Cryoprotective Effects of Some Materials on Cod-Surimi Proteins during Frozen Storage

Freeze-induced protein denaturation of cod surimi was studied as affected by carbohydrates (sucrose and glucose syrup at 8% w/w), polyols, (sorbitol and glycerol at 8% w/w), protein hydrolysates (fish protein and casein hydrolysates at 4% w/w), hydrocolloids (pectin-1% w/w, sodium alginate, lambda- and iota-carrageenan-0.5% w/w) and combinations of the above, (sucrose/sorbitol 1:1 mixture at 8% w/w, or combined with protein hydrolysates at 4% w/w). Salt extract-able protein (SEP) and heat induced denaturation by differential by differential scanning calorimetry (DSC) were used to monitor protein changes in surimi stored 16 wk at -20°C. The best cryoprotection effect was achieved from sorbitol, glucose syrup (DE = 60), sucrose and sucrose/sorbitol 1:1 w/w mixture at 8% w/w in surimi. Correlations between certain DSC parameters and SEP were high.     

Effects of adding fish gelatin on Alaska pollock surimi gels

Fish gelatin is a food additive obtained after hydrolysis of collagen from fish skin. The importance of fish gelatin as a food additive is increasing due to its increased commercial availability. Surimi is washed minced fish meat used as the raw material for seafood analogs like crabmeat substitutes. The most important attributes of surimi are gelling and whiteness. The objective of this work was to determine the effect of using fish gelatin as an additive in surimi to improve the mechanical and functional properties of gels. Surimi gels were prepared by mixing grade A or FA surimi (Alaska pollock) with salt (20 g/kg w/w) and commercial fish gelatin at 0 (control), 5, 7.5, 10, or 15 g/kg (w/w) previously dissolved in water (200 mL/kg surimi). The solubilized paste was incubated at 40 °C for 30 min followed by cooking at 90 °C for 15 min. Changes in mechanical properties (torsion test), a functional property (expressible water content) and color attributes of surimi gels were measured. Grade FA surimi gels containing 7.5–15 g/kg of fish gelatin showed an improved expressible moisture. However, gelatin added at 15 g/kg showed a disruptive effect detrimental to the mechanical properties. Color parameters were modified slightly. Whiteness attribute as affected by increasing the fish gelatin was instrumentally detected but not observed by sensory panelists. Gelatin did not change the overall color attributes and all gels remained in the grayish region. These results indicated that fish gelatin did not have an advantage for using as a functional additive in Alaska pollock surimi grades A or FA. However, it can be used at up to 10 g/kg without a negative effect on the mechanical properties.     

The effect of low- or non-sweet additives on the stability of protein functional properties of frozen cod surimi

The cryoprotective effect of low- or non-sweet additives, Palatinit^R, Polydextrose^R, casein hydrolysate and fish protein hydrolysate (at 8% w/w) as well as lactitol (at 4% and 8% w/w) were compared to an industrial control containing sucrose/sorbitol (8% w/w) and a control without additive in cod surimi stored at –20°C for 4 months. Freeze-induced protein denaturation was evaluated monthly by salt extractable protein and differential scanning calorimetry analyses of surimi followed by texture and expressible moisture analyses of surimi cooked gels. Results revealed that protein functionality was similarly maintained during frozen storage by lactitol, Palatinit^R and Polydextrose^R when incorporated in cod surimi at the 8% level. Surimi gels could be produced with textural attributes comparable to 8% w/w sucrose/sorbitol surimi gels, and the level of lactitol in cod surimi could be reduced to 4% w/w without significant alteration of cryoprotection. Some benefits in gel-forming properties were obtained by adding 8% casein hydrolysate to cod surimi.     

Porcine plasma protein as proteinase inhibitor in bigeye snapper (Priacanthus tayenus) muscle and surimi

Porcine plasma protein (PPP) showed inhibitory activity towards trypsin, papain, digestive enzymes and modori‐inducing proteinases from bigeye snapper. Among the fractions prepared, fraction IV‐1 exhibited the highest inhibitory activity against all proteinases tested and the autolysis of fish muscle. At a level of 0.5% (w/w), both PPP and fraction IV‐1 effectively prevented the degradation of myosin heavy chain in fish muscle. The inhibitory activity of fraction IV‐1 was stable up to 60 °C. Incorporation of fraction IV‐1 significantly increased the breaking force, deformation and water‐holding capacity of surimi gel from bigeye snapper (P < 0.05). However, no increase in breaking force and deformation was found when fraction IV‐1 was added at a level above 0.3% (w/w) (P > 0.05). No significant change in whiteness of surimi gel was observed with the addition of fraction IV‐1 (P > 0.05). © 2001 Society of Chemical Industry     

GEL PROPERTIES OF BIGEYE SNAPPER (PRIACANTHUS TAYENUS) SURIMI AS AFFECTED BY SETTING AND PORCINE PLASMA PROTEINS

Effects of setting temperature, time, and addition of porcine plasma protein (PPP) on gel properties of surimi from bigeye snapper (Priacanthus tayenus) were investigated. Breaking force and deformation of the surimi gels increased as the setting time and temperature increased. The gel preincubated at 35C for 90 min in the presence of 0.5% PPP, followed by cooking at 90C for 20 min showed the maximum force and deformation. The decrease in solubility of the resultant suwari and kamaboko gels in solution containing sodium dodecyl sulfate, urea and β‐mercaptoethanol suggested that gel enhancement was mainly mediated through the formation of nondisulfide covalent bonds catalyzed by both transglutaminase (TGase) in fish muscle and porcine plasma. Addition of PPP slightly decreased the whiteness of the kamaboko gels.     

鳕鱼皮的添加对鱼糜凝胶特性及其蛋白质结构的影响

目的 研究添加黑线鳕鱼(Melanogrammusaeglefinus)皮对鱼糜凝胶特性和蛋白质结构的影响。方法以傅里叶变换红外光谱法和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳技术的分析方法,探究黑线鳕鱼皮不同添加比率对鱼糜凝胶的凝胶强度、质构、持水性、p H和蛋白质分子组成及其二级结构的影响规律。结果 当鱼皮添加比率为5%时,混合凝胶的凝胶强度、弹性和持水性虽下降但无显著变化(P>0.05),分别为2654.4 g·mm、2.83 mm和85.7%,而硬度显著下降至22.83 N (P<0.05);随着鱼皮添加比率的增加,鱼糜凝胶的凝胶强度、质构、持水性均下降;鱼皮的添加阻碍了肌球蛋白重链发生交联,同时,鱼糜凝胶蛋白质结构无显著变化(P>0.05)。结论为提高鱼皮的利用率,可适量将鱼皮与鱼糜混合制备鱼糜凝胶,鱼皮添加比率不宜超过5%。     

Bovine Plasma Protein Functions in Surimi Gelation Compared with Cysteine Protease Inhibitors

The protease inhibitory activity of bovine plasma protein (BPP) and its gel strengthening effect on Pacific whiting surimi were compared with E-64 [L-trans-epoxysuccinylleucylamido (4-guanidio) butane], iodoacetic acid (IAA), and a recombinant soybean cystatin (RSC). In terms of inhibitory activity, as low as 1.2 mM E-64,37.7 mM IAA, or 17.9 mg RSC were equivalent to 1% BPP. To produce the same gel strength as the 1% BPP-treated surimi, 10 times that level of E-64 and RSC were required, while 100 times that level of IAA did not increase the gel stress as effectively. Thus, plasma contributed to enhanced gelation of Pacific whiting surimi by inhibition of fish protease and also by other gel-enhancing factors in the plasma.     

Surimi Production from Partially Processed and Frozen Pacific Whiting (Merluccius productus)

Pacific whiting surimi was made from stabilized mince (SM), unstabilized mince (UM), and headed and gutted (H&G) fish kept in frozen storage and compared to a surimi control made from fresh fillets. SM was made by mixing fresh mince with 12% w/w sucrose and 0.2% w/w polyphosphates. Surimi was produced from SM, UM, H&G at 1, 30, 90, and 180 days and evaluated by torsion, measuring shear stress, and true strain. After 6 months, there were no differences (p>0.05) between surimi samples prepared from SM stored at - 20° and -50° and the control surimi. UM and H&G fish produced surimi of inferior quality.     

Characteristics of surimi and kamaboko from sardines

Sardines of varying freshness (1 to 3 days in ice) were manually or mechanically processed into fish mince and surimi using 1 to 3 washing steps. Standard kamaboko gels were prepared by grinding thawed surimi with 3% NaCl and 5% potato starch, stuffing into sausage casings, holding at 37°C for 30 min and cooking at 90°C for 50 min.
Three washing steps decreased the yield of washed fish mince (21-27 g per 100 g of whole fish), and the protein recovery (50-55% of that present in the unwashed mince), but caused efficient lipid removal (80%) leading to surimi containing only 0.2-1.4% lipid. The texture and colour of the final kamaboko were also improved.
The texture parameters (folding score, rigidity, elasticity index and gel strength) of kamaboko prepared from very fresh sardines were markedly enhanced by gel setting during incubation at 37°C for 30 min or 4°C for 24 hr. Incubation at 60°C for 30 min led to soft, coarse gels. Omitting potato starch or replacement by spray dried egg white had little effect on texture.
The texture of kamaboko prepared from less fresh sardines was less firm and elastic, did not improve when incubation was carried out at 37 or 4°C before cooking, and was softer and coarser after incubation at 60°C. Partial or total replacement of potato starch by egg white, soy protein isolate or bovine serum albumin markedly improved the texture. Egg white also increased the colour lightness.     

Optimal blending of differently refined fish proteins based on their functional properties

Two different mixtures (Alaska pollock surimi with grass carp fish protein isolate (FPI) and grass carp surimi with grass carp FPI) were investigated for their compatibility and functionalities. As the proportion of FPI increased, it was observed surface hydrophobicity and surface reactive sulfhydryl (SRSH) content increased significantly, indicating the degree of fish protein unfolding prior to gelation was much higher than surimi alone. Comparable results were shown as measured by storage modulus (G′) in oscillatory dynamic rheology, demonstrating the gelling temperature was reduced when the proportion of FPI increased. Effects of mixing surimi and FPI on gel functionality (hardness, cohesiveness, and whiteness) exhibited a linear pattern when the proportion of surimi was larger than or equal to that of FPI. However, there were no linear relationships when the proportion of FPI exceeded that of surimi.

Practical applications

Commercial surimi has been successfully used in the Western world over 30 years. Unlike surimi which is a refined fish myofibrillar protein composite, fish protein isolate (FPI) is a refined composite of myofibrillar protein and sarcoplasmic protein. The former is made by avoiding any chemical/physical denaturation, while the latter can be made by inducing chemical denaturation and renaturation with pH shift. Even though FPI is not currently available in a commercial scale, it has a great potential to replace all or a part of surimi for the manufacture of fish protein gel products. This study reveals how to optimally mixed these two differently refined fish proteins based on their functional properties. The results suggested that blending surimi and FPI may be feasible only when the proportion of FPI does not exceed 50%.     

Functional aspects of blood plasma proteins.

The viscosity of solutions (6% w/w protein in 45% sucrose) of porcine and bovine whole blood plasma, porcine serum and porcine plasma fractions exhibited Newtonian behaviour between 20°C and 73°C. On further heating, the viscosity of these solutions increased exponentially producing a reversible gel structure at 76°C and an irreversible gel at 79°C. In contrast, egg albumen protein solutions indicated a relatively low initial viscosity but started to thicken at 65°C, forming reversible gels at 73°C and irreversible gels at 76°C. The viscosity of the egg albumen protein solutions was similar to that of the serum proteins and plasma protein fractions and less than that of whole plasma protein solutions. Viscosities lower than expected were exhibited by mixtures of whole porcine or bovine plasma and egg albumen proteins. However, synergistic interaction between the proteins of egg albumen and porcine plasma fraction I and fraction III (albumin) and porcine serum occurred at high temperatures of heating.     

Thermophysical properties of silver hake and mackerel surimi at cooking temperatures

Thermal diffusivity values obtained using a transient method both from heating and cooling information and apparent specific heat of surimi made from silver hake and mackerel as a function of temperature (60–110 °C) and added potato starch content (3% and 7%, w/w) were determined. The water content of all samples was kept constant at about 77% (w/w) in order to determine the effect of starch. Thermal diffusivity and apparent specific heat of all samples increased with temperature. The effect of temperature on diffusivity was found significant (p=0.001) in all samples at temperatures above 85 °C. This effect may be caused by structural changes as temperature is raised. Thermal diffusivity increased with temperature more rapidly in samples with high levels of starch than in those with no starch. However, thermal diffusivity of silver hake surimi preset at 40 °C for 30 min did not show a significant increase (p<0.05) over the temperature range studied. Thermal diffusivities calculated from cooling and heating data were significantly different (p<0.05).

The differential scanning calorimetry (DSC) thermograms of silver hake and mackerel surimi showed three endothermic peaks. When starch was added to surimi samples an endothermic peak having a large area was observed, which overlapped the third highest temperature peak of surimi samples. No significant shifts in the endothermic peaks of myofibrillar proteins were detected with increasing starch content. Transition temperatures for starch–surimi system were higher than those for starch–water system. There were deviations in the apparent heat capacity function calculated from DSC measurements in surimi samples containing starch. These are attributed to gelatinization of starch and modification of water structure.     

解冻方式及漂洗方法对冷冻竹荚鱼鱼糜品质的影响

探讨了解冻方式及CaCl_2溶液漂洗对冷冻竹荚鱼鱼糜加工品质的影响。实验中采用流水解冻、4℃空气解冻及微波解冻3种解冻方式,对解冻后竹荚鱼鱼肉盐溶蛋白含量、ATPase酶活以及其鱼糜凝胶的变化做了比较;同时以凝肢强度、持水性及微观结构为鱼糜品质的检测指标,考察了不同浓度CaCl_2溶液漂洗对冷冻竹荚鱼鱼糜凝胶特性的影响。结果表明:4℃空气解冻得到的鱼糜品质最好,流水解冻次之,但4℃空气解冻时间较长。CaCl_2溶液漂洗对冷冻竹荚鱼鱼糜的凝胶强度有较大影响,低质量分数的CaCl_2(<0.6%)漂洗可以增强冷冻竹荚鱼鱼糜凝胶强度,0.6%CaCl_2溶液漂洗时,凝胶强度最大,随后凝胶强度随CaCl_2质量分数增大而减小。     

Cryoprotective Effects of Lactitol, Palatinit and Polydextrose® on Cod Surimi Proteins during Frozen Storage

The cryoprotective effects of lactitol dihydrate, Polydextrose® and Palatinit (Isomalt) at 8% w/w in codsurimi were compared to an industrial control containing a sucrose/sorbitol 1:1 mixture and a control without additive. Surimi was stored at ?20°C for 12 wk and examined for freeze-induced protein changes every 2 wk by salt extractable protein and differential scanning calorimetry analyses: Palatinit®, lactitol and Polydextrose® stabilized surimi proteins equally well as did the sucrose/sorbitol mixture. Salt extractable protein and myosin peak enthalpy for surimi were maintained at the same level as the industrial control. Confirming earlier results, initial T_max-myosin yielded information regarding surimi protein stability over extended periods of frozen storage.     

竞争性ELISA检测鱼糜制品中蛋清含量

通过纯化蛋清中主要成分卵清蛋白(ovalbumin,OVA),制备抗OVA多克隆抗体,利用制备的抗体建立鱼糜制品中蛋清定量检测的竞争性酶联免疫吸附测定方法(competitive enzyme linked-immunosorbent assay,c-ELISA)。十二烷基硫酸钠-聚丙烯酰氨凝胶电泳和Western blot结果显示,制备的抗OVA多克隆抗体特异性良好。以热处理的OVA为竞争抗原建立的c-ELISA法检测限为1.82 mg/kg,组内变异系数为3.1%,组间变异系数为7.8%,回收率为87.4%~97.2%,表明建立的方法重复性好,准确性较高。利用建立的方法对6种商品化的鱼糜制品进行检测,发现其蛋清的添加量在2.7~83.5 g/kg之间。本研究为今后鱼糜制品中蛋清含量规范标识的监管提供了重要的技术支持。     

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     

Effect of reducing agents on physicochemical properties and gel-forming ability of surimi produced from frozen fish

Effects of different reducing agents (cysteine, ascorbic acid and sodium bisulfite) at various levels on physicochemical properties of protein, transglutaminase activity and gel properties of surimi produced from frozen croaker, lizardfish, threadfin bream and bigeye snapper were studied. Addition of cysteine resulted in the highest increase in the breaking force and the deformation of surimi gels, compared with other reducing agents. The optimum levels of cysteine were 0.05, 0.1, 0.05 and 0.1% (w/w) for surimi from frozen croaker, lizardfish, threadfin bream and bigeye snapper, respectively. Surimi from frozen croaker with cysteine added showed a similar breaking force and deformation to that produced from fresh fish. With addition of cysteine, an increase in sulfhydryl content with a concomitant decrease in disulfide bond content was generally observed. Ca²⁺ ATPase activity also increased, indicating the renaturation of the myosin molecule. T_max of peak 1 (myosin peak) of all surimi sols in the presence of cysteine was shifted to higher temperature. The increased transglutaminase activity was observed with addition of cysteine. Therefore, reducing agents, especially cysteine, recovered the denatured muscle proteins and activated the transglutaminase in the muscle, leading to the increased gel-forming ability of surimi produced from frozen fish.     

Rheological changes during thermal gelation of meat batters containing surimi from alaska pollack (Theragra chalcogramma) or sardine (Sardina pilchardus)

The objective of this study was to use a thermal scanning rigidity monitor to analyse the changes occurring in rheological behaviour during thermal gelation induced by the presence of surimi in meat batters. These studies were conducted on systems prepared with pork meat to which varying proportions of surimi from Alaska pollack (Theragra chalcogramma (Pallas)) or sardine (Sardina pilchardus) (Walb) were added. The results indicated that gelation in pork proteins did not occur in the same way as in fish proteins. Whereas the addition of Alaska pollack surimi to the meat preparations produced scarcely any change with respect to the meat alone, the sardine surimi caused major alterations. These changes depended upon the proportion of protein from surimi added: addition of 100 g kg^?1 caused a protein matrix to form, inducing the formation of stiffer gels and the appearance of the setting phenomenon, although at higher temperatures than are found with fish proteins. Such behaviour was not apparent when the proportion of protein from surimi was raised to 200 g kg^?1.     

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%.     

罗非鱼与四种海水鱼混合鱼糜的凝胶特性

本文选择罗非鱼分别与四种海水鱼(马鲛鱼、海鲈鱼、金鲳鱼、鸢乌贼)制备混合鱼糜,来获得凝胶特性较好且成本较低的鱼糜制品。通过对混合鱼糜凝胶特性的测定,得出最佳的鱼糜混合比例。结果表明,当罗非鱼鱼糜分别添加60%马鲛鱼、60%海鲈鱼、40%金鲳鱼、40%鸢乌贼时,混合鱼糜的凝胶强度比单一的罗非鱼鱼糜分别提高了82.5%、79.4%、44.3%、27.2%,混合鱼糜的盐溶性蛋白含量比单一的罗非鱼鱼糜分别提高了115.6%、104.5%、100.4%、75.6%,罗非鱼与马鲛鱼、海鲈鱼混合得到的鱼糜制品凝胶特性较好。