含益生菌的牛初乳生物学作用研究进展

牛初乳是母牛分娩后最初几天分泌的乳汁，是宏量营养素、微量营养素、免疫球蛋白和生长因子等营养物质的良好天然来源，其营养素构成和活性成分均有着独特之处，具有多种生物学作用。鉴于益生菌和牛初乳都对机体免疫和肠道健康有许多益处，近年来人们开始关注两者联合应用对机体健康的影响。本文对牛初乳的营养学特点、生物活性成分、生物学作用及与益生菌的联合应用进行了综述，旨在为含益生菌牛初乳的深入研究与开发利用提供理论基础。     

牛初乳免疫球蛋白稳定性研究概述

牛初乳富含很多营养成分,其中含有大量的免疫球蛋白,能够抵抗外界病毒侵害,增强机体自身免疫力,但在加工过程中,其活性受到很多因素影响。文中综述了温度、p H值、蛋白酶、超高压等因素对牛初乳免疫球蛋白稳定性的影响,对提高其稳定性的方法如食品添加剂保护法及微胶囊法的研究现状做出总结,为进一步开展牛初乳免疫球蛋白研究提供了参考。     

牛初乳辐照灭菌效果及辐照对免疫球蛋白质量分数的影响

研究了用辐照技术对牛初乳进行灭菌的效果和辐照对牛初乳中免疫球蛋白的影响.用0,2,4,6,8 kGy的剂量进行对牛初乳进行辐照,检测辐照后的菌落总数、大肠菌群、霉菌酵母菌和免疫球蛋白IgG.结果表明,随着辐照剂量的增加,菌落总数、大肠菌群、霉菌酵母菌显著下降,而免疫球蛋IgG下降不显著.用辐照技术对牛初乳进行灭菌,效果显著且不降低免疫球蛋白IgG质量分数.     

牛初乳加工预处理方式对免疫球蛋白活性的影响

以新鲜牛初乳为原料,考察不同的贮藏方法(直接冷冻保存,脱脂牛初乳冷冻保存,乳清冷冻保存)及解冻方法(60℃热水水浴解冻,室温解冻,微波解冻),对牛初乳中免疫球蛋白的提取率和活性的影响。实验结果表明:工业化提取牛初乳中免疫球蛋白时,将生鲜牛初乳从牧场取回后直接放入-20℃冷冻贮藏一个月,解冻时采用60℃水浴加热解冻。     

牛初乳中生物活性成分的研究进展

牛初乳中含有大量的免疫调节因子和生长因子,这些生物活性成分具有免疫调节等一系列的生物学功能。本文综述了牛初乳中主要生物活性物质-免疫球蛋白、乳铁蛋白、胰岛素样生长因子的生物学功能、免疫调节以及提取利用方面的研究现状。     

牛初乳免疫球蛋白微胶囊化方法的研究进展

免疫球蛋白是牛初乳中最重要的免疫因子,大量研究表明:牛初乳免疫球蛋白具有多种生理功能.通过对各种微胶囊化方法进行比较,阐述了不同方法的特点,并对牛初乳免疫球蛋白微胶囊化方法进行了展望.     

牛免疫球蛋白G的应用及检测研究进展

牛免疫球蛋白G(IgG)是一类具有多种生物活性的免疫因子,主要来源于牛初乳中,已成为功能性食品的重要营养添加成分,牛IgG的含量直接决定了此类产品的质量.本文对牛免疫球蛋白的生物活性及功能进行了概述,并对牛IgG含量分析检测技术进行了阐述.     

牛初乳免疫球蛋白体外稳定性研究

研究了牛初乳中免疫球蛋白的体外稳定性,包括热稳定性、酸碱稳定性、消化系统中的稳定性。牛初乳免疫球蛋白在不高于65℃范围内具有较高的稳定性,随温度升高残存率逐渐降低,当85℃、3min时IgG基本完全失活;牛初乳免疫球蛋白在pH<3.0和pH>11.0时稳定性较差,而在pH4.0～11.0之间具有较好的稳定性;在人工胃液中,pH值的影响最大,牛初乳添加量的影响次之;人工肠液中,胰蛋白酶是影响IgG活力的主要因子,消化时间次之,牛初乳添加量的影响最小。     

牛初乳制品功能性成分的分析

利用牛初乳中的免疫球蛋白活性因子，开发具有独特生理功能的乳制品成为牛初乳利用的热点。本研究利用十二烷基硫酸钠-聚丙烯酰胺电泳法和酶联免疫吸附法对市售的牛初孔制品的质量进行了分析与评价。结果表明，目前牛初乳制品的蛋白含量与组成有很大的差异，并且活性免疫球蛋白含量较低。目前牛初乳制品存在的问题亟待解决，市场亟待规范。     

超滤法分离牛初乳中免疫球蛋白IgG

用实验级切向流浓缩纯化系统装置以梯度洗脱方式对牛初乳中的免疫球蛋白IgG乳清液进行分离浓缩,及SDS-聚丙烯酰胺电泳检测分离后的纯度,并同SephadexG-200层析后的IgG纯度进行比较分析。实验结果显示,梯度洗脱方法中超滤膜对牛初乳中的免疫球蛋白IgG具有分离纯化作用。超滤技术可以作为一种分离纯化牛初乳免疫球蛋白的有效手段。     

响应面法优化牛初乳免疫球蛋白热保护剂的配方

为筛选一种最佳的牛初乳免疫球蛋白（Immunoglobulin G,IgG）热保护剂,以牛初乳为原料对其IgG进行提取,在单因素实验基础上,以IgG活性保留率作为响应值,选取甘氨酸、麦芽糖醇和菊粉三种物质作为响应因子,采用Box-Behnken响应面法对IgG热保护剂配方进行优化,并通过傅里叶变换红外光谱和内源性荧光光谱表征不同方式处理的牛初乳IgG结构。结果表明,IgG热保护剂的最佳配方:甘氨酸0.48%,菊粉14.98%,麦芽糖醇12.50%,在75 ℃,5 min条件下热处理的IgG活性保留率为36.59%,各因素添加量对IgG活性保留率的影响主次顺序均为:麦芽糖醇>甘氨酸>菊粉。傅里叶变换红外光谱和内源性荧光光谱分析结果表示:与未添加复合热保护剂的牛初乳IgG相比,添加复合热保护剂后的牛初乳IgG,β-折叠含量显著下降（P<0.05）,无规则卷曲含量显著下降（P<0.05）,二级构象呈现较为有序的状态;荧光强度降低,IgG分子堆积更加紧密,结果表明添加复合热保护剂后的牛初乳IgG结构稳定性有所提高。本研究探索出一种新型牛初乳IgG的复合热保护剂配方,为牛初乳功能性食品的进一步开发和利用提供了参考。     

牛初乳中免疫球蛋白G双抗夹心ELISA检测方法的建立

将牛免疫球蛋白G（immunoglobulin G,IgG）作为免疫原免疫BALB/c小鼠,通过细胞融合、筛选获得分泌抗牛IgG单克隆抗体的细胞株。制备小鼠腹水抗体,进一步纯化获得抗牛IgG单克隆抗体。建立双抗夹心酶联免疫吸附法检测牛初乳中IgG质量浓度,该方法在7.8～1 000 ng/mL范围内有良好的线性关系,最低检出限为7.06 ng/mL,批内变异系数为4.52%,批间变异系数为4.94%,回收率为91.85%～102.45%。此法操作简便、准确度高、稳定性好,可用于实际牛初乳样品的快速检测。     

Colostrum from cows immunized with a veterinary vaccine against bovine rotavirus displays enhanced in vitro anti-human rotavirus activity

Human rotaviruses represent a major cause of severe diarrheal disease in infants and young children. The limited impact of oral vaccines on global estimates of rotavirus mortality and the suboptimal use of oral rehydration justify the need for alternative prophylactic and therapeutic strategies, especially for immunocompromised hosts. The protective effects of colostrum—the first milk produced during the initial 24 to 48 h after parturition—are well documented in the literature. In particular, the ingestion of hyperimmune bovine colostrum has been proposed as an alternative preventive approach against human rotavirus gastroenteritis. Although the immunization of pregnant cows with human rotavirus boosts the release of specific immunoglobulin G in bovine colostrum, it raises regulatory and safety issues. In this study, we demonstrated that the conventional bovine rotavirus vaccine is sufficient to enhance the anti-human rotavirus protective efficacy of bovine colostrum, thus providing a conservative approach to produce hyperimmune bovine colostrum, making it exploitable as a functional food.     

牛初乳的营养保健功能及其生物活性成分的开发利用

天然的牛初乳含有丰富的营养及生物活性成分,有很强的营养保健功能。介绍了天然牛初乳的营养成分和生物活性物质,列举了牛初乳的一些加工特性及目前国内外牛初乳产品的开发现状,阐述了在开发功能性牛初乳制品中存在的问题,展望了牛初乳功能性保健制品的未来发展前景。     

乳制品中牛IgG含量间接竞争性ELISA检测方法的研究

建立了牛初乳制品和添加了牛初乳成分的乳制品中牛IgG含量间接竞争性酶联免疫吸附测定方法,主要研究步骤包括:制备牛IgG保守区(Fc段),以Fc段为免疫原免疫Balb/C小鼠,取其脾细胞进行细胞融合,制备特异性单克隆抗体及合成适合实际测定用途的ELISA试剂盒。应用本研究建立的方法对标准品和实际样品进行牛IgG含量检测的结果表明,该方法回收率在78.9%～117.5%,批内变异系数小于10%,批间变异系数小于15%,检测结果稳定可靠,可满足目前国内牛初乳制品和添加了牛初乳成分的乳制品品质监控的需要。     

Bioactive Compounds of Colostrum and Its Application

Colostrum is the initial milk secreted by bovine during parturition and the first few days after birth. Colostrum is a gift of nature used to protect the newborn’s immune system and provides passive immunity against pathogens. The presence of bioactive components such as insulin-like growth factor I and II (IGF-I and IGF-II), lactoferrin, lysozyme, lactoperoxidase, and immunoglobulin make the colostrum active against pathogens such as Escherichia coli, Salmonella typhimurium, Shigella dysenteria, Listeria monocytogens, Streptococcus mutans, Bacillus stearothermophilus, and Bacillus subtilis. It is also active against Herpes simple virus type-I (HSV-I), Human Immuno-deficiency virus-I (HIV-I), and human cytomegalovirus. Lysozyme is an antibacterial and lytic enzyme; whereas lactoperoxidase is a major antibacterial found in colostrum; it is toxic to gram-positive and gram-negative bacteria. Lactoperoxidase inactivates the polio virus, vaccinia, and human immunodeficiency virus type-I in-vitro. Immunoglobulins are considered an important bioactive component in colostrum, and it contains high levels of immunoglobulin G (Ig G). Immunosupplementation with bovine milk antibodies has been shown to provide local protection to the gastrointestinal tract against disease. The restricted technical and hygienic problems, along with the unstable physio-chemical nature of colostrum, has resulted in minimal utilization of colostrum on Industrial scale.     

Bioactive Compounds of Colostrum and Its Application

Colostrum is the initial milk secreted by bovine during parturition and the first few days after birth. Colostrum is a gift of nature used to protect the newborn's immune system and provides passive immunity against pathogens. The presence of bioactive components such as insulin-like growth factor I and II (IGF-I and IGF-II), lactoferrin, lysozyme, lactoperoxidase, and immunoglobulin make the colostrum active against pathogens such as Escherichia coli, Salmonella typhimurium, Shigella dysenteria, Listeria monocytogens, Streptococcus mutans, Bacillus stearothermophilus, and Bacillus subtilis. It is also active against Herpes simple virus type-I (HSV-I), Human Immuno-deficiency virus-I (HIV-I), and human cytomegalovirus. Lysozyme is an antibacterial and lytic enzyme; whereas lactoperoxidase is a major antibacterial found in colostrum; it is toxic to gram-positive and gram-negative bacteria. Lactoperoxidase inactivates the polio virus, vaccinia, and human immunodeficiency virus type-I in-vitro. Immunoglobulins are considered an important bioactive component in colostrum, and it contains high levels of immunoglobulin G (Ig G). Immunosupplementation with bovine milk antibodies has been shown to provide local protection to the gastrointestinal tract against disease. The restricted technical and hygienic problems, along with the unstable physio-chemical nature of colostrum, has resulted in minimal utilization of colostrum on Industrial scale.     

Production of monoclonal antibodies to bovine leukocyte cell-surface components

Fusion of murine myeloma cells with syngeneic spleen lymphocytes has led to development of hybridomas secreting antibodies. Hybrid cells retain the immortality and clonability of myeloma parents as well as the antibody-producing property of lymphocytes. Specificity of monoclonal antibody produced is based on the one lymphocyte-one antibody phenomenon and represents the most effective process for producing specific antisera. spleen cells from mice immunized with desired antigen are hybridized with nonsecreting mouse myeloma cells. Resulting hybrids are cloned and culture fluids tested for specific antibody activity to the antigen. Positive clones are cultivated in vitro and injected into mice for monoclonal antibody production. This technology has been extended to the bovine species to obtain monoclonal antisera to immunoglobulins and cell-surface components of leukocytes for study of mammary gland immunity. Recent progress in monoclonal research has led to interspecific fusion of murine myelomas with bovine lymphocytes, resulting in hybridomas that produce monoclonal bovine immunoglobulins. Monoclonal antibodies will be useful in investigations applicable to bovine research including purification of immunoglobulins, determining immunoglobulin concentration in colostrum and milk, reference reagents for bovine serology, antibody localization in tissue, gene sequencing, characterizing histocompatibility antigens, distinguishing and quantitating cell types in blood, milk, and udder tissue, and elucidating role of cell subpopulations in the immune response.     

微滤-超滤联用技术优化牛初乳乳清中IgG富集工艺

为了高效富集IgG的同时减轻牛初乳的浪费问题,提高产品价值,本文采用微滤-超滤联用技术对牛初乳乳清中IgG进行富集。首先探究了微滤技术在牛初乳乳清除菌中的应用,并对其操作工艺进行优化,其次,利用超滤技术对微滤除菌后的牛初乳乳清进行富集,在单因素实验基础上,采用响应面对超滤工艺进行优化,并对富集后的牛初乳乳清进行品质分析。结果表明:牛初乳乳清微滤除菌的最佳工艺参数为:微滤压力为0.2 MPa、温度为30 ℃,超滤富集的最佳工艺参数为:超滤压力为0.15 MPa、温度为35 ℃、浓缩倍数为6倍、稀释次数为4次,按此条件进行牛初乳乳清的微滤-超滤操作,此时的IgG浓缩率为58.19%,膜通量为204.46 L/m2·h。富集后的牛初乳乳清品质分析表明:IgG含量为22760 μg/mL,IgG活性为718.31 IU/L,蛋白质含量为7.86%,脂肪含量为0.035%,菌落总数为2.4 lg CFU/mL。本研究为牛初乳乳清中IgG的进一步开发与综合利用提供了一定的参考依据。