Properties of soluble protein powders from Alaska pollock (Theragra chalcogramma)

Soluble protein powders were produced from pollock by‐products and evaluated for their functional, nutritional and rheological properties. Soluble protein powders were made from pollock viscera (PVSP), viscera without liver (PVWLSP), heads (PHSP), frames (PFSP), trimmings (PTSP), and liver (PLSP) and had protein contents ranging from 65.0% to 78.9%. Yield of PVWLSP was higher than that of other pollock proteins powder and PTSP had the highest nitrogen solubility value (85.7%). Emulsion capacity and emulsion stability of the pollock protein powders ranged from 29% to 34.5% (mL of oil per 200 mg of protein) and 65.3% to 77.6%, respectively. Highest and lowest fat adsorption values were observed for PFSP (10.6 mL of oil per gram of protein) and PVSP (4.1 mL of oil per gram of protein), respectively. Fish protein powder samples were good sources in K, P, and Mg and amino acids. Emulsions made with pollock soluble protein powders exhibited viscoelastic characteristics.     

Marine and farmed fish in the Polish market: Comparison of the nutritional value

The proximate composition and fatty acids profiles of the muscle tissues of nine fish species that are popular on the Polish market were examined. The nine studied fish species were: Baltic fish (cod, herring, salmon), fish farmed in Poland (carp, trout), oceanic fish imported from China (walleye pollock, sole), and farmed fish imported from Vietnam and China (sutchi catfish, tilapia). The lowest lipid content (below 0.1%) was noted in the muscle tissues of Baltic cod and walleye pollock caught in the Pacific. The muscle tissue of walleye pollock also had the lowest protein content (12.2 ± 2.0%). The highest lipid content was noted in the muscle tissues of Baltic salmon (13.1 ± 2.4%). The highest percentage content of eicosapentaenoic (C20:5 n − 3 – EPA) and docosahexaenoic (C22:6 n − 3 – DHA) acids (over 40%) was noted in the fat extracted from the oceanic fish and Baltic cod. However, due to the low fat content, the concentrations of EPA + DHA in these fish species and in imported farmed fish expressed in mg/100 g of muscle tissues are the lowest and range on average from 24.8 ± 5.7 mg/100 g (sutchi catfish) to 207.4 ± 125.4 mg/100 g (sole). This is why the consumption of these fish species has no significant meaning for coronary heart disease prevention. Consumers with symptoms of cardiovascular diseases should include the following fish species, which have high concentrations of EPA + DHA: Baltic salmon (3807.2 ± 666.3 mg/100 g); Polish farmed trout (1804.0 ± 279.2 mg/100 g); and Baltic herring (940.9 ± 306.6 mg/100 g) in their diets. However, the consumption of Baltic salmon must be limited on account of the levels of persistent organic pollutants found in it.     

Salmon by-product storage and oil extraction

Oils extracted from wild salmon by-products are excellent sources of long chain omega-3 polyunsaturated fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, quality loss is expected if time delays are encountered before oil extraction. The free fatty acid levels (FFA), fatty acid profile and total fat soluble antioxidant activity in extracted oil from aging pink salmon heads and viscera stored at two temperatures (6 and 15 °C) for four days were determined. The FFA values in raw salmon heads and viscera increased with storage time and temperature. A significant difference (p < 0.05) from the starting material was noted at day 1 at both temperatures for FFA. Fatty acid composition data indicated no changes in the levels of long-chain omega-3 fatty acids with the respective temperature. The concentration of long-chain omega-3 fatty acids EPA ranged from 9.3 to 11.3 g/100 g of crude oil and DHA ranged from 12.3 to 13.1 g/100 g of crude oil. The antioxidant activity of the pink salmon oils at day 0 was 0.89 ± 0.15 μmole Trolox equivalent/g of crude oil. Significant decreases (p < 0.05) from the starting material were noted on day 2 for 15 °C samples and day 3 for 6 °C samples. After four days of storage antioxidant levels (Trolox equivalent/g of crude oil) were approximately 25% of initial values. Oil extracted from raw salmon heads and viscera remained a good source of long chain omega-3 fatty acids even after 4 days of raw material storage at 15 °C; however, fat soluble antioxidant activity was reduced and free fatty acid levels increased with increased raw material storage temperature and time.     

Evaluation of the nutritional aspects and cholesterol oxidation products of pork liver and fish patés

A comparison of traditional pork liver and fish patés (salmon, anchovy and cod) was carried out. Nutritional value and cholesterol oxidation products (COP) were evaluated. Salmon paté showed similar fat content (24–28%) and energy value (300 kcal/100 g) to pork liver patés, whereas patés made with anchovy and cod showed less fat (13–16%) and calories (200–236 kcal/100 g). PUFA/SFA ratios were much higher in all fish patés (1.55–4.95) than in liver pork patés (0.36–0.44). No great differences were found in ω-6/ω-3 ratio between salmon and pork liver patés (11.3–18.4), this ratio being even higher in anchovy (32.3) and cod patés (62.8). EPA and DHA supply was around 0.63 for salmon, 0.21 for anchovy and 0.07 for cod patés. Cholesterol concentrations were lower in fish patés (31–37 mg/100 g) than in pork liver patés (77–102 mg/100 g). Total COP ranged from 0.38 to 2.83 ppm, without clear differences between pork liver and fish patés.     

Enzymatic hydrolysis of by‐products from the fish‐filleting industry; chemical characterisation and nutritional evaluation

Fish frames without heads from Atlantic cod and Atlantic salmon were proteolysed with the industrial enzymes neutrase®, alcalase® and pepsin for 1, 15, 30, 45, 60, 90 and 120 min. After 120 min of hydrolysis, salmon treated with alcalase and cod treated with pepsin yielded significantly (p < 0.05) higher protein recoveries (67.6 and 64% respectively) as compared to salmon treated with neutrase or pepsin and cod treated with neutrase or alcalase (53–62%). To minimise bitterness in the fish hydrolysates, kojizyme™ was added after 120 min of pre‐hydrolysis with alcalase, and the hydrolysis was run for additional times of 120, 240, 360, 480, 600 and 720 min. Protein recovery did not change significantly during the hydrolysis with kojizyme, but the degree of hydrolysis increased significantly (p < 0.01) in both the cod and salmon hydrolysates. A hydrolysate from cod treated with alcalase (150 min) followed by treatment with kojizyme (510 min) was produced. The final hydrolysate was freeze‐dried to a fish protein hydrolysate (FPH) and chemically characterised. The nutritional value of the FPH was established in an experiment with rats. Inclusion of 10% FPH‐N showed significantly (p < 0.05) higher nutritional value as compared to rats fed higher inclusion levels of FPH. © 2000 Society of Chemical Industry     

Effect of extracting time and temperature on yield of gelatin from different fish offal

The aim of the study was to determine the optimal conditions for preparing gelatin from different kinds of fish offal: heads and backbones of Baltic cod, skins of fresh and cold-smoked salmon, and skins of salted and marinated herrings. The yield of gelatin extraction at 45 °C was 71–75% for fresh salmon skins or cod backbones, and 86%, for smoked salmon skins. When heating marinated herring skins for 15 min or salted herring skins for 45 min, about 100% of collagen was converted to gelatin. For fish skins, 45 °C and 15–60 min extraction time, depending on the kind of skins, were established as optimal conditions for preparing gelatin. The yield of gelatin extraction from the cod heads did not exceed 70%, even when a three stages process was used. In the case of backbones, 100% of collagen in the form of gelatin was isolated using this procedure. SDS-PAGE analysis showed that gelatin from fish skins was much less degraded than gelatin from pigskins.     

硬骨鱼纲鮟鱇鱼与其他鱼皮基本成分对比及分析

对鮟鱇鱼鱼皮、金鳟鱼鱼皮和大马哈鱼鱼皮的基本成分、氨基酸含量、脂肪酸含量及矿物质含量进行比较和分析。3种鱼皮的粗蛋白质含量是大马哈鱼鱼皮(31.1%)>金鳟鱼鱼皮(30.41%)>鮟鱇鱼鱼皮(20.46%),氨基酸组成相似,3种鱼皮中氨基酸含量最高的均为甘氨酸,分别为26.83,180.00和71.78 mg/g,3种鱼皮的EAAI值均为1.29,均可作为开发蛋白质类产品的优质蛋白源;3种鱼皮饱和脂肪酸占脂肪酸总量比例分别为23.03%,33.37%和26.18%,占比最大的是金鳟鱼鱼皮,单不饱和脂肪酸占比最大的是大马哈鱼鱼皮,多不饱和脂肪酸占比最大的是鮟鱇鱼鱼皮;鮟鱇鱼鱼皮和金鳟鱼鱼皮含有丰富的矿物质元素,含量最丰富的均为钙,含量分别为1537.15和9199.03 mg/kg;大马哈鱼皮中的矿物质元素较少。鮟鱇鱼鱼皮与其他2种鱼皮氨基酸组成相似,脂肪酸相差较大,矿物质元素较其他2种更丰富。     

Effect of Fish and Oil Nature on Frying Process and Nutritional Product Quality

ABSTRACT: The modifications on a lean fish (cod—Gadus morhua) and a fatty fish (farmed salmon—Salmo salar) after the application of pan-frying using 2 types of oil with different lipid profile (extra virgin olive oil and sunflower oil) was the aim of this study. Fat content and total energetic value increased significantly after the frying process only in the lean fish, without relevant changes in the fatty fish. Extra virgin olive oil led to a higher fat absorption rate than sunflower oil in both fish. Frying hardly affected the lipid profile of farmed salmon regardless the oil used, however it drastically changed in fried cod compared to raw cod. Omega-6/omega-3 ratio increased from 0.08 in raw cod to 1.01 and 6.63 in fried cod with olive oil and sunflower oil, respectively. In farmed salmon, the omega-6/omega-3 ratio was 0.38 (raw), and 0.39 to 0.58 in fried salmon. The amount of EPA + DHA slightly decreased with frying in salmon, and increased in cod. The type of oil has more influence in the nutritional fish quality for the lean fish compared to that of the fatty fish. The use of extra virgin olive oil was efficient to avoid a significant increase of the lipid oxidation intensity during frying in cod but not in salmon. Practical Application: Food modifies its composition and nutritional value with the application of cooking technologies. As most food table composition tables are based on raw food products, this article contributes with interesting data on pan-fried fish composition, which may improve the approach to achieve a real intake of healthy nutrients as omega 3 fatty acids.     

鳙鱼、金枪鱼和三文鱼鱼头的营养分析与品质评价

对鳙鱼、金枪鱼和三文鱼头的营养成分进行分析和品质评价,为鱼头的食用提供基础数据和理论支持。用国标及文献的方法,对三种鱼头的一般营养成分含量和脂肪酸、氨基酸、矿物质的组成以及重金属残留进行了分析和评价。三种鱼头粗脂肪含量有显著性差异(P<0.05),三文鱼粗脂肪含量最高(14.37%±2.63%),其次是金枪鱼(10.70%±0.97%),鳙鱼粗脂肪含量较低(3.82%±0.04%)。金枪鱼头的粗蛋白含量显著性高于鳙鱼头和三文鱼头(P<0.05)。三种鱼头肉均含有丰富的不饱和脂肪酸,占总脂肪酸含量的61.30%~82.40%。三种鱼头都含有丰富的EPA和DHA,尤其是金枪鱼头,EPA和DHA含量占总脂肪酸的37.79%,显著性高于鳙鱼头和三文鱼头(P<0.05)。三种鱼头蛋白质的氨基酸组成合理,总必需氨基酸/总氨基酸的比例在39.73%~40.16%之间,氨基酸评分都大于100,表明这三种鱼头可以作为优质的氨基酸来源。三种鱼头富含矿物质,其中常量元素中都是K和Na含量较高,微量元素中都是Fe和Zn含量较高。三种鱼头的重金属残留(铅、砷、汞、镉、铬)均不超过国家限量标准,表明鱼头来源安全可靠。     

Minced Fish Production From Capelin (Mallotus villosus). A New Method for Gutting, Skinning and Removal of Fat from Small Fatty Fish Species

A new method for the production of fish mince from a small fatty fish is presented. The method involves (a) cutting the fish into short pieces, (b) washing out the depot fat, dark pigments and viscera under acid (pH 4) or neutral conditions, and (c) bone separation. The resulting mince has a white appearance and a low fat content (approximately 7% of dry wt). The water-holding capacity of the acid mince is low, whereas neutral minces have values corresponding to cod mince. The fish oil can easily be recovered. Characterization of the lipids in capelin mince is presented.     

Properties of a propionic acid/formic acid preserved silage of cod viscera

Protein of cod viscera has an amino acid composition which resembles that of cod muscle. A fully preserved silage of minced viscera is obtained by addition of 0.75% (v/w) propionic acid and 0.75% (v/w) formic acid. After a few days of autolysis at 27°C, the silage can be separated into three phases: a lipid phase, an aqueous soluble phase and a sediment. The aqueous phase, which contains most of the protein and very little fat, is suitable for animal feed. Moist mixtures of silage and barley straw meal stored at room temperature do not deteriorate by microbial attack.     

Atlantic salmon (Salmo salar,L) as raw material for the smoking industry. II: Effect of different smoking methods on losses of nutrients and on the oxidation of lipids

The changes in total fat content, fatty acid composition, tocopherol, ascorbic acid, pH and oxidation were analysed in Atlantic salmon (Salmo salar, L.) in response to either cold smoking (20 or 30 °C) or electrostatic smoking. Both fresh and frozen fillets were dry-salted before smoking. The fish smoked were the lean ocean-ranched salmon caught off Iceland in June 1998 and farmed Norwegian salmon, slaughtered in either November 1998 or April 1999, differing in fresh fillet fat content from 84 to 169 g·kg⁻¹ wet weight. The fresh material used in smoking significantly affected the smoking loss of nutritive components in the fillets. The leaner the fish the higher percentile loss in fillet fat. Ascorbic acid decreased about 80 percent from the fresh value, independent of smoking temperature (20 or 30 °C). The fish that were dry-salted and electrostatically smoked only lost about 10 percent of the fresh ascorbic acid content, independent of the type of raw material used, indicating a conserving effect on ascorbic acid by the electrostatic process. Also, the electrostatically smoked fish showed a smaller drop in fillet pH than cold-smoked fillets, while tocopherol was little affected by the smoking methods tested.     

Updraft Gasification of Salmon Processing Waste

ABSTRACT:  The purpose of this study was to judge the feasibility of gasification for the disposal of waste streams generated through salmon harvesting. Gasification is the process of converting carbonaceous materials into combustible "syngas" in a high temperature (above 700 °C), oxygen deficient environment. Syngas can be combusted to generate power, which recycles energy from waste products. At 66% to 79% moisture, raw salmon waste streams are too wet to undergo pyrolysis and combustion. Ground raw or de-oiled salmon whole fish, heads, viscera, or frames were therefore "dried" by mixing with wood pellets to a final moisture content of 20%. Ground whole salmon with moisture reduced to 12% moisture was gasified without a drying agent. Gasification tests were performed in a small-scale, fixed-bed, updraft gasifer. After an initial start-up period, the gasifier was loaded with 1.5 kg of biomass. Temperature was recorded at 6 points in the gasifier. Syngas was collected during the short steady-state period during each gasifier run and analyzed. Percentages of each type of gas in the syngas were used to calculate syngas heating value. High heating value (HHV) ranged from 1.45 to 1.98 MJ/kg. Bomb calorimetry determined maximum heating value for the salmon by-products. Comparing heating values shows the efficiency of gasification. Cold gas efficiencies of 13.6% to 26% were obtained from the various samples gasified. Though research of gasification as a means of salmon waste disposal and energy production is ongoing, it can be concluded that pre-dried salmon or relatively low moisture content mixtures of waste with wood are gasifiable.     

Effect of Soy Flour, Soy Protein Concentrate and Sodium Alginate on the Textural Attributes of Minced Fish Patties

A mixture response statistical design was used to investigate the textural attributes of minced fish patties. Patties formulated with pollock were significantly firmer than those made from turbot and pollock blends or from turbot alone. Breakpoint values and firmness scores were negatively correlated with flavor and acceptability scores indicating that as patty firmness increased general acceptability declined. Higher acceptability for softer patties formulated with more turbot were attributable to the higher fat content. Increasing the soy protein levels and decreasing alginate content increased patty firmness regardless of fish composition. The patty formulation with maximum predicted acceptability was 78% turbot, 11% soy flour, and 11% soy protein concentrate.     

Texture and colour properties of proteins recovered from whole gutted silver carp (Hypophthalmichthys molitrix) using isoelectric solubilisation/precipitation

BACKGROUND: According to an FAO report, carp are the cheapest and by far the most commonly consumed fish in the world. Carp have minimal growth requirements, yet rapid growth rates. Although carp are generally considered unsuitable for human consumption in the USA, they have rapidly started populating major bodies of fresh water in the USA to the extent that commercial processing becomes of interest. However, typical mechanical means of meat recovery from carp are impractical owing to the bony nature of the carp carcass. Therefore the aim of the present study was to devise processing strategies to recover fish meat from carp that could be used in the development of human food products. RESULTS: Isoelectric solubilisation/precipitation at acidic and basic pH values was applied to whole gutted silver carp. Depending on the solubilisation pH, protein and fat recovery yields were approximately 420–660 and 800–950 g kg^?1 respectively. The process effectively removed impurities such as bones, scales, skin, fins, etc. from whole gutted carp. The proteins were concentrated to approximately 900 g kg^?1, while the fat was reduced by 970–990 g kg^?1. Functional additives (potato starch, beef plasma protein, transglutaminase and polyphosphate) improved (P < 0.05) the texture of carp protein‐based gels such that it was generally comparable to the texture of Alaska pollock surimi gels. Although titanium dioxide improved (P < 0.05) the whiteness of carp gels, it was lower (P < 0.05) than the whiteness of Alaska pollock surimi gels. CONCLUSION: Isoelectric solublisation/precipitation allows protein and lipid recovery from whole gutted carp. However, if the proteins are used as a gelling ingredient in fish food products, functional additives are recommended. Copyright © 2008 Society of Chemical Industry     

Chemical Characterization of Liver Lipid and Protein from Cold-Water Fish Species

ABSTRACT:  The largest US harvests of marine fish for human consumption are from Alaska waters. Livers from these fish are combined with other fish offal and made into fish meal and oil or discarded. The purpose of this study was to characterize liver lipids and proteins from important commercial species including walleye pollock (WP), pink salmon (PS), Pacific halibut (PH), flat head sole (FS), and spiny head rock fish (RF), and underutilized species including arrow tooth flounder (AF) and big mouth sculpin (BS). Liver lipid content ranged from 50.3% in WP to 3.3% in PS. Protein content ranged from 7.7% in WP to 18.4% in BS. PS livers had the highest content of ω-3 fatty acids at 336 mg/g of oil and AF had the lowest content at 110 mg/g of oil. There were significant differences in the content of 9 amino acids with methionine and lysine values ranging from 2.66% to 3.43% and 7.19% to 9.45% of the total amino acids, respectively. Protein from the cold water marine fish livers was of high quality and the oils contained substantial quantities of ω-3 fatty acids. Fish livers had distinct chemical properties and can be used for the development of unique food ingredients.     

Injection‐Salting and Cold‐Smoking of Farmed Atlantic Cod (Gadus morhua L.) and Atlantic Salmon (Salmo salar L.) at Different Stages of Rigor Mortis: Effect on Physical Properties

ABSTRACT: Processing of fish is generally conducted postrigor, but prerigor processing is associated with some potential advantages. The aim of this study was to study how 5 processing regimes of cold‐smoked cod and salmon conducted at different stages of rigor influenced yield, fillet shrinkage, and gaping. Farmed cod and salmon was filleted, salted by brine injection of 25% NaCl, and smoked for 2 h at different stages of rigor. Filleting and salting prerigor resulted in increased fillet shrinkage and less increase in weight during brine injection, which in turn was correlated to the salt content of the fillet. These effects were more pronounced in cod fillets when compared to salmon. Early processing reduced fillet gaping and fillets were evaluated as having a firmer texture. In a follow‐up trial with cod, shrinkage and weight gain during injection was studied as an effect of processing time postmortem. No changes in weight gain were observed for fillets salted the first 24 h postmortem; however, by delaying the processing 12 h postmortem, the high and rapid shrinking of cod fillets during brine injection was halved.     

Salmon farms as a source of organohalogenated contaminants in wild fish

Organohalogenated contaminants (OHCs), including organochlorines (OCs; PCB, and OC-pesticides), brominated flame retardants (BFRs; polybrominated diphenyl ethers [PBDE], hexabromocyclododecane [HBCD]) and perfluorooctane sulfonate (PFOS), were measured in livers of Atlantic cod (Gadus morhua) and saithe (Pollachius virens) caught in the vicinity of salmon farms (n = 75) and control sites (n = 80) in three regions (59°-70°N) in Norway. Forty-five percent of the farm-associated (FA) fish (60% of the saithe and 30% of the cod) and none of the control fish had salmon feed (aquaculture food pellets) in their digestive tracts. Concentrations of OCs and BFRs were about 50% higher and dominated more by persistent compounds in Atlantic cod compared to saithe. After controlling for a set of confounding variables (location, sex, size, weight, gonads size, hepatosomatic index, and % lipids in the liver), the concentrations of ∑OC and ∑BDE were 50% higher in FA cod compared to control fish, whereas they were 20% higher in FA saithe than control fish. Hence, salmon farms are a source of lipid-soluble OHCs to wild marine fish, but variation in life-history and habitat use seems to affect the levels of OHCs in the different fish species. In contrast to the lipid-soluble OHCs, control fish had 67% higher PFOS levels than FA fish, which suggests that natural food contains higher loads of this compound than the commercial feed used in salmon farms. Some OHCs are known to act as endocrine disruptors, thus further work is required to determine if OHCs negatively affect reproductive processes of wild fish associated with salmon farms.     

Ultramicroscopical Structures and Liquid Loss in Heated Cod ( Gadus morhuaL) and Salmon ( Salmo salar) Muscle

This study was performed in order to assess the effect of heating in pre- and post-rigor muscle of fed cod, wild cod and farmed salmon harvested at different times of the year. The structural changes in muscle samples pre-heated from 5 to 60°C were qualitatively evaluated using both light and transmission electron microscopy techniques. The microstructural changes are discussed in relation to the liquid loss measured by a low-speed centrifugation test. The heat-induced structural changes varied between the fish tested, reflecting different degrees of post mortem degradation prior to heating, the muscle-pH and species-specific structural properties. The fed fish, both cod and salmon, underwent the most severe structural degradation. This reflected both the low muscle pH and the more severe post mortem degradation observed in these fish prior to heating, compared with the wild cod. Heating caused extensive shrinkage of the myofibrils and hence, widened intermyofibrillar and extracellular spaces in both the fed cod and the salmon muscle. In the sample of wild cod muscle, the extracellular spaces were narrow and the myofibrils were closely packed. The difference in heat-induced liquid loss of the fed compared with the wild cod muscle coincides with their different structural features, as observed both by LM and TEM. The better liquid-holding properties of the salmon muscle than the cod muscle are attributed to the species-specific ultrastructural features as observed with TEM. In addition to the denser appearance of the salmon myofibres, it is suggested that both fat droplets and aggregated sarcoplasmic proteins filling the intermyofibrillar and extracellular spaces are important in preventing release of liquid upon heating.     

Effects of pan-frying in margarine and olive oil on the fatty acid composition of cod and salmon

Effects on the fatty acid composition of cod (Gadus morhua) and salmon fillets (Salmo salar) after pan-frying in margarine and olive oil were determined. The fatty acids of the margarine used were 55.5% saturated (SFA), 33.0% mono-unsaturated (MUFA) and 11.5% polyunsaturated (PUFA). The olive oil used contained 15.4% SFA, 76.1% MUFA and 8.5% PUFA. Using margarine or olive oil increased the SFA and MUFA percentages, respectively, in both species. For cod fillets (lean), pan-frying increased the fat content (0.55–4.15 g/100 g and 0.55–2.30 g/100 g before and after pan-frying, with margarine and olive oil, respectively), whereas, for salmon fillets (fat), it decreased (13.91 to 10.57 g/100 g and 15.35 to 12.95 g/100 g before and after pan-frying with margarine and olive oil, respectively). In conclusion, the culinary fat selection affects the total fatty acid content and composition of the prepared fish fillet.