鸡蛋分子检测技术的研究

采用PCR方法检测市售鸡蛋的卵清蛋白基因片段,分析市售鸡蛋的蛋白质含量及蛋白质电泳图谱,用薄层层析检测卵磷脂,以作为区别市售真假鸡蛋的鉴别方法,为分子技术鉴别真假鸡蛋奠定基础。     

我们只想要颗“放心蛋”

最近,“假鸡蛋”在各地闹得沸沸扬扬。一位记者的邻居的朋友,从广州康王路某大型超市买了一些鸡蛋,煮熟后发现蛋黄能弹能跳,一度以为这就是传说中的“假鸡蛋”。记者送检其中一颗,结果被禽蛋专家一口否认涉假,“这哪里是假的!根本就是真蛋。”     

辨别五大食品流言的真相

不可否认,在我国,食品安全问题日益突出,但我们也大可不必“谈食色变”,而应当理性地看待食品安全问题,不盲目听信流言,正确辨别事情的真相,让自己吃得更安全,更健康!假鸡蛋流吉：假鸡蛋的蛋黄可以做乒乓球,那弹跳力,杠杠的!真相：制作假鸡蛋的成本大大高于真鸡蛋,哪有商家会那么傻呢？所以,你大可放心。另外,散养鸡所产的蛋,也有可能是“橡皮蛋”（通常是指煮熟后的蛋黄有弹性）。     

肉类耐热蛋白提取及双向电泳条件优化

物种定量鉴别检测技术,已成为肉类真伪鉴别研究的热点。现有常用的实时荧光PCR法在定量检测方面存在方法缺陷。而基于蛋白质的ELISA检测方法,具有抗干扰能力强、快速、对仪器要求低的优点,已越来越多应用于食品中特征蛋白的定量检测。肉制品加工工艺中,热处理是蛋白质变性的主要原因,因此应选择热稳定特征蛋白,而建立常见肉类热稳定蛋白质双向电泳图谱是选择热稳定特征蛋白的基础。然而双向电泳是一个复杂的过程,想获得良好的电泳图谱并找到特征蛋白点需要多方面进行优化。从蛋白质提取纯化方法、IPG胶条长度、p H范围、上样量选择方面对其进行优化,最终获得稳定的、能够找到特征蛋白点的双向电泳图谱。     

鸡蛋产品鉴伪技术的构建

本实验建立了一种综合蛋白质和基因组两种检测方法的鸡蛋产品鉴伪技术。一方面,研究选择鸡蛋蛋清中的溶菌酶、卵白蛋白、伴白蛋白作为蛋清蛋白质的标志性成分,采用改进后的离子交换树脂法对上述三种目标蛋白进行分离,经聚丙烯酰胺凝胶电泳分析从而实现蛋白质水平的鉴定。另一方面,针对鸡蛋产品中常见的掺假物玉米粉、大豆粉,以高等植物18S r DNA基因作为内源参照基因,设计这两种掺假物的特异引物进行PCR扩增,经过琼脂糖凝胶电泳显示特异性条带的有无,从基因组水平实现鸡蛋产品的鉴伪。结果表明:离子交换法对轻加工鸡蛋产品中有良好的鉴定效果,对深加工鸡蛋产品中蛋白质的提取效果欠佳;PCR反应设计的引物特异性良好,鸡蛋产品中掺杂的最低检测限可高达2%。结合离子交换树脂和PCR法两种检测手段可对市售大部分鸡蛋产品进行鉴定。     

鸡蛋的营养与人体健康

蛋黄也是好东西蛋类食物含有全价蛋白质和脂肪,并含有维生素A、D、B1和B2。蛋类中含有重要的矿物质,如铁、磷、镁、钙。许多人对蛋黄没有好感,往往偏爱蛋白,其实这是有失偏颇的。蛋黄与蛋白相比,其含水量低35%、蛋白质的含量高36%,其生理价值也高于蛋白。鸡蛋的脂肪含量约11%～     

不同鸡蛋中鸡卵黄免疫球蛋白的比较

采用PEG分步沉淀法分别从京红一号鸡蛋、市售鸡蛋、土鸡蛋中制备鸡卵黄免疫球蛋白(IgY).通过SDS-PAGE分析提取物,发现存在2条主要的蛋白带:分别为66.4kDa和29.0kDa,与文献报道的IgY重链(～ 60kDa)和轻链(～ 30kDa)的分子量相符.     

鸡蛋蛋黄的功能及其制品

鸡蛋富含营养价值高的蛋白质，脂质，也是维生素和矿物质的良好来源，特别是其中的蛋白质人体吸收率达99．7％，且必需氨基酸十分丰富。鸡蛋不仅是个营养宝库，而且作为快餐食品，糕点和面包的食品原料，蛋白与蛋黄的热凝笥，蛋白的起泡性，蛋黄的乳化性等特性在食品工业上也得到普遍的应用。     

巧夺天工的人造食品

人造鸡蛋 美国市场上推出一种大小、形状和其鸡蛋一样的人造鸡蛋。这种人造鸡蛋是用玉米油、蛋白质、牛奶、维生素B_1、B_2及人体所需的矿物盐混合制成蛋白与蛋黄,外用无毒塑料制成鸡蛋壳,其厚度比真鸡蛋还要薄,弹性好,不易破碎,便于运输,     

基于机器视觉的鸡蛋品质无损检测方法

目的以蛋品质量评价指标—哈夫单位值为检测标准,建立一种基于机器视觉的鸡蛋品质无损检测方法。方法通过摄像头捕捉到鸡蛋图像信息,利用MATLAB对鸡蛋图像的G分量以及I分量进行特征参数提取,并计算出与鸡蛋新鲜度相关的4个特征参数:蛋黄面积比、气室面积比、气室高度比与气室直径比,将其作为自变量,通过高精度游标卡尺实测每个鸡蛋样本哈夫值作为因变量,分别建立一元回归模型,寻找特征参数与哈夫值的关系,并根据哈夫值对鸡蛋新鲜度进行分级。结果实验表明,所测4个特征参数中,蛋黄面积比与哈夫值存在较强的相关性,相关系数为0.78,拟合优度为0.62,蛋黄面积比越小,鸡蛋哈夫值越大,说明鸡蛋越新鲜。结论基于机器视觉的鸡蛋品质无损检测方法不仅具有较强的应用价值,还可以为鸡蛋品质智能分级提供技术支撑。     

蛋源降血压肽研究进展

鸡蛋不仅是人们饮食营养的重要来源,而且还含有许多生物活性蛋白。鸡蛋活性蛋白经酶解后会产生许多具有生物活性的多肽,其中最重要的就是具有降血压活性的多肽。本文介绍了鸡蛋来源的降血压多肽的发现、特性、生产和分离及体内外活性,以期为国内相关研究提供参考。     

Effect of pasteurisation on the chemical composition of liquid whole egg. III.—Effect of staling and freezing on the protein fractionation patterns of raw and pasteurised whole egg

Two particular fractions of the soluble proteins were consistently reduced by heating liquid egg for 5 min at 150°F. These fractions were quantitatively greater in the soluble proteins from frozen egg. The soluble proteins appeared to be more stable to heat in eggs that had been stored for 15 days at 70°F than in new-laid eggs. Unfrozen new-laid and stale egg and frozen new-laid egg all showed an increase in insoluble material after pasteurisation, and frozen egg contained more insoluble materials than unfrozen egg. Gel filtration showed that the proportion of compounds of high molecular weight in the insoluble proteins was markedly increased by pasteurisation and even more markedly increased by freezing.     

Identification of preserved egg white protein glycation and insight into the bioactivity

Preserved eggs have been reported to possess anti-inflammatory and antioxidant bioactivities, which are enhanced after protein glycation. However, it is still unknown which proteins are glycated during pickling process of preserved eggs and whether the glycated proteins are related to the bioactivity of preserved eggs. In this study, UPLC-ESI-MS/MS was used to identify glycation of proteins in preserved egg white (PEW) and duck egg white (DEW). Altogether, 142 sites on 53 glycated proteins were detected in PEW while 9 sites on 2 glycated proteins were found in DEW. Bioinformatic analysis suggested that the glycation of PEW proteins (e.g. Ovalbumin, Ovotransferrin, Albumin) were supposed to be connected with allergenicity reduction, and the enhancement of antibacterial and antioxidant bioactivities. These findings provide some indications for the future studies on the detailed bioactivities of glycated proteins in PEW, and pave the way for applied research on glycation and the development of functional foods.     

鸡蛋蛋白质凝胶特性影响因素的研究进展

为了进一步了解不同因素对鸡蛋蛋白质凝胶特性的影响，国内外研究者已经针对性的进行了大量的研究工作。本文综合论述了鸡蛋中蛋白质的组成和凝胶的形成机理，分析了温度、压力、pH、酶、盐、蛋白质浓度、处理时间等因素对鸡蛋蛋白质凝胶特性的影响，其中温度、压力、pH、盐、处理时间几个因素对鸡蛋蛋白质凝胶特性的影响研究已较为全面，但生物酶对鸡蛋蛋白凝胶特性的影响研究相对较少，所研究的酶种类较为单一。通过对这些影响因素的研究状况进行综述，以期为鸡蛋深加工过程中工艺参数的控制提供一定依据，为进一步提升鸡蛋加工产品的凝胶品质提供理论参考。     

Effects of body weight and nutrition on mammary protein expression profiles in Holstein heifers

A proteomics approach was used to characterize biochemical and cellular mechanisms governing effects of peripubertal feeding on heifer mammary development. Mammary parenchymal tissue from 24 Holstein heifers randomly assigned to treatments arranged in a 2 × 2 factorial design was used to generate 2-dimensional protein maps of mammary tissue extracts. Heifers were reared on 1 of 2 dietary treatments, restricted (650 g/d of daily gain) or elevated (950 g/d of daily gain) and killed at 1 of 2 body weights (BW, 200 or 350 kg). Cytosolic mammary gland extracts were prepared from frozen mammary parenchyma. Proteome maps of extracts were constructed using PDQuest software. Densities of 820 protein spots were analyzed using the MIXED procedure of SAS. Protein spots were characterized by changes in profiles of expression in response to increased BW, dietary treatment, or both. Dietary treatment influenced the expression of 131 protein spots, whereas heifer BW influenced the expression of 108 spots. The 22 most highly influenced (statistically) spots were excised and submitted for mass spectrometric analyses. Returned protein names and accession numbers were used in National Center for Biotechnology Information database searches to obtain information on the identified proteins. For example, one of the proteins that differed by dietary treatment, transferrin, a binding protein of insulin-like growth factor binding protein-3, was identified via these methods. Possible roles of this and other proteins in mammary development are described. We concluded that a proteomic approach is an effective tool for identifying the proteins involved in bovine mammary development.     

间歇超声辅助加快咸蛋腌制速度工艺优化

为加快咸蛋腌制速率,缩短腌制周期,本实验通过测定腌制过程中咸蛋含盐率、含水率、蛋黄出油率及蛋清粘度指标的变化,探究超声波技术对咸蛋腌制的影响。通过超声波单因素试验探究超声波处理次数、超声时间、超声功率以及超声频率对超声波辅助咸蛋腌制效果的影响,后由L₉(34)正交实验对间歇超声辅助腌制咸蛋工艺进行优化,由蛋清、蛋黄含盐率以及蛋黄出油率得出最优的间歇超声辅助腌制工艺为:超声波处理3次,超声时间30 min,超声功率350 W,超声频率20 kHz,此工艺相对传统腌制工艺,蛋清含盐率6.37%,蛋黄含盐率1.58%,蛋黄出油率达到57.53%。在保证咸蛋出油率等品质上,与传统工艺相比腌制时间缩短了15~20 d,且蛋白细嫩,咸蛋黄松沙出油,蛋黄外周黑圈等优点。     

Antigenicity of Ovomucoid Remaining in Boiled Shell Eggs

Antigenicity of egg white proteins which remained in heated shell eggs was analyzed quantitatively by using rabbit antibodies specific to egg white proteins and human antibody from patients allergic to egg. The major antigenic component in heated (100°C for 20 min) and coagulated egg white was ovomucoid. A considerable amount of ovomucoid remained immunoreactive even after heating at 100°C for 15 min, though ovomucoid in stored eggs was a little less stable to heating than that of fresh eggs. Even long-time heating (100°C for 45 min) could not completely eliminate the ovomucoid immunoreactivity to human IgE antibody.     

大气滑动弧放电对沙门氏菌的灭活机制及在鸡蛋保鲜中的应用

为了保持鸡蛋的新鲜度、延长其保质期,本研究提出了一种可在室温和大气环境中进行灭菌处理的新型冷杀菌技术,即滑动弧放电技术。首先,将配制好的沙门氏菌液均匀接种在鸡蛋表面,然后使鸡蛋以一定的自旋速率通过等离子体放电区域进行灭菌处理,从鸡蛋表面取得菌样后进行灭活机制研究,并将灭菌处理后的鸡蛋在37℃条件下进行贮藏,通过测定质量损失率和哈夫单位来评价大气放电技术对鸡蛋品质的影响。扫描电子显微镜观察和细胞外蛋白质质量浓度检测结果表明,大气滑动弧放电技术可对沙门氏菌产生有效的刻蚀作用,导致细胞膜破碎和胞内蛋白质泄漏。同时,鸡蛋品质检测表明,滑动弧放电处理组无论作用时间长短,鸡蛋质量损失率增大的程度均比对照组明显,但哈夫单位的降低程度小于对照组,说明大气滑动弧放电可在一定程度保持鸡蛋的新鲜度。     

云南盐津乌骨鸡与武定鸡肌肉蛋白质组学差异研究

选取云南两种具有代表性的地方优质鸡种盐津乌骨鸡和武定鸡为研究对象,采用双向电泳(2DE)分析其腿肌与胸肌中蛋白表达差异,并以基质辅助激光解析电离-串联飞行时间质谱(MALDI-TOF/TOF MS)鉴定腿肌与胸肌中差异蛋白质点。结果表明,经双向电泳图谱分析所获得的肌肉组织蛋白点分布于pH4.0~7.0之间,其中盐津乌骨鸡腿肌、胸肌中分别检测到(1421±34)、(1329±25)个蛋白点;武定鸡腿肌、胸肌中检测到(1585±19)、(1516±28)个蛋白质点。对比分析盐津乌骨鸡与武定鸡的DE图谱,发现有178个点存在明显的表达差异,在盐津乌骨鸡中高表达的点有72个,在武定鸡中高表达的点有106个。选取的蛋白质点经鉴定主要为核纤层蛋白A、磷酸葡萄糖变位酶1、β-烯醇酶、原肌球蛋白1、三磷酸腺苷合成酶、C-反应蛋白前体、B链α-晶状体蛋白、肌酸激酶M型、乙二醛酶1、磷酸甘油酸激酶 PGK1、慢骨肌肌钙蛋白T、蛋白酶体非ATP酶调节亚单位14、热休克蛋白β-1超氧化物歧化酶、以及一些假设蛋白和非特征性蛋白。     

Biological value of the proteins of a sausage product incorporating a combined protein preparation based on slaughterhouse blood

The authors discuss experimental data obtained in the course of investigation of the biological value of proteins of combined meat products containing decolorized blood obtained with the use of a new physical method. Analysis according to the amino acid score revealed that the combination prepared from blood protein, milk serum and eggs would make it possible to replace beef and pork proteins to any extent. The biological experiments showed that the designed protein mixture of blood, milk serum and egg powder would replace not less than 25% of meat proteins. The replacement by 50% and more resulted in a decrease of the biological value of proteins contained by the combined product as compared to control.