delays that may occur in the processing process. As has been stated another level bleeding, haemorrhage (bleeding), washing and cooling are important on board fishing vessels, the same applies to the efficiency and maintenance of low temperatures during fillet processing. 

Although every effort is made to work well in processing fish into fillets, it may happen that fish do not find their way through the processing as quickly as expected or that fish pass through a space that is warmer than would be preferable. . The results of the study show well the consequences if one deviates from the established procedure, ie. to maintain a low temperature throughout the processing process, even if the deviation is short-lived. High ambient temperatures and processing delays lead to a reduction in the weight and value of products. It is therefore important to avoid bottlenecks that lead to the accumulation of fish in processing channels, especially in slightly chilled conditions. In addition, it is important that the temperature of the products during packaging is as close as possible to the storage temperature. 

The knowledge created by the research is an example of the fruit of Matís' long and successful collaboration United Nations University School of Fisheries with Icelandic fisheries companies as well as companies that serve the Icelandic fisheries sector, such as Marel. Extensive knowledge is created in the university community and researchers have worked in extensive collaboration on its development and implementation at strong, responsible fisheries companies. Cooperation on the application of knowledge has enabled the Icelandic fishing industry to make great strides, and this has been noticed around the world. It has made the Icelandic fishing industry theirs knowledge industry who he is today and lives in the field for his development for the future.

Marel is one of Iceland's largest export companies and a world leader in the development and production of advanced equipment and systems for fish processing.

Matís provides advice and services worldwide to customers such as companies fisheries and agriculture. Matís assists customers in the development and implementation of knowledge, including new processes for companies with the application of science.

Icelandic fisheries companies work on value creation with sustainability as a guiding principle, biological, economic and social. 

The United Nations University School of Fisheries is one of four United Nations universities hosted in Iceland with the aim of enhancing fisheries expertise; fisheries and fish processing in developing countries.

Peer-reviewed articles

Thermoactinoamide A, an Antibiotic Lipophilic Cyclopeptide from the Icelandic Thermophilic Bacterium Thermoactinomyces vulgaris

The thermophilic bacterium Thermoactinomyces vulgaris strain ISCAR 2354, isolated from a coastal hydrothermal vent in Iceland, was shown to contain thermoactinoamide A (1), a new cyclic hexapeptide composed of mixed d and l amino acids, along with five minor analogues (2-6). The structure of 1 was determined by one- and two-dimensional NMR spectroscopy, high-resolution tandem mass spectrometry, and advanced Marfey's analysis of 1 and of the products of its partial hydrolysis. Thermoactinoamide A inhibited the growth of Staphylococcus aureus ATCC 6538 with an MIC value of 35 μM. On the basis of literature data and this work, cyclic hexapeptides with mixed d / l configurations, one aromatic amino acid residue, and a prevalence of lipophilic residues can be seen as a starting point to define a new, easily accessible scaffold in the search for new antibiotic agents.

Link to article

Peer-reviewed articles

Antioxidant effect of water and acetone extracts of Fucus vesiculosuson oxidative stability of skin care emulsions: Seaweed extracts in skin care products

A water and an acetone extract of the Icelandic brown algae Fucus vesiculosus were evaluated as potential natural sources of antioxidant compounds in skin care emulsions. To assess their efficacy in inhibiting lipid oxidation caused by photo- or thermoxidation, they were stored in darkness and room temperature as control conditions, and compared to samples stored under accelerated conditions (light and room temperature, or darkness and 40 ° C). The presence of extracts in the skin care emulsions induced remarkable color changes when the emulsions were exposed to light, and more extensively under high temperature. High temperature also caused greater increments in the droplet size of the emulsions. The analysis of the tocopherol content, peroxide value and volatile compounds during storage revealed that, whereas both water and acetone extracts showed (at 2 mg / g of emulsion) protective effect against thermooxidation, only the water extract showed antioxidant activity against photooxidation.

Link to article

Peer-reviewed articles

Oxidative stability and microstructure of 5% fish-oil-enriched granola bars added natural antioxidants derived from brown alga Fucus vesiculosus: Lipid oxidation in foods and antioxidant application

The aims of this study were to (i) investigate the ability of Icelandic brown algae Fucus vesiculosus extracts to inhibit lipid oxidation in granola bars fortified with fish oil-in-water emulsion; (ii) investigate whether addition of the seaweed extracts affected the physical microstructure of the oil droplets in granola bars. The oxidative stability of the bars at 20 ° C was evaluated over a period of 10 wk by measuring the development of peroxides and volatile compounds using dynamic headspace gas chromatography mass spectrometry (DHS GC-MS). The physical microstructure was determined using microscopy. All extracts - except water extract in low concentration - reduced lipid oxidation during 10 wk of storage when added in a concentration of 0.5 or 1 g extract / 100 g emulsion. Ethanol (EE) and acetone extracts (AE) (in the lowest concentration) were found to be most efficient as antioxidants in the bars. The antioxidant efficacy of these two extracts was among others related to an improved incorporation of the fish oil-in-water emulsions in the bars, high total phenolic content, high radical scavenging activity together with high interfacial affinity of phenolic compounds and probably regeneration of tocopherol .

Link to article

Peer-reviewed articles

Bioactivity of cod and chicken protein hydrolysates before and after in vitro gastrointestinal digestion

Bioactivity of cod (Gadus morhua) and chicken (Gallus domesticus) protein hydrolysates before and after in vitro gastrointestinal (GI) digestion was investigated using yeast Saccharomyces cerevisiae as a model organism. Both hydrolysates were exposed to in vitro GI digestion prior to cellular exposure to simulate digestion conditions in the human body and therefore investigate the role of modulations in the GI tract on the cell response. The effect of digested and undigested hydrolysates on intracellular oxidation, cellular metabolic energy and proteome level was investigated. No difference in the effect on intracellular oxidation activity was obtained between cod and chicken hydrolysates, while higher affect on intracellular oxidation was provided by digested hydrolysates, with relative values of intracellular oxidation of cod of (70.2 ± 0.8) and chicken of (74.5 ± 1.4 ) % than by undigested ones, where values of cod and chicken were (95.5 ± 1.2) and (90.5 ± 0.7) %, respectively. Neither species nor digestion had any effect on cellular metabolic energy. At proteome level, digested hydrolysates gave again significantly stronger responses than undigested counterparts; cod peptides here also gave somewhat stronger response than chicken peptides. The knowledge of the action of food protein hydrolysates and their digests within live cells, also at proteome level, is important for further validation of their activity in higher eukaryotes to develop new functional food ingredients, such as in this case chicken and cod muscle-derived peptides.

Link to article

Peer-reviewed articles

Mineralization and Preservation of an Extremotolerant Bacterium Isolated from an Early Mars Analog Environment

The artificial mineralization of a polyresistant bacterial strain isolated from an acidic, oligotrophic lake was carried out to better understand microbial (i) early mineralization and (ii) potential for further fossilization. Mineralization was conducted in mineral matrices commonly found on Mars and Early-Earth, silica and gypsum, for 6 months. Samples were analyzed using microbiological (survival rates), morphological (electron microscopy), biochemical (GC-MS, Microarray immunoassay, Rock-Eval) and spectroscopic (EDX, FTIR, RAMAN spectroscopy) methods. We also investigated the impact of physiological status on mineralization and long-term fossilization by exposing cells or not to Mars-related stresses (desiccation and radiation). Bacterial populations remained viable after 6 months although the kinetics of mineralization and cell-mineral interactions depended on the nature of minerals. Detection of biosignatures strongly depended on analytical methods, successful with FTIR and EDX but not with RAMAN and immunoassays. Neither influence of stress exposure, nor qualitative and quantitative changes of detected molecules were observed as a function of mineralization time and matrix. Rock-Eval analysis suggests that potential for preservation on geological times may be possible only with moderate diagenetic and metamorphic conditions. The implications of our results for microfossil preservation in the geological record of Earth as well as on Mars are discussed.

Link to article

Peer-reviewed articles

Influence of blanching treatment and drying methods on the drying characteristics and quality changes of dried sardine (Sardinella gibbosa) during storage

The aim of this study is to examine the drying characteristics of blanched and unblanched sardines during indoor and open sun drying processes. Changes in temperature and relative humidity of the air during drying were recorded. The color, peroxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA) content, fatty acid composition, and sensory attributes of dried samples were also evaluated once a month for 5 months of storage. High drying rates were obtained in all samples at the start of drying and then decreased with increasing drying time. The highest drying rate and effective water diffusivity (Deff) were observed in blanched sardine during open sun drying. Blanching treatment slowed down the FFA progression during product storage but adversely affected the color, PV, and TBARS content as well as sensory properties. Although sardine dried for a longer time under indoor drying conditions, it attained a stable moisture ratio that was lower than in open sun-dried samples. Indoor drying produced a quality stable product with less lipid oxidation and the desired moisture content, higher polyunsaturated fatty acids and sensory properties. Blanching treatment negatively affected the fish quality and is therefore not recommended for commercial sardine drying.

Link to article

Peer-reviewed articles

Influence of lipid content and packaging methods on the quality of dried capelin (Mallotus villosus) during storage

Capelin annual catch exceeds half a million tons in Iceland, with only a small quantity (<20%) of female with roe used for human food. There is a potential to use dried male capelin as a new product for human consumption, but its lipid content varies considerably (4-20% body weight). Earlier studies were more concentrated on the influence of drying conditions than the influence of storage conditions on the quality of dried fish, as dried fish are usually considered to be stable and safe during storage. Three batches of dried male capelin differing in lipid content were packaged and studied during 5 months storage at 22 ± 2 ° C to establish appropriate lipid content at harvesting and product packaging method. Lipid composition, lipid hydrolysis and oxidation, sensory attributes and microbial activity were evaluated. Batches differed in composition and stability, with low lipid capelin constituting higher proportion of polyunsaturated fatty acids (22% lipid) than high lipid (18% lipid) capelin. Lipid oxidation was influenced by lipid content and packaging method, as accelerated oxidation occurred in high lipid and open packed capelin. Lipid hydrolysis was less influenced by packaging and was greater in low lipid capelin. High lipid capelin in open bags scored the highest for rancid odor. All batches were micro-biologically stable with colony-forming unit counts increasing less than log 1 (log 5-6) during 5 months storage.

Link to article

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