[show abstract][hide abstract] ABSTRACT: The relations between smoking parameters and the characteristics of salmon raw material were investigated with respect to yield, colour, flesh content of phenol and salt, and sensory properties. The fish studied were ocean ranched salmon harvested in Iceland in July 1998 and farmed salmon from Norway slaughtered in October 1998 and April 1999. Seven treatments were applied on fresh or frozen raw material combining dry or brine salting with cold smoking at 20 or 30°C. Electrostatic smoking was tested on dry-salted salmon fillets. The results show a lower yield after filleting and trimming with ocean ranched fish. Although freezing had little effect on yield, total loss was slightly greater, especially for fish with low fat content. Sensory differences were also apparent. The brine salting technique resulted in lower losses. Fish with higher fat content gave a better yield after processing, although careful control of the smoking procedure was required (especially at 30°C) to avoid a case-hardening effect. With brine salting, salt uptake was higher for smaller, leaner fish. The phenol content of flesh depended on the technique and/or smoking temperature used, regardless of the fish studied. However, for a smoking temperature of 30°C, the flesh of smaller, leaner fish showed a higher phenol level. Smoking conditions and preliminary treatment such as freezing produced similar differences in sensory characteristics, regardless of the fish studied, although smaller, leaner individuals appeared to be more sensitive to these processes.
[show abstract][hide abstract] ABSTRACT: Cereal-based snacks are usually low in protein and other nutrients. Increased health awareness of consumers has led the food industry to develop fortified snacks with functional ingredients. Three types of extruded corn-fish snacks, containing 150 g kg(-1) carp mince and 150 g kg(-1) trout mince, 30 g kg(-1) freeze-dried saithe protein and a regular corn snack (control). were produced to study quality changes and storage stability of the products during 6-month storage at 27±2 °C.
All products had the same level of water activity and proximate composition except for protein. Fortified snacks had a protein content of 93-98 g kg(-1) , compared with 65 g kg(-1) in the control. A significant increase was observed for peroxide value during storage (0.0 to 2.8 meq kg(-1)). Scores for attributes describing oxidation and off odors and flavors increased after 5-6 months' storage but attributes describing puffed corn snack odor and flavor did not change during storage of any of the products.
Extrusion of corn grits with fish flesh/fish protein can be used to produce high-protein products that would be an option to provide nutrient snacks for consumers and to increase fish consumption.
Journal of the Science of Food and Agriculture 03/2011; 91(5):886-93. · 1.76 Impact Factor
[show abstract][hide abstract] ABSTRACT: The use of injection and brining as the first step in heavy salting of cod increases weight yields of the products through both salting and rehydration, compared to other pre-salting methods, like brining only and pickling. This is interesting since salt content of the muscle exceeds 20% NaCl, in all procedures. Therefore, the dissimilarities in yield were presumed to depend on the degree of protein denaturation and aggregation as influenced by the different salting procedures. This hypothesis was studied and confirmed with the aid of SDS–PAGE and DSC-analysis. Higher water retention of injected products was explained by stronger salting-in effects on proteins during pre-salting, reducing aggregation of muscle proteins during the dry salting step. The degree of protein aggregation during salting increased in the following order with regard to the different pre-salting methods: injection and brining < brining < pickling. These effects were still observed after rehydration. Furthermore, differences in denaturation/aggregation were assigned to both myosin and collagen.
[show abstract][hide abstract] ABSTRACT: The aim of this study was to investigate the effects of salting and different pre-salting procedures (injection and brining versus brining only) on the microstructure and water retention of heavy salted cod products. Salting resulted in shrinkage of fibre diameter and enlargement of inter-cellular space. Water was expelled from the muscle and a higher fraction became located in the extra-cellular matrix. These changes were suggested to originate from myofibrillar protein aggregation and enzymatic degradation of the connective tissue. During rehydration, the muscle absorbed water again and the fibers swelled up to a similar cross-sectional area as in the raw muscle. However, the inter-cellular space remained larger, resulting in a higher water content of the muscle in the rehydrated stage. The effects of different salting procedures were strongest after salting. At that stage of the process, the inter-cellular space tended to be larger in the injected and brined muscle than in the brined only.
[show abstract][hide abstract] ABSTRACT: Functional and biochemical properties of fish protein hydrolysates (FPH) from blue whiting (BW) were studied. FPH (2.5%, 5%, 10%, and 15% degree of hydrolysis [DH]) were made from isolated proteins from headed and gutted BW with Alcalase 2.4 L. The properties of dried BW mince and protein isolate compared to 4 reference proteins (soy and milk protein) were studied: color, solubility, water-holding capacity (WHC), oil-binding capacity (OBC), emulsion capacity (EC), and emulsion stability (ES). The angiotensin I-converting enzyme (ACE) inhibitory activities of the soluble fraction of BW powders were also investigated. Furthermore, the products were characterized by analyzing their chemical composition. Chemical composition, solubility, OBC, and EC of the BW powders was significantly (P < 0.05) different with different DH, while color, ES, and WHC were not significantly (P > 0.05) different. Salt content of the FPH was high (4% to 19%) and increased with increased DH. Protein solubility varied from 10% to 70% and increased with increased DH. WHC of the FPH was around 97% and was higher than that of all the reference proteins tested. OBC decreased with increased DH (from 3.5 to 2.1 g oil/g protein) and was higher than OBC of the soy and milk proteins (1.6 to 1.9 g oil/g protein). EC of FPH was similar or lower than the reference proteins. ES of FPH (60% to 90%) was similar to or lower than soy and whey proteins (60% to 98%) but higher than casein (20%). ACE inhibition activity increased as DH was increased. Practical Application: The results from this study demonstrate that a functional bioactive hydrolysate can be produced from BW, which is an underutilized fish species, and may aid the industry in better utilizing this raw material. The novelty of this research was the use of BW as a raw material where the protein has been isolated with the pH shift method. Furthermore, it was novel that bioactivity and functionality was measured in the same samples.
Journal of Food Science 11/2010; 76(1):C14-20. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: The production of heavy-salted cod (Bacalao) has changed from being a single-step process (kench) salting to a multistep procedure varying between producers and countries. Presalting by injection, brining, or pickling is increasingly applied prior to pile (dry) salting. This article describes the effects of different presalting methods (injection and brining, brining only, and pickling) on yield and chemical composition of salted cod fillets, in comparison to a single-kench salting step. The procedures used influenced the weight yields and chemical composition of the products. Injection was significantly different from other methods in increasing weight yields throughout brining, dry salting, and rehydration. The yield of nitrogenous compounds tended to be lower for injected and brine-salted fillets, mainly due to higher losses of nonprotein nitrogen. Practical Application: Salting procedures for cod have changed rapidly in recent years. Injection is increasingly used as a presalting method. It has been suggested to have strong effects on weight yields of salted cod products. This article describes the effects of injection on weight yields on products in salted, rehydrated, and cooked stage.
Journal of Food Science 10/2010; 75(8):E544-51. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bacteria dominating the cultivable gut community of overall successful first feeding halibut (Hippoglossus hippoglossus L.) larvae were tested for their in vitro growth inhibition activity against selected fish pathogenic bacteria and isolates dominating the cultivable gut community of larvae with an overall poor success. A mixture containing equal numbers of three isolates was selected for the treatment of halibut eggs through repeated bathing, and larvae through grazing of live prey in a mixture of the selected isolates prior to offering to larvae. The isolates were found as a part of the dominating bacterial community of treated eggs and treatment was not found to affect egg survival. Improved larval survival was observed as a result of offering bacteria-treated live prey to larvae, and improved larval growth was observed in one of the two experiments that were carried out in commercial size production units. The bacterial community structure of the live prey, analysed using PCR and denaturing gradient gel electrophoresis, was only partly reflected in larvae after one week in feeding. A successful colonization of fertilized eggs by the isolates used for treatment entails the possibility to establish a favourable bacterial environment already prior to hatching.
[show abstract][hide abstract] ABSTRACT: A pollock protein hydrolysate was used for enrichment of the live feed offered to halibut larvae from the onset of exogenous feeding and the effects of treatment on selected innate immune parameters studied. The effects of treatment on the bacterial community structure of larvae were furthermore studied using the PCR-DGGE method. C3 and lysozyme were identified in larvae already at the onset of first feeding and low concentrations of IgM detected at this stage indicate maternal origin. Endogenous production of IgM was validated in the gastrointestinal tract of larvae from 29 days post onset of first feeding, with similar concentrations found in both groups. Feeding the peptide-enriched live feed stimulated production of lysozyme and affected the distribution of C3 in larval tissue but survival and normal development of halibut larvae were not affected by the treatment. Vibrio sp. and Pseudoalteromonas sp. dominated the bacterial community of larvae from both groups and peptide enrichment of the live feed was not found to affect the bacterial community structure associated with surface sterilized larvae.
Fish & Shellfish Immunology 06/2009; 27(5):595-602. · 2.96 Impact Factor
[show abstract][hide abstract] ABSTRACT: The high mortality commonly observed during the early life stages of intensively reared halibut (Hippoglossus hippoglossus L) is believed to be caused by e.g. opportunistic bacteria. However, the impact of particular bacterial species is poorly defined and still remains disputable. The study describes the bacterial diversity in the gastrointestinal tract of halibut larvae in a large number of incubators at a commercial production site. The overall success of larvae was found to be highly variable and analysis of the gut microbiota revealed high variation of the cultivable part as well as the bacterial community of surface sterilised larvae analysed by denaturing gradient gel electrophoresis (DGGE) of PCR amplified 16s rDNA products. Analysis of the bacterial community of unfed yolk sac larvae revealed higher diversity than previously reported, with Marinomonas, Marinobacter, Aeromonas and Shewanella dominating the community structure. There are indications that Marinomonas is found only in the overall most successful first feeding larvae of the period where the Vibrio group dominated the bacterial community together with Shewanella. Vibrio wodanis was identified as a part of the bacterial community of feeding larvae that yielded the poorest overall success of the period. α-Proteobacteria, not previously reported in halibut, were also found as a part of the bacterial community of first feeding larvae. The diverse bacterial community was only partly reflected in the cultivable part which, however, may reflect the dominating bacterial groups of the highly heterogeneous bacterial community of larvae in the production system as a whole. The bacterial community of the Artemia was found to be highly variable in different samples collected through the period. Only a small part of the different groups observed in the bacterial community of surface sterilised larvae was reflected in the cultivable part which was dominated by highly variable groups in different samples of Artemia. Also, the numbers of cultivable bacteria were found to positively correlate with jaw deformation of unfed yolk sac larvae as well as incomplete metamorphosis of feeding larvae.
[show abstract][hide abstract] ABSTRACT: The aim of this work was to evaluate the effects of freezing and frozen storage at -24 degrees C on the quality of Icelandic herring fillets, focusing on protein solubility and viscosity at pH 2.7 and 11 used for pH-aided protein isolation. The evaluation of quality was based on chemical analyses, protein degradation measurements, and changes in protein solubility and viscosity at pH 2.7 and 11 after up to 6-mo frozen storage of the herring fillets. Lipid oxidation measured as TBARS values increased significantly during the frozen storage (P < 0.05). Protein solubility at pH 2.7 decreased during frozen storage for 6 mo, where the solubility was about 10% lower after 6-mo frozen storage compared to the beginning (P < 0.05). At pH 11, the solubility became approximately 15% lower after 6-mo frozen storage compared to initial solubility (P < 0.05). Viscosity, measured at pH 2.7, increased after 3 mo of frozen storage (P < 0.05). At pH 11, the viscosity increased significantly after 1-wk frozen storage, compared to fresh herring fillets, but did not increase significantly with further storage (P < 0.05). Changes found in solubility and viscosity indicated protein degradation due to freezing and frozen storage. SDS-PAGE analysis did not reveal any protein cross-linking or aggregation formation, either with frozen storage or due to exposure to low pH.
Journal of Food Science 09/2007; 72(7):C376-80. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: Relevance of fat content and fillet shape of Atlantic salmon for quality and yield during smoking processing was investigated. Fat content significantly influenced quality of raw and smoked products, although the interactions varied according to the raw material used and smoking temperature. In raw and smoked fillets, increasing fat content coincided with increasing L* and b*-values and decreasing fat holding capacity. In smoked salmon, fat content also correlated positively to the a*-value, smoke-intensity-/wood-fire flavor and fatty texture, and negatively to water holding capacity and shear-force. Weight loss during salting and smoking decreased with increasing fat content, and voluminous shaped fillets gave higher yield than slim fillets.
Journal of Food Science 10/2001; · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study was carried out to examine differences in microstructure and texture of fresh and smoked farmed Atlantic salmon Salmo salar L. fillets with different biological characteristics. The left fillet was analysed fresh and compared with the salted and smoked right fillet from each individual fish. Light microscopy and image analysing techniques were used to study both transversal and longitudinal sections of the muscle. The fish muscle fibres shrank during the salting and smoking process, but sarcomere length did not change. After smoking, a considerable number of fat globules were dispersed among the muscle fibres. The biological characteristics studied were based upon diploid and triploid fish held in both sea cages and land-based tanks. Different starvation times were used and one group was stressed during slaughter. The cross-sectional area of muscle fibres from triploid fish was found to be larger than from diploid fish, both in fresh and smoked fillets.
Aquaculture Research 12/2000; 32(1):1 - 10. · 1.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: The changes in microstructure and texture during smoking of fresh and frozen/thawed Atlantic salmon was studied in fish from three different origins; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon from northern and western Norway. The muscle fibers from the frozen and thawed fish shrank, and the extracellular space increased compared to the fresh muscle. The muscle fibers from salmon fillets with smaller fiber diameter shrank to a less extent than fibers from salmon material with a larger fiber diameter. After smoking the space between the fibers and the fiber shrinkage increased to a higher extent in the muscle from the salmon that were frozen prior to smoking than muscle smoked from fresh salmon. The initial cross-sectional area of the fibers was not found to be related to the yield during smoking.
[show abstract][hide abstract] ABSTRACT: The effect of different conditions during the salting and smoking process on the microstructure and the texture of salmon fillets was studied in interaction with different raw salmon material; ocean-ranched Atlantic salmon (Salmo salar) from Iceland and two groups of farmed Atlantic salmon (Salmo salar) from Norway, one from Northern Norway and one from Western Norway. The ocean-ranched salmon was found to have significantly smaller fiber diameters and higher shear force compared to the farmed fish. The cross-sectional area of the muscle fibers decreased during the salting and smoking process. Small differences were noted in the cross-sectional area between smoked fillets processed by different salting and smoking methods. However, the cross-sectional area of fibers in dry salted fish fillets from the farmed groups were significantly smaller than in the brine salted fillets, as the fibers shrunk more during dry salting than brine salting. The force required to shear the smoked fillets was significantly higher than for the unprocessed fillets, but was not found to be related to the different salting and smoking processes. Yield during smoking was not related to the initial cross-sectional area or the shear force of the unprocessed muscle.
[show abstract][hide abstract] ABSTRACT: Textural properties of raw Atlantic salmon (Salmo salar) fillets from different origin were studied on different locations of the fillets. Three instrumental methods were applied for evaluation of textural properties. Two methods were based on puncture tests, using flat-ended cylinder or spherical probes measuring the hardness of the fillet. The third method was based on cutting the fillet with a blade and measuring the shear force. Hardness and shear force increased from head to tail, and the location below the dorsal fin was found to be most reliable. The shear force method was found to be more sensitive than the puncture methods and best suited for practical application.
[show abstract][hide abstract] ABSTRACT: The objective of this paper is to review the important quality parameters, standards, and simple tools or methods to determine the quality of fresh Atlantic salmon (Saltno salar). Based on a literature review and interviews conducted in several companies throughout Europe, the following quality parameters are of particular importance: fat content, composition and distribution of the fat in the fillet; color intensity and distribution of the color in the fillet; and texture, where firmness (hardness and elasticity) and gaping are the main parameters for fresh salmon. Other parameters cited are white stripes (connective tissue), bleeding, blood stains, marbles, and melanin. Fat, pigments, and collagen are distributed differently over the salmon fillets. Consequently, the numerical values of the quality parameters are different depending on where the sample is collected from the fillet. Sampling is the most important factor in the evaluation of salmon fillet quality. Many sampling procedures are available and the technique differs widely and samples are collected from the head to the gut opening, depending on the country, research institute, or company. Fat content can be measured by both destructive and non‐destructive methods. Several destructive chemical extraction methods are commonly used, but the non‐destructive methods available are, for example, the Tony Fish Fat meter and near infrared technology, but they are used to a limited extent in the industry. The elite image and high market value of salmonids are due in part to the characteristic color of their flesh. The color of the flesh is an important criterion for the quality of salmon and hence crucial for marketing. It is not only important that the fish have satisfactory flesh color, but the pigmentation must be uniform and stable during storage. Methods to determine the degree of pigmentation of salmon fillets can be divided into two main groups; destructive chemical analysis for quantification of the pigments astaxanthin/ canthaxanthin in the flesh and non‐destructive methods based on estimating the color appearance. Color of salmon fillets is determined by using the Roche color card or a chroma meter reflectance instrument. Texture is commonly examined by the so‐called finger method in the industry. A finger is pressed on the skin or the fillet and the firmness is evaluated. Texture of salmon fillets is measured by different tests using “Instron‐like”; instruments. However, the results depend on the location where the fish/fillet is pressed and how firmly it is pressed. To select one method and recommend it depends on the application purposes. These methods have to be tested further and comparisons made between different methods before it is possible to recommend the best available method for each application.
Reviews in Fisheries Science - REV FISH SCI. 01/1997; 5(3):223-252.