Functional Properties of Heat-Treated Egg Yolk Low Density Lipoprotein

Egg yolk low density lipoprotein (LDL) was heated at various temperatures from 55°C to 100°C for 5 min and transmission, extractability of lipid, emulsifying property and foaming property of each solution were examined. Transmission of LDL solution decreased for treatments above 60°C and was almost 0 at 75°C. Above 70°C, lipid extractability gradually decreased with increase of treatment temperature. Emulsifying property and apparent viscosity were significantly correlated with the extractability of lipid.     

咸鸭蛋腌制过程中蛋黄凝聚变化分析

为研究贵州三穗特色咸鸭蛋腌制过程中,蛋黄凝聚过程的变化及关键控制点,采用低盐腌制,检测氯化钠作用下,蛋黄凝聚部分的蛋白质相关指标的变化。结果表明：腌制8 d时,离子键及疏水相互作用增强,氢键及二硫键减弱,α-螺旋与β-折叠的占比降低,γ-随机结构与β-转角的占比增加,蛋白质二级结构发生变化,蛋白质发生变性,NaCl改变了低密度脂蛋白结构,蛋黄的蛋白质-脂肪乳化体系被破坏,未发生聚集形成凝胶结构。腌制12～16 d时,离子键强度减弱,氢键、疏水作用、二硫键含量增加,α-螺旋结构占比继续下降,γ-随机、β-折叠、β-转角结构占比均略有上升,蛋黄蛋白质分子发生聚集,并出现较明显的松沙口感,出油量在40%以上。腌制16～28 d时,低密度脂蛋白结构继续更新,蛋黄水分继续流失,为脂质分子聚集形成油滴提供了更有利的环境,蛋黄的脱水与蛋白质凝胶的结合使蛋黄最终成为球状凝聚体。观察腌制过程中蛋黄凝聚部分的微观结构,发现蛋黄颗粒逐渐减小,排列紧密,且出现交联作用,这是腌制咸蛋黄产生特殊的松沙感的主要原因。结论：腌制12～16 d是咸蛋黄形成独特松沙口感及渗油现象的关键阶段,蛋白质分子的聚集有利于油脂渗出...     

Isolation of Egg Yolk Granules as Low‐Cholesterol Emulsifying Agent in Mayonnaise

Egg yolk is an essential ingredient for many food products due to its excellent functional properties such as emulsification. However, the consumers’ concern of its cholesterol level has led food industry to seek solutions for its replacement. Utilization of low‐fat egg yolk granules as emulsifier can be an alternative strategy. In this study, granules with low cholesterol content were separated from egg yolk by a simple method under easily scalable centrifugal conditions. The egg yolk granules isolated within 0.17 M NaCl solution achieved a 22.5% yield that was similar to that using higher centrifugation speeds and longer time. The yield of egg yolk granules increased from 25% to 32% when the yolk:water ratio was changed from 1:1 to 1:2. Mayonnaise was prepared to evaluate the emulsifying capacity of the egg yolk granules. It was found that egg yolk granules exhibited similar emulsifying activity as that of whole egg yolk, but a better emulsion stabilizing property that is evidenced by the higher viscosity of mayonnaise prepared with the granules. In addition, the viscosities of mayonnaise prepared by spray dried yolk and granules were slightly higher than the liquid counterpart, showing a further improvement by spray drying on the emulsion stabilizing properties. The mechanical spectra of mayonnaise samples by frequency sweep also suggested that granules favored the formation of stronger 3‐dimensional arrangements of oil droplets and therefore a more stable emulsion. Results suggest that granules isolated within 0.17 M NaCl solution present best emulsifying properties and can be applied as whole yolk replacer in food emulsions.     

咸蛋黄制备过程中理化指标变化规律的研究

对鸡蛋蛋黄单独腌制,测定咸蛋黄在不同腌制条件下含盐量、水分含量、出油率、蛋黄色差的变化规律,分析其指标间的相关性,并用扫描电子显微镜观察内部结构变化。结果表明:随着腌制液浓度的提高以及腌制时间的加长,含盐量、出油率、蛋黄色差增加,水分含量下降,且各指标间存在相关性。同时,蛋黄内部因腌制使得蛋黄颗粒之间变得疏松。     

咸蛋黄成熟机制及品质影响因素研究进展

论述咸蛋黄在腌制中的蛋黄指数、出油、起沙的变化规律及其品质影响因素,归纳出成熟机制主要是食盐的渗透作用和脱水作用引起蛋内物理化学性质变化。腌制温度、腌制方法、保藏时间、食盐用量、酸性、碱性添加剂等因素都会影响蛋黄品质,在加工中对其进行控制,对提高产品的稳定性和质量会有所帮助。     

Cholesterol and Other Lipid Extraction from Egg Yolk Using Organic Solvents: Effects on Functional Properties of Yolk

Cholesterol extraction from dehydrated egg yolk, using petroleum ether or petroleum ether-ethanol (35:65) resulted in decreased cholesterol content with petroleum ether and almost complete removal with petroleum ether-ethanol. Yolk extracted with petroleum ether gave emulsions of similar rates of coalescence to those prepared with dried yolk and mayonnaise-like emulsions of higher Theological properties. Yolk extracted with petroleum ether-ethanol gave emulsions of lower stability and did not lead to preparation of mayonnaise-like emulsions. Both yolk protein concentrates showed better foaming activity and foam stabilizing ability than dried yolk.     

食盐对咸蛋黄蛋白质特性的影响

研究氯化钠对咸鸭蛋蛋黄中蛋白质特性的影响。新鲜蛋黄可溶性蛋白含量为1.95g/100g湿基,第15周咸蛋黄中为4.30g/100g湿基;新鲜蛋黄的巯基含量为0.057mmol/g pro,到第3周出现峰值0.102mmol/g pro;差示扫描量热仪(DSC)分析表明食盐对咸蛋黄蛋白质的耐热性有促进作用,新鲜蛋黄热转变温度为79.06℃,第15周转变温度升高到80℃;SDS-PAGE电泳表明食盐的腌制没有对蛋白质肽链结构产生影响;傅里叶变换红外光谱表明,蛋白质的二级结构发生较大变化,新鲜蛋黄蛋白质的二级结构以α螺旋和β折叠为主,占74.67%,腌制以后α螺旋和β折叠结构部分转化为T转角。     

卵黄高磷蛋白磷酸肽的制备及钙结合性质研究

以卵黄高磷蛋白质为原料 ,经碱法脱磷、胰蛋白酶水解后分离制备得到一种新型的卵黄高磷蛋白磷酸肽 (PPP) .卵黄高磷蛋白质经 0 .1,0 .2 ,0 .3,0 .4mol/LNaOH处理 3h ,脱磷率分别为34.6 % ,81.6 % ,92 .5% ,96 .3% .SDS PAGE电泳结果显示 ,脱磷卵黄高磷蛋白质经胰蛋白酶水解后 ,产物为小分子肽 .经BaCl2 法和超滤法分离得到的磷酸肽的平均氨基酸残基数分别为 10个与2 0个 .对PPP的钙结合能力进行了研究并同商品化酪蛋白磷酸肽 (CPP)进行了比较 .PPP能有效地与钙络合 ,因而它在功能食品中有着较好的应用前景 .     

蛋黄蛋白-植酸静电复合物对蛋黄乳液物理稳定性的影响

为改善蛋黄（egg yolk,EY）在酸性乳液体系的物理稳定性,采用EY蛋白与植酸（phytic acid,PA）形成静电复合物稳定EY乳液。研究酸性条件下PA质量分数（0%～0.8%）对EY蛋白及EY乳液物理稳定性的影响。结果表明,pH 3.0时,EY与0.012 5%～0.8% PA形成不溶性的静电复合物EY-PA;最优质量分数（0.2%）PA与含1%蛋白的EY形成复合物制备乳液较对照组的乳液黏度升高,粒径及乳析指数显著降低（P＜0.05）,界面蛋白质吸附量显著提高（P＜0.05）,乳滴分布更均匀,乳液的抗聚结效果提高。因此,EY蛋白与PA形成的静电复合物可调控EY乳液的理化特性,提高EY在酸性乳液体系的物理稳定性。     

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。     

咸蛋腌制添加抗氧化剂改善蛋黄的内质特性

为解决实际生产中咸蛋黄硬心、黑圈的问题,将三种天然抗氧化剂应用于咸蛋包泥腌制工艺中,比较其对咸蛋内质理化指标的影响.试验结果表明:料泥中添加茶多酚、虾青素、酵母硒不改变咸蛋成熟期(19 d),可显著减小蛋黄硬心质量比(5.75％、6.68％、9.06％,对照15.32％)和抑制黑圈生成(1％～6％、2％～5％、8％～1...     

Super Chilling Enhances Preservation of the Freshness of Salted Egg Yolk During Long-Term Storage

ABSTRACT:  Pasteurized egg yolk with 10% (w/w) salt was stored at 5, –5, –15, –20, and –30 °C for 1 to 6 mo, respectively. Changes in generation of volatiles of the stored samples (5 and −5 °C for 6 mo) were analyzed by SPME-GC-MS. Emulsifying properties of egg yolk stored at −5, −15, −20, and −30 °C for 1 mo, respectively, were also evaluated by measurement of emulsion particle diameters in model emulsions prepared with the yolk samples. In addition, structural changes in low-density lipoprotein (LDL) in the egg yolks dependent on storage conditions for 6 mo were evaluated by ³¹P–NMR. Volatile compounds such as hexanal, 2-methylbutanal, and 3-methylbutanal increased in egg yolk during storage at 5 °C; however, volatile compounds hardly increased in any samples stored at −5 °C (super chilling). The mean emulsion particle diameter in super chilled egg yolk was significantly smaller than that in egg yolk stored at the other lower temperatures. In addition, the results of ³¹P–NMR evaluation suggested that prevention of structural changes of LDL resulted in maintenance of emulsifying properties of egg yolk. Thus, these results indicate that super chilling is an effective means of preserving salted egg yolk during long-term storage.     

Conditions Affecting Emulsifying Properties of Egg Yolk Phosvitin

The effects of protein concentration (0.1–2.0%), oil volume fraction (0.17–0.67), mixing speed (10,000–22,000 rpm) and mixing time (0.5–8 min) on the emulsifying properties of phosvitin and bovine serum albumin (BSA) were compared. Emulsifying activity and emulsion stability increased with protein concentration, oil volume fraction and mixing. Effects of these variables were assessed quantitatively using an empirical equation. Mixing speed had the greatest influence and protein concentration had the least influence on emulsifying activity for both phosvitin and BSA. For emulsion stability, mixing speed had the greatest influence for phosvitin; oil volume fraction had the greatest influence for BSA. Phosvitin was a better emulsifier than BSA at pH7.     

Heat Denaturation and Emulsifying Properties of Egg Yolk Phosvitin

Phosvitin in water at pH 7 had a denaturation temperature (T_d) of 79.7 ± 1.4°C when heated at 10°C/min. When dissolved in 0.1M and 1.0M NaCl, the T_d decreased to 77.7 ± 1.2°C and 77.2 ± 1.3°C, resoectivelv. and in 10 and 20% sucrose there was no change in T_d. Heat treatment of phosvitin solutions at ≥65°C led to decreased emulsifying activity (EA). The emulsion stability (ES) decreased when phosvitim solutioni were heated at 70, 80 or 96°C for up to 60 min. The ES was not affected (p < 0.05) for phosvitin solutions after heating at ≤67.5°C for up to 60 min.     

热处理对鸡蛋蛋黄性质的影响

研究了不同强度的热处理(处理温度59、62、65、68℃,处理时间0～9 min)对鸡蛋蛋黄上清和颗粒的蛋白质组成、溶解性、乳化性和游离巯基含量的影响。结果表明:蛋黄上清中的γ-卵黄蛋白和蛋黄颗粒中的部分高密度脂蛋白在加热处理过程中发生变性形成大分子聚集体,加热处理对蛋黄上清蛋白质溶解度的影响大于对蛋黄颗粒的影响,温和的热处理对蛋黄上清与颗粒的乳化性质均没有显著影响,68℃处理较长时间会使蛋黄上清与颗粒的乳化活力下降,乳化稳定性提高。热处理过程中蛋黄上清和颗粒的游离巯基含量变化均未表现出明显的规律性。     

β-环状糊精包合法脱除胆固醇对蛋黄卵磷脂及其功能性质的影响研究

研究了β-环状糊精包合法脱除鸡蛋黄胆固醇工艺对卵磷脂物质及蛋黄功能性质的影响。高效液相色谱（HPLC）检测结果表明，利用该法脱除蛋黄中90％以上的胆固醇时，蛋黄卵磷脂物质损失不超过8．0％。与普通蛋黄粉相比，起泡性能增强但色泽略浅，乳化稳定性略有下降。     

物理、化学、生物法处理蛋黄颗粒对其乳化特性影响的研究进展

蛋黄颗粒（Egg Yolk Granules, EYGs）是蛋黄经过稀释离心后的沉淀部分,因其主要成分为脂蛋白,所以具有一定的乳化性能。天然颗粒的乳化性能由于其内部结构的影响,乳化性能较差,但经过不同方式处理后可使其乳化性能得到明显改善。然而到目前为止,关于蛋黄颗粒乳化性能的改善方式和效果等仍缺乏深入探讨和系统总结。基于此,该研究综述了几种较为广泛的处理方式,包括机械处理、加热处理、外源添加处理、化学处理和酶法处理等对蛋黄颗粒乳化性和乳化稳定性的改善效果,发现大部分方法均可不同程度增强蛋黄颗粒的乳化性或乳化稳定性,且作用机制不尽相同。该研究阐述了各种处理方式对蛋黄颗粒结构、乳化性能的影响及其作用机制,为改善蛋黄颗粒乳化性能、明确作用机理提供了理论参考。同时,对蛋黄颗粒的发展方向提出展望,以期提高蛋黄颗粒在未来食品领域中的应用价值。     

卵黄高磷蛋白的功能性质及其制备方法研究

卵黄高磷蛋白是已知所有蛋白质中磷酸化程度最高的一种蛋白质,不仅具有乳化性、抗氧化性和热稳定性,还有一定的杀菌功能,其水解产物卵黄高磷蛋白磷酸肽能够与Ca2+相结合,作为载体促进小肠对钙的吸收,因此具有良好的开发应用前景。     

不同蛋黄组分对蛋黄风味的影响

采用有机溶剂萃取法将新鲜蛋黄分成非脂成分、非极性脂成分和极性脂成分三个部分,感官分析结合GC-MS鉴定,研究了不同部分对蛋黄风味的贡献。结果表明蛋黄的特征香味是由蛋黄中的极性脂成分与非脂成分共同作用产生的;非极性脂成分对蛋黄的风味贡献不大;美拉德反应与脂肪氧化反应的共同作用是产生蛋黄特征风味的主要途径。     

热处理对酶解蛋黄液功能特性和热稳定性的影响

胰蛋白酶改性是制备功能性蛋黄液的一个有效方法,而巴氏杀菌热处理是保证液态蛋微生物安全的必要手段。本文研究了不同热处理温度(60,64,68,72℃,4 min)对胰蛋白酶改性蛋黄液的功能特性及热稳定性的影响。结果表明,同等热处理条件下,胰蛋白酶改性蛋黄液的乳化活性和乳化稳定性、蛋白质溶解度、持水性、持油性、起泡性和泡沫稳定性均显著高于未改性组(P 0.05);随着处理温度的升高,改性组和未改性组的乳化活性、蛋白质溶解度、起泡性等功能特性均呈显著下降趋势(P 0.05)。SDS-PAGE结果显示:酶解处理可明显改变蛋黄液蛋白质分子质量分布,较高温度热处理(68℃和72℃)使蛋白质发生明显聚集。FTIR结果证实胰蛋白酶处理与热处理对蛋黄-OH官能团影响较明显。