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The fiber structure of tissue in meat and seafood has a significant impact on their perceived quality. However, quantifiable description of muscle structure is challenging. We investigate diffusion tensor imaging (DTI) magnetic resonance imaging (MRI) as a method to quantitatively describe tissue structure. DTI measures the anisotropy of water molecule diffusion within muscle fibers. A pilot study evaluated three different cod loin samples: one of high-quality, one of medium-quality, and one of poor-quality. DTI parameters such as fractional anisotropy, axial diffusion and radial diffusion showed clear differences between the sample qualities. Changes in the DTI metrics consistent with freezing and thawing damage to the tissue were observed. The DTI maps were compared to T2-weighted images and DTI detected significant details that were not visible in T2-weighted images. Overall, these results indicate that DTI is a promising method for spatially-resolved characterization of tissue structure in seafood and meat.

Freezing of fish is an important processing method that can extend the shelf life of the product but can also lead to significant damage to the tissue if performed incorrectly. In order to thoroughly evaluate different freezing protocols, a method to characterize the extent and distribution of damage from freezing is needed. Magnetic resonance imaging (MRI) was tested as a technique to map and quantify tissue damage from freezing in fish. Groups of packaged cod (Gadus morhua) loin were frozen to either −5, −20, or −40 °C, thawed and then imaged with a T2-weighted MRI sequence. Areas of damage appear as bright clusters in the muscle tissue. To provide repeatable, objective classification, image analysis using a convolutional neural network was then performed on the MRI data to identify regions of damaged tissue. As expected, the colder the freezing procedure, the less damage the process generally produced. Results show non-uniform damage throughout the fillet, with tissue damage due to freezing concentrated in the center of the fillet. This suggests that surface limited methods, such as hyperspectral imaging, may not fully capture the extent of damage due to freezing and thawing. The percent of tissue classified as damaged by the neural network generally correlated well with liquid loss (cor = 0.83).

Fish is a highly perishable product and freezing is the obvious way to increase shelf life. The freezing process involves the initial freezing, a frozen storage period and thawing—all of which influence the quality of the end product. In this study, the quantity of liquid loss is used as an indication of the structural damage induced by these processes. A full factorial experiment design addresses the effects of freezing and thawing rates (fast vs. slow), number of freezing cycles (1 vs. 2) and frozen storage (1 year vs. 1 week). The results show strong evidence that fast processes of freezing and thawing reduce the subsequent liquid loss. However, 1 year frozen storage at −20°C induces high liquid loss independently of the freezing and thawing rates. Adding a second freezing cycle also adds to the liquid loss upon final thawing. By increasing the number of processing steps (additional freezing cycles) the strain put upon the samples progressively increases. This leaves samples at the end of long sequences of processing especially sensitive to damage caused by ice crystals. In this way, the thawing protocol might be of high importance, especially during the last freezing cycle of twice frozen samples. Practical Application In order to minimize liquid loss through production of frozen seafood, it is imperative that producers use the best practice at every stage. Liquid loss influences yield through production, but it also contributes to quality parameters relevant to both producers and consumers. Every stage of the production impacts liquid loss, and examining and classifying the different processing steps separately is the common approach to assess the effect. For the final product however, the impact of one isolated step is entangled in the combined effect off all the different processing steps. In this study, we have examined the processing continuum from the first freezing to the last thawing, including the effects of an extra freeze cycle and frozen storage period. In this way, we demonstrate the risk of pitfalls through such processing and also highlight the process combinations that are synonymous with low liquid loss.

In this study, we targeted the surface bacteria of high quality vacuum-packed cod loins to investigate how this affected the shelf life. After heat processing, the storage temperature was kept at 4...

Summary In a study between October and November 2015 in northern Norway, bait prepared from the by-product of the shrimp and snow crab industry was employed in the pot fishery to capture cod and saithe. Frozen natural herring was used as control bait. Pots with the three bait types were placed 1,000 m apart in order to eliminate the risk of interaction between the different baits. In total 11 sampling periods were conducted. There were no significant differences in catch rates between the different baits tested on cod and saithe. The manufactured bait tested in this study showed a continuous release of odours over a 14-day period. Results show that the water content of the bait increases rapidly in the first phase of the immersion (until day 7), and the corresponding loss of bait mass (dry weight) suggest some physical disintegration (erosion) of the bait until the water content stabilizes. This study illustrates that it is possible to replace natural herring with hydrolysates from by-products from shrimp or snow crab industry in the Norwegian pot fishery of cod and saithe.

Freezing, storage and thawing all significantly affect the quality of seafood products. In this article, we explore the potential for estimating these parameters using online optical spectroscopic measurements. Fillets of cod were vacuum packed and underwent different programs of freezing, thawing and storage. Hyperspectral imaging of the fillets was performed at each program stage. Both single and double-frozen samples are studied. Different freezing and thawing methods are also investigated. Multivariate analysis of the hyperspectral data show that freezing history can clearly be determined on samples in the frozen state and to some degree on samples in the thawed state. Analysis of the data shows a less clear distinction between methods of thawing. Measurement on samples after a year of storage still showed the ability to classify samples based on their freezing history. These results show that hyperspectral technology can be used to evaluate the freeze-thaw history and potentially estimate quality of cod products in a manner that meets the speed and non-invasive requirements of an industrial setting.

As the ability to appraise the quality of every fish in a delivery in a consistent, objective, and rapid manner has numerous advantages for both sellers and buyers, there has been much research into methods to achieve this. One possible proxy for quality assessment is liquid loss, which correlates with undesirable sensory attributes. This study evaluated whether hyperspectral imaging could predict liquid loss on samples that had undergone a program of freezing and thawing. Vacuum-packaged cod loins were split into two groups, one which was kept chilled and the other that underwent a program of freezing and thawing. Multivariate analysis of the hyperspectral imaging data on the chilled samples could predict liquid loss with good accuracy for samples that underwent no further processing. Analysis of data from the hyperspectral images of the frozen and thawed cod samples also showed a good ability to predict their liquid loss. These results indicate that hyperspectral imaging is a promising method for non-invasive quality monitoring of cod products in different processing states. Also, whereas previous research had been unable to predict sample processing protocols, improvements to the hyperspectral imaging technology now enables identification of samples based on freezing and thawing procedures.

International audience; Documentation of surface temperature is challenging for short food surface pasteurization treatments, particularly in steam environments. In this study a spectroscopic approach is investigated for estimating thermal load while heat transfer modeling is used to estimate the surface temperature of a model fish product when heated in steam or immersed in water. Reflectance spectroscopic measurements show that visible spectroscopy (400-550 nm) has potential for assessing the thermal load of surimi heated in water in the temperature range between 70 and 95 degrees C. For treatment times >10 s, robust models (r(2) >= 0.9) with acceptable prediction errors (

A new method for blood detection in whitefish fillets is presented. The method is based on diffuse reflectance hyperspectral imaging in the VIS/NIR range, and unmixing of measured absorbance spectra into known spectra for hemoglobin, water and muscle tissue. Scattering effects are modelled as a polynomial function of wavelength, and are included in the unmixing procedure. The unmixing method is based on a modified Beer-Lambert law and is performed using a non-negativity constrained least squares algorithm. Application of the method to images of samples with varying amounts of blood results in a very good fit between measured and modelled spectra. Reference measurements on homogenized cod muscle with controlled concentrations of added blood are used to model the relationship between the spectral unmixing results and hemoglobin concentration, enabling pixel-by-pixel estimation of hemoglobin concentration. The method is seen as a useful tool for automatic quality grading and processing of fillets in the whitefish industry.

Intake of long-chain omega-3 polyunsaturated fatty acids (LC-n3-PUFA) is commonly recognized to reduce cardiovascular disease (CVD). In previous studies, cold-pressed whale oil (CWO) and cod liver oil (CLO) were given as a dietary supplement to healthy volunteers. Even though CWO contains less than half the amount of LC-n3-PUFA of CLO, CWO supplement resulted in beneficial effects on anti-inflammatory and CVD risk markers compared to CLO. In the present study, we prepared virtually lipid-free extracts from CWO and CLO and evaluated the antioxidative capacity (AOC) and anti-inflammatory effects. Oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays were used to test the AOC, and the results indicated high levels of antioxidants present in all extracts. The anti-inflammatory effects of the extracts were tested with lipopolysaccharide- (LPS-) treated THP-1 cells, measuring its ability to reduce cytokine and chemokine secretion. Several CWO extracts displayed anti-inflammatory activity, and a butyl alcohol extract of CWO most effectively reduced TNF-α(50%,p<0.05) and MCP-1 (85%,p<0.001) secretion. This extract maintained a stable effect of reducing MCP-1 secretion (60%,p<0.05) even after long-term storage. In conclusion, CWO has antioxidant and anti-inflammatory activities that may act in addition to its well-known LC-n3-PUFA effects.

From a microbiological point of view thermal processing is useful to preserve food and keep it safe. Assessing endpoint temperatures (EPT) enables effective temperature control throughout processing, but assessment methods have so far been labour-intensive or sensitive to water associated with the sample. The aim of this study was to develop a non-invasive method able to deal with the water levels of fresh samples. Visible spectroscopy measurements were combined with multivariate analysis for EPT prediction of surimi samples. No measures were carried out to control the water on the surface or the water content of the samples. In the range from 400 to 700 nm an apparent correlation between temperature treatment and spectra intensities was observed. The spectral changes reflect the changes in relative scattering intensities caused by protein denaturation. A similar correlation was not observed for the near infrared (NIR) region. By excluding the NIR region, where water absorbs strongly, we present a model in range from 400 to 700 nm that show a prediction error less than 2 °C in the temperature range 46.6–74.4 °C. This model is robust ( r 2 = 0.96) and covers the temperature range for mild surface pasteurization, thereby showing potential for use in the food processing industry.

Chlorophyll in dead plants ordinarily decomposes completely before permanent burial through exposure to light, water and oxygen. Here we describe 8000-year-old terrestrial mosses that retain several percent of its original chlorophyll. The mosses were ripped of the land surface, carried 50–100 m off the Norwegian coast of the time, and deposited in depressions on the sea floor by the Storegga tsunami. A little of the chlorophyll survived because, within hours after entraining it, the tsunami buried the mosses in shell-rich sediments. These sediments preserved the chlorophyll by keeping out light and oxygen, and by keeping the pH above 7—three factors known to favour chlorophyll's stability. Because the green mosses were buried alive, their radiocarbon clock started ticking within hours after the Storegga Slide had set off the tsunami. Radiocarbon measurement of the mosses therefore give slide ages of uncommon geological precision, and these, together with a sequence of ages above and below the boundary, date the Storegga Slide to the chilliest decades of the 8.2 ka cold event at 8120–8175 years before AD 1950. North Atlantic coastal- and fjord- climatic records claimed to show evidence of the 8.2 cold event should be carefully examined for possible contamination and disturbance from the Storegga tsunami.

The population of Laos PDR has increased rapidly in recent years, reaching 2.5% per annum. This growth threatens food security, which in Asia is often equated with rice production. The country has to feed almost 50% more people now than 16 years ago. The role of aquatic rice field species in rural Laotian diets has been underestimated, as almost 200 species are consumed, supplying a range of nutrients needed by the villagers. Nevertheless, national and regional food composition databases contain limited information on the nutritional composition of these species. Field sampling was undertaken in Champasak and Savannakhet provinces for nine species of aquatic animals, including fish, amphibians, crustaceans, molluscs and insects. Four samples of fermented fish products were included. The objective was to gain knowledge on the nutritional composition of the aquatic species included in Laotian diets. The aquatic animals consumed on a daily basis contained high amounts of protein (11.6–19.7% for fish, crustaceans, molluscs, amphibians and insects and 3.3–7.8% for fermented fish), and a generally acceptable essential amino acid profile. They were also excellent sources of calcium, iron and zinc. However, they had low contents of fat (0.1–4.6%), fatty acids and vitamin A. Essential amino acids, iron and zinc are nutrients that are scarce in rural Laotian diets. As the food supply of rural households in rice farming areas of Laos is critically dependent on the environment, the sustainable existence of the rice field aquatic animals is a crucial factor for the nutritional status of the Laotians.

Fillet and residuals of farmed Atlantic salmon ( Salmo salar ) and wild caught cod ( Gadus morhua ) have been analysed for taurine concentration and angiotensin converting enzyme (ACE) inhibitory effect. With respect to taurine concentration, the residual fractions showed great variations, with the lowest concentration found in cod eye, 0.8 mg/g, and salmon fillet muscle, 0.7 mg/g, while for both cod and salmon the highest concentration was found in the heart with 8.3 mg/g and 5.6 mg/g, respectively. For the analysis of the ACE-inhibitory effect, the fractions were subjected to a simplified gastrointestinal digestion to produce hydrolysates which were then subjected to an ACE (1 mU) inhibitory assay to find the inhibition coefficient, IC 50% . The lowest ACE-inhibitory effect was found in cod bile with an IC 50% at 7.6 μg/mU. Also the skin from both cod and salmon showed a low effect with 6.3 μg/mU and 6.0 μg/mU, respectively. For both the species the highest inhibitory effects were found in hydrolysates from the fillets, with 1.6 μg/mU and 2.2 μg/mU, respectively. Lesser used residuals, like organs connected to the cardiovascular system, such as heart, kidney and gills, with high taurine concentration and medium ACE-inhibitory effect, may be interesting as raw materials for niche products.

Processing of fish generally leads to losses of water soluble compounds, and some of these may have beneficial health effects. The aim of this study was to determine the loss of taurine, creatine, free glycine and free alanine from cod during brining and cooking. Fillet pieces ( n = 80 ) were excised from 10 cods, and divided among 8 groups subjected to different preparations: raw, brined, boiled, fried, baked, brined & boiled, brined & fried and brined & baked. The concentration of the compounds decreased during brining and true retention (TR) was calculated to be 83% and 84% for taurine and creatine, respectively. Followed by cooking, TR dropped to 69–73% for taurine, and 68–78% for creatine depending upon heat treatment. Glycine and alanine had similar losses and there were only small differences in TR between the four components. The results indicated that baking had the highest retention, followed by frying and then boiling, but the differences were not significant. Brining had no significant effect on retention of components after cooking. In addition, the experiments revealed a large variation in taurine concentration between pieces sampled from different locations of the loin.

A promising method for detection of parasites in whitefish fillets has been developed. By use of imaging spectroscopy it is possible to record both spectral and spatial information from an object. In this work it is shown that by applying a white light transmission setup and imaging spectroscopy to cod (Gadus morhua) fillets, it is possible to make spectral images containing information to differentiate between fish muscle and parasites. The spectral images are analyzed by discriminant partial least square regression as well as image-filtering techniques. The method identifies parasites on the surface of the fillets as well as embedded parasites. One parasite was detected at 0.8 cm below the fillet surface, which is 2 to 3 mm deeper than what can be found by manual inspection of fish fillets. The method is nonintrusive and should thus be feasible for industrial purposes.

During the last few years blood spots in fresh and smoked Atlantic salmon fillets have become a concern to the industry. At present there are no appropriate methods to assess the number and severity of blood spots and residual blood in the fillets. In this work the main objective was to study the effects of slaughter procedure on residual blood in the fillet as measured by the number of blood spots and amount of haemoglobin. The haemoglobin method was well suited for measuring the quantity of blood in the fillet. The amount of residual blood was influenced by anaesthetisation and killing procedures. Fish that were chilled alive and CO2/O2 anaesthetised then directly gutted had less residual blood in the fillet (P 0.05) of residual blood compared to live-chilled fish not anaesthetised, killed by gill cutting. In terms of fish welfare CO2/O2 anaesthesia is not recommended, since it creates vigorous activity among the fish, before full anaesthesia is reached. The blood coagulation time was strongly influenced by temperature. At low temperatures, as with live-chilling, the blood coagulation time is prolonged, keeping the blood fluid up to 1 h and possibly improving bleeding.

A carotenoid-producing yeast strain, isolated from the sub-arctic, marine copepod Calanus finmarchicus, was identified as Rhodosporidium babjevae (Golubev) according to morphological and biochemical characteristics and phylogenetic inference from the small-subunit ribosomal RNA gene sequence. The total carotenoids content varied with cultivation conditions in the range 66-117 microg per g dry weight. The carotenoid pool, here determined for the first time, was dominated by torularhodin and torulene, which collectively constituted 75-91% of total carotenoids under various regimes of growth. Beta-carotene varied in the range 5-23%. A high-peptone/low-yeast extract (weight ratio 38:1) marine growth medium favoured the production of torularhodin, the carotenoid at highest oxidation level, with an average of 63% of total carotenoids. In standard yeast medium (YM; ratio 1.7:1), torularhodin averaged 44%, with increased proportions of the carotenes, torulene and beta-carotene. The anticipated metabolic precursor gamma-carotene (beta,psi-carotene) constituted a minor fraction (

The objective of this study was to contribute to the development of technology that will be able to replace manual operations in processing of fish fillets. Removal of parasites, black lining, remnants of skin, and bloodstains are costly and time-consuming operations to the fish processing industry. The presence of parasites in fish products tends to spoil consumers' appetites. Recent reports questioning the safety of eating cod infected with parasites might lower consumer acceptance of seafood. Presently, parasites are detected and removed manually. An average efficiency of about 75% under commercial conditions has been reported. In this study, we focused on biochemical differences between cod muscle and the prevalent anisakine nematode species (Anisakis simplex and Pseudoterranova decipiens) infecting Atlantic cod (Gadus morhua). Using reversed phase high-performance liquid chromatography equipped with a photodiode array detector, substances absorbing in the range 300 to 600 nm were identified in extracts from parasite material. These substances were not detected in extracts from cod tissue. Significant biochemical differences between cod muscle and parasite material have thus been demonstrated.

Application experiments have suggested that short-day-induced cessation of elongation growth in trees is caused by photoperiodic regulation of the conversion of gibberellin GA 19 to GA 20 . In the present study we examined further the photoperiodic control of GA metabolism in trees with focus on the conversion of GA 19 in Salix pentandra, hybrid aspen (Populus tremula × tremuloides) and silver birch (Betula pendula) using [17,17- 2 H 2 ]-GA 19 or unlabelled GAs in application studies. GA 20 and GA 1 were able to restore growth also in hybrid aspen and silver birch under short days (SD), whereas GA 19 had no or only a very small activity. Contrary to hybrid aspen and S.pentandra, the activity of GAS in silver birch was significantly lower than that of GA 1 . Gas chromatography-mass spectrometry (GC-MS) analysis revealed a smaller turnover of [ 2 H 2 ]-GA 19 in SD than in long days (LD) in hybrid aspen. No such difference in turnover of [ 2 H 2 ]-GA 19 was observed in photoperiod-insensitive hybrid aspen overexpressing PHYA. Application of unlabelled GAs to seedlings of S. pentandra, hybrid aspen and silver birch under SD followed by quantification of metabolites by GC-MS analysis, showed that applied GA 19 was not readily converted to GAS and GA 1 Although the sensitivity to GAs is also known to decrease under SD, the present data are in favour of a photoperiodic regulation of the metabolism of GA 19 in vivo in the woody species S.pentandra, hybrid aspen and silver birch. The data might also suggest that silver birch differs from S.pentandra and hybrid aspen by exhibiting a possible photoperiodic control also of the conversion of GAS to GA 1 .

This study investigates how product quality and shelf life of vacuum-packed cod loins are affected when surface bacteria are targeted in thermal processing regimes. A mathematical heat transfer model was used to generate two mild thermal processing regimes for temperature controlled water baths at 70 °C and 90 °C. The results show that shelf life assessment based on sensory evaluation is closely linked to microbial growth. This study shows that even if mild heat treatments do have a noticeable effect of inactivating bacteria on the surface of the fish muscle, such processes do not prolong shelf life considerably. This may be due to the overall limited effect of mild heat processing on bacterial inactivation, but may also be explained by the fact that for postrigor fish, the microbial contamination might be at a too advanced stage for the investigated mild processing to have significant effect. Practical applications For the consumer fresh fish is a superior product compared to frozen fish. Consequently, there is a higher demand and a higher market price for fresh seafood products. The aim of the present study was to evaluate in-pack surface pasteurization as a mean to increase shelf life for a prepackaged white fish product. Since the surface of the fish fillet is the entry point of microbial contamination as well as the main colonization area, targeting the surface seems the obvious choice to minimize the negative impact of extensive heat processing. We show that modeling the heat treatment is a valuable tool for limiting the detrimental effect of heat treatment. However, when microbial contamination is high, very mild heat processing does not prolong shelf life considerably.

Traditional quality control of cod fillets is currently made by manual inspection on candling tables. This is a time consuming and expensive operation, contributing to a significant share of the cost with cod fillet production. In this study, transillumination hyperspectral imaging was implemented as a method for automatic nematode detection in cod fillets moving on a conveyer belt, and evaluated on industrially processed cod fillets. An overall detection rate of 58% of all nematodes (N= 922), with detection rate of 71% and 46% for dark and pale nematodes, respectively, is reported. This is comparable, or better, than what is reported for manual inspection under industrial conditions. The false alarm rate was high, with 60% of the fillets reported with one or more false alarms. These results show that the method is promising, but needs further refinements to reduce the false alarm rate and increase the imaging speed from 25 to 400 mm/s. Practical Application: Manual inspection of cod fillets is a huge bottleneck for the industry, accounting for half the production cost with cod fillet processing and reducing the processing speed. Transillumination hyperspectral imaging has the potential to reduce the manual labor required for cod fillet inspection and hence reduce the cost and increase the end product quality.

SUMMARYThird-stage larvae ofPseudoterranova decipienscommonly infect whitefish such as cod, and the parasite can be transferred to humans through lightly prepared (sushi) meals. Because little is known about the nematode's cold tolerance capacity, we examined the nematode's ability to supercool, and whether or not cold acclimation could induce physiological changes that might increase its ability to tolerate freezing conditions. Even if third-stagePseudoterranova decipienslarvae have some supercooling ability, they show no potential for freezing avoidance because they are not able to withstand inoculative freezing. Still, they have the ability to survive freezing at high subzero temperatures, something which suggests that these nematodes have a moderate freeze tolerance. We also show that acclimation to high temperatures triggers trehalose accumulation to an even greater extent than cold acclimation. Trehalose is a potential cryoprotectant which has been shown to play a vital role in the freeze tolerance of nematodes. We suggest that the trehalose accumulation observed for the cold acclimation is a general response to thermal stress, and that the nematode's moderate freeze tolerance may be acquired through adaptation to heat rather than coldness.

The occurrence of parasites in fillets of commercially important fish species affects both food quality and safety. Presently, the detection and removal of nematode parasites is done by inspection on a light table (candling) and manual trimming of the fillets. This operation is costly and time-consuming and is not effective for detecting and removing all the nematodes in the fillets. In the last decades, several alternative methods have been proposed, but these methods have failed to replace the candling method. A newly described method called imaging spectroscopy has produced promising results because the operator can record both spectral and spatial information from an object. In this work, we studied single-wavelength bands from a spectral image. Discrimination between nematodes and other objects in the fillets is dependent on the level of contrast. Quantification of the contrast in such images revealed that the level of contrast varied when different wavelengths were selected, and these variations are correlated with the absorption properties of the nematode. Visible light scatters greatly in fish muscle, generally complicating the detection of nematodes. In this study, light scattering was used in a way that reduces the background complexity in spectral images. When light scattering properties were used in a wavelength range different from the bulk of the nematode light absorption, spectral images with significantly higher contrast were produced.

A kerosene type hydrocarbon fraction (equivalent to 7 L m(-2)) was added to enclosures in the surface layer of high-arctic intertidal beach sediment. The experimental spill was repeated in two consecutive years in the period July-September. The rate and extent of hydrocarbon removal and the accompanying bacterial response were monitored for 79 days (2002) and 78 days (2003). The bulk of added kerosene, i.e. 94-98%, was lost from the upper 5 cm layer by putatively abiotic processes within 2 days and a residual fraction in the range 0.6-1.2mg per g dry sediment was stably retained. Concomitant addition of oleophilic fertilizer led to higher initial retention, as 24% of the kerosene remained after 2 days in the presence of a modified, cold-climate adapted version of the well-known Inipol EAP 22 bioremediation agent. In these enclosures, which showed an increase in hydrocarbon-degrader counts from 6.5 x 10(3) to 4.1 x 10(7) per g dry sediment within 8 days, a 17% contribution by biodegradation to subsequent hydrocarbon removal was estimated. Stimulation in hydrocarbon-degrader counts in fertilizer-alone control enclosures was indistinguishable from the stimulation observed with both kerosene and fertilizer present, suggesting that the dynamics in numbers of hydrocarbon-degrading bacteria was primarily impacted by the bioremediation agent.