Nucleotide Degradation Profiles of Iced Barramundi (Lates calcarifer) and Nile Perch (Lates niloticus) Muscle

Adenine nucleotides and their related compounds were determined in muscle extracts from two species of fish that were stored in ice after thawing. The fish were the closely related species, Australian barramundi (Lates calcarifer) and Kenyan Nile perch (Lates niloticus) which had different process histories. For all samples, adenine nucleotides did not exceed 6% of the total nucleotide pool. Inosine monophosphate (IMP) decreased steadily with storage. Hypoxanthine (Hx) was the major product of adenosine triphosphate (ATP) degradation in both barramundi and Nile perch, showing a steady increase with days of iced storage. The Hx level did not reach a maximum during the 9d storage period. The K-value also increased regularly with time of storage and for the later stages (i.e., 7 and 9d) and was significantly different (P < 0.01) for the species. The iced storage life of these typical samples of barramundi and Nile perch was estimated to be 3d after thawing using a K-value of < 30% to indicate excellent quality. Despite the differences in process history the nucleotide profiles were remarkably similar during storage. This precludes the use of nucleotide levels as a means of differentiating between these species.     

不同干燥方式对卵形鲳鲹鱼片风味的影响

为探究不同方式干燥卵形鲳鲹鱼片的风味差异,实验选取冰鲜卵形鲳鲹为原料,采用热风干燥、热泵干燥和冷冻干燥3种方式干制卵形鲳鲹鱼片,分别测定并分析其TBA值、呈味核苷酸含量、游离氨基酸含量和挥发性风味物质等指标。结果显示,干燥后的卵形鲳鲹鱼片中TBA值与K值均显著上升,其中冷冻干燥鱼肉的TBA值仅比冰鲜鱼片增加1.6倍,但热泵干燥和热风干燥则分别增加了5.5和4.5倍。干燥后鱼肉中的总游离氨基酸含量及味精当量较冰鲜卵形鲳鲹鱼片显著降低,其中热风干燥鱼肉的味精当量则下降了50.83%。热泵干燥鱼肉中苦味氨基酸含量和鲜味氨基酸含量分别占总氨基酸含量的19.11%和7.37%,而冷冻干燥组鱼肉中甜味氨基酸相对百分含量最高,为53.62%。3种干燥方式中,热泵干燥卵形鲳鲹的味精当量最高,为4.47谷氨酸钠(MGS)/100 g,表明热泵干燥卵形鲳鲹鱼片的鲜味程度最高。就挥发性风味成分而言,热泵干燥鱼肉酯类和酮类较多,其主要呈现果香味和焙烤坚果味;热风干燥中烃类和芳香类的相对含量约占70%,醛类和酯类相对含量达20%;而冷冻干燥中烃类与芳香类相对含量占到90%以上,醛类和酯类相对含量不足8%,其风味...     

Quality characteristics in raw and smoked fillets of Atlantic salmon, Salmo salar, fed high-energy diets

Atlantic salmon, Salmo salar , were fed four levels of dietary fat (256, 308, 346 and 389 g kg⁻¹ of diet) for 138 days, with the purpose of studying quality characteristics in raw and smoked fish fillets. Dietary fat levels up to 346 g kg⁻¹ resulted in increased fat content of the raw fillets. The dietary fat levels had a less systematic effect on perceived fatness of the smoked fillets and caused a trend towards better odour and flavour. The fat content of raw fillets was significantly ( P ≤ 0.05) correlated to lower smoke odour, greater rancid flavour, fatness, and a yellower hue of the smoked fillets. Astaxanthin levels of the raw fillets varied between 6 and 11 mg kg⁻¹ of fillet and were significantly ( P ≤ 0.05) correlated with greater intensity of smoke odour, lower off-odour, and less whiteness, greater colour intensity and a redder hue of the smoked fish. It is proposed that salmon fillets can be graded according to weight, fat content and colour values prior to smoking to obtain more standardized quality characteristics of the final product after processing.     

Low-Dose X-Ray Treatment of Fresh Channel Catfish Fillets Does Not Affect Color,Texture, or Oxidation

Consumer uncertainty of irradiated food products has slowed implementation of food irradiation, even though it has been proven as a safe and effective technology. For acceptance, irradiated products should not be distinguishable from alternatively processed products. The present research was designed to determine if X-ray irradiation treatment results in changes in selected quality parameters (color, texture, and oxidation) of fresh aquacultured channel catfish fillets. Fillets (Ictalurus punctatus) were treated to 0, 0.5, 1.0, and 1.5 kGy using an X-ray irradiator and stored at 3°C for 17 days. Periodically during storage, samples were removed and instrumentally measured for color, texture, and oxidation (thiobarbituric acid reactive substances). Color, texture, and oxidation did not change (p > 0.05) over time or with irradiation dose. Results indicated that low-dose X-ray treated raw catfish fillets were not distinguishable from untreated controls.     

Effect of Freeze-Chilled Treatment on Flavor of Grass Carp (Ctenopharyngodon idellus) Fillets and Soups During Short-Term Storage

ABSTRACT

In order to evaluate the effect of chilled (T1), frozen (T2), and freeze-chilled (T3) treatment on the flavor of grass carp fillets and soups, adenosine triphosphate (ATP)-related compounds, umami-taste amino acids (UTAA), thiobarbituric acid (TBA), peroxide value (PV), and soup sensory score were analyzed. Results showed that the sum of ATP, ADP, and AMP contents in T2 fillets were significantly higher (p < 0.05) than others, but the sum of hypoxanthine riboside (HxR) and hypoxanthine (Hx) contents for T2 fillets and soups were significantly lower (p < 0.05) than others during storage. The T3 fillets and soups had lower inosine 5-monophosphate (IMP) contents than T1 after Day 2, but higher UTAA contents than T1 during storage. The T3 fillets had the highest TBA and PV values among the three groups during storage. According to the total aerobic counts, K value, and sensory score, all the fillets and soups kept good quality during storage. Therefore, freeze-chilled treatment not only can extend fish shelf life but also retain excellent fish flavor.     

Chemical Parameters for Traceability of Raw Material Freshness of Tropical Surimi

ABSTRACT

Changes in chemical parameters of tropical fish used for surimi production—namely, threadfin bream (TB; Nemipterus spp.), lizardfish (LZ; Saurida spp.), and goatfish (GF; Upeneus spp.)—during ice storage and their respective washed mince were investigated. Total volatile basic nitrogen (TVB-N), trimethylamine (TMA), hypoxanthine (Hx), and total biogenic amine (BA) content of mince increased with storage time. Crude protein of fish and their respective washed mince reduced as storage time of fish was prolonged. Principal component analysis (PCA) revealed that washed mince produced from fish stored in ice for 7–12 days showed chemical characteristics that were distinct from those of washed mince prepared from spoiled fish. The TMA, TVB-N, and Hx content of washed mince appeared to be sufficient raw material freshness indicators in these three species.     

The Effect of Liquid Smoking of Anchovy (Engraulis encrasicolus,L. 1758) Fillets on Sensory,Meat Yield,Polycyclic Aromatic Hydrocarbon (PAH) Content,and Chemical Changes

In this study, the effects of a commercial liquid smoke flavoring agent and two different brining solutions applied on fillets of anchovy were investigated by performing sensory analyses, meat yield, polycyclic aromatic hydrocarbon (PAH) content, and chemical composition analyses. Fillets were brined at 40 and 65% for 4 h at 4°C. Meat yield, sensorial acceptability, and chemical compositions were affected by each brining level. No detectable PAH levels were found in smoke flavoring treated fish samples. Sixty-five percent salt level was rejected by the participants due to high salt content. The results of the study showed that liquid smoke flavoring treatment is applicable to the anchovy fillets, and 40% brining level is recommended.     

Effect of bleeding on the quality of amberjack Seriola dumerili and red sea bream Pagrus major muscle tissues during iced storage

The effect of bleeding on white muscle quality in amberjack and red sea bream was evaluated by measuring ATP-related compounds, volatile basic nitrogen (VBN), and the trimethylamine (TMA) content. The freshness was evaluated by the K value, and the degree of spoilage was elucidated by VBN and TMA. ATP was rapidly converted to ADP and AMP in the muscle and IMP was the main product of ATP degradation during iced storage. For both species, the IMP content was higher in the muscles of fish that were bled than in those unbled during iced storage. Conversely, the K value and the levels of hypoxanthine (Hx) and VBN were higher in the muscle tissue of unbled fish than in the bled tissue of both species. Similarly, the TMA content was higher in the unbled muscle tissues of both species after a week of storage.     

The Effects of Light Salting on Physicochemical Characteristics of Frozen Cod (Gadus morhua) Fillets

Abstract

The effects of light salting by brine injection and brine immersion on physicochemical and textural properties of cod fillets were evaluated. Light salting significantly increased yield and water holding capacity. Adding brine injection to the process can be used to shorten the process time needed to obtain the desired salt content and increase yield. The effects on chemical composition were most significant in salt content, but water and protein content were also affected. Water content decreased from the tail to head direction of the fillets, both in unsalted and light salted fillets. Changes in protein content were in opposite proportion to changes in water content. This could be seen in the fresh fish and also after freezing, both in unsalted and light salted fillets. Texture of the fish was not significantly affected by salting and freezing.     

Comparative composition and shelf-life of fillets of wild and cultured turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus)

Turbot and Atlantic halibut are highly valued fish species. However,very little is known about fillet shelf-life characteristics associated withboth species. Thus, fillet -tocopherol content and proximate compositionof wild turbot (1.5 kg) and Atlantic halibut (1.1 kg)caught off the south coast of Ireland and the north-west coast of Iceland,respectively, were investigated. In addition, the susceptibility of fillets, storedunder retail conditions, to lipid oxidation and colour change was studied.Proximate composition analysis showed that turbot had significantly highermoisture (P < 0.001) and lower protein (P < 0.001) contents compared toAtlantic halibut. Atlantic halibut incorporated significantly higher (P <0.001) levels of -tocopherol into fillets than turbot. Over 14 days ofstorage on ice, fillets from Atlantic halibut exhibited significantly lower (P =0.020) levels of lipid oxidation than those of turbot. However, malondialdehyde(MDA) concentrations were generally very low, never exceeding 0.6 gg^–1 fillet. Turbot maintained a significantly higher (P< 0.001) pH over the storage period. The lightness (L^* values) offillets from both species increased over 14 days of storage, but wassignificantly higher (P < 0.001) in Atlantic halibut than in turbot. Turbotdeveloped a relatively intense yellow colour during storage (decrease in hueangle and increase in b^* values), whereas this was not the case forAtlantic halibut. The results of this study demonstrate that fillets of wildAtlantic halibut stored on ice, were less prone to lipid oxidation anddiscolouration than those of wild turbot. However, quality changes in turbotwere very small showing that both fish have tremendous shelf-life capacities interms of lipid oxidation. These findings are considered in the context of knownmaterial for farmed fish.     

Effect of Chitosan Coating Enriched with 6-gingerol on Red Drum Fillets Quality and Shelf Life during Refrigerated Storage

The effect of chitosan coating enriched with 6-gingerol on the quality and shelf life of red drum fillets during refrigerated storage was investigated in this study. Samples were applied with chitosan coating (CH), 6-gingerol (GI), and chitosan coating with 6-gingerol (CH+GI) before storing at 4°C for 20 days. The data in this study showed that treatment with CH+GI could significantly decrease pH value, K-value, thiobarbituric acid value, and total volatile basic nitrogen in red drum fillets during refrigerated storage. The counts of microorganisms, such as Enterobacteriaceae, psychrotrophic, mesophilic bacteria, and lactic acid bacteria, were also significantly lower in the CH+GI group compared with those in the CH and GI groups. Moreover, the combination of chitosan coating and 6-gingerol was more effective in relieving the deterioration of tissue texture and sensory characteristics in the red drum fillets. In addition, the results suggested that chitosan coating and 6-gingerol had a synergistic effect on the quality improvement of red drum fillets. This work demonstrates that chitosan coating enriched with 6-gingerol may be a promising natural preservative for red drum during refrigerated storage.     

Quality Changes in Gamma Irradiated Marinades of Anchovy (Engraulis anchoita) During Refrigerated Storage

The effect of gamma irradiation (0, 1.8, and 3.3 kGy) on the microbiological, chemical, and color characteristics of marinated (7% acetic acid and 10% NaCl) and vacuum-packed anchovy fillets was analyzed during 20 months of refrigerated storage (4 ± 1°C). Acidity, pH, water activity (a_w), total volatile basic nitrogen (TVBN), lipid oxidation, and color parameters were determined. Mesophilic and psychrotrophic bacteria, sulphite-reducing clostridia, total and fecal coliforms, Staphylococcus spp., yeasts, and molds were investigated. Gamma irradiation reduced the initial mesophilic bacterial counts and inhibited mesophils growth during 20 months. As a result, the production of TVBN during storage was lower in irradiated samples than in control. Also, lipid oxidation was lower in irradiated samples than in nonirradiated. The color of anchovy fillets was not affected by the irradiation treatment. Even if nonirradiated anchovy fillets presented a high stability in comparison with the traditional product (in flasks with vegetable oil and spices), gamma irradiation improved the microbiological and chemical quality of anchovy fillet marinades without inducing changes on its characteristic color for 20 months.     

Factors Affecting Quality of Role Sole (Lepidopsetta bilineata) Fillets

Fillet yield, defect levels, thaw drip, cooked texture and bacteriological content were determined for rock sole (lepidopsetta bilineata) heandled and Processed under a variety of conditions. Fillets having the highest quality were boxed, hand unloaded, hand filleted and wet trimmed. Lowest quality fillets were from fish bulkstowed, unloaded by wet pump and machine filleted. The lowest bacterial counts were found in machine-filleted, wet-trimmed fish. Morsxella predominated the microbial flora of whole rock sole and Flavobacterium predominated that for the fillets.     

Cage Culture of Hybrid Striped Bass in Indiana and Evaluation of Diets Containing Three Levels of Dietary Protein1

Culture of hybrid striped bass Morone saxatilis × M. chrysops has been increasing in selected regions of the United States. Because of their thermal tolerance, hybrids may have potential as a new commercial aquaculture species in the Midwest. In these studies, hybrid striped bass were reared in cages located in southern, central and northern Indiana and offered one of three practical diets. Diets contained either 32, 36 or 40% crude protein. Additionally, a preliminary 8 wk laboratory experiment was conducted in which fish were offered the same diets. All diets were formulated to meet the established dietary lysine requirement; optimal levels of other essential amino acids in the diet were predicted by the whole-body essential amino acid profile of hybrid striped bass. In the laboratory experiment, weight gain of fish fed 36% crude protein was significantly higher than those fed either other level of dietary protein. After 205 days, final average weight gains of fish in the field experiment were not significantly different and ranged from 233 to 426 g with an overall average daily gain of 1.6 g/fish/d. Overall survival was 89.1%. Dress-out percentages were 81.2, 69.8, and 34.9% for eviscerated, eviscerated and headed, and fillets, respectively. Those values were not significantly different among dietary treatments or sites. Lipid content of fillets from fish fed 32% dietary crude protein was significantly higher than in fish fed 36 or 40% crude protein.     

Chemometrics Approaches to Monitoring of Biogenic Amines Changes in Three Fish Species

The biogenic amine contents in fillets of three freshwater fish of kutum (Rutilus frisii), common carp (Cyprinus carpio), and Caspian salmon (Salmon caspius) were monitored during storage at 4°C for 20 days. The amounts of biogenic amines were determined at regular intervals using high performance liquid chromatography after derivatization with benzoyl chloride. Significant differences in the levels of selected biogenic amines among the fish samples were found (p < 0.05) during storage times. While the amount of putrescine, cadaverine, histamine, and tyramine in the fish fillets increased during the storage time, the changes in spermine and spermidine contents of the fish species were minor and both showed low and inverse correlations with storage time. For each of the three fish species, the sensory acceptability limit was found to be 4–8 days. The quality and biogenic amine indices of fish samples showed high correlation with storage time (r > 0.9). The principal component analysis of the results indicated that the formation of biogenic amines displays a certain behavioral pattern in all fish samples.     

Sensory Quality and Shelf Life of MAP Redfish (Sebastes marinus) Fillets as Affected by Previous MA Bulk Storage of Whole Fish

Abstract

The shelf life of iced redfish is known to be 16–19 days. This study evaluated the effects of modified atmosphere (CO₂/N₂: 60/40) in bulk storage of redfish and subsequent modified atmosphere packaging (MAP) of fillets. Fish were evaluated by sensory, microbiological and chemical methods. Modified atmosphere (MA) bulk storage of whole fish for more than 5 to 10 days did not improve their sensory quality or significantly increase shelf life. In fact, the study showed negative effects in texture and overall appearance. MAP of fillets processed from 10-day MA bulk stored fish showed a modest increase in shelf life, but negatively affected their texture. Sensory qualities, i.e., tenderness, that decreased under MA bulk storage were improved upon aerobic storage for fish stored under MA for 5 to 10 days, but not 14 days. Lower microbial levels were found in MA bulk stored fish and MAP fillets compared to traditionally iced fish, while higher TMA levels were found in MAP fillets.     

Effect of Soluble CO2 Stabilization on the Quality of Fillets from Farmed Gilthead Sea Bream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

ABSTRACT

Soluble gas stabilization (SGS) is a relatively recent methodology of active packaging that has been proposed to extend the shelf life of packaged fish. The aim of the present work was to study the effect of SGS applied at different extents (2 bars: 30 and 60 min) on the shelf life of sea bream and sea bass fillets packed in air during chilled storage. Quality changes were evaluated by sensory assessment, microbiological analysis (TVC), TBARs, pH value, TVB-N, and TMA-N. No significant extension of sensory shelf life was visible as a function of SGS treatment. The treatment of fillets in CO₂ at 2 bars during 60 min had a positive effect on the microbiological shelf life of both species. On the other hand, TMA-N and TVB-N showed similar changes during storage period and were not affected by the CO₂ treatment. Sea bream treated with SGS always presented higher TBARs than control samples. Nevertheless, oxidation of sea bream and in particular, of sea bass fillets, did not appear to be a significant problem during chilled storage.     

The effects of phase‐feeding rainbow trout (Oncorhynchus mykiss) with canola oil and Alaskan pollock fish oil on fillet fatty acid composition and sensory attributes

Rainbow trout (186 g) were fed three test diets where the lipid source (150 g kg^?1) was either menhaden oil (MO), pollock oil (PO) or canola oil (CO) for eight weeks to an average weight of 370 g. The CO group was then divided into two groups, one continuing on the CO diet and the other switched to the PO diet (CO–PO). After nine additional weeks of feeding, the average fish weight approximately doubled (719–749 g). No significant differences were found in average final weight or fillet yield among dietary treatment groups. Fatty acid profiles of fillets from trout fed MO, PO or CO‐supplemented diets reflected the fatty acid profiles of the added oils, whereas the fatty acid profile of fillet from trout in the CO–PO group exhibited values similar to those of fish fed PO. The ratio of ω3 : ω6 FA was nearly 2.5 times higher in fillets from the CO–PO group compared to the CO group. Sensory analysis showed that panelists preferred CO‐fed fillets over those fed MO, PO, or CO–PO. Phase‐feeding CO and PO reduced fish oil use and resulted in fillets with double the content of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) over CO‐fed fish, similar to levels in MO‐fed fish.     

Size-fractionated fish hydrolysate as feed ingredient for rainbow trout (Oncorhynchus mykiss) fed high plant protein diets. II: Flesh quality, absorption, retention and fillet levels of taurine and anserine

In the work to find replacement for fish meal in feed for fish, the inclusion of plant protein sources at high dietary level is an important issue. The present experiment was carried out to reveal how different feed ingredients affected the eating quality of the grown up fish with focus on nitrogen compounds as amino acids, taurine and anserine. Six experimental diets were fed to rainbow trout in triplicates for 90 d. All diets were composed to be equal in protein, lipid, energy and lysine. Three levels of a mixture of plant sources (full fat soy, extracted soy, soy protein concentrate, corn gluten) constituting 57.2%, 73.9% and 90.6% of total dietary protein were used. A small amount of fish meal was added in 5 diets constituting 9.4% of total protein. A fish hydrolysate that was high in free amino acids, taurine and anserine was tested at 16% and 32% dietary inclusion of total protein. Two other diets contained the same level of protein from the same hydrolysate that was ultra filtrated to remove low molecular weight compounds. Digestibility of taurine and anserine was found to be close to 99% for all groups, except for the group containing high level of plant sources. The levels of taurine in whole trout and fillets decreased during the feed experiment, but were about the same for all groups at the end of the feeding experiment and independent of dietary levels. The level of anserine in fish and fillets was equal from start to end of the experiment and independent of dietary inclusion. Taurine and anserine therefore seem to be homeostatic regulated in trout and independent on dietary levels. Amino acid content in fish and fillet was also equal for all groups and independent of protein sources used in the diets. The chemical composition showed higher lipid and dry matter levels in fish and fillet in fish that grew the fastest. In conclusion, plant protein sources may be included in diets for trout at high levels without affecting the eating quality as evaluated by amino acids, taurine and anserine levels.     

琼胶寡糖及EGCG对冰藏花鲈鱼片新鲜度与蛋白质生化特性的影响

花鲈贮运期间易受微生物与内源酶的联合作用,导致新鲜度及蛋白质生化特性改变,影响其食用价值。因此,采用适当的保鲜方式对花鲈贮运流通过程中的品质变化加以调控,以保证其品质安全显得尤为重要。为探究表没食子儿茶素没食子酸酯(EGCG)及琼胶寡糖(AO)对冰藏花鲈鱼片的保鲜效果,对硬度值、色差及新鲜度指标(硫代巴比妥酸值、K值、挥发性盐基氮、菌落总数、感官评分)进行测定,并对蛋白质生化特性(肌原纤维蛋白含量、二级结构、巯基、羰基含量)进行分析。结果显示,对照组在第16天时感官得分低于8,且菌落总数和K值已分别高达(6.78±0.15) lg(CFU/g)与67.37%±1.75%,不可食用,而EGCG组(EG)、琼胶寡糖组(AO)及复合组的样品仍具有较好的硬度、色泽及新鲜度。贮藏至20 d时对照组的TBA值高达(0.81±0.03) mg/kg,而EG组、AO组及复合组的TBA值在贮藏期间均未出现大幅度增加,且始终低于对照组。另外,贮藏至12 d时对照组的羰基含量已显著高于其他保鲜处理组,对照组在贮藏末期的羰基含量上升至(1.63±0.04)nmol/mg,而EG组、 AO组及复合组的羰基含量仅为(1.14±0.03)、(1.28±0.08)与(0.99±0.09) nmol/mg。贮藏末期复合组的蛋白含量、α螺旋、巯基均高于对照组和单一保鲜组。研究表明,EGCG及琼胶寡糖均能较好地维持鱼片的新鲜度,能显著抑制蛋白质变性与氧化,且二者复合后的保鲜效果优于单一保鲜剂,延长鱼片保质期至20 d以上。该研究为EGCG及琼胶寡糖的保鲜机理提供了理论基础,为开发高效的新型生物保鲜剂提供参考。