Quality Improvement of Mackerel Surimi with NADPH-Sulfite Reductase from Escherichia coli

The application of NADPH‐sulfite reductase, produced from Escherichia coli, on mackerel surimi was investigated. The activity of this reductase was very stable. There was about 70%, 80%, and 90% activity left even after 8–wk storage at 25 °C and 12–wk storage at 4 or ‐30 °C, respectively. Increase in mackerel‐surimi gel properties containing reductase was consistent with the amounts of reactive sulfhydryl groups detected. SDS‐PAGE indicated that NADPH‐sulfite reductase could reconstitute myosin heavy‐chain and increase soluble actomyosin. From the data obtained, E. coli NADPH‐sulfite reductase effectively improved the gel properties of mackerel surimi.     

Functionality Changes in Oxidatively/Antioxidatively Washed Beef-Heart Surimi During Frozen Storage

Beef‐heart surimi prepared using 4 washing solutions (sodium phosphate buffer alone, buffer+NaCl, buffer+propyl gallate, and buffer+sodium tripolyphosphate) and mixed with cryoprotectants was stored at 29°C and analyzed periodically up to 12 mo. All samples showed increases in gelling capacity during storage, corresponding to oxidative changes in proteins (carbonyls, hydrophobicity). Emulsifying activity of surimi, however, did not change during storage. No major differences were found between washing conditions, but propyl gallate‐washed surimi tended to have the least oxidation and least increase in gel elasticity. Overall, frozen storage not only preserved the shelf life but also enhanced gelation of beef‐heart surimi washed with these solutions.     

Effect of microbial transglutaminase on autolysis and gelation of lizardfish surimi

In the absence of microbial transglutaminase (MTGase), the textural properties of lizardfish surimi (Saurida spp) improved when pre‐incubated at 4 and 25 °C for 24 and 4 h, respectively. MTGase optimally catalyzed incorporation of monodansylcadaverine (MDC) into surimi at 40 °C. Addition of MTGase appeared to reduce autolytic activity at 25 and 40 °C, but had no effect on autolytic activity at 65 °C. Breaking force and deformation of lizardfish surimi significantly improved when 0.1 unit MTGase g^?1 surimi (1.8 g kg^?1) was added and pre‐incubated at either 25 or 40 °C. Textural properties improved concomitant with cross‐linked polymers of myosin heavy chain and tropomyosin, but not actin. Addition of MTGase also improved the storage modulus (G′). The gel network of surimi mixed with MTGase and pre‐incubated at 40 °C readily formed during the pre‐incubation period, while formation of the gel network began at 48.1 °C in the absence of MTGase. Copyright © 2005 Society of Chemical Industry     

Original article: Gel properties of red tilapia surimi: effects of setting condition,fish freshness and frozen storage

This study aimed to determine effects of setting condition, fish freshness and storage time of frozen surimi on properties of red tilapia surimi gel. To investigate the effect of setting condition, a combination of eight setting temperatures (35–70 °C) and four setting times (30–120 min) was used. Maximum breaking force, deformation and gel strength were obtained after the gel had been set at 40 °C for 90 or 120 min. Setting at 65 °C resulted in the lowest obtained gel strength, because of proteolytic degradation of myosin heavy chain. Increasing storage time of raw fish material in ice caused a significant decrease in gel strength of the resultant surimi gel (P < 0.05). Gels produced from surimi kept in frozen storage for up to 9 months also exhibited reduced gel strength, with a concomitant increase in the expressible drip, with increasing storage time (P < 0.05).     

Extractability and thermal stability of frozen hake (Merluccius merluccius) fillets stored at −10 and −30 °C

The relationship between thermal stability changes and functionality loss was monitored in hake muscle fillets stored for 40 weeks at ?10 and ?30 °C. The evolution of changes in apparent viscosity, dimethylamine formation and extractability of muscle proteins in NaCl, sodium dodecyl sulphate (SDS) or SDS plus mercaptoethanol showed drastic differences as a function of temperature. At the higher storage temperature, both myosin heavy chain and collagen were the most severely unextracted in salt and SDS solutions, with actin becoming unextractable at the end of storage. Differential scanning calorimetry showed differences with storage time and temperature in both onset temperature and thermal denaturation enthalpy, mostly affecting the myosin transitions. Some protein denaturation occurred with little or no functionality loss. A considerably high fraction of hake muscle proteins remained in the native‐like condition even at the higher frozen storage temperature. In these conditions both apparent viscosity and myosin and actin extractability in NaCl were very low. © 2002 Society of Chemical Industry     

海藻糖、乳酸钠对冻藏鳙鱼鱼糜蛋白抗冻效果的影响

以凝胶强度、盐溶性蛋白含量、Ca~(2+)-ATPase活性、总巯基、表面疏水性为指标并结合DSC分析(差示扫描量热分析),研究了海藻糖、乳酸钠在8%(w/w)水平上对鳙鱼鱼糜蛋白在-18℃冻藏24周的抗冻效果,并将其抗冻效果与传统商业抗冻剂(4%蔗糖+4%山梨糖醇)进行了对比。结果表明,海藻糖、乳酸钠的加入能较好地抑制冻藏鳙鱼鱼糜蛋白的冷冻变性,表现在这2种物质加入后,冻藏鳙鱼鱼糜的凝胶能力得到较好的维持,盐溶性蛋白含量、Ca~(2+)-ATPase活性和巯基含量的下降及表面疏水性的增加也得到很好的抑制,2种物质的抗冻效果比传统商业抗冻剂具有明显的优势。DSC分析表明,抗冻剂的添加可能改变了鳙鱼鱼糜肌球蛋白的结构,使其变得更稳定,从而表现出较好的冻藏稳定性。海藻糖、乳酸钠都属于低甜度、低热值物质,因此在鱼糜加工业中有望成为传统商业抗冻剂的替代物。     

Elucidation of protein aggregation in frozen cod and haddock by transmission electron microscopy/immunocytochemistry,light microscopy and atomic force microscopy

Polyclonal antibodies raised to both native cod myosin and actin as well as to aggregated proteins obtained from frozen cod stored for 11 months at ?10 °C were used to investigate disposition of muscle proteins in frozen cod and haddock fillets by transmission electron microscopy. Specimens from cod and haddock fillets, stored at ?10 °C, treated with anti‐aggregate antibody as the primary antibody, showed significantly more gold particles, especially around the protein aggregates and muscle fibres compared with fish stored at ?30 °C. Samples that were treated with anti‐myosin or anti‐actin antibody showed opposite results. Similar binding properties were observed in ELISA experiments involving the reaction of actin and myosin to both native and aggregate antibodies; thus immunological tests can be used for monitoring aggregate and texture changes in frozen stored fish. In addition, atomic force microscopy images obtained from cod muscle also indicated structural changes in frozen cod muscle proteins. The mica surface was covered with a continuous layer of muscle proteins comprising mainly small globular particles and a few large particles for the control cod sample stored at ?30 °C for 11 months. In contrast, cod fillets stored at ?10 °C showed a thin layer of proteins with small holes and an increased number of large particles denoting aggregates. Formation of ice crystals between the muscle fibres of frozen cod and haddock muscle was monitored without thawing by light microscopy at ?20 °C. The micrographs showed a greater proportion of large ice crystals and extensive protein fibre changes in fillets stored at ?10 °C compared with the control at ?30 °C. Copyright © 2004 Society of Chemical Industry     

Cathepsin Degradation of Pacific Whiting Surimi Proteins

Cathepsin B was the most active cysteine protease in Pacific whiting fish fillets; cathepsin L was predominant in surimi. Cathepsin L showed highest activity at 55°C in both fish fillets and surimi, indicating its function in myosin degradation during conventional heating of fillets and surimi, gels. Washing during surimi processing removed cathepsin B and H but not cathepsin L. Myosin heavy chain was the primary substrate during autolysis of surimi paste and actin and myosin light chain showed limited hydrolysis during 2 hr incubation. Purified Pacific whiting cathepsin L hydrolyzed myofibrils, myosin and native and heat-denatured collagen. The degradation pattern of myofibrils by the protease was the same as the autolytic pattern of surimi.     

Heat-Induced Gelation Properties of Surimi From Mechanically Separated Chicken

Chicken surimi was prepared from fresh mechanically separated chicken meat using a sodium bicarbonate washing process. The heat-induced gelation properties were assessed under different conditions of pH, temperature, heating rate, protein and sodium tripolyphosphate (TPP) concentrations. Surimi gel strength increased (p < 0.05) after: reducing pH from 6.4 to 6.0, increasing temperature from 40°C to 80°C, reducing heating rate from 5°C/min to 1°C/min, increasing protein concentration from 4% (w/w) to 8% (w/w) or addition of 0.3% (w/w) TPP. Freeze thaw stability studies revealed that the gel strength of surimi decreased (p < 0.05) when subjected to frozen storage at – 18°C.     

The change of thermal gelation properties of horse mackerel mince led by protein denaturation occurring in frozen storage and consequential air floatation wash

This study investigated the protein deformation of horse mackerel muscle after frozen storage and consequential air-floatation wash (AFW) and its effect on thermal gelation property change. As frozen storage period of whole fish increased, the rigidity and gel strength of surimi products decrease, and longer washing time was needed for surimi products to gel. The reactive sulfhydryl group decreased with frozen storage time but increased with AFW time. Moreover, the addition of reducing agent (NaHSO₃), which was able to reduce disulfide bond, could effectively improve the gelling ability of surimi made of the muscle with long term frozen storage but not significantly of the one made of unfrozen AFW treated mince. The chemical bonding behavior and the thermal analysis results indicated that the myosin rod was unfolded after AFW to interact with other protein, unlike the effect of frozen storage which resulted in denaturation and oxidative disulfide bond formation.     

Proteinase inhibitory activity of sarcoplasmic proteins from threadfin bream (Nemipterus spp.)

BACKGROUND: Thailand is the second largest surimi producer in the world and 50% of surimi is produced from threadfin bream. During surimi processing, sarcoplasmic proteins are removed through water washing and discarded in the waste stream. This study was aimed at investigating the proteinase inhibitory activity of sarcoplasmic proteins. RESULTS: Sarcoplasmic proteins from threadfin bream (TBSP) exhibited inhibitory activity toward trypsin but did not inhibit papain and chymotrypsin. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis under non‐reducing condition stained by trypsin inhibitory activity revealed three protein bands of molecular mass of 95, 41 and 37 kDa. Inhibitory activity of TBSP reached a maximum when subjected to 45 °C and completely disappeared at 60 °C. The breaking force and deformation of lizardfish surimi gel with added TBSP and pre‐incubated at 37° for 20 min increased with additional levels of TBSP (P < 0.05). Trichloroacetic acid–oligopeptide content of lizardfish surimi gel with added TBSP decreased with the addition of 4 g kg^?1 TBSP (P < 0.05). Retention of myosin heavy chain (MHC) increased when TBSP concentration was increased. TBSP effectively protected MHC from proteolysis at 37 °C to a similar extent as egg white powder, but efficacy of TBSP was not observed at 65 °C. CONCLUSION: TBSP could be applied to reduce proteolytic degradation of lizardfish surimi or other surimi associated with trypsin‐like proteinase, rendering an improvement in surimi gelation set at 37–40 °C. Copyright © 2009 Society of Chemical Industry     

Thermal Effects on Fast Skeletal Myosins from Alaska Pollock, White Croaker, and Rabbit in Relation to Gel Formation

Thermodynamic properties in differential scanning calorimetry (DSC) and changes in viscoelasticity upon heating of myosins from white croaker, Alaska pollock, and rabbit fast muscles were investigated in relation to their thermal gel formation abilities. Alaska pollock myosin unfolded in a wide temperature range of 19 to 69°C as revealed by DSC, whereas rabbit myosin unfolded in very narrow range of 32 to 56°C. Thermal unfolding of white croaker myosin occurred in an intermediate temperature range of 30 to 60°C. Viscoelastic properties determined as storage modulus, G′, and loss modulus, G″, reflected differences observed in DSC for the 3 myosins.     

Determining Washing Conditions During the Preparation of Frozen Surimi from Surubí (Pseudoplatystome Coruscans) Using Response Surface Methodology

The effect of process temperature (2 to 18 °C), time (1 to 7 min/ cycle), and water‐mince ratio (2:1 to 8:1) on the quality attributes of surubí (Pseudoplatystoma coruscans) surimi was studied using Response Surface Methodology (RSM). Conditions were identified that allowed to achieve 25% of extracted proteins and a moisture content of 79%, compatible with an acceptable quality of surimi gel. The verification of the prediction models was acceptable. Two cryoprotectant mixtures (sucrose‐sorbitol and maltodextrin‐sorbitol) were also evaluated, with regard to the freezing and frozen storage and the functional quality of the gels. Freezing proved to be an aggressive method, and the 2 mixtures tested showed to be efficient for 6 months of frozen storage.     

Effect of harvesting stress and storage conditions on protein degradation in fillets of farmed gilthead seabream (Sparus aurata): A differential scanning calorimetry study

A trial was undertaken to evaluate Differential Scanning Calorimetry (DSC) as a fast analytical tool to differentiate gilthead seabream subjected to variable conditions of slaughter stress and post-mortem storage. Fish were subjected to different harvesting stress conditions: profound anaesthesia (PA, low stress) and net crowding (NC, high stress). Fish were slaughtered in an ice-salt water slurry, and subsequently stored on ice (7 days). Additional NC fish were frozen (−20 °C) and subjected to a freeze–thaw cycle. Dorsal muscle was assessed for cathepsins activity, liquid loss and DSC analysis. It is demonstrated that DSC analysis is capable of differentiating fresh, frozen and thawed-re-frozen fish, while liquid loss and cathepsin B activity are good markers to distinguish fresh from frozen fish. Harvesting stress had little effect on myosin and actin enthalpy transitions, as observed by DSC at 49 and 74 °C, respectively, but a lower ΔH actin/myosin ratio was found in PA fish, suggesting that intense exercise prior to slaughter promoted partial denaturation of muscle myosin.     

Oxidative Stability and Sensory Attributes of Prerigor Cooked Beef Steak

Beef sirloin tip steaks from 12 steer carcasses were cooked prerigor and postrigor using three heating methods and stored at 4 °C or ‐20 °C. Prerigor cooked steak had lower cook loss, higher pH, higher shear force, and sensory hardness than postrigor cooked steak. Conventional oven cooking produced the lowest cook loss for prerigor steak. Prerigor cooked steak had lower thiobarbituric acid value than postrigor cooked samples after 2 wks at 4 °C or 3 mo at ‐20 °C. Sensory warmed‐over flavor intensity scores were low and showed no differences between prerigor and postrigor cooked steaks for refrigerated or frozen samples.     

Assessment of protein changes in farmed giant catfish (Pangasianodon gigas) muscles during refrigerated storage

Farmed giant catfish (Pangasianodon gigas) muscles (dorsal and ventral sites) were stored in a refrigerator (at 4 °C) for 14 days to determine the effect of refrigerated storage on biochemical and physical changes. The analyses were carried out at 0, 2, 4, 7, 10 and 14 days of storage. At day 14, Ca²⁺ ‐ATPase activity markedly decreased when compared to its value at day 1 (>90%), while a small decrease was observed for surface hydrophobicity and reactive sulfhydryls content. Total volatile basic nitrogen and trichloroacetic‐soluble peptide content gradually increased when the storage period was extended. The myosin heavy chain decreased slightly on SDS‐PAGE for both meat cuts with increased storage time. Expressible drip and cooking loss were highest during the first day of storage and slightly decreased with storage time. Instrumental hardness was significantly higher in the ventral compared to the dorsal muscle, while the toughness was the highest at the second day of storage. The muscle bundles with scanning electron microscopy were less attached, resulting in the observed big gaps over increasing storage time. Results indicated that changes of proteins have detrimental effects on the quality attributes of farmed giant catfish muscles during refrigerated storage, particularly physical and biochemical properties.     

CHANGES IN PROXIMATE COMPOSITION OF THORNBACK RAY (RAJA CLAVATA, L. 1758) SURIMI DURING WASHING AND FROZEN STORAGE

The effects of frozen storage of surimi produced from thornback ray and the washing of mince on the chemical composition were investigated. The crude ash content which was initially found as 1.38% in raw thornback ray decreased approximately 12 and 80% after the first and second washing, respectively. After the third washing, crude ash content increased to 207% of the amount in the second washing because of addition of salt to the last washing water. The crude protein content of mince also decreased approximately to 28 and 20% after the first and second washing, respectively. After the third washing, the decrease in the lipid levels was approximately 30%. At the end of 6 months of frozen storage at − 23.8  ±  2C, dry matter, crude ash and crude protein contents increased in a greater ratio in surimi containing 4% sorbitol, 4% sucrose and 0.3% Na-tripolyphosphate than surimi prepared with 8% sorbitol and 0.3% Na-tripolyphosphate.

PRACTICAL APPLICATIONS

In the present study, the effects of frozen storage of surimi produced from thornback ray and the washing of mince on the chemical composition were investigated. Washing procedure significantly decreased crude ash, crude protein and crude fat content of mince. There were significant differences in moisture, crude ash, and crude protein contents during the 6 months storage period of frozen surimi obtained by using different cryoprotectant mixtures. The folding test scores were highest in fresh surimi and during the first two months of storage. Thornback ray can be used for the production of surimi.     

Gelation process in two different squid (Dosidicus gigas) surimis throughout frozen storage as affected by several cryoprotectants: Thermal, mechanical and dynamic rheological properties

Differential scanning calorimetry (DSC) was used to follow the thermal denaturation of two differently processed surimis from giant squid (Dosidicus gigas), A (isoelectric precipitation) and B (acid washing). Both surimis were added with several cryoprotectants (sucrose, sorbitol and trehalose), and kept in frozen storage at −15 °C for 6 months. DSC profiles and transition enthalpies showed that protein quality was better in B than in A surimis whether fresh or frozen. It was also demonstrated that the sucrose-plus-sorbitol mixture and trehalose were the most efficient for preserving B and A type formulations respectively after frozen storage. Mechanical (puncture), small amplitude oscillatory (SAOS) and dynamic-mechanical thermoanalyses were performed on both gels from A and B series surimis throughout frozen storage. Gels from surimi A (GA) were considerably brittler than gels from surimi B (GB) and presented significantly lower strain amplitudes. Several correlations among different experimental data have been developed.     

Quality change in Bombay duck (Harpadon nehereus) surimi during frozen storage using different freezing methods

To inhibit the quality deterioration caused by the frozen storage of surimi products, this work investigated the effect of freezing methods, including raw-freezing-setting-heating, raw-setting-freezing-heating, and raw-setting-heating-freezing, on quality changes in surimi gel. The moisture loss, physical–chemical properties, and protein structure conformation of surimi gel derived from Bombay duck (BD) were assessed following frozen storage periods of 20, 40, and 60 days. The findings suggest that the raw-setting-heating-freezing method yielded optimal surimi gel properties with extended frozen storage time. Employing this approach led to a reduction in thawing loss, while cooking loss remained constant. After 60 days of frozen storage, the hardness exhibited an initial increase followed by a subsequent decrease, and water-holding capacity increased to 68.2%. Notably, the impact on surimi gel during the late stage of frozen storage was more pronounced throughout the formation of ice crystals, resulting in decreased disulfide bond content. Scanning hematoxylin–eosin (HE) staining slices of samples following thawing and heating demonstrated that the raw-setting-heating-freezing method could better resist the effect of ice crystals in frozen storage period on surimi tissue, while the gel on setting process could delay the erosion imposed on by ice crystals during frozen storage. This study provides a scientific foundation for the industrialization on frozen BD surimi products.     

Temperature conditions for the frozen storage of representative marine products in Japan

Abstract

Four representative seafoods in Japan were examined for quality changes during frozen storage up to 1 year, and reasonable temperature conditions for their frozen storage were determined.

Tuna meat was stored at ‐20 ～ ‐80°C for 1 year and its quality changes were followed by using parameters such as the metmyoglobin to total myoglobin ratio, water‐holding capacity, and pH. Ikura, a salted product of salmon eggs, was stored frozen. Quality changes were followed by using the following parameters: toughness of the egg membrane, carotenoid content, and TBA value. Surimi, meat paste from Alaska pollack, was kept frozen, and the quality changes were followed by analyzing protein composition, SDS‐gel electrophoretic and ultracentrifugal patterns, and the gel strength of kamaboko processed therefrom. Finally, prawn was stored frozen. At selected time intervals, the meat was analyzed for changes in water‐holding capacity, pH, tyrosine content, protein composition, and SDS‐gel electrophoretic pattern.

From the present experiments, it was concluded that ‐20°C is low enough for frozen storage to keep the quality unchanged for 2–3 months, irrespective of the types of seafood tested. In frozen storage for 1 year, however, lower temperatures are needed to maintain the quality. Temperatures between ‐30 and ‐40°C seemed to be more reasonable from the viewpoint of energy saving.