提取条件对鲨鱼肉盐溶蛋白热诱导凝胶特性的影响

以鲨鱼肉为材料,研究NaCl 浓度、pH 值、静置提取时间及加热时间对鱼肉盐溶蛋白热诱导凝胶保水性和质构特性的影响。结果表明：鲨鱼肉盐溶蛋白凝胶的保水性、硬度、弹性和黏聚性与NaCl 溶液浓度呈正相关;在NaCl 溶液浓度0.8mol/L、pH6.5～7.0、静置提取时间24h、40℃加热40～60min 时形成的凝胶保水性及其质构指标较理想;40℃加热盐溶蛋白,有利于形成凝胶结构,但随着加热时间的延长,盐溶蛋白凝胶硬度增加,保水性降低。     

NaCl对猪肉干燥过程中质构特性的影响

以猪背最长肌为研究对象,经不同浓度NaCl溶液腌制后,60 ℃下热风干燥后其质构特性参数随含水率和NaCl含量的变化规律。结果表明:随含水率降低,各样品的剪切力值、硬度及咀嚼性均逐渐增加,而弹性、内聚性则逐渐下降;在相同含水率下,腌制液NaCl浓度≤8%腌制样的剪切力值、硬度、咀嚼性随NaCl浓度的增大而增大,腌制液NaCl浓度＞8%腌制样的上述参数随NaCl浓度增大而减小,各腌制样的弹性随腌制液NaCl浓度升高而逐渐减小,内聚性受NaCl浓度的影响较小。由部分物理指标与质构特性参数之间的相关性分析可知:肉样的质构特性参数与样品的含水率、横向收缩比(LSR)、纵向收缩比(TSR)、体积变化率等极显著相关(p<0.01),而相关系数的大小与腌制液NaCl浓度有关。研究结果为腌制肉的品质控制提供参考。     

模糊数学结合响应曲面法优化麻鸭肌原纤维蛋白凝胶工艺

以麻鸭胸脯肉为原料,提取肌原纤维蛋白并对其进行加热诱导形成凝胶,研究不同的因素(蛋白浓度、p H值、凝胶温度、Na Cl浓度)对蛋白凝胶特性的影响并对诱导条件进行优化。在单因素实验基础之上,利用模糊数学对凝胶质构性质和保水性进行综合评价选择p H、加热温度、Na Cl浓度为自变量,蛋白凝胶综合评价得分为响应值,进行响应曲面优化分析。结果表明:蛋白浓度、p H、凝胶温度、Na Cl浓度都会对肌原纤维蛋白凝胶的保水性和质构特性产生影响。得到最佳诱导条件为:p H 7.0、Na Cl浓度0.6 mol/L、凝胶温度72℃;在此条件下得到的蛋白凝胶的综合评价得分为0.541。     

稻秸灰水提物对咸蛋黄理化特性的影响

本研究将稻秸灰水提物与食盐混合配制腌制液腌制咸蛋,并比较了食盐水腌制和水提物腌制对咸蛋黄含盐量、含水量、出油率、流变特性、质构特性、蛋白结构的影响,研究表明:由于盐类的进入和油脂渗出,蛋黄的质构特性如:硬度、胶黏性、咀嚼性呈先增大后减小的趋势(p0.05),其中水提物组硬度从272.89 g增至最大值458.65 g后又逐渐降至228.87 g。流变学结果显示蛋黄弹性模量和粘性模量均显著增大。水提物组蛋黄蛋白二级结构中α-螺旋在25d时显著减少至12.36%(p0.05),β-折叠在25d时显著增大至41.71%(p0.05)。SDS-PAGE表明水提物的加入不会影响蛋黄蛋白质肽链结构。水提物组咸蛋黄的出油率达到20.12%,较盐水组高,出油率是评价咸蛋品质的一个重要指标。此研究既优化了传统草木灰包裹法工艺又保持着草木灰咸蛋的优良品质,为咸蛋腌制提供了一种新思路。     

右旋糖酐/蚕豆蛋白复合凝胶的流变特性

为研究乳酸菌右旋糖酐对蚕豆蛋白食品相关性质的影响，采用哈克流变仪和质构仪等测定了添加不同浓度右旋糖酐时GDL诱导的酸致蚕豆蛋白复合凝胶质构和流变特性等指标。结果表明：添加右旋糖酐能显著增加蚕豆蛋白凝胶保水性，空白组蚕豆蛋白凝胶保水性为60.38%，1%右旋糖酐与蚕豆蛋白形成的复合凝胶保水性为70.08%（p<0.05）；右旋糖酐浓度在0.25%~1%之间，对复合蛋白凝胶色泽有一定影响；0.5%右旋糖酐与蚕豆蛋白形成的复合凝胶强度为0.27 N，与空白组蚕豆蛋白凝胶（0.37 N）差异显著，可软化含高蚕豆蛋白食品质构特性；右旋糖酐/蚕豆蛋白复合凝胶流动曲线符合carreau模型（R2>0.99），具有假塑性流体的特性；应变扫描的弹性模量G''均高于黏性模量G''，说明右旋糖酐/蚕豆蛋白复合凝胶的弹性占主导；频率扫描结果显示添加右旋糖酐可软化蚕豆蛋白凝胶，使凝胶G''、G''降低，更易于加工。在蚕豆食品中添加右旋糖酐可改善蚕豆蛋白的质构和流变特性，为拓展其应用范围提供参考。     

蛋白质量浓度对鸡蛋热诱导凝胶特性的影响

以蛋清、蛋黄和全蛋液为原料,研究蛋清、蛋黄和全蛋蛋白热诱导凝胶的形成能力以及蛋白质量浓度对蛋清、蛋黄和全蛋蛋白热诱导凝胶特性的影响。结果表明：蛋清、蛋黄和全蛋形成热诱导凝胶的最低蛋白质量浓度分别为50、55、50mg/mL;在50～135mg/mL范围内,随蛋白质量浓度的增加,蛋清、蛋黄和全蛋蛋白的凝胶强度和保水性不断增大,蒸煮损失整体呈下降趋势;蛋白质量浓度对蛋清、蛋黄和全蛋凝胶的弹性也有显著影响。     

真空滚揉腌制对伊拉兔肉品质特性的影响

本实验研究了真空滚揉腌制前后伊拉兔肉食用品质特性、质构特性、肌浆蛋白、肌原纤维蛋白、总蛋白溶解度和游离氨基酸含量的变化。结果表明：真空滚揉腌制可以显著改善兔肉的食用品质,提高兔肉的pH值,改善兔肉的色泽,降低兔肉的蒸煮损失和压榨损失,提高保水性,改善兔肉嫩度和质构特性;真空滚揉腌制会导致肌原纤维蛋白分解、肌浆蛋白溶出、游离氨基酸含量下降,引起兔肉品质特性的变化。     

不同腌制方式对猪排骨品质的影响

为探索不同腌制方式对猪排骨品质的影响,该研究以猪排骨为原料分别进行常压静态腌制(static pressure marination, ST)、间歇真空滚揉腌制(vacuum intermittent tumbling marination, IT)和连续真空滚揉腌制(vacuum continuous tumbling marination, CT),腌制时间均为6 h。分别测定腌制后猪排骨的腌制吸收率、水分含量及水分状态、离心损失、剪切力及TPA质构、肉内部盐溶性蛋白浓度。结果显示, IT组和CT组较ST组在腌制吸收率、保水性以及嫩度等方面均显著改善(p0.05),其中CT组具有最佳改善效果。CT组的腌制吸收率较ST组和IT组分别改善了168.49%和27.50%;剪切力和硬度也显著降低(p0.05);不易流动水峰面积百分比例较其他组显著增加(p0.05),保水性显著提高(p0.05);肉内部盐溶性蛋白浓度降低,溶出量显著增加。综上,真空滚揉提高了猪排骨的腌制效果,加快盐溶性蛋白的溶出,并提高了肉的保水性,改善其嫩度。研究结果为连续式真空滚揉腌制改善猪排骨的保水性、嫩度等品质提供了理论依据,并为相关设备的开发提供参考。     

利用核磁共振技术研究食盐对鸭蛋黄品质的影响

利用低场核磁共振及其成像技术研究食盐对鸭蛋黄品质影响的作用机制。在不同食盐添加量条件下,测定蛋黄质构特性、可溶性蛋白含量和出油率的变化,并分析蛋黄弛豫特性分别与质构特性和出油率之间的相关性。结果表明:食盐对蛋黄质构特性及弛豫特性有显著性影响,且随着食盐添加量的增加呈现规律性变化,而随着食盐添加量的增加,蛋黄可溶性蛋白含量先增加后下降,出油率先下降后上升,并分析得出蛋黄弛豫特性与蛋黄质构特性和出油率均呈显著相关性。表明食盐会改变鸭蛋黄内部氢质子的迁移及分布,导致鸭蛋黄质构特性及出油率发生改变,进而影响鸭蛋黄的品质。     

皮蛋腌制过程中碱度、pH及质构特性变化规律的研究

采用简易传统铜盐清料法腌制皮蛋,研究皮蛋腌制过程中料液碱浓度、蛋内pH和游离碱度、蛋白的质构特性的变化规律,旨为皮蛋加工过程中的质量控制,开发代金属添加剂和研究新加工工艺提供基础数据。结果表明,在腌制过程中,料液碱浓度呈下降趋势;蛋白pH和游离碱度呈现先迅速升高,后逐渐下降,再缓慢回升的趋势;蛋黄pH和游离碱度则一直呈升高的趋势;蛋白硬度总体呈上升趋势;蛋白弹性、咀嚼性、内聚性均是先上升再略有下降,然后基本保持稳定。     

NaCl、糖类和木瓜蛋白酶对碱诱导蛋清凝胶性的影响

为了研究不同添加物在高温条件下对碱诱导蛋清凝胶硬度和色度所作出的贡献,把NaCl、糖类和木瓜蛋白酶加入到碱诱导的蛋清中并加热,以蛋清凝胶强度和色差等为评价指标,对不同添加剂作用于碱诱导下的蛋清凝胶进行研究。结果表明:1%的Na Cl使凝胶硬度显著上升(p<0.05),透光率显著下降(p<0.05),且显著增加了凝胶的白度(p<0.05),硬度从81.94g上升到144.94g,增加了77%,透光率从34.33%下降到9.10%,持水性随盐浓度增加而上升。蔗糖和麦芽糖的加入使凝胶质构变化较小,高浓度麦芽糖可降低凝胶的硬度,5%浓度的麦芽糖使凝胶的透光率显著下降(p<0.05),从25.3%下降到9.34%,减少了63%,而蔗糖的透光率却增加了26%,凝胶的总体白度都下降。木瓜蛋白酶的添加使凝胶的透光率显著上升(p<0.05),从34.33%上升到54.27%,增加了60%,凝胶的总体白度略微下降,凝胶硬度和咀嚼性下降了30%左右。综上所述,Na Cl、木瓜蛋白酶、蔗糖和麦芽糖对高温条件碱诱导的蛋清凝胶均有不同的影响,可为不同蛋制品的理化和感官需求提供参考依据。     

Effect of Sodium Chloride and Osmotic Dehydration on Viscoelastic Properties and Thermal-Induced Transitions of Duck Egg Yolk

The effects of NaCl and osmotic dehydration on the linear viscoelastic behavior of duck egg yolk were evaluated. An increase in NaCl concentrations from 0% to 3.0% (w/w) resulted in a remarkable change in the linear viscoelastic behavior by inducing a sol–gel transition, specifically. The transition was more pronounced when 1.5% (w/w) NaCl was incorporated. The effect of dehydration on aggregation and network formation was predominant than that of the NaCl addition. Nevertheless, at a lower degree of dehydration, the addition of NaCl could modulate the viscoelastic behavior of duck egg yolk, resulting in a well-developed gel network. Addition of NaCl into duck egg yolk could stabilize the protein molecules as evidenced by an increase in denaturation temperature as well as a delay in gel network formation. As visualized by a scanning electron microscope, the denser network with smaller voids was observed in duck egg yolk gel with increasing NaCl concentration and degree of dehydration.     

不同解冻方法对冰蛋黄功能特性、理化特性及蛋白质结构的影响

为缓解冻融对蛋黄品质的劣变影响,本研究以鲜蛋黄为对照组,以经室温自然解冻、静水浴解冻、超声波解冻及微波解冻处理的冰蛋黄为实验组,对其主要功能特性（蛋白质溶解性、乳化特性和凝胶特性等）、理化特性（质构特性、粒径和巯基与二硫键含量等）进行表征与对比分析,同时结合拉曼光谱探究各解冻方法下蛋白质结构的变化。结果表明：冰蛋黄在室温下自然解冻后的浊度最大,拉曼光谱显示脂蛋白烷基链C＝C伸缩振动强度最小,蛋白质二级结构中β-折叠相对含量最高,该解冻方法下蛋白质的交联聚集程度最高;静水浴解冻后蛋黄的蛋白质溶解性、乳化活性及乳化稳定性均显著低于超声波解冻（P＜0.05）,表面疏水性最强;微波解冻下蛋黄的二硫键含量显著高于超声波解冻（P＜0.05）,脂肪族氨基酸非对称C—H弯曲振动强度最大,蛋白质α-螺旋结构相对含量最低,解冻后有凝胶微粒形成;超声波解冻下蛋黄的乳化活性与乳化稳定性均较高,粒径最小且分布最为集中,硬度、内聚性及黏性等质构特性均较小且与鲜蛋黄无显著性差异（P＞0.05）。综上,本研究证明超声波解冻是冰蛋黄较为适用的解冻方法。     

热处理对酶改性蛋黄液乳化性的影响及拉曼光谱分析

蛋黄液对热敏感,64 ℃左右开始变性形成凝胶,加工过程中的热处理会导致其乳化性质下降,限制了其在食品工业中的应用。因此,本实验研究不同热处理条件（60、65、70 ℃均处理4 min）对酶改性蛋黄液乳化性质及蛋白质结构的影响。结果表明：随着热处理温度的升高,蛋黄液的乳化活性呈现下降的趋势,所形成的乳化体系平均粒径表现出增大的趋势。同一热处理条件下,酶改性蛋黄液的乳化活性及乳化稳定性均显著高于未改性蛋黄液（P＜0.05）,酶改性蛋黄液所形成的乳化体系粒径明显减小,粒径分布更加接近正态分布。拉曼光谱分析结果显示,在不同热处理条件下酶改性蛋黄液中蛋白质二级结构发生变化,在65 ℃以下随温度升高α-螺旋结构相对含量显著升高,无规卷曲结构相对含量显著下降（P＜0.05）;其色氨酸残基、酪氨酸残基及脂肪族疏水基团较未改性蛋黄液更倾向于暴露。采用偏最小二乘法建立了基于拉曼光谱的蛋黄液乳化性质模型,结果表明蛋黄液中蛋白质二级结构及构象变化（特别是低密度脂蛋白的构象变化）对蛋黄液乳化性质影响最大。     

Emulsifying characterization of hens egg yolk proteins in oil-in-water emulsions

Emulsifying properties of egg yolk as a function of pH and oil volume were studied. Egg yolk proteins formed larger emulsion particles at pH 3 and the mean droplet size of the emulsions was decreased with increasing pH. A linear relationship between turbidity and mean droplet size of egg yolk emulsions could not be obtained. This may be due to the floculation of the emulsions. Egg yolk proteins formed thicker multilayers at low oil volume, however total protein adsorption ratio against original proteins was 55–65%, independent to protein and oil concentration. Electrophoretic analysis of the egg yolk emulsion revealed that the main components to adsorb at the interface was glanular lipovitellins, even though its emulsifying property was lower than that of plasma because of poor solubility at low ionic strength (0.1 M NaCl) at pH 7. These results indicate that the main contributor for egg yolk emulsion is granules and it can affect the emulsifying properties of egg yolk at different pH values.     

SMALL DEFORMATION MEASUREMENTS OF SINGLE AND MIXED GELS OF LOW CHOLESTEROL YOLK AND EGG WHITE

Isolates of reduced-cholesterol egg yolk were prepared by extracting cholesterol from spray-dried yolk using the following solvents: (1) petroleum ether, (2) petroleum ether/ethanol, (3) ethanol/water and (4) supercritical carbon dioxide. Differential scanning calorimetry demonstrated that the temperature of minimum heat flow of the denatured isolates was about 75C. Mechanical properties of extracts were compared using small deformation oscillatory rheology. Ethanol/water and petroleum ether treated yolk had the strongest and weakest gelling characteristics respectively, following protein denaturation at 75C. When compared to egg white, yolk isolates formed stronger networks at 75C. Heating at higher temperatures denatured ovalbumin which produced slightly stronger gels than egg yolk. Binary mixtures of egg white and yolk formed phase separated gels. The best agreement between experimental data and calculated composite moduli by using isostrain and isostress Takayanagi models, was obtained for egg white keeping 37% more water per unit concentration than the egg yolk.     

Physicochemical and functional properties of Chinese soft-shell turtle (Pelodiscus sinensis) egg

The physicochemical properties of Chinese soft-shell turtle egg were characterized for functional use in the food industry. The egg yolk of un-fertilized soft-shell turtle eggs was separated and fractionated into granules and plasma. Then, the egg yolk, albumen, granules, and plasma were freeze-dried for further analysis. Results showed that the Chinese soft-shell turtle egg typically comprised 50% egg yolk, 34% albumen, and 16% shell in average. The egg yolk composed of 61% granules and 39% plasma. The granules contained most of the protein, while the plasma contained most of the lipid in egg yolk. The albumen contained about 26% ash on a dry weight basis. Lysozyme was the major component in turtle egg albumen. The protein solubility of egg yolk, granules, and plasma was affected by the changes in pH, while that of albumen remains constant. The emulsifying and foaming properties increased when the concentration increased for all samples. Both the yolk and the albumen in turtle egg exhibited better functional properties than those in normal hen egg. These physicochemical and functional properties of Chinese soft-shell turtle egg are fundamental and essential for future study and food applications.     

血浆蛋白对调理猪排品质特性的影响

本文以大豆分离蛋白、鸡蛋白为对照,探讨血浆蛋白对调理猪排品质特性的影响,对-18℃冷冻调理猪排解冻损失、压榨损失、质构特性、凝胶强度、流变特性、水分迁移和微观结构进行分析。结果表明:2.5%血浆蛋白可以改善调理猪排的品质特性,有效降低猪排的解冻损失和压榨损失(P<0.05),提高不易流动水含量和蛋白凝胶强度(P<0.05),促使微观结构更加致密。与3.0%大豆分离蛋白相比,添加2.5%血浆蛋白的猪排硬度、弹性、咀嚼性更高;与2.5%鸡蛋白相比,血浆蛋白可明显提高肌原纤维蛋白的储能模量(G')、损耗模量(G″),延迟肌原纤维蛋白的变性温度(50~65℃);蛋白种类对猪排色泽无明显影响。因此,血浆蛋白在猪排保水性、凝胶特性、质构特性、流变特性方面展现出极大优势,为血浆蛋白在肉质品中的应用提供理论基础。     

Enhanced mass transfer of osmotic dehydration and changes in microstructure of pickled salted egg under pulsed pressure

Pulsed pressure osmotic dehydration (PPOD) technology is much more effective than the traditional pickling for salted egg. This study was designed to compare the changes of water and salt in salted egg under five pressures and five pulsation frequencies in saturated brine solution (?25% NaCl (w/w)). Results showed that moisture content of both egg white and yolk significantly decreased with concomitant increase in salt content compared to traditional pickling. PPOD caused increases in water loss and salt gain of eggs and the optimal pressure and pulsation frequency were 160 kPa and 7.5 min/15 min. Moreover, hardening ratio of egg yolk increased as pickling time and storage time increasing. About 2.92–15.63 fold diffusivity was found for the egg under PPOD compared to traditional pickling over the same time period. Environmental Scanning electron microscopic study revealed that yolk granule was aligned closely and became increasingly smaller after pickling.     

基于低场核磁共振技术分析不同贮藏条件下白煮蛋水分分布及品质变化

研究去壳及带壳白煮蛋在冷藏（4 ℃）和室温（25 ℃）贮藏过程中水分体积分数、氧化情况、质构及颜色 等品质的变化,采用低场核磁共振、质构分析及扫描电子显微镜等技术分析样品的水分分布、质构特性和微观结 构,通过测定羰基含量及硫代巴比妥酸反应产物含量反映蛋白质和脂肪氧化情况。结果表明：在贮藏过程中,白煮 蛋蛋清和蛋黄的水分体积分数,尤其是不易流动水体积分数,随着贮藏时间的延长而减少（P＜0.05）,蛋白及脂 肪氧化程度逐渐增加,去壳处理是这些变化的重要影响因素;同时,白煮蛋硬度和咀嚼性随贮藏时间的延长逐渐 增加,凝胶微观结构更加致密,感官品质下降,但在所有实验组中,4 ℃带壳贮藏的白煮蛋品质变化幅度最小;贮 藏温度对白煮蛋颜色无显著影响（P＞0.05）,但去壳处理使得白煮蛋颜色发生显著变化（P＜0.05）。综合分析表 明,白煮蛋在贮藏中水分的损失和氧化是导致其品质下降的重要原因,带壳冷藏是白煮蛋较好的贮藏条件。