含冷冻带鱼糜的复合鱼糜凝胶特性的研究

通过质构测定和SDS-PAGE方法,分析了冷冻带鱼糜加入到白鲢鱼糜后带鱼糜对复合鱼糜凝胶特性的影响。结果表明,非热处理带鱼糜可显著降低复合鱼糜的凝胶强度,而凝胶劣化特性则被显著提高;带鱼糜经热处理后使复合鱼糜的凝胶强度和凝胶劣化指数都得到明显改善;加入带鱼糜的蛋白酶提取液经55℃反应240min后肌球蛋白重链（Myosin Heavy Chains,MHC）全部消失。证明冷冻带鱼糜中含有蛋白酶能够降低复合鱼糜凝胶特性。      

不同蛋白添加剂对秘鲁鱿鱼鱼糜凝胶特性的影响

为了改善秘鲁鱿鱼鱼糜的凝胶特性,本文研究了添加不同种类的蛋白添加剂（卵清蛋白,猪血浆蛋白,乳清蛋白,大豆蛋白）对秘鲁鱿鱼鱼糜凝胶破断力,凹陷距离,凝胶强度,色泽的影响,并通过SDS-PAGE电泳分析其肌原纤维蛋白的降解情况。结果发现:添加卵清蛋白可显著增强鱿鱼鱼糜的破断强度和凝胶强度（p<0.05）,添加乳清蛋白和大豆蛋白对秘鲁鱿鱼鱼糜破断强度和凝胶强度的提高没有明显的促进作用,而添加猪血浆蛋白粉则对秘鲁鱿鱼鱼糜的破断强度和凝胶强度有一定的降低作用。添加各种蛋白粉的鱿鱼鱼糜凝胶凹陷度变化不大。而添加几种蛋白粉均会使鱼糜凝胶的白度降低,其中添加猪血浆蛋白粉对鱼糜白度的影响最大。通过SDS-PAGE分析,秘鲁鱿鱼鱼糜在添加蛋白后肌球蛋白的变化不明显。这表明蛋白添加剂的蛋白酶抑制剂作用效果不大。      

Comparison of the properties of gels derived from cod surimi and from unwashed and once-washed cod mince

Surimi is a washed and stabilized fish mince with valuable gel-forming properties. However the preparation process is wasteful and a modified process, with less washing, was investigated. The properties of the gels (cooked at 40°C for 30 min followed by 90°C for 40 min) were assessed by instrumental and sensory methods. Gels prepared from surimi were soft and very flexible; gels from unwashed fresh cod mince were firmer and less elastic, but still gave a maximum score on the folding test. A single wash made the gels firmer and slightly more elastic than those from unwashed mince. Gels from unwashed mince of frozen cod were firmer than surimi-derived gels, and were the most brittle. Sensory assessment of the gels found no difference in firmness between the different washing procedures and small differences in elasticity and toughness. The addition of starch (fish: starch, 100:5, w/w) increased the firmness and sensory toughness of each derived gel, and reduced the elasticity in the mouth of non-surimi gels. The colour of gels derived directly from fish was off-white, compared with the white surimi-derived gels. The colour of the former darkened during frozen storage, but lightened again after thawing.     

食盐和大豆蛋白对牛肉凝胶特性的影响

主要研究了食盐和大豆蛋白对牛肉凝胶特性及颜色的影响,结果表明:随食盐添加量的增加,牛肉糜的凝胶硬度、弹性和粘聚性均增加,亮度L值显著降低,对红色度a值影响不显著;随大豆分离蛋白添加量的增加,凝胶硬度逐渐增加,弹性逐渐降低,对粘聚性的影响不显著,并使牛肉糜的亮度L值显著降低,但对红色度a值影响不显著。     

冷冻大豆分离蛋白凝胶的功能性分析

为明确冷冻后SPI凝胶的功能性变化,分析了SPI凝胶在冷冻前后的质构特性、可溶性蛋白含量及成分、扫描电镜的图像等指标。研究发现:SPI的凝胶在冷冻后硬度增加,弹力、持水率、可溶蛋白含量降低;SDS-PAGE电泳结果表明冷冻后凝胶可溶蛋白部分γ亚基消失、A亚基增多;扫描电镜分析结果显示,冷冻后水分聚集凝结成较大冰晶,凝胶由致密的结构变成多孔的网状结构。      

鱼糜凝胶形成机理及提高鱼糜凝胶特性的添加物研究新进展

鱼糜凝胶特性是评价鱼糜品质的重要指标,介绍了鱼糜凝胶形成机理及引起凝胶劣变的内在因素,综述了目前用于提高鱼糜凝胶特性的添加剂最新研究进展,为我国淡水鱼鱼糜加工发展提供理论依据。     

The effect of modified starches on the gel properties and protein conformation of Nemipterus virgatus surimi

The study investigated the effect of native cassava starch (NCS), hydroxypropylated starch, acetic acid esterification starch (AAES), acetylated distarch phosphate on gel properties and protein conformation of Nemipterus virgatus surimi. Addition of 10 g kg^?1 NCS or 20 g kg^?1 AAES could significantly promote the gel strength and textural profiles of the surimi gels (p < .05). The water holding ability and whiteness of surimi were remarkably increased when the four types of starch were added at all concentrations (p < .05). In rheological test, the lower G′ was observed in surimi samples added with starch at low temperature, suggesting starch played an inactive filler role in surimi. Along with the increase of starch additive amount, ionic bond and hydrophobic interaction first increased and then decreased, while hydrogen bond first decrease and then increased. According to Raman spectroscopy data, small content of starch promoted the heat‐induced conformational transition of surimi protein from α‐helix to β‐sheet, leading to the change in gel properties of surimi gels. Scanning electron microscopy photographs showed surimi gels added with 20 g kg^?1 starch had the finer and denser network structure. Therefore, 20 g kg^?1 AAES or 10 g kg^?1 NCS or 10 g kg^?1 HS could be proposed to a potential modifier to effectively improve the quality of surimi products.     

Cryoprotective effects of trehalose and sodium lactate on tilapia (Sarotherodon nilotica) surimi during frozen storage

The cryoprotective effects of trehalose and sodium lactate at level of 8% (w/w) in tilapia surimi were studied in comparison with a conventional cryoprotectant (sucrose/sorbitol, 1:1) during extended storage at −18 °C for up to 24 weeks. All present cryoprotectants retarded the protein changes as evidenced by the lowered decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, total sulfhydryl content as well as the impeded increase in disulfide bond content and surface hydrophobicity. The gel-forming ability of frozen surimi was more retained with addition of cryoprotectants. Among all cryoprotectants used, trehalose exhibited the greatest protective effect on protein denaturation as shown by the effectiveness in maintaining Ca²⁺-ATPase activity and protein solubility. Additionally, the greatest breaking force and deformation were obtained in surimi added with 8% trehalose throughout the frozen storage up to 24 weeks. Sodium lactate showed a similar cryoprotective effect to sucrose/sorbitol blend. Therefore, trehalose and sodium lactate appeared to be promising alternative cryoprotectants for surimi owing to their low sweetness and caloric value.     

蒸制对冷冻荞麦熟面品质的影响研究

为了改善冷冻荞麦熟面的品质特性,采用汽蒸的方式对其进行预处理,研究蒸面预处理对冷冻荞麦熟面品质(面条吸水率、蒸煮损失及质构特性)的影响。同时采用快速黏度分析仪(RVA)和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析蒸面预处理对面条的糊化特性及蛋白质亚基结构的影响。结果表明,汽蒸处理能显著降低面条的蒸煮损失,提高其复热后的硬度、弹性和咀嚼性,并且蒸制3 min时,其总蒸煮损失达到最小值。RVA分析表明,随着汽蒸时间的增加,淀粉的崩解值和峰值黏度降低,而糊化温度增加。SDS-PAGE图谱显示,随着蒸面时间的延长,低分子质量亚基条带的颜色变浅,说明汽蒸可能诱导其发生了交联聚合行为。因此,蒸面预处理可以提高面条的蒸煮特性和质构特性,改善冷冻荞麦熟面的品质特性。     

淘汰蛋鸡肉糜功能特性影响因素研究进展

淘汰蛋鸡肉糜加工过程中的漂洗，加热，添加剂应用是影响其功能特性的主要因素。作者介绍了淘汰蛋鸡肉糜的功能特性，并对其主要影响因素－加工工艺和添加剂进行了综述论述。     

谷氨酰胺转氨酶及辅料对珍珠蚌肉糜凝胶性质的影响

以采珠后的蚌肉为试验对象,研究谷氨酰胺转氨酶(TG酶)及辅料对蚌肉肉糜凝胶硬度、内聚性和弹性质构特性的影响。结果表明:TG酶改善蚌肉糜凝胶性的最佳作用条件为:酶的添加量2%,pH 7,45℃反应1.0h。蚌肉肉糜凝胶性得到了良好的改善,该条件下的硬度为5 910.647g,内聚性为0.820,弹性为0.914。辅料的添加也能改善蚌肉糜凝胶性质,马铃薯淀粉、蛋清蛋白和大豆分离蛋白的最佳添加量分别为6%,6%和9%。为蚌肉糜制品的质构性质优化提供了理论依据。     

冻结温度对速冻方竹笋品质特性的影响

为评价速冻方竹笋的品质特性,实验以金佛山方竹笋为原料,研究不同冻结温度对速冻方竹笋的品质特性影响。结果表明:-23℃和-40℃冻结温度的速冻方竹笋水分含量分别为91.62%、90.49%,与对照组比较显著下降（p<0.05）;硬度分别为628.50±55.72、（746.67±30.2）g,剪切力分别为2286.03、2851.13 g（p<0.05）,但均与对照组呈显著性下降（p<0.05）;L*值分别为70.73±0.26、68.52±0.54,a*值分别为-1.50±0.08、-2.03±0.20,显著下降（p<0.05）;b*值分别为24.06±0.15、25.20±0.19,显著增加（p<0.05）。说明速冻对方竹笋的品质特性有显著影响,但-40℃冻结更有利于保持方竹笋的质地。      

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%.     

Structural and functional properties of soy protein isolate and cod gelatin blend films

The structure-function relationship of composite films obtained from soybean-protein isolate (SPI) and cod gelatin was studied. Films with different ratios of SPI:gelatin (0, 25, 50, 75, 100% [w/w]) and plasticized by a mixture of glycerol and sorbitol were prepared by casting. Regardless of the soybean-protein concentration, the thickness and water-vapor permeability of the composite films diminished significantly as compared to pure-gelatin films. The formulation containing 25% SPI: 75% cod-skin gelatin had the maximum force at the breaking point, which was 1.8-fold and 2.8-fold greater than those of 100% gelatin and 100% SPI films, respectively. Moreover, this formulation offered high percent-deformation values lower than those of gelatin but higher than all other films containing SPI-, and the same relatively low water-vapor permeability as the 100% SPI film. While all the films exhibited high water solubility, a slight reduction in film solubility and soluble protein was observed with increasing SPI concentration. Differential-scanning calorimetry analyses revealed that gelatin was completely denatured in all films, while soy proteins largely maintained their native conformation. Analysis by fourier-transform–infrared spectroscopy revealed that the presence of 25% SPI produced gelatin conformational changes, self-aggregation of gelatin chains, and intermolecular associations via CO bonds between gelatin and SPI proteins. All films were translucent in appearance, but the yellowish color increased with increasing proportions of the soybean proteins.     

Effect of pretreatment of hydrostatic pressure on physicochemical properties of tilapia muscle protein gels induced by setting

ABSTRACT:  Tilapia meat pastes were subjected to pretreatments of hydrostatic pressure (50 to 300 MPa/4 °C/60 min) followed by setting (50 °C/60 min) with or without subsequent cooking (90 °C/20 min) to investigate the changes of rheological properties, gel-forming ability, whiteness, and protein solubility of gels. The gel by setting only as the control was elastic, rigid, and mainly constituted by covalent bonds. The gel by pretreatments of 50 MPa was similar to the control. A 100-MPa pretreatment induced a viscous and soft gel with mainly noncovalent bonds. The 200-MPa pretreatment produced a gel with strongest breaking force and strain compared with all the treatments in this study; moreover, the gel was mainly constituted by hydrogen bonds. A gel induced by a 300-MPa pretreatment was the most viscous. Via subsequent cooking (90 °C/20 min), all the gels became more rigid and elastic except that induced by a 100-MPa pretreatment.     

海鲈鱼鱼糜冻藏过程中流变特性及凝胶结构的变化规律

为研究不同冻藏温度和冻藏时间对海鲈鱼鱼糜的流变特性和凝胶结构的影响,实验采用流变仪和显微镜对冻藏过程中的鱼糜进行分析观察。结果显示,海鲈鱼鱼糜的黏度随剪切速率增加而减小,存在剪切变稀现象;鱼糜的弹性模量(G′)和损耗模量(G″)随频率的增加而升高;鱼糜凝胶过程经历了三个阶段(不同冻藏温度和冻藏时间的鱼糜有所偏差):第一阶段在40℃之前,第二阶段出现在40~50℃,第三阶段在50℃之后,蛋白开始形成最终的凝胶;鱼糜随冻藏温度的升高和冻藏时间的延长,鱼糜的G′和G″减小,黏弹性下降,损耗角正切(tanδ)增大,流动性增加。鱼糜凝胶的微观结构显示,随冻藏温度升高和冻藏时间延长,纤维基质的损伤越大,形成的凝胶性能越差。本研究对海鲈鱼鱼糜的应用具有一定的借鉴意义。      

4种鱼糜加工漂洗液回收蛋白对罗非鱼鱼糜凝胶特性与质构的影响

目的 探究4种回收水溶性蛋白对罗非鱼鱼糜凝胶特性及质构的影响。方法 分别将等电点沉降法回收蛋白、海藻酸钠单一絮凝剂回收蛋白、壳聚糖单一絮凝剂回收蛋白和海藻酸钠-壳聚糖复合絮凝剂沉降回收蛋白以0%、5%、10%、15%、20%掺入罗非鱼鱼糜制备鱼肠,比较各样品在凝胶强度与全质构分析(texture profile analysis, TPA)参数上的差异,包括硬度、胶着性、咀嚼性、内聚性与弹性。结果 4种回收蛋白替代会对凝胶强度产生不利影响,通过等电点沉降法回收的蛋白对凝胶强度的影响最大,凝胶强度持续下降,最低达1708g·mm;以复合絮凝剂回收蛋白的掺入对原凝胶强度的影响最小,通过替代5%鱼糜,凝胶强度降为3833 g·mm。当用壳聚糖单一絮凝剂回收蛋白掺入5%时,与原鱼糜制品的TPA参数最接近,表现为硬度2505 g,胶着性1788 g,咀嚼性192.3 mJ,且内聚性和弹性也没有表现出明显差异。结论 这4种回收蛋白均以5%的添加量替代罗非鱼鱼糜时,制品凝胶强度在企业的可接受线性范围内,综合凝胶强度与TPA参数,以壳聚糖单一絮凝剂回收的蛋白替代产生的影响最小,可为回收鱼糜蛋白这一资源...     

Effect of freeze–thaw cycles and additives on rheological and sensory properties of ready to bake frozen chapaties

The wheat grains were conditioned at 18% moisture level for 1 h followed by heating for 80 s in a microwave oven to reduce the activity of polyphenol oxidase as well as other lipolytic and oxidative enzymes. The dough samples were prepared from whole wheat flour (milled from microwave treated wheat grains) using 68% water and 2% salt on flour weight basis as common ingredients. The additives like glycerol monostearate and glycerol (5% and 1% respectively on flour weight basis) were also used in order to study their effects on the quality of ready to bake frozen chapaties (R-BFC) during freeze–thaw cycles. Alveographic properties of R-BFC as well as textural profile and sensory quality of chapaties prepared from R-BFC samples were evaluated during repeated freeze–thaw (FT) cycles. Results showed that the alveographic properties (P, L, and W) decreased significantly ( P  ≤   0.05) in all the samples after each FT cycle, while glycerol added samples showed the least changes. Chapati hardness increased in all the samples up to fourth FT cycle, thereafter sharply decreased. However, chapaties with 1% glycerol were rated better in terms of mouth feel and texture during FT cycles.     

四种非肌肉蛋白对冷冻竹荚鱼鱼糜凝胶能力的影响研究

探讨了四种常用的非肌肉蛋白对竹荚鱼鱼糜凝胶特性的影响,对不同鱼糜加热过程中凝胶强度、持水力、白度、SDS-PAGE电泳图谱以及微观结构的变化进行比较。实验结果表明,血浆蛋白对冷冻竹荚鱼的蛋白酶有很强的抑制效果,最佳添加量为1%。卵清蛋白及乳清蛋白在5%高浓度时其凝胶增强效果与1%的血浆蛋白添加效果近似,大豆蛋白的效果较差,四种蛋白对鱼糜白度、持水力影响不大。非肌肉蛋白应用于竹荚鱼鱼糜的品质改善中,对凝胶劣化有一定的抑制,这对竹荚鱼鱼糜的品质控制具有一定意义。     

食品添加剂对牛初乳免疫球蛋白(IgG)稳定性的影响

探讨了几种常用食品添加剂对牛初乳免疫球蛋白稳定性的影响,根据食品添加剂对IgG的变性率的影响,选择了几种在食品加工中常用的添加剂进行正交试验,考察其相互综合作用。结果表明:随着柠檬酸、乳酸和磷酸二氢钠浓度的增大,免疫球蛋白的稳定性逐渐降低,变性率逐渐增大;山梨酸钾对免疫球蛋白的稳定性影响较小;磷酸氢二钠、乳酸钙、增稠剂和甜味剂对免疫球蛋白有一定的保护作用。添加剂最佳用量为:乳酸用量为0.3%,乳酸钙用量为0.015%,黄原胶用量为0.5%,蔗糖用量为8%,此时IgG的变性率为14.7%,在4℃的贮藏条件下最佳保存期为30天。