Changes in physico-chemical properties and gel-forming ability of lizardfish (Saurida tumbil) during post-mortem storage in ice

Changes in physico-chemical properties and gel-forming ability of lizardfish muscle (Saurida tumbil), stored in ice, were investigated up to 15 days. Heading and eviscerating, prior to iced storage, retarded myosin heavy chain degradation and formaldehyde formation. Additionally, denaturation of myosin and troponin was slightly impeded as monitored by the lower decrease in Ca²⁺-ATPase and lower increase in Mg²⁺–EGTA-ATPase, respectively. Gel-forming ability of surimi, prepared under different setting and/or heating conditions, decreased as storage time increased (P<0.05). However, superior breaking force and deformation of surimi gel, from headed/eviscerated fish, to that from whole fish was observed throughout the storage. Whiteness of surimi gel from headed/eviscerated fish was much higher than that from whole fish, especially when the storage time increased. Therefore, storage time and pretreatment were found to be crucial factors, determining the changes in physico-chemical properties and gel-forming ability of lizardfish during iced storage.     

CHARACTERISTICS OF MUSCLE FROM TWO SPECIES OF BIGEYE SNAPPER, PRIACANTHUS TAYENUS AND PRIACANTHUS MACRACANTHUS

Composition and some properties of muscle from two species of bigeye snapper, P. tayenus and P. macracanthus, were investigated. Both species had a similar composition with the same myofibrillar protein content. However, muscle proteins from P. tayenus had higher thermal stability than those from P. macracanthus, as indicated by the higher enthalpy for transitions as well as the lower inactivation rate constant (K_D). Upon 15 days of iced storage, natural actomyosin Ca^2*‐ATP ase and Mg²⁺‐Ca²⁺‐ATPase activities decreased, whereas Mg²⁺‐EGTA‐ATPase activity increased, suggesting the denaturation of myosin, actomyosin and troponin/tropomyosin complexes, respectively. Increased surface hydrophobicity and decreased sulfhydryl groups indicated the denaturation possibly occurred via hydrophobic interaction and disulfide formation. Heading and eviscerating offish retarded the denaturation and physicochemical changes of proteins during iced storage. The results indicated that a rapid and proper post harvest handling was of importance to maintain the muscle quality of bigeye snapper.     

Effect of iced storage of bigeye snapper (Priacanthus tayenus) on the chemical composition,properties and acceptability of Som-fug,a fermented Thai fish mince

The effect of iced storage of bigeye snapper (Priacanthus tayenus) on the chemical composition, properties and acceptability of Som-fug was investigated. During 15 days of iced storage, total volatile base (TVB), trimethylamine (TMA) and TCA-soluble peptide contents as well as thiobarbituric reactive substances (TBARS) of fish muscle increased continuously after 3 days of storage (p < 0.05). It was suggested that deterioration, protein degradation and lipid oxidation proceeded with increasing storage time. Som-fug prepared from surimi of bigeye snapper stored in ice for different times had similar pH, acidity and lactic acid bacteria count at the end of the fermentation (30 °C, 48 h). Generally, higher content of TCA-soluble peptides and higher TBARS were found in fermented Som-fug produced from bigeye snapper stored in ice for a longer time (p < 0.05). Hardness, adhesiveness, springiness, cohesiveness, and resilience of fermented Som-fug decreased with a concomitant increase in weight loss, released water and expressible water contents when fish kept for a longer time were used (p < 0.05). L^∗, a^∗, b^∗, whiteness and the likeness for appearance, colour, texture and flavour of Som-fug decreased when fish kept in ice for an extended time were used (p < 0.05). However, the taste likeness was not affected by iced storage time (p > 0.05). No differences in overall liking were noticeable when fish kept in ice for up to 12 days were used for Som-fug production (p > 0.05). Therefore, the quality of fish used as raw material should be an important factor in determining the characteristics of Som-fug.     

Transglutaminase-mediated setting in bigeye snapper Surimi

Effect of setting induced by endogenous transglutaminase (TGase) in two species of bigeye snapper, Priacanthus tayenus and Priacanthus macracanthus, on gel properties and protein cross-linking was investigated. Setting at either 25 or 40 °C, prior to heating at 90 °C resulted in the increase in both breaking force and deformation of surimi from both species, particularly when setting time increased (P<0.05). A decrease in solubility of surimi gels in a mixture of sodium dodecyl-sulfate, urea and β-mercaptoethanol suggested increased formation of non-disulfide covalent bonding which coincided with increased gel strength and the decrease in myosin heavy chain (MHC) polypeptide. The optimum conditions for setting of surimi sol was found to be 40 °C for 2 h for P. tayenus and 25 °C for 3 h for P. macracanthus. Assayed by monodancylcadaverine (MDC)-incorporation method, TGase from P. tayenus and P. macracanthus exhibited an optimum temperature at 40 and 25 °C, respectively. In addition, the breaking force and deformation of surimi from both species increased markedly with the addition of calcium chloride, while they decreased considerably in the presence of EDTA, N-methylmaleimide and ammonium chloride. The results confirmed that endogenous transglutaminase played an important role in gel enhancement of surimi from both species of bigeye snapper.     

Effect of Slurry Ice on the Functional Properties of Proteins Related to Quality Loss during Skipjack Tuna (Katsuwonus pelamis) Chilled Storage

The effect of slurry ice on the quality of Skipjack tuna (Katsuwonus pelamis) during chilling storage was investigated and compared to flake ice. Slurry ice‐treated samples showed significantly higher springiness and chewiness variables than the blank and flake ice‐treated samples (P < 0.05). The growth of microorganisms in tuna muscle treated with slurry ice was also down significantly (P < 0.05), and the total aerobic counts didn't reach higher scores than 5.0 log CFU/g during the whole chilling storage. Additionally, the myofibrillar protein, Ca²⁺‐ATPase activity, and total sulfydryl (SH) content in muscle treated with slurry ice were all significantly higher than the blank and flake‐iced samples (P < 0.05). This was probably due to the faster cooling, subzero final‐temperature, and larger heat exchange derived from slurry ice. Standard error of mean and sodium dodecyl sulfate–polyacrylamide gel electrophoresis results also confirmed that slurry ice treatment could effectively retard the degradation of myofibrillar proteins and showed a positive effect on the stability of tissue structures.     

Effects of washing with oxidising agents on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus)

The effects of washing with hydrogen peroxide (H₂O₂) and sodium hypochlorite (NaOCl) solutions on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus), stored in ice for up to 14 days, were investigated. Generally, pH and the trichloroacetic acid (TCA)-soluble peptide content of washed mince varied, depending on the type of oxidizing agent and storage time of the fish. With increasing time of storage, the pHs of water- and H₂O₂-washed mince were lower than that of NaOCl-washed mince (P < 0.05). However, no differences in the TCA-soluble peptide contents of the resulting mince washed with any media were observed (P > 0.05). Washing with 20 ppm NaOCl resulted in the highest increase in both the breaking force and the deformation of mince from fish stored in ice for all the times studied (P < 0.05). Natural actomyosin (NAM) extracted from NaOCl-washed mince had higher surface hydrophobicity and disulfide bond (SS) content than that of water-washed mince (P < 0.05). With no effect on Ca²⁺-, Mg²⁺-, or Mg²⁺–Ca²⁺-ATPase activities, NaOCl washing resulted in an increase in Mg²⁺–EGTA-ATPase activity of NAM (P < 0.05). The results suggested that washing mince with the appropriate type and concentration of oxidizing agent can improve the gelling ability of surimi, particularly from low quality fish.     

Inhibition of quality loss in chilled megrim (Lepidorhombus whiffiagonis) by employing citric and lactic acid icing

This study focuses on the quality retention of megrim (Lepidorhombus whiffiagonis) during chilled storage. Aqueous solutions of two different concentrations of citric (CA) and lactic (LA) acids were employed as icing media (0.125% CA–0.050% LA and 0.175% CA–0.050% LA, respectively; w/v). The effects of each solution on microbial activity, lipid damage and sensory acceptance were monitored for up to 13 days of storage. Lower (P < 0.05) bacterial growth was detected according to microbiological (aerobe and psychrotroph counts) and chemical (trimethylamine‐N and pH) assessments, which led to an enhancement of sensory appreciation. Whereas control fish were determined as unacceptable at day 13, the acid‐iced fish were still acceptable at that time. Concerning lipid damage, an inhibitory effect (P < 0.05) on fluorescent compound formation was observed in the acid‐iced fish. Present results allow to conclude that the use of a CA–LA icing system can provide a profitable strategy to obtain higher quality chilled fish.     

Physicochemical properties, gel-forming ability and myoglobin content of sardine (Sardinella gibbosa) and mackerel (Rastrelliger kanagurta) surimi produced by conventional method and alkaline solubilisation process

Characteristics and gel properties of sardine and mackerel surimi produced by conventional washing process and alkaline solubilising process were investigated. The decrease in Ca²⁺-ATPase activity with the changes in the surface hydrophobicity was found in surimi produced by alkaline solubilising process (p<0.05), suggesting the denaturation of protein induced by this process. The alkal-ine solubilising process with prewashing could remove myoglobin most effectively from sardine muscle, whereas the process without prewashing resulted in the greatest myoglobin removal in mackerel muscle (p<0.05). Surimi conventionally prepared by water or NaCl washing showed the gel with greater breaking force and deformation than that from alkaline solubilising process (p<0.05). The hig-her expressible moisture was found in the gels of surimi pre-pared by alkaline process, indicating the poor water holding capacity of the gel matrix. The highest whiteness was found in the gel of sardine surimi produced by alkaline process with prewashing but the highest whiteness was obtained in the gel of mackerel surimi washed with distilled water.     

Properties of Kamaboko Made From Red Hake (Urophycis chuss) Fillets, Mince, or Surimi

Fresh red hake (Urophycis chuss) was randomly assigned to three treatments: whole fillets, minced flesh, and surimi. These treatments were stored at −5°C for 10 wk and tested for salt-extractable protein, actomyosin, and Ca⁺⁺– ATPase activity prior to the manufacture of Kamaboko. Kamaboko quality was determined by the fold test and percent expressible fluid. Salt-extractable protein, actomyosin, and Ca⁺⁺– ATPase activity all decreased throughout the storage period and were found to be good measures of the ultimate quality of Kamaboko. The data suggest red hake is suitable for the manufacture of surimi which can be stored frozen and subsequently manufactured into an acceptable Kamaboko.     

Comparative study on proteolysis of two species of bigeye snapper,Priacanthus macracanthus and Priacanthus tayenus

Proteolytic activity in muscle from two species of bigeye snapper (Priacanthus macracanthus and Priacanthus tayenus) was studied. Autolysis of mince and washed mince at 50 and 60 °C was compared. Higher degradation of myosin heavy chain was observed in both mince and washed mince from P macracanthus than in those from P tayenus, especially when the incubation time was increased. Autolysis of washed mince from both species was inhibited by soybean trypsin inhibitor, suggesting that myofibril‐associated proteases were serine proteases. When sarcoplasmic proteolytic activity in P macracanthus muscle was studied, two activity peaks with an optimum temperature of 60 °C were observed at pH 6.5 and 8.5. The activities of both peaks were mostly inhibited by soybean trypsin inhibitor, suggesting that the major protease was a serine protease. Major sarcoplasmic proteolytic activity in P macracanthus muscle was found at M_r 62 000 on sodium dodecyl sulphate substrate gel. For P tayenus sarcoplasmic proteolytic activity, two activity peaks with an optimum temperature of 60 °C were found at pH 5.0 and 8.5. The pH 5.0 peak activity was effectively inhibited by pepstatin A, while the pH 8.5 peak activity was inhibited by several inhibitors. The results indicated that various sarcoplasmic proteases were present in P tayenus muscle. The two species contained different sarcoplasmic proteases in terms of composition and activity level. P macracanthus muscle generally had higher sarcoplasmic proteolytic activities than P tayenus muscle. Copyright © 2003 Society of Chemical Industry     

Quality Assessment of Commercially Processed Carbon Monoxide‐Treated Tilapia Fillets

Carbon monoxide (CO) has been used to stabilize the color of fish muscle during frozen storage and distribution. This study compared changes in the quality profiles of CO‐treated and untreated (UT) tilapia fillets stored at 21 to 22 °C (room temperature), 4 to 5 °C (refrigerated), and 0 °C (iced). Samples (n = 3) were analyzed at different time intervals for chemical, lipid oxidation, microbiological, color, and expert sensory profiles. CO samples contained greater (P < 0.05) apparent ammonia and total volatile base nitrogen (TVB‐N) at day 0, with greater (P < 0.05) TVB‐N throughout refrigerated and iced storage. At time 0, peroxide values (POV) and thiobarbituric‐acid‐reactive substances were lower (P < 0.05) for CO samples and continued to have lower trends throughout all storage temperatures. Microbiological analysis at time 0 did not show any differences between UT and CO samples. Redness (a*) color values were greater (P < 0.05) in CO tilapia at time 0; however, treated product showed a more rapid decline in a* throughout all storage temperatures. While expert sensory evaluation showed no statistical differences between UT and CO tilapia at time 0, CO product failed sensory assessment sooner than UT product when stored refrigerated and in ice.     

Color improvement by titanium dioxide and its effect on gelation and texture of proteins recovered from whole fish using isoelectric solubilization/precipitation

Whiteness is a critical attribute for restructured fish products such as surimi seafood. However, the whiteness of gels made from proteins recovered from fish processing by-products or whole fish using isoelectric solubilization/precipitation is poor. The by-products and whole fish contain bones, scales, skin, etc. that affect gel color. Therefore, whiteness needs to be improved if marketable products are to be developed from recovered proteins. The objectives of this study were to determine effects of titanium dioxide (TiO₂) on: (1) color; (2) texture; and (3) viscoelasticity (G′) of gels made from isolated carp proteins and Alaska pollock surimi. Carp proteins were recovered with isoelectric solubilization/precipitation. TiO₂ was added to carp proteins at 0-0.5 g/100 g. TiO₂ was not added to surimi. Due to much higher (P < 0.05) yellowness (b^∗) and lower (P < 0.05) lightness (L^∗), the whiteness of carp gels without TiO₂ was lower (P < 0.05) than surimi gels. TiO₂ at ≥ 0.2 g/100 g resulted in better (P < 0.05) whiteness of carp gels than surimi gels without chalky and artificially white appearance. TiO₂ did not affect texture or viscoelasticity. This research demonstrates that whiteness of restructured fish products based on proteins recovered from whole fish via isoelectric solubilization/precipitation can be similar to the whiteness of surimi seafood.     

Inhibition of frozen storage‐induced oxidation and structural changes in myofibril of common carp (Cyprinus carpio) surimi by cryoprotectant and hydrolysed whey protein addition

The objective of the present study was to evaluate the efficacy of combined cryoprotectants (sucrose + sorbitol) and whey protein isolate (WPI) hydrolysates to inhibit protein oxidation and quality loss in common carp (Cyprinus carpio) surimi during frozen storage at ?25 °C. With increasing storage time, the carbonyl content of myofibrillar proteins increased from 4.02 nmolmg^‐1 protein (0 day) to 7.25, 6.31, 5.26 and 4.83 nmol mg^?1 protein (180 days; P < 0.05) for the control and samples with cryoprotectants, with cryoprotectants + WPI hydrolysates and with cryoprotectants + propyl gallate, respectively; protein surface hydrophobicity and turbidity increased in a similar trend, while sulfhydryl content, Ca‐ATPase activity, protein solubility and protein thermal stability decreased (P < 0.05). These results suggest that treatments with combined cryoprotectants and antioxidative WPI hydrolysates offer an effective approach to reducing the extent of protein oxidation in common carp surimi, thereby limiting protein structural changes known to impair texture of surimi products.     

Effect of microbial transglutaminase on rheological properties of oxidised and non‐oxidised natural actomyosin from two species of bigeye snapper

The contribution of microbial transglutaminase (MTGase) to the thermal gelation of non‐oxidised and oxidised natural actomyosin (NAM) from two species of bigeye snapper was studied by dynamic rheological testing. Under two‐step heating, the addition of MTGase increased the gel‐forming ability of both species. During setting at 40 °C, Priacanthus macracanthus NAM seemed to show higher reactivity to MTGase than P tayenus NAM, resulting in a higher rate and magnitude of G′ development. An increase in final G′ of NAM from P macracanthus and P tayenus by 13.7–24 and 6.6–10.8 times respectively was observed compared with NAM alone. Iron‐catalysed oxidation substantially decreased the gel‐forming ability of P tayenus NAM but enhanced that of P macracanthus NAM. However, oxidation decreased the reactivity of both NAM types to added MTGase. The results suggested that the native NAM structure was essential for MTGase to maximise the setting response. The gel‐forming ability and setting response of denatured NAM were partially recovered by the addition of MTGase. © 2002 Society of Chemical Industry     

Changes in lipids and fishy odour development in skin from Nile tilapia (Oreochromis niloticus) stored in ice

Changes in lipids, lipoxygenase activity and fishy odour development in the skin of Nile tilapia (Oreochromis niloticus) during iced storage of 18 days were monitored. Triacylglycerol content of skin decreased with coincidental increases in free fatty acid, monoacylglycerol, diacylglycerol and phospholipid contents during storage (p < 0.05). During iced storage, peroxide value increased at day 9 and subsequently decreased up to 18 days (p < 0.05). Thiobarbituric acid reactive substances values and lipoxygenase activity increased throughout 18 days of iced storage (p < 0.05). With increasing storage time, a progressive formation of hydroperoxide was found as evidenced by the increase in amplitude of peak at 3600–3200 cm⁻¹ in Fourier transform infrared spectra. Those changes indicated that lipid oxidation took place during iced storage. The increase in fishy odour of skin was observed as the storage time increased. The development of fishy odour in Nile tilapia skin during iced storage was mostly governed by lipid oxidation via autoxidation or induced by lipoxygenase. Thus, the extended storage time of whole fish resulted in the pronounced changes in lipids and the increased fishy odour in the skin.     

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).     

Changes of lipids in sardine (Sardinella gibbosa) muscle during iced storage

Changes in lipids of sardine (Sardinella gibbosa) muscle during 15 days of iced storage were investigated. Lipid deterioration, lipolysis and lipid oxidation, occurred throughout the storage. The progressive peroxide formation was monitored by the increase in the absorbance band at 3600–3200 cm⁻¹ in Fourier transform infrared (FTIR) spectra and increased peroxide values were observed in sardine muscle up to 6 days of iced storage, followed by a continuous decrease from then for 9 days (P < 0.05). The increase in thiobarbituric acid reactive substances (TBARS) was noticeable throughout the iced storage (P < 0.05). However, no difference in conjugated diene (CD) of sardine muscle was found within the first 12 days of iced storage (P > 0.05). Marked decreases in unsaturated fatty acids, especially eicosapentaenoic acid (EPA; C20:5(n − 3)) and docosahexaenoic acid (DHA; C22:6(n − 3)) were observed as the storage time increased. Those changes indicated that lipid oxidation occurred in sardine muscle. A gradual increase in free fatty acid formation, with decreases in triglyceride and phospholipid contents, was found during iced storage (P < 0.05), suggesting hydrolysis induced by lipases and phospholipases.     

Comparison of the Cryoprotective Effects of Trehalose,Alginate, and Its Oligosaccharides on Peeled Shrimp (Litopenaeus Vannamei) During Frozen Storage

The cryoprotective effects of trehalose, alginate, and its oligosaccharides on peeled shrimp (Litopenaeus vannamei) during frozen storage was investigated by monitoring thawing loss, color, texture, myofibrillar protein content, Ca²⁺‐ATPase activity, and performing microscopic structural analysis. Data revealed significant (p < 0.05) inhibitory effects on thawing loss and textural variables (springiness and chewiness) in trehalose‐, alginate oligosaccharides‐, and sodium pyrophosphate‐treated shrimp compared with the control and alginate‐treated batches. L* values revealed that these saccharides had a positive effect on color stability during frozen storage. In addition, the results of chemical analyses showed that trehalose and alginate oligosaccharide treatments effectively maintained an increased myofibrillar protein content and Ca²⁺‐ATPase activity in frozen shrimp. In addition, hematoxylin & eosin staining and SDS‐PAGE confirmed that these cryoprotective saccharides slowed the degradation of muscle proteins and the damage to muscle tissue structures. Overall, the application of trehalose and alginate oligosaccharides to peeled frozen shrimp might maintain better quality and extend the commercialization of these refrigerated products.     

Extraction and characterisation of pepsin‐solubilised collagens from the skin of bigeye snapper (Priacanthus tayenus and Priacanthus macracanthus)

BACKGROUND: Fish collagen has been paid increasing attention as an alternative to the mammalian counterpart owing to the abundance of fish skin as a processing by‐product. Generally, the low yield of collagen extracted using the typical acid solubilisation process has led to the use of mammalian pepsin as an aid for increasing the yield. Alternatively, fish pepsin, especially from tuna stomach, can be used for the extraction of pepsin‐solubilised collagen (PSC). Therefore the objective of this study was to extract and characterise PSC from the skin of bigeye snapper, a fish widely used for surimi production in Thailand. RESULTS: PSCs from the skin of two species of bigeye snapper, Priacanthus tayenus and Priacanthus macracanthus, were extracted with the aid of tongol tuna (Thunnus tonggol) pepsin and porcine pepsin. PSCs from the skin of both species extracted using porcine pepsin had a higher content of β‐chain but a lower content of α‐chains compared with those extracted using tuna pepsin. All PSCs contained glycine as the major amino acid and had an imino acid (proline and hydroxyproline) content of 189–193 residues per 1000 residues. Transition temperatures of PSCs were in the range 30.6–31.3 °C. Fourier transform infrared spectra revealed some differences in molecular order between PSCs extracted using porcine pepsin and tuna pepsin. Nevertheless, the triple‐helical structure of PSCs was not affected by pepsin digestion. Zeta potential analysis indicated that PSCs from P. tayens and P. macracanthus possessed zero net charge at pH 7.15–7.46 and 5.97–6.44 respectively. CONCLUSION: Tongol tuna pepsin could be used as a replacement for mammalian pepsin in PSC extraction. However, a slight difference in PSC properties was found. Copyright © 2009 Society of Chemical Industry     

Effect of medium temperature setting on gelling characteristics of surimi from some tropical fish

Effects of setting at 25 °C on textural properties and cross-linking of myofibrillar proteins in surimi produced from threadfin bream (Nemipterus bleekeri), bigeye snapper (Priacanthus tayenus), barracuda (Sphyraena jello) and bigeye croaker (Pennahai macrophthalmus) were investigated. Increase in setting time (0–8 h) resulted in a higher breaking force and deformation for all surimi gels tested (P<0.05). Increased gel strength was associated with increase in non-disulfide bond formation and decreased heavy chain myosin. Proteins underwent degradation during setting; however polymerization occurred to a much higher extent, leading to a strengthened gel matrix. Therefore, setting at 25 °C, for an appropriate time, should be a promising means to improve gelling properties of surimi produced from tropical fish.