Application of recombinant chum salmon cystatin to Alaska pollock (Theragra chalcogramma) surimi to prevent gel weakening

ABSTRACT:  Recombinant chum salmon cystatin (RC) expressed in Saccharomyces cerevisiae was purified by His-select nickel affinity chromatography. The specific inhibitory activities of RC against papain and cathepsin L were 7.45 and 10.24 U/mg, respectively. RC was stable over pH 5.0 to 7.0 and at temperature below 65 °C. RC was used to prevent the gel weakening of Alaska pollock surimi. RC at 100 μg/g showed the highest inhibitory activity against the autolysis of surimi based on the analysis of TCA-soluble peptides. As the concentration of RC increased, both the breaking force and deformation of modori gel greatly increased ( P < 0.05). The addition of RC resulted in less expressible drip, which coincided with the increase of whiteness. More myosin heavy chain (MHC) was retained as the addition of RC increased. Therefore, RC could prevent the degradation of proteins in Alaska pollock surimi and was better than egg white (EW). Thus, RC could be applied to Alaska pollock surimi to prevent gel weakening and RC at 100 μg/g was the optimal concentration.     

USE OF CYSTEINE PROTEINASE INHIBITORS FROM INJURED TOMATO LEAVES IN WHITING SURIMI

Cooking surimi paste from Pacific whiting results in a gel with poor texture due mainly to myosin degradation caused by a cysteine proteinase. Cysteine and serine proteinase inhibitors were isolated from injured and methyl jasmonate treated tomato leaves. Tomato cysteine proteinase inhibitor was stable at 60C but inactivated at 90C, making it suitable for use in surimi. Tomato proteinase inhibitors (TPI), having 7.9 papain inhibitor units, inhibited autolysis about 95% in 10 g of Pacific whiting surimi. Gel strength of Pacific whiting surimi was improved by adding only 0.0 27% of TPI to the surimi formulation. Addition of TPI did not affect the color of whiting surimi gel, while egg white needed to prevent gel weakening caused the gels to have more yellow hue (P<0.05). SDS-PAGE showed that myofibrillar protein degradation was prevented during cooking when 0.027% of TPI was included in the surimi. TPI extracted from tomato plants has potential for use as food grade additive in Pacific whiting surimi.     

Qualification and quantification of fish protein in prepared surimi crabstick

ABSTRACT:  Species identification and protein quantification in surimi crabstick were achieved using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). When the Lowry and Kjeldahl protein determination methods were compared, the former showed more consistent results. Densitometric scanning of the gels was used for quantification of total fish protein as well as total egg white protein. The lower molecular weight proteins, 30 kDa and lower, proved to be the most useful in fish species identification as well as egg white protein addition. Using a combination of the myosin heavy chain band and the species-specific myosin light chain (Alaska pollock: 22.5 kDa; Pacific whiting: 24.4 kDa) proved the most accurate in calculating fish protein content of the crabstick sample, while for those samples that contained egg white, quantification was accomplished from the densitometric analysis of the overlapping bands of actin (45 kDa) from fish and ovalbumin from egg white. Lysozyme (14.3 kDa) proved to be a unique protein band in determining the presence of egg white when the content of dried egg white was equal to or exceeded 0.5% of the total weight of the final crabstick.     

Gelation of Surimi by High Hydrostatic Pressure

The effects of high hydrostatic pressure (HHP) on gel strength of Pacific whiting and Alaska pollock surimi were determined by torsion. Pacific whiting gels were made with and without 1% beef plasma protein (BPP) as protease inhibitor. HHP treated whiting (1% BPP added) and pollock gels showed greatly increased strain values at all pressure/temperature combinations compared with heat-set controls. Stress values for the same samples were variable depending on treatment and species. A three-fold increase in strain and stress was found for HHP treated whiting gels made without inhibitor.     

Optimum chopping conditions for Alaska pollock, Pacific whiting, and threadfin bream surimi paste and gel based on rheological and Raman spectroscopic analysis

Rheological and Raman spectroscopic properties of surimi from three species [Alaska pollock (AP) (cold water), Pacific whiting (temperate water), and threadfin bream (warm water)] were investigated as affected by various chopping conditions. Comminuting Alaska pollock surimi at 0 °C demonstrated superior gel hardness and cohesiveness when chopping time was extended to 15-18 min; however, long chopping time at higher temperatures resulted in a significantly decreased gel texture particularly at 20 °C. Warm water fish threadfin bream exhibited higher gel texture when chopping was done longer at higher temperature. Rheological properties were significantly affected by both chopping time and temperature. Species effect, based on their thermal stability, was readily apparent. Raman spectroscopy revealed a significant change in disulfide linkage and the reduction of secondary structure upon extended chopping. Dynamic oscillation rheology demonstrated the damage of light meromyoisn and lowering of onset of gelling temperature as the chopping time was extended. PRACTICAL APPLICATION: Chopping conditions to determine gel quality and manufacture surimi seafood are varied by all manufacturers. This paper covering three primary species for surimi with their suggested optimum chopping conditions: 15 min for Alaska pollock when chopped at 0 °C, 15 min for Pacific whiting at 15-20 °C, and 18 min for threadfin bream at 25-30 °C. The use of optimum chopping condition should maximize the value of each surimi and provide consistent quality to the end users.     

Biochemical characterisation of Alaska pollock,Pacific whiting,and threadfin bream surimi as affected by comminution conditions

Salt-soluble protein, surface reactive sulfhydryl content, and surface hydrophobicity of Alaska pollock, Pacific whiting, and threadfin bream surimi were characterised, as affected by various comminution conditions. Chopping time/temperatures were explored in consideration of their habitat temperatures. Salt-soluble protein (SSP) significantly decreased when chopping time was extended. Corresponding to our follow-up study, no relationship between SSP and gel texture was found. Surface hydrophobicity was inversely proportional to SSP concentration, indicating the unfolding of protein upon comminution. Alaska pollock surimi demonstrated aggregation during chopping at 10 and 20 °C, based on the surface hydrophobicity. Surface reactive sulfhydryl (SRSH) contents of the three fish species behaved differently. The SH groups were oxidized to disulphide bonds when higher chopping temperature was applied. As a result, increased SRSH content was not observed in Alaska pollock (10 and 20 °C chopping) and threadfin bream paste (25 and 30 °C chopping).     

EFFECT OF PACIFIC WHITING WASH WATER PROTEINS ON ALASKA POLLACK SURIMI GELS

The objective of this work was to evaluate the effect of adding insoluble proteins recovered from Pacific whiting surimi wash water (SWW) on the mechanical and functional properties of Alaska pollack surimi gels. Insoluble proteins from Pacific whiting SWW were added at 0 (control), 10, 30 or 50 g/kg into Alaska pollack grade FA surimi. Changes on mechanical properties, expressible water ( EW ) and color attributes were evaluated in pastes and gels. Results obtained showed that texture profile analysis, puncture test and EW parameters increased significantly by increasing the amount of insoluble proteins added. Although slight changes in color attributes were detected, all surimi gels remained in the same color zone. The results obtained suggest that insoluble proteins from Pacific whiting SWW could be used to improve the mechanical properties of Alaska pollack grade FA surimi gels with a minimum effect on color.

PRACTICAL APPLICATIONS

Insoluble proteins recovered from surimi wash water (SWW) of Pacific whiting added at 10–50 g/kg to Alaska pollack surimi showed no adverse effects on their textural properties (hardness, fracturability, springiness and chewiness) and slight changes on color attributes. The results obtained suggest that it is feasible the use of insoluble proteins recovered from SWW of Pacific whiting in Alaska pollack surimi. Therefore, a double target is obtained: the preservation of environment and an increase in the yield of surimi processing without negative effects on texture.     

Yield and Composition of Surimi from Pacific Whiting (Merluccius productus) and the Effect of Various Protein Additives on Gel Strength

Based on round fish weight, the yields from processing Pacific whiting into surimi included 43.3% planks, 36.2% minced flesh, 23.8% washed and pressed flesh, 19.5% refined flesh and 21.4% surimi (91.7% refined flesh plus 8.3% cryoprotectants). After washing (3:1; watenminced flesh) and pressing twice, 40.6% of the original lipid and 77.4% of the original ash were removed from the minced flesh. Surimi contained 54% extractable myofibrillar protein. Egg white (EW), whey protein concentrate and soy protein isolate at 0 to 5.0% levels were evaluated as protein additives to heat-set gels. EW, at the 3.0% level produced superior gel hardness and elasticity (P≤0.05).     

Protease Inhibitor Effects on Torsion Measurements and Autolysis of Pacific Whiting Surimi

Beef plasma protein (BPP), egg white and potato extract were tested for their ability to inhibit proteolysis in fish mince and surimi made from Pacific whiting (Merluccius productus). Strong inhibition resulted from all three compounds in fish mince when measured by autolysis. However, when tested in surimi significant differences occurred among the compounds. BPP showed strongest inhibition of proteolytic effect followed by egg white and potato extract when measured by autolysis, gel electrophoresis and torsion. BPP was an effective inhibitor in surimi at a concentration as low as 1%.     

TEMPERATURE-TOLERANT FISH PROTEIN GELS USING KONJAC FLOUR

Shear stress and strain values of surimi gels made from Alaska pollock and Pacific whiting were measured upon cooling, reheating, and freeze/thawing. Konjac flour was introduced to investigate its ability to maintain fracture properties of surimi gels against various temperatures. Gel colors (CIE L*,a*,b*) were also measured as affected by various levels of konjac flour. Konjac flour (5%) showed its ability to reinforce shear stress of gels 8-10 times in both whiting and pollock surimi. Gels with 4% konjac flour were the most heat-tolerant in both surimi. Surimi gels with konjac flour exhibited an ability to maintain consistent shear strain values against repeated freeze/thaw abuse. Konjac flour, up to 2%, increased lightness of gels, while yellow hue increased gradually up to 5%.     

Assessment of Added Protein/Starch on the Functional Properties of Surimi Gels Manufactured from Atlantic Whiting

ABSTRACT: The functional properties (hardness, cohesiveness, color, and whiteness) of 5 food ingredients (2 whey protein concentrates [WPC 45 and WPC 76], whey protein isolate [WPI], egg white [EW], and potato starch [PS]) added to surimi gels were evaluated using 2 different thermal regimes. Hardness and cohesiveness of whiting surimi gels prepared using a rapid cook treatment (90°C for 15 min) did not significantly change on the addition of test ingredients. Hardness and cohesiveness of whiting surimi with added ingredients prepared using a suwari set treatment (0° to 4 °C for 12 h followed by 90°C for 15 min) were increased ( P < 0.05) on addition of additives with the exception of WPC 76, which decreased ( P < 0.05) surimi hardness and cohesiveness. Results showed that starch was more effective in improving the functional properties of surimi when compared with all other protein additives assessed.     

Effect of rainbow trout (Oncorhynchus mykiss) plasma protein on the gelation of Alaska pollock (Theragra chalcogramma) Surimi

ABSTRACT:  The effect of rainbow trout plasma protein (RPP) on the gelation of Alaska pollock surimi was determined to evaluate the possibility of its commercialization as a new protein additive. For modori gel, the breaking force, deformation, whiteness, and water holding capacity increased as the addition amount of RPP (0 to 0.75 mg/g) increased, and decreased at higher concentration of RPP (0.75 to 1.50 mg/g) ( P < 0.05). Protein solubility of modori gel in the mixture of SDS, urea, and β-mercaptoethanol decreased as the addition amount of RPP increased up to 0.75 mg/g, and increased at higher concentration of RPP (0.75 to 1.50 mg/g) ( P < 0.05). The contents of trichloroacetic acid-soluble peptide decreased as the addition amount of RPP (0 to 1.50 mg/g) increased ( P < 0.05). Based on the result of sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), most myosin heavy chain of surimi was not degraded when RPP was added. Thus, RPP was supposed to act as a protease inhibitor in the gelation of Alaska pollock surimi. An RPP of 0.75 mg/g was the optimal concentration to prevent the gel weakening of Alaska pollock surimi. Compounds with molecular weights less than 10 kDa in RPP had no significant effect on the gelation of Alaska pollock surimi based on the result of the dialyzed RPP.     

Effect of soy protein isolate on gel properties of Alaska pollock and common carp surimi at different setting conditions

The effects of soy protein isolate (SPI) on the gel properties of different grade Alaska pollock and common carp surimi at different setting conditions were evaluated and compared. Breaking force and distance of gels decreased with increasing SPI concentrations in direct cook (85 °C for 30 min) and in cook after setting at 30 °C for 60 min conditions. The effect of SPI on gel strength of common carp surimi was less than in Alaska pollock surimi. The breaking force obtained for addition of 10% SPI to Alaska pollock surimi was higher than for surimi alone when cooked after incubation at 50 °C for 60 min. Addition of SPI decreased the whiteness and increased the yellowness of the gel. The gel structure showed that the addition of SPI modified the microstructure of the fish protein gel, thus resulting in surimi with different gelling properties. Copyright © 2004 Society of Chemical Industry     

Proteolytic Activity of Surimi from Pacific Whiting (Merluccius productus) and Heat-Set Gel Texture

The protease activity in mechanically deboned Pacific whiting flesh was reduced to 56.3% by two watenminced 3:1 (wt:wt) flesh wash exchanges and refining. Surimi (91.7% refined flesh, 4.0% sorbitol, 4.0% sucrose, and 0.3% condensed phosphate) produced very poor gels but the strength was markedly improved by the addition of egg white. Hardness increased 1.5-fold and elasticity 4.5-fold over the control with the addition of 3.0% egg white. Further improvement in gel strength was observed with the addition of 5.0% potato starch in combination with egg white. Sodium dodecyl sulfate polyacrilamide gel electrophoresis (SDS-PAGE) of heat-set gels verified the action of inhibitors in egg white on residual proteases contained in whiting surimi.     

κ-卡拉胶和魔芋胶及其复配对咸蛋清鱼糜混合凝胶品质的改良

研究了κ-卡拉胶和魔芋胶及其复配在添加了咸蛋清的罗非鱼鱼糜凝胶中的应用,通过质构测定和感官评价,结果发现:κ-卡拉胶和魔芋胶及其复配均能够显著提高鱼糜凝胶的凝胶强度和持水力(p<0.05),随着添加量的增大,鱼糜凝胶断面也逐渐变得粗糙从而影响其质构。当κ-卡拉胶与魔芋胶的质量比为2:1,添加量为0.1%时,咸蛋清鱼糜凝胶品质较好,整体接受性强。     

Characterization of Thermorheological Behavior of Alaska Pollock and Pacific Whiting Surimi

ABSTRACT: Thermorheological behavior of Alaska pollock (AP) and Pacific whiting (PW) surimi was evaluated during gelation at different moisture contents (80% to 95%). The temperature sweep data (storage modulus, G', compared with temperature) for both surimi clearly indicated G' minima. Unlike for the PW surimi, the minimum values of the AP surimi was moisture-content dependent and there was a linear relationship between logarithm of concentration and reciprocal absolute temperature at gelation. The activation energy ( Ea ) for aggregation after gelation temperature at each moisture content was calculated by a nonisothermal kinetic model for both AP and PW Surimi. The Ea values increased with moisture content of the system and ranged from 172.8 to 232.9 kJ/mol. Based on the assumption that melting temperature for a thermo-reversible gel may be considered equivalent to gelation temperature for thermo-irreversible gels, an Arrhenius-type model was used to estimate the enthalpy of cross-links formation for AP surimi to be 300.3 kJ/mol.     

Linear Programming in Blending Various Components of Surimi Seafood

Shear stress, shear strain, whiteness of surimi gels made with high and low grades of Alaska pollock and Pacific whiting were investigated to determine linearity of their relationships. A canonical form of least square linear model in mixture design showed a greater linearity (r²0.99) for blending high and low grade surimi lots. Due to linearity without interaction (p<0.001), a least cost linear program provided optimum blending for surimi lots based on value, constraints, and decision variables. Linear programming to determine optimum formulation of surimi with starches and water content was not feasible due to interactions between surimi and starch, or starch and water.     

Sodium Asocorbate Affects Surimi Gel-forming Properties

Effect of sodium-L-ascorbate (SA) on the gel-forming properties of Alaska pollock surimi was studied with respect to optimum level, surimi quality, gel setting, vacuum chopping, freeze-thaw and thermal stabilities, and salt and moisture levels. SA significantly improved gel cohesiveness and sensory firmness of fiberized products with maximum strengthening effect at a 0.2% level. Its effectiveness was directly related to surimi quality regardless of vacuum treatment indicating the unimportance of airborne oxygen. Freeze-syneresis promoted by ascorbatc during frozen storage was moderated by the use of hydrox-ypropylatcd-modified starch.     

EFFECT OF CHICKEN PLASMA PROTEIN AND SOME PROTEIN ADDITIVES ON PROTEOLYSIS AND GEL-FORMING ABILITY OF SARDINE (SARDINELLA GIBBOSA) SURIMI

The effect of chicken plasma protein (CPP) and various protein additives on autolysis and gel‐forming ability of sardine (Sardinella gibbosa) surimi was investigated. CPP and other protein additives showed inhibitory activity toward autolysis of sardine surimi incubated at 70C in a concentration‐dependent manner. Porcine plasma protein (PPP) and egg white (EW) were more effective in proteolysis prevention than CPP and other protein additives. Breaking force and deformation of both modori and kamaboko gels increased when CPP and other protein additives were added at levels up to 2% (P < 0.05). Nevertheless, PPP and EW showed a greater gel‐strengthening effect than CPP and other protein additives (P < 0.05). Addition of CPP and other plasma proteins resulted in decreased whiteness, especially with increasing amount (P < 0.05). However, no change in whiteness was observed with gels containing EW and soy protein isolate (SPI) (P > 0.05). Proteolysis of sardine surimi can be retarded by the addition of CPP and protein additives, leading to increased gel‐forming ability.     

Purification and determination of inhibitory activity of recombinant soyacystatin for surimi application

A recombinant soyacystatin (r-soyacystatin) was tested for its inhibitory activity against cysteine proteinase of Pacific whiting and its activity was compared to that of egg white cystatin. A recombinant soyacystatin expressed in Escherichia coli was purified to electrophoretic homogeneity using phenyl-Sepharose and DEAE-Sepharose. Native egg white cystatin was purified by using affinity chromatography on CM-papain-Sepharose generated in our lab. Egg white cystatin and soyacystatin were tested for proteinase inhibitory activity against commercial papain and also cathepsin L purified from Pacific whiting muscle. The r-soyacystatin exhibited papain-like protease inhibition activity comparable to that of the egg white cystatin, which could inhibit papain and Pacific whiting cathepsin L. The r-soyacystatin subsequently inhibited the autolytic activity of Pacific whiting surimi.