Negative Roles of Salt in Gelation Properties of Fish Protein Isolate

ABSTRACT: Salt effect on gelling properties of fish protein isolate (FPI) prepared by acid‐ and alkali‐aided extraction was investigated. Acid‐ or alkali‐extracted FPI formed significantly better gel texture with 0% NaCl than with 3% NaCl. Texture properties of acid‐ or alkali‐extracted FPI decreased as NaCl content increased, especially at 2% to 3% salt. Contrarily, salt significantly promoted texture qualities of conventional surimi gels. The effect was highlighted when they were subjected to low temperature setting. The myofibrillar proteins in FPI were not solubilized when NaCl was added, perhaps due to protein aggregation caused by acid or alkali extraction. FPI solubility, however, was not closely related to their texture properties. Cold setting did not promote texture properties of FPI gels as much as conventional surimi gels. Acid‐extracted gels gave the best color properties.     

鱼糜凝胶形成过程中物理化学变化

采用化学法测定鱼糜凝胶形成过程中离子键、氢键、疏水相互作用和二硫键的变化,借助拉曼光谱仪分析草鱼鱼糜凝胶形成过程中鱼糜蛋白质构象的变化,进而研究化学作用力和蛋白质构象对鱼糜凝胶形成的影响。结果表明：在草鱼鱼糜凝胶的形成过程中,离子键、氢键显著减少,疏水相互作用、二硫键和非二硫共价键增加;α- 螺旋结构部分转化为无规卷曲结构。疏水相互作用、二硫键及非二硫共价键是影响凝胶形成的主要作用力,α- 螺旋和无规卷曲是草鱼鱼糜凝胶形成过程中维持鱼糜凝胶稳定结构的主要蛋白质构象。     

Comparison of functional properties and SDS-PAGE patterns between fish protein isolate and surimi produced from silver carp

The purpose of this study was to investigate and compare the physicochemical properties of fish protein isolate (FPI) produced from silver carp (Hypophthalmichthys molitrix), which is a relatively cheap fish with low consumption in Fars (a state of Iran). In this research, proteins were isolated using pH shifts method. Results showed that in terms of production efficiency, protein recovery, lipid reduction and functional properties such as water-holding capacity, emulsifying capacity, foaming capacity and water absorption, FPI was better than conventional surimi. The treated samples at pH?=?2.5 represented better functional properties relative to other samples. The electrophoretic patterns demonstrated that acidic pH led to vanish high molecular weight protein bands because these proteins were converted to low molecular weight proteins, whereas basic pH caused the formation of high molecular weight proteins relative to myosin heavy chain. It seems that in basic pH, the proteins were linked together after denaturation and then aggregated. Overall, the results showed that physicochemical qualitative properties of FPI were better than those of conventional surimi.     

3种鱼糜蛋白质特性及油炸特性比较

目的：探究3种鱼糜的蛋白质特性及其油炸特性。方法：以草鱼、鲢鱼和巴沙鱼为原料,通过测定孔隙率、硬度和吸水性等指标表征鱼糜的油炸特性,测定鱼糜的动态流变学性质、泡沫稳定性和SDS-PAGE探究其影响机制。结果：相较于草鱼鱼丸和鲢鱼鱼丸,巴沙鱼鱼丸组织疏松,孔洞大,孔隙率最高,且硬度最低,吸水率最高。巴沙鱼鱼糜的凝胶强度远大于鲢鱼鱼糜和草鱼鱼糜,且草鱼、鲢鱼和巴沙鱼鱼糜的泡沫稳定性分别为63.0%,27.7%,82.0%。SDS-PAGE凝胶电泳结果表明巴沙鱼鱼糜的肌动蛋白和肌球蛋白含量较高。结论：巴沙鱼鱼糜含有较高的肌动蛋白和肌球蛋白,是提高鱼糜凝胶强度和泡沫稳定性的关键因素之一,最终影响鱼糜的油炸特性。     

大豆分离蛋白及卡拉胶对泥鳅肌原纤维蛋白凝胶特性的影响

目的：开发品质优良的淡水鱼鱼糜制品。方法：将不同含量的大豆分离蛋白和卡拉胶添加到泥鳅肌原纤维蛋白中,采用质构仪、色差仪、扫描电镜和红外光谱等探究其对泥鳅肌原纤维蛋白凝胶特性的影响。结果：随着大豆分离蛋白含量的增加,泥鳅肌原纤维蛋白凝胶硬度先降低后升高,弹性先升高后降低,保水性增加,蒸煮损失降低,凝胶网络孔洞越来越大,各二级结构相对含量发生变化;而卡拉胶对凝胶硬度和弹性有减弱作用,对白度及蒸煮损失有较好的改善作用,凝胶网络结构规则有序且无规则卷曲结构消失。结论：大豆分离蛋白对泥鳅肌原纤维蛋白凝胶的作用效果较卡拉胶更明显,形成的复合凝胶性能更好。     

低温冷链贮藏对鱼糜凝胶化学作用力和肌原纤维蛋白结构及功能特性的影响

为研究低温冷链对鱼糜肌原纤维蛋白和凝胶化学作用力的影响。本实验以鱼糜为研究对象,测定了低温冷链贮藏时间对肌原纤维蛋白功能基团、二级结构、三级结构和凝胶化学作用力的影响,并进一步通过主成分分析和相关性分析探究凝胶化学作用力与肌原纤维蛋白之间的关系。结果表明,贮藏过程中鱼糜盐溶性蛋白含量、Ca2＋-ATPase活力和总巯基含量呈下降趋势,而羰基含量上升。此外,蛋白质二级结构由有序向无序转变,肌原纤维蛋白荧光强度下降,说明蛋白极性环境发生改变。揭示了肌原纤维蛋白中的活性基团与凝胶化学作用力的形成密切相关。因此,在贮藏初期防止蛋白氧化和冷冻变性是维持鱼糜凝胶化学作用力,保持鱼糜凝胶特性的有效途径。本研究可为鱼糜在低温冷链贮藏过程中的品质保持提供基础理论支持。     

Effects of CaCl<Subscript>2</Subscript> on chemical interactions and gel properties of surimi gels from two species of carps

Effects of CaCl₂ on chemical interactions, textural properties and expressible moisture content of suwari and kamaboko gels from yellowcheek carp and grass carp were investigated. And the correlations between the contents of chemical interactions and physical properties of surimi gels were analyzed. The contents of chemical interactions, especially non-disulfide covalent bonds, disulfide bonds and hydrophobic interactions of suwari and kamaboko gels, varied with addition concentration of CaCl₂ and fish species. Suwari and kamaboko gels from yellowcheek carp exhibited higher breaking force, deformation and gel strength than these from grass carp. Surimi gels (suwari and kamaboko gels) from yellowcheek carp and grass carp exhibited their maximum gel strength when 40 mmol/kg and 100 mmol/kg CaCl₂ was added, respectively. Addition of CaCl₂ at high concentration resulted in low water holding capacity of surimi gels. Correlation analysis indicated that the contents of nonspecific associations, ionic bonds, hydrophobic interactions and sulfhydryl groups exhibited significant correlation with breaking force of surimi gels from yellowcheek carp and grass carp. Additionally, the content of non-disulfide covalent bonds had significant positive correlations with breaking force and expressible moisture of surimi gel from yellowcheek carp.     

添加剂对羊栖菜-鱼糜凝胶特性的影响

目的 探究添加剂对羊栖菜-鱼糜凝胶特性的改善作用。方法 以白鲢鱼糜为原料,添加羊栖菜浆液制备羊栖菜-鱼糜,添加大豆分离蛋白、玉米淀粉及卡拉胶,用物性分析仪和离心法测定羊栖菜-鱼糜复合凝胶的凝胶强度和持水性,并与不含添加剂的羊栖菜-鱼糜测定结果进行比较。结果 与只含20%羊栖菜浆液的鱼糜对照组相比,添加4%大豆分离蛋白、10%玉米淀粉及0.75%卡拉胶时,所制得的羊栖菜-白鲢鱼复合鱼糜的凝胶强度分别提高13%、5%和16%,持水性分别提高9%、10%和8%。结论 添加4%大豆分离蛋白、0.75%卡拉胶及10%玉米淀粉有利于提高鱼糜复合凝胶强度及持水性,改善凝胶品质。     

不同糖类对草鱼鱼糜凝胶的影响

研究葡聚糖,蔗糖,海藻糖,低聚木糖,低聚果糖对草鱼鱼糜凝胶微观结构、蛋白质结构、水分子分布及质构特性的影响.扫描电镜结果表明,与空白样相比,添加4％葡聚糖、蔗糖和海藻糖的鱼糜凝胶中能观察到更紧密的网络结构,糖的加入促进了蛋白质的交联和凝胶网络结构的紧密性,改善了鱼糜制品的凝胶特性.添加低聚果糖的样品使鱼糜蛋白α-螺旋结...     

大豆分离蛋白、木薯淀粉与转谷氨酰胺酶组合对鲢鱼鱼糜凝胶品质的影响

探究了大豆分离蛋白、木薯淀粉及转谷氨酰胺酶对鲢鱼鱼糜制品的影响并确定最适添加量。结果表明,当大豆分离蛋白添加量6%,木薯淀粉添加量9%以及转谷氨酰胺酶添加量4U/g·蛋白时,能有效增加鱼糜的持水性,降低其蒸煮损失,且不会使鱼糜带有大豆分离蛋白的淡黄色,同时提高了鱼糜的凝胶强度,鲢鱼鱼糜制品各项指标较好。通过低场核磁共振和扫描电镜检测发现,未添加的对照组在6次冻融后凝胶结构完全被破坏,不易移动水峰面积(A_(23))下降了25%,试验组凝胶结构比较致密,A_(23)下降了11%,进一步验证了此配方组合对鱼糜在冻融循环过程中凝胶结构的稳定性具有保护作用。     

Gel‐forming ability of surimi from grass carp (Ctenopharyngodon idellus): influence of heat treatment and soy protein isolate

The effects of setting conditions and soy protein isolate (SPI) on textural properties of surimi produced from grass carp were investigated. Effects of setting temperature, setting time and protein concentration on the breaking force and distance were evaluated and compared utilizing response surface methodology. Models for breaking force and breaking distance of grass carp surimi were established. Protein concentration was the major factor affecting the gel strength of grass carp surimi. Breaking force and distance of grass carp surimi gels decreased with increase of protein ratio from SPI at 30 °C and 40 °C for 60 min setting and heating at 85 °C for 30 min, but the breaking force obtained for addition of 100 g kg^?1 SPI protein to grass carp surimi was higher than that for surimi alone at 60 °C for 60 min incubation and heating at 85 °C for 30 min. Copyright © 2005 Society of Chemical Industry     

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     

不同辅料对草鱼鱼糜品质的影响

为了研究不同辅料对鱼糜品质的影响,以新鲜草鱼鱼糜为原料,分别加入糖类辅料和蛋白类辅料,对鱼糜的组织蛋白酶活性、pH值、凝胶强度、折叠柔韧性、持水性能和白度值进行测定。结果表明：不同辅料对草鱼鱼糜组织蛋白酶B、L产生不同抑制效果,对凝胶强度提升最大的辅料为蔗糖＋山梨醇;马铃薯淀粉加入草鱼鱼糜后,鱼糜凝胶的持水性最强;除紫山药和魔芋精粉外,其余辅料对鱼糜白度值的影响无显著性差异;马铃薯淀粉、蔗糖＋山梨醇、魔芋精粉和胶原蛋白能明显增强草鱼鱼糜折叠等级。     

Effects of konjac glucomannan on physicochemical properties of myofibrillar protein and surimi gels from grass carp (Ctenopharyngodon idella)

The cryoprotective effect of konjac glucomannan (KGM) on myofibrillar protein from grass carp (Ctenopharyngodon idella) during frozen storage at −18 °C and the influence of five levels of KGM (0%, 0.5%, 1%, 1.5%, and 2%) on texture properties, water-holding capacity, and whiteness of grass carp surimi gels were investigated. KGM as a novel cryoprotectant could significantly mitigate the decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, and total sulphydryl and active sulphydryl contents of myofibrillar protein during frozen storage. KGM at the level of 1% showed the same good cryoprotective effect as a conventional cryoprotectant (10% sucrose–sorbitol, 1:1, w/w). As the levels of KGM increased, breaking force and deformation of grass carp surimi gels increased significantly. Water-holding properties of the surimi gels are improved with the increasing addition of KGM, but the whiteness decreased and the colour became darker. The optimum addition level of KGM was suggested to be 1%.     

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).     

鲢鱼与金线鱼混合鱼糜的凝胶特性

为研究鲢鱼与金线鱼混合鱼糜的凝胶特性,本实验对混合鱼糜凝胶的凝胶强度、持水性、蒸煮损失、白度值、横向弛豫时间、微观结构和肌原纤维蛋白进行分析。结果表明：混合鱼糜的白度值较纯金线鱼鱼糜显著提高（P＜0.05）,且鲢鱼鱼糜与金线鱼鱼糜质量比5∶1混合后的凝胶白度值高于纯鲢鱼鱼糜;此配比下的混合鱼糜凝胶性能最好,其中凝胶破断力、凹陷距离、凝胶强度和持水性较鲢鱼鱼糜分别提高了18.33%、27.29%、51.01%和5.65%,较金线鱼鱼糜分别提高了5.84%、19.50%、26.49%和3.45%;该配比下的混合鱼糜凝胶的蒸煮损失较鲢鱼鱼糜和金线鱼鱼糜分别降低了15.88%和7.48%。低场核磁共振分析显示鲢鱼鱼糜与金线鱼鱼糜质量比5∶1混合后的鱼糜凝胶的横向弛豫时间T22比鲢鱼鱼糜凝胶T22缩短了10.34 ms。通过扫描电镜观察发现鲢鱼鱼糜与金线鱼鱼糜质量比5∶1混合时可形成高度均匀、致密的空间凝胶网络结构。肌原纤维蛋白凝胶电泳图显示该配比下肌球蛋白重链（myosin heavy china,MHC）发生交联,大分子聚集体形成,进入凝胶中MHC更少,条带更细窄。     

转谷氨酰胺酶对鲤鱼肌原纤维蛋白乳化活性和凝胶特性的影响

目的:研究添加转谷氨酰胺酶(Transglutaminase,TG)对鲤鱼肌原纤维蛋白乳化活性和凝胶特性的影响,为改善鱼糜制品的品质特性提供理论依据。方法:肌原纤维蛋白溶液浓度为40 mg/mL,TG添加量为蛋白溶液的0%、0.1%、0.2%、0.3%、0.4%(W/V),测定蛋白溶液的乳化活性及凝胶特性指标。结果:随着TG添加量的增加肌原纤维蛋白溶液乳化活性降低(p<0.05);TG添加增大了蛋白浊度(p<0.05);蛋白流变结果表明,随着TG添加量的增加显著增大储能模量(G')(p<0.05),降低起始凝胶温度,并提高蛋白变性温度;与对照相比,添加0.1%的TG会降低凝胶持水性,但是进一步增加TG对凝胶持水性影响不显著(p>0.05);添加TG显著降低了凝胶白度(p<0.05);凝胶质构测定结果显示,随着TG添加量的增加,会改进蛋白质的凝胶特性,显著增加凝胶弹性和硬度(p<0.05)。结论:肌原纤维蛋白中添加TG到能够降低蛋白的乳化特性,但会改进肌原纤维蛋白的凝胶特性。     

表没食子儿茶素没食子酸酯对冷冻罗非鱼鱼糜抗冻作用机制

通过肌原纤维蛋白理化指标、鱼糜凝胶特性的测定及十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）,研究表没食子儿茶素没食子酸酯（epigallocatechin gallate,EGCG）对冷冻罗非鱼鱼糜的抗冻效果并探讨其作用机制。结果表明,罗非鱼鱼糜中添加EGCG具有一定的抗冻效果,对比空白组具有显著差异性。冻藏期间空白组鱼糜中盐溶性蛋白含量、总巯基含量分别下降了68.2%和62.9%,而添加0.01% EGCG后二者的降幅分别为54.5%和49.2%,且EGCG还明显延缓了肌原纤维蛋白的氧化羰基化作用。此外,冻藏过程中,EGCG组和空白组鱼糜凝胶强度和持水性随冻藏时间延长逐渐降低,且EGCG添加量较大时,反而加快凝胶劣化。SDS-PAGE显示,EGCG能够有效抑制肌原纤维蛋白降解,其中质量分数为0.01%的EGCG效果最佳。EGCG能延缓肌原纤维蛋白变性和降解程度,延缓鱼糜氧化变质程度,有望成为一种新型的鱼糜抗冻剂。     

辅料改善草鱼鱼糜凝胶性能的机理

以草鱼为原料,通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、质构分析和化学作用力测定等方法,研究辅料改善草鱼鱼糜凝胶性能的机理。结果表明：草鱼鱼糜蛋白自溶最适温度和pH值分别为65 ℃和6.5;马铃薯淀粉对鱼糜蛋白交联结构的填充能力强于胶原蛋白,而胶原蛋白对鱼糜组织蛋白酶的抑制效果好于马铃薯淀粉;辅料加入后,改变了鱼糜蛋白间的离子键、氢键、疏水性相互作用和二硫键等化学作用力,从而达到改善鱼糜品质的目的。     

Gel Properties of Surimi from Bighead Carp (Aristichthys nobilis): Influence of Setting and Soy Protein Isolate

ABSTRACT: The effects of setting conditions and soy protein isolate (SPI) on textural properties and microstructures of surimi produced from bighead carp were investigated. The incubation conditions of bighead carp surimi affected the breaking force and distance. The optimum setting conditions were 35 °C to 40 °C for 60 min. When the surimi was cooked after 50 °C incubation for 30 to 120 min, the breaking force and distance were inferior to that of no incubation. The gel structure showed that the incubation conditions affected the bighead carp surimi gel microstructures, thus producing surimi with different gelling properties. Breaking force and distance of surimi gels decreased when the protein ratio of SPI was increased in the total protein at 30 °C and 40 °C for 60 min setting and heating at 85 °C for 30 min, but the breaking force obtained for 90% surimi protein plus 10% SPI protein was higher than surimi alone at 50 °C for 60 min incubation and heating at 85 °C for 30 min.