Quality of Filleted Atlantic Mackerel (Scomber Scombrus) During Chilled and Frozen Storage: Changes in Lipids,Vitamin D,Proteins, and Small Metabolites,including Biogenic Amines

Quality changes of vacuum-packed Atlantic mackerel (Scomber scombrus) fillets during 12 months’ frozen storage at ?27°C and 9 days’ chilled storage at +4°C were evaluated. Freezing at ?27°C preserved the long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), both in light and dark muscle, vitamin D, and the low molecular weight metabolites (LMW) (studied by high resolution nuclear magnetic resonance spectroscopy, HR NMR). Protein oxidation took place, especially between 1 and 7 months, decreasing water holding capacity and protein extractability. During chilled storage, no lipid or protein oxidation was observed, but lipolysis increased, and several LMW metabolites relevant for sensory and nutritional quality degraded into non-favorable compounds. The content of biogenic amines was high at day 9 (e.g., 18 mg histamine/100 g), jeopardizing safety. Preservation of mackerel fillets by freezing at ?27°C is thus a better option compared to prolonged chilled storage at +4°C; the quality was well preserved for 12 months’ frozen storage.     

Textural and Sensory Properties of Fish Sausage from Rainbow Trout

The aim of this study was to determine the textural and sensory properties of fish sausage which were prepared from refrigerated and frozen rainbow trout (Onchorynchus mykiss) and stored for 14 days at 0?4 °C. These two groups of sausages were compared for texture, physical, and sensory properties by carrying out texture profile analysis (TPA), shear test, water holding capacity (WHC), cook loss, color, and sensory analyses. According to TPA and shear test, sausages prepared from frozen fillets exhibited a texture significantly (p < 0.05) weaker than those prepared from refrigerated fillets, but no difference in overall liking was observed.     

Relationship between Lipid Oxidation,Protein Function Properties,and Freshness Changes of Salt-Treated Blunt-Snout Bream (Megalobrama amblycephala) Fillets Stored at 4°C

The aim of this study was to investigate the relationship between lipid oxidation, protein function properties, and freshness changes of blunt-snout bream (Megalobrama amblycephala) fillets treated with 2% and 4% salt during storage at 4°C. Salting with 2% and 4% salt could delay quality deterioration and protein denaturation, thus improving sensory attributes to some extent. But, 4% salt promoted lipid oxidation of blunt-snout bream fillets. There is a significant correlation (p < 0.05) between freshness indexes and lipid oxidation or protein function properties (total SH content, Ca²⁺-ATPase activity). Salting with 2% salt is an ideal treatment to control the quality of blunt-snout bream fillets stored at 4°C.     

Comparison of Postmortem Changes in Blunt-Snout Bream (Megalobrama amblycephala) During Short-Term Storage at Chilled and Partial Freezing Temperatures

In order to obtain more information about the consumption and process of blunt-snout bream, this study investigated postmortem changes of pH, cooking loss, texture properties (hardness, cohesiveness, springiness, and gumminess), and adenosine triphosphate (ATP)-related compounds in blunt-snout bream during short-term storage at 4 and ?3°C. The pH value declined quickly within 12 h postmortem, and those samples stored at ?3°C were lower than 4°C. High values of cooking loss occurred within 2–4 h postmortem, with maximum values of 20.94% (4°C) and 27.64% (?3°C), respectively. The cooking loss rapidly decreased to 13.59% (4°C) and 17.62% (?3°C) at 8 h postmortem, respectively. Texture properties (hardness, cohesiveness, springiness, and gumminess) decreased with storage time at both temperatures. Fish stored at ?3°C had a higher level of inosine monophosphate (IMP) compared with 4°C and was more than 15 μmol g^?1 during 8–24 h postmortem. The overall results indicated that it is better to preserve blunt-snout bream at ?3°C for short-term storage and utilize the fish within 8–24 h postmortem.     

The effects of stress and storage temperature on the colour and texture of pre-rigor filleted farmed cod (Gadus morhua L.)

This experiment deals with the effects of pre‐slaughter stress and storage temperature on muscle pH, fillet contraction, colour and texture in pre‐rigor filleted farmed cod fillets. The fish were either sedated with a low dose of MS‐222 (14.3 mg L^?1) (unstressed groups) or exposed to the air for 3 min (stressed groups) before being submerged in a benzocaine bath (150 g L^?1). The fish were then killed by a blow to the head, their gills cut, filleted and finally stored at either 4 or 20°C. The stressed groups had significantly lower pH values after slaughter (pH=7.0) than the unstressed groups (pH=7.3). This difference was maintained until post rigor for the fish stored at 4°C, but at 20°C it was immediately overshadowed by a decrease in pH caused by temperature‐dependent processes. The length contraction and changes in registered colour values were more pronounced at both the higher temperature and the higher level of pre‐slaughter stress. Again temperature dominated, but significant and consistent effects were registered from stress. No significant effects of stress on texture post rigor were observed. It is concluded that high storage temperature masks the majority of effects caused by pre‐slaughter stress on the measured variables. Stress management protocols, however, are important when the fillets are kept at the common storage temperature of 4°C.     

Biochemical,Physical, Chemical,and Microbiological Assessment of Blue Shrimp (Litopenaeus stylirostris) Stored in Ice

Postmortem changes in blue shrimp (Litopenaeus stylirostris) muscle were studied on the basis of biochemical, chemical, physical, and microbiological changes during an 18 day storage period at 0°C. Adenosine 5′-triphosphate (ATP) content, breakdown products, K-value, pH, trimethylamine nitrogen (TMA-N), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), color, and texture (shear force) changes were examined. Also, total mesophilic and psychrophilic bacterial counts were measured. K-value increased linearly (r² = 0.98) from an initial value of 1.37 ± 0.59 to 59.42 ± 6.05% at Day 18. Spoilage indicators TVB-N and TMA-N increased from 29.56 ± 1.33 and 0.69 ± 0.25 to 39.04 and 2.04 ± 0.59 mg of N/100 g at Day 18, respectively; meanwhile, the total viable counts of mesophilic and psychrophilic bacteria increased from 3.48 ± 0.44 and 2.61 ± 0.29 log CFU/g to 6.27 ± 0.21 and 7.14 ± 0.39 log CFU/g, respectively, which indicated spoilage at the end of the storage period. The pH, texture, WHC, and color were affected (p < 0.05) during the storage period. Overall, results indicate that blue shrimp muscle quality was maintained for 12 days of storage in ice.     

Processing Method Effect on Texture,Color, and Microbial Load of Channel Catfish Fillets

Abstract

Catfish shelf life depends largely on post-harvest handling and storage conditions. Three methods of processing catfish fillets were studied to evaluate quality and shelf life. In one method catfish were hand-dressed, chilled in water at 0°C, and hand-filleted (HC). In the other methods, catfish were mechanically filleted and chilled immediately (MC) or held unchilled for one hour at 18°C prior to chilling (MU). All fillets were stored in HDPE bags at 2°C for analyses at 0, 3, 6, and 9 d. Shear force for MC and MU fillets decreased (P ≤ 0.05) to the same levels as HC fillets after 3 d storage. HC fillets had higher (P ≤ 0.05) ‘L’ and ‘b’ and lower ‘a’ values than MU or MC fillets throughout storage. Initial psychrotrophic counts (PPC) were lower (P ≤ 0.05) for MC (3.9 log CFU/g) and MU (4.1 log CFU/g) than for HC fillets (5.2 log CFU/g). The PPC increased (P ≤ 0.05) after 3 and 6 d in HC and MU fillets, respectively. Coliform growth showed similar patterns as PPC. Spoilage levels indicated a doubling in shelf life of machine-cut fillets (～8 d) as compared to hand-cut fillets (～4 d).     

Optimization of Heat Processing of Farmed Atlantic Cod (Gadus morhua) Muscle with Respect to Cook Loss,Water Holding Capacity,Color, and Texture

Convenience products of fish that are heat processed in-pack are often subjected to a compromise between quality and durability within the framework of required safety. The purpose of this study was to provide knowledge for optimizing pasteurization of cod muscle by quantifying changes in water holding capacity (WHC), cook loss, color, and texture within a wide range of processing times and temperatures. A heat load equivalent to 2 min at 70°C may be applied to the cod while maintaining the WHC above 66%, the cook loss below 5.6%, and keeping hardness and whiteness low, provided that the processing temperature is kept in the range 68 ± 4°C.     

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.     

Effects of Chilled Storage,Freezing Rates,and Frozen Storage Temperature on Lipid Oxidation in Meat Blocks from Cultured Bluefin Tuna Thunnus thynnus

ABSTRACT

The effects of a short chilled storage period before freezing, frozen storage temperature, and freezing rate on lipid oxidation of bluefin tuna (Thunnus thynnus) meat during frozen storage were investigated. After 12-months storage, all samples had increased in peroxide value though they were less at the lower temperatures (?45 and ?60°C). Peroxide values in all samples stored at ?20°C increased after 3 months storage, particularly those processed and stored 51 h after harvest. The lowest increase in peroxide value occurred in the samples frozen rapidly 3 h after harvest. Vitamin E levels decreased faster during frozen storage at ?20°C. There were no apparent differences in levels of triacylglycerides nor in n-3 fatty acid levels between treatments, storage periods, and storage temperatures. After 12-months storage, headspace oxidative volatiles were highest in samples stored at ?20°C and lowest in those stored at ?60°C. Lipid oxidation in tuna meat stored at ?45°C is similar to that at ?60°C, and rapid freezing rather than slow freezing should be used.     

Effect of Frozen Storage Temperature on Quality-Related Changes in Rainbow Trout (Oncorhynchus mykiss)

The effect of frozen storage temperature on quality-related parameters of rainbow trout (Oncorhynchus mykiss) muscle was studied in the interval from ?10 to ?80°C on samples stored for 1 to 18 months. The following quantities were measured: drip loss, water holding capacity and water distribution, color, lipid oxidation (thiobarbituric acid-reactive substances, TBARS), and membrane stability (enzyme activity). No effect of temperature on drip loss, water holding capacity, water distribution, or membrane stability was observed for samples stored below ?20°C, whereas storage at ?40°C or lower compared to ?30°C or higher resulted in a reduced level of secondary lipid oxidation (TBARS). No advantage was gained by using temperatures below ?40°C for frozen storage of trout regarding any of the properties investigated.     

Effects of rested-harvest using the anesthetic AQUI-S™ on channel catfish,Ictalurus punctatus,physiology and fillet quality

Trials were conducted to determine effects of AQUI-S™ sedation during harvest (rested-harvest) on physiological responses and fillet quality of channel catfish, Ictalurus punctatus. Rested-harvest is defined as application of an anesthetic immediately before harvest to reduce fish activity associated with a normal harvest. Doses of 25–35 ppm AQUI-S™ were effective for rested-harvest of catfish (loss of equilibrium in 3 to 10 min and 100% survival following recovery). Time to loss of equilibrium and time to recovery following sedation with 35 ppm AQUI-S™ increased as water temperature decreased from 30 °C to 10 °C. Catfish exposed to 25 ppm AQUI-S™, 35 ppm AQUI-S™, 100 ppm trincaine methanesulfonate, and 8 ppm metomidate had lower blood lactate, cortisol, and glucose and higher blood pH than unsedated fish exposed to a low-water stress. Rested-harvest (RH) catfish had higher muscle and blood pH, lower blood and muscle lactate, and higher muscle ATP levels than catfish exposed to a 45 min low-water stress. Rates of muscle pH decrease, ATP decrease, and lactate increase accelerated as storage temperature decreased from 15 °C to 5 °C in RH fish acclimated to summer temperatures (33 °C), conversely these rates accelerated as storage temperature increased from 5 °C to 15 °C in RH fish acclimated to winter temperatures (7 °C). Based on physiological response (higher muscle pH, lower blood lactate, delayed time to rigor), post-sedation euthanasia by CO₂ was superior to post-sedation euthanasia by AQUI-S™ overdose (150 ppm), nitrogen gas, or electrical stunning. Compared to fillets from fish exposed to simulated industry transport conditions, fillets from RH/CO₂ euthanised fish had higher pH 1 h post-slaughter, and less drip-loss and lower L^⁎ and a^⁎ color values during 7 days of iced storage. RH/CO₂ and control fillets were not different for shelf-life based on bacterial counts. Rested-harvest with AQUI-S™ followed by CO₂ euthanasia has potential to improve catfish fillet quality, but AQUI-S™ approval, development of rested-harvest strategies, and demonstration of economic benefits of rested-harvest will be required for adoption of rested-harvest to commercial catfish production.     

Behavior of histamine-producing bacteria in shimesaba, raw mackerel salted and marinated in vinegar during processing and storage at various temperatures

To study the behavior of histamine-producing bacteria during the processing and storage of shimesaba, we inoculated histamine-producing bacteria into raw mackerel and then evaluated bacterial counts and histamine content at each shimesaba processing step. Six histamine-producing bacteria—Morganella morganii, Enterobacter aerogenes, Raoultella planticola, Photobacterium damselae (2 strains), and Photobacterium phosphoreum—were inoculated onto the surface of mackerel fillets at various cell densities (no inoculation, 10⁴, and 10⁷ cfu ml^?1). The fillets were then treated according to the common procedure used for processing shimesaba. The concentration of NaCl in brine during the salting procedure was 10 % (w/v), and the main ingredients of the marinade broth were 27 % vinegar, 3.8 % sucrose, 0.3 % sodium glutamate, and 0.1 % sodium succinate. The level of histamine-producing bacteria and of histamine did not increase during the salting and marinating procedures. However, during the storage tests, histamine content increased remarkably in the shimesaba products stored at 10 °C for 3 days, and organoleptical degradation was also observed. However, significant deterioration, based on bacterial count, histamine content, and organoleptic evaluation, was not observed in samples stored at 5 °C. These results indicate that the use of traditional marinade broth during the processing of shimesaba and storage below 5 °C are effective methods for preventing histamine accumulation.     

Effects of Freezing and Frozen Storage on Protein Functionality and Texture of Some Cephalopod Muscles

The aim of this study was to investigate the effects of freezing and frozen storage on protein functionality and texture of squid (Loligo vulgaris), octopus (Octopus vulgaris), and cuttlefish (Sepia officinalis) muscles. Squid, octopus, and cuttlefish samples were cut into pieces of 4 × 4 cm. These pieces were packed in polyethylene bags. The bags were frozen in a blast freezer at ?45°C until the thermal center reached ?18°C. Frozen samples were stored in a deep freezer at ?18°C for 30 days. After freezing and during frozen storage, total soluble protein and water holding capacity decreased and total free amino acid and cooking loss increased in all cephalopod muscles. According to instrumental texture analysis results, freezing and frozen storage affected textural characteristics of squid and cuttlefish but not of octopus. Sensory hardness and chewiness values of all cephalopods increased after freezing, but elasticity values did not change. There were no significant differences between storage days in hardness values of squid and octopus. However, significant differences in hardness values of cuttlefish were observed between the 1st day of storage and the last day.     

The Influence of Cooking Parameters and Chilled Storage Time on Quality of Sous-Vide Atlantic Mackerel (Scomber scombrus)

The aim of the present study was to evaluate the effects of various sous-vide time–temperature regimes and their interactions on quality parameters of Atlantic mackerel (Scomber scombrus) during chilled storage. The mackerel ?llets were exposed to sous-vide treatment at 60, 75, and 90°C for 10, 15, and 20 min and further stored for 1, 3, and 7 days at 4 ± 1°C before analysis. Changes in pH, water content and cook loss, amount of water- and salt-soluble proteins, texture, and color parameters, as well as accumulation of lipid oxidation products in sous-vide-cooked mackerel were assessed. Sous-vide cooking time and temperature had the lowest contribution to the formation of primary and secondary products of lipid oxidation, as well as increase in yellowness of the fish flesh due to their accumulation; whereas duration of chilled storage led to a significant increase in oxidation and yellowness (p < 0.05). Duration of chilled storage also affected structural and textural properties of the fish muscle, leading to a decreased cook loss. At the same time, sous-vide cooking decreased the firmness of the fish muscle. Duration of chilled storage was found to have the highest significant effect (p < 0.001) on all physicochemical characteristics of sous-vide-cooked mackerel.     

Changes During Chilled Storage of Whole Tilapia and Short-Term Frozen Storage of Tilapia Fillets

This study evaluated the physicochemical changes in Nile tilapia (n = 82, 373.71 ± 61.91 g) refrigerated for up to 92 h and in the frozen fillets. The tilapias were captured with nets, slaughtered by ice and water shock (1:1) in a temperature of approximately 2°C for 30 min, and stored refrigerated at 4°C in polystyrene boxes containing ice. The fish were filleted, and filets were weighed and frozen. The drip loss and protein were determined after 23 days of frozen storage. After 4 h of storage, all fish were in full rigor mortis. The pH of the muscles decreased for up to 45 h of the storage period. The fillets obtained from tilapia stored for more than 72 h lost more weight and protein. Thus, the filleting or processing of tilapia should be done before 72 h of cold storage, since deterioration of the fish starts to occur after this period.     

Effects of temperature and dietary protein on gene expression of Hsp70 and Wap65 and immunity of juvenile mirror carp (Cyprinus carpio)

Juvenile mirror carp were fed diets containing 303.4, 321.7, 341.2, 361.0 and 379.1 g kg^?1 proteins, respectively, and reared at different water temperatures (18, 23 and 28°C) for 60 days. Gene expression of heat shock protein gene (Hsp70) and the warm temperature acclimation‐related 65 kDa protein gene (Wap65), immunity and antioxidant status in the carp were investigated. Results indicated that the contents of serum complement 3 (C3), complement 4 (C4) and immunoglobulin M (IgM), as well as activities of liver superoxide dismutase (SOD) and lysozyme (LSZ) were significantly enhanced with increasing dietary protein (P < 0.05), while content of malondiadehyde (MDA) decreased. Gene expression level of Wap65 in the liver significantly increased with dietary protein, while gene expression of Hsp70 decreased. The contents of C3, C4 and IgM, the activities of SOD and LSZ and gene expression level of Wap65 in the liver significantly increased with temperature. These results suggest that: Serum immune parameter, antioxidant enzymes and Hsp70 and Wap65 expression interact in fish to improve ability to adapt to the environment; and the optimal conditions for the immunity of carp are 348.1?354.5 g kg^?1 protein at 18°C, 352.3?364.9 g kg^?1 at 23°C and 360.2?364.3 g kg^?1 at 28°C, and the optimum temperature for carp is 23°C.     

Microbial Quality,Safety, and Sensory Acceptability of X-ray Treated Fresh Channel Catfish Fillets

This study was designed to determine if treatment with low dose X‐ray irradiation changes microbial quality (microbial load), safety (Listeria monocytogenes incidence), and sensory characteristics (aroma, appearance, and texture) of fresh aquacultured Channel catfish (Ictalurus punctatus) fillets during refrigerated storage. Fillets 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. Fillet aerobic plate count (APC), psychrotrophic plate count (PPC), total coliform count (TCC), and L. monocytogenes incidence were measured every 4 days during storage. A Difference-From-Control test was used to measure aroma, appearance, and texture. Fillet microbial counts were significantly different (p < 0.05) with time, irradiation dose, and the interaction of these two treatments. As expected, APC, PPC, and TCC increased as storage time increased. Overall L. monocytogenes incidence was 40%, 27%, 0%, and 7% at 0, 0.5, 1.0, and 1.5 kGy, respectively. Aroma of irradiated and non‐irradiated catfish fillets was significantly different, with greater aroma differences recorded as storage time increased due to progressional spoilage of the untreated controls. However, there were no significant aroma differences noted among the different irradiation doses. Neither appearance nor texture was significantly different between any treatments throughout testing. This study indicated that exposure to low dose X-ray irradiation improved the microbial quality and safety of fresh catfish fillets without affecting sensory acceptability at time of purchase.     

花鲈冰藏过程中肌原纤维蛋白生化特性与新鲜度变化的相关性

【目的】为研究冰温贮藏期间海鲈鱼(Lateolabrax japonicus)鱼片的品质及蛋白质生化特性的变化,【方法】该研究通过感官评分、pH、质构、色差、硫代巴比妥酸值(TBA值)、挥发性盐基氮(TVB-N值)、菌落总数(TVC)的测定和肌原纤维蛋白含量、巯基、羰基含量变化及十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析确定了冰温贮藏0 d、4 d、8 d、12 d、16 d、20 d下海鲈鱼片理化指标变化,并对肌原纤维蛋白生化特性与主要的新鲜度指标进行相关性分析。【结果】结果表明,海鲈鱼片冰温贮藏期间亮度值由57.92±0.66降低至46.62±1.54、红度值由-4.34±0.39降低至-5.21±0.08,硬度值由174.92±16.8显著降低至122.25±15.73(P<0.05),pH呈先降低后增加的趋势,TBA值、TVB-N值随贮藏时间的延长分别由0.35±0.01 mg/kg与9.41±1.03 mg/100 g增加至0.97±0.04 mg/kg与33.18±0.83 mg/100 g,贮藏至第16天时菌落总数达6.35±0.41 log10(CFU/g),已超过二级鲜度标准,且感官分值不可接受。贮藏期间肌原纤维蛋白含量、巯基含量分别由104.21±3.42 mg/g与145.81±1.02 mmol/g prot下降至72.03±5.25 mg/g与137.28±1.29 mmol/g prot,羰基含量由0.63±0.03 nmol/mg增加至1.45±0.06 nmol/mg。SDS-PAGE电泳图谱显示,在30 kDa附近产生新的蛋白条带。相关性分析表明TBA值、菌落总数、蛋白含量与羰基含量之间具有良好的相关性。【结论】研究表明：海鲈鱼片冰温贮藏至第16天时达到不可食用程度,贮藏后期微生物的大量繁殖、脂质氧化与蛋白质氧化间的相互作用可能是品质劣变的主要原因。