一种适用于乳制品基因组DNA快速提取方法的研究

目的对比NaOH裂解法、PBS裂解法以及直接煮沸法3种方法提取乳制品中核酸的提取效果,优化提取条件,确定一种更适用于现场检测、简便快速的的乳制品DNA快速提取技术。方法以牛奶、水牛奶、牦牛奶、羊奶、骆驼奶、以及驴奶6种常见的乳制品为材料,分别用NaOH裂解法、PBS裂解法以及直接煮沸法3种提取方法提取乳制品中的DNA,并根据裂解液用量和裂解时间进行优化,通过PCR扩增和琼脂糖凝胶电泳分析,检测DNA提取的质量和灵敏度。结果 NaOH裂解法能够提取所有物种的乳制品DNA,而且可以在最佳裂解条件下提取模拟掺假混合乳的DNA进行检测,发现其检测限能达到1%的牛奶含量。结论该方法取样量小,成本低,在15 min内即可完成快速提取,为实验室乳制品DNA定性或定量鉴别,以及乳制品的现场掺假鉴别提供了一种快速灵敏低成本的样品前处理技术。     

Use of ultrasound for characterizing dairy products

It has been known for a long time that acoustic measurements offer some unique features for characterizing liquid food products in their intact state, without any preparation or destruction of the product sample. Acoustic characterization can yield information about fat content, droplet size distribution, and kinetics of product variation with time. Furthermore, acoustic methods are very attractive for on-line process control. This paper addresses several questions: Why does ultrasound attenuate when propagating through a heterogeneous system? What properties of dairy products can be extracted from such ultrasound measurements? Which measurement is better for product characterization: attenuation or sound speed? What measurement precision is required to adequately characterize product properties? What frequency range is of most value for determining these product properties?It is possible to provide answers to many of these questions using experimental data, thereby avoiding, for the moment, any complex mathematical analysis. We present several applications of acoustic spectroscopy for characterizing dairy products, including characterization of the fat content in a wide variety of dairy products; calculation of the fat droplet size distribution in milk without dilution; and calculation of water droplet size in butter, without dilution or melting.     

乳饮料及乳制品中游离甘氨酸的测定

利用氨基酸分析仪测定乳饮料及乳制品中游离甘氨酸含量。研究了样品前处理方法和仪器色谱分离条件对乳饮料及乳制品中甘氨酸测定的影响。该方法具有较好的重现性,加标回收率为96.4%～100.6%,方法精密度为0.99%,标准曲线线性相关系数为0.999 9,20μL进样最低检出限为1.0 pmol。     

乳及乳制品中常见“活的非可培养态”食源致病菌研究进展

细菌在环境胁迫下能够进入一种“活的非可培养态”（viable but nonculturable state,VBNC）,常规的平板培养方法无法检测出该种状态细菌,但其仍具有可测量的代谢活性,能够在适合的条件下复苏并产生毒力。乳及乳制品因其含有丰富的营养物质而成为理想的细菌培养基,其中几种常见的食源致病菌如副溶血性弧菌、空肠弯曲杆菌、金黄色葡萄球菌、单核增生李斯特氏菌、阪崎肠杆菌等也被证实能够进入VBNC,对乳及乳制品品质安全造成严重威胁。因此,本文综述了VBNC细菌的研究进程和细胞形态、毒力等生理学特性,并介绍了乳及乳制品中几种常见VBNC致病菌的诱导与复苏因素及其检测方法。通过对VBNC细菌的综述进而为乳及乳制品中致病菌研究提供新思路,以期减少乳及乳制品中该状态致病菌对公共安全的威胁,提升乳及乳制品中生物性安全水平。     

基于生物酶解法的牛乳蛋白脱敏技术研究进展

牛乳是婴幼儿主要食物蛋白来源,但也是引起食物过敏的八大类食物之一,研究生产低致敏乳制品对牛乳过敏者具有重要意义.目前,生物酶法是研发低致敏乳制品的主要技术途径.本文详细列举了牛乳过敏蛋白及其能够被识别的致敏表位,介绍了应用生物酶法处理得到低抗原性牛乳蛋白水解产物的技术及其作用效果,并提出了一些对后续研究的思考,为低致敏...     

Practical Food Safety Interventions for Dairy Production

Consumers are increasingly concerned about the safety of their food and uncertain about food production practices. Potential threats to human health related to dairy products and dairy farming include errors in pasteurization, consumption of raw milk products, contamination of milk products by emerging heat-resistant pathogens, emergence of antimicrobial resistance in zoonotic pathogens, chemical adulteration of milk, transmission of zoonotic pathogens to humans through animal contact, and foodborne disease related to cull dairy cows. Most dairy farmers feel responsible for the safety of milk and beef that originate on their farms, but linkage between farm production practices and the quality of processed products have been weak. The safety of dairy products can be enhanced by adoption of a number of management practices. Sources of microbial contamination of milk must be minimized by adoption of hygienic standards that can be easily evaluated. Uniform adoption of milking practices that reduce microbial contamination of milk should be emphasized. The diagnosis of salmonellosis or listeriosis on a dairy farm should be regarded as an indication that other potentially infected animals may be present in the herd. Coliform counts on bulk tank milk should be routinely performed as an indicator of fecal contamination. A reduction in the national regulatory limit for somatic cells in bulk tank milk should be considered based on potential enhancements in milk safety. Dairy farmers must take responsibility for the market cattle leaving their farms. The inappropriate or prophylactic use of antimicrobial agents must be minimized to ensure that antimicrobial resistance does not develop in animal pathogens. Consumers can have confidence in food safety programs on dairy farms that promote awareness and accountability for the products that are produced.     

湖南省市售国产乳制品中硫氰酸盐检测结果分析

目的掌握湖南省市售国产乳制品中硫氰酸盐含量,有效指导消费者科学消费。方法利用离子色谱法对湖南省388批次市售国产乳制品硫氰酸钠进行检测。结果 388批次乳制品硫氰酸钠检出率为93.3%,折算为生乳后的含量均在国家食药监总局风险监测参考值10 mg/kg范围内。其中,307批次液体乳制品硫氰酸盐检出率为91.5%,按系数折算为生乳后含量在1.0~6.9 mg/kg之间的为86.98%;81批次奶粉检出率为100%,按系数折算为生乳后含量在0.1~5.9 mg/kg之间的为97.35%。结论经过分析原料乳中硫氰酸盐的可能来源,认为湖南省市售国产乳制品中硫氰酸盐主要来源于原料生鲜乳本底,非法添加的可能性较小,有必要立刻全面开展生乳中硫氰酸盐本底值调查,系统地为乳制品硫氰酸盐监测提供有效依据。     

乳和乳制品中抗生素残留的危害及检测方法

综述了乳与乳制品中抗生素残留现状和危害，比较了抗生素检测Delvotest法与其他几种方法。认为Delvotest法优于其他几种方法，建议有关部门尽快引进该技术，以加强我国乳和乳制品中的抗生素监测，解决目前乳业中面临的难题。     

The diversity and proteolytic properties of psychrotrophic bacteria in raw cows' milk from North China

Most psychrotrophic bacteria have the ability to produce thermoresistant proteases that can destroy the quality of milk and dairy products. To investigate the population dynamics of psychrotrophic bacteria during refrigeration, three raw cows' milk samples (sample A comprising milk from 10 farms in Beijing, sample B comprising milk from 5 farms in Heihe, and sample C comprising milk from 7 farms in Harbin) were refrigerated at 0–5 °C and 5–10 °C. PCR-DGGE (Polymerase chain reaction-denaturing gradient gel electrophoresis) analysis revealed that the bacterial community profiles varied from geographical site to site, and with refrigeration temperature. The dominant psychrotrophic bacteria among the samples after storage were affiliated with the order Pseudomonadales. Following isolation and identification, 8 psychrotrophic isolates were selected as stronger protease producers and their growth and proteolytic activities were assessed. The results indicate that the composition of psychrotrophic bacteria play an important role in the determination of the quality of milk and dairy products.     

抑制牦牛乳制品脂肪氧化的研究进展

乳脂肪是牦牛乳中的主要营养成分,但其易氧化产生酸败。牦牛乳平均脂肪含量为5.51%,脂肪含量高于普通荷斯坦牛乳,且含有普通牛乳所没有的功能性脂肪酸。牦牛乳本身的高脂肪含量易使其乳制品受到各种内在因素和外在因素影响而发生脂肪氧化。深入分析影响牦牛乳脂肪氧化的因素,可以更好地控制牦牛乳制品的品质。本文综述了抑制牦牛乳制品脂肪氧化的内在和外在因素,并从自动氧化、光敏氧化和水分含量及酶引发的酶促氧化三个氧化途径对外在因素的影响的研究进展进行了阐述,研究各种因素如何影响其脂肪氧化的发生,对调控牦牛乳制品脂肪氧化和青藏高原牦牛乳产业化发展有着重要意义。     

毛细管电泳技术在乳品蛋白分析中的应用

乳品在全球范围内生产和消费,受到广泛且持续的关注,蛋白质是乳品评价最重要的指标之一。毛细管电泳技术(capillary electrophoresis, CE)具有样品用量少、分离模式多、分析效率高的优势,在乳品蛋白质分析方面具有巨大的应用潜力。本文简要介绍了CE技术检测乳品中蛋白质的特点和难点,总结了毛细管凝胶电泳法、涂层毛细管电泳法、胶束电动毛细管色谱法、免疫亲和毛细管电泳法、毛细管区带电泳法等模式在乳品蛋白质分析中的优劣势,列举了CE技术在乳品品质鉴定、过敏原分析、真伪鉴别、蛋白质糖基化分析、乳品处理和蛋白水解过程等相关生产和质控环节的应用情况,展望了CE技术在乳品分析应用中的发展趋势。     

牛奶脂肪酸检测方法的研究进展

牛奶脂肪酸组成不仅与其理化性质和营养品质密切相关,还是评价奶牛健康状况的重要指标。建立准确的定性定量方法,能够全面地了解牛奶脂肪酸组成,有利于奶牛场对奶牛的饲养管理和乳品加工厂对乳制品的质量控制。本文针对牛奶脂肪酸分析中的样品前处理技术和仪器检测技术进行了综述,旨在对比不同检测方法的优缺点,为建立牛奶脂肪酸高通量、高灵敏度的分析方法提供参考。     

Economic Issues and Implications of a United States Milk Quota Program

Interest in adoption of a national mandatory milk quota program has grown considerably in the last 2 yr primarily due to mounting dairy surpluses and burgeoning costs of the dairy price support program. If this type of program were to be adopted, all segments of the dairy industry would be affected. This article examines the potential economic issues and implications of such programs on current and future generations of dairy farmers, milk handlers, government, and consumers. In part, it is argued that a national mandatory milk quota program would most likely raise farm milk prices, reduce milk surpluses, provide windfall gains to current producers, reduce government budgetary costs, increase retail prices for consumers of dairy products, increase costs of production, encourage the use of substitutes for dairy products, and slow adoption of new technologies by farmers. Although the political climate in Congress and the Administration is not very receptive, support for these programs has grown during the past year among farmers and the dairy lobby. At the very least, there undoubtedly will be political pressure for a national mandatory milk quota program in the near future.     

Description of herd level criteria for good and poor udder health in Norwegian dairy cows

Data from the Norwegian dairy herd recording system were used to evaluate herd level criteria for good and poor udder health in dairy cows. All dairy herds with at least 10 cow-years were included (n = 12,780). The association between bulk milk somatic cell count (BMSCC) and clinical mastitis rate (CM) was weak (R2 = 0.002), indicating that studies based on BMSCC provide different information regarding udder health than studies based on CM. The strongest correlations were found between average cow milk somatic cell count (CMSCC) and BMSCC and between percentage of individual cow milk sample >200,000 cells/mL and the variables BMSCC and CMSCC. A new variable called new infection rate (NEWINF) based on individual cow somatic cell count measurements and CM was evaluated. The NEWINF is influenced by the frequency of individual cow milk samplings, and, to compare herds, it is necessary to adjust for the frequency of cow milk samplings on each farm. The NEWINF was found to be a useful tool for describing overall udder health status at the farm level, as it combines both CM and somatic cell count.     

蛋白质组学技术及其在乳及乳制品中的应用研究进展

蛋白质组学技术是近年来生命科学研究的重要工具,在食品、医学及动植物研究领域具有独特优势。利用蛋白质组学技术研究乳及乳制品,深入阐明其中蛋白质的表达及动态变化已成为当前的研究热点。该文主要综述了蛋白质组学的概念、常用技术及应用领域,重点介绍蛋白质组学在乳及乳制品领域,特别是在乳脂肪球膜蛋白、乳清蛋白、乳及乳制品加工过程以及干酪制品中的研究应用,探讨了目前乳及乳制品蛋白质组学研究中存在的问题与局限,并对蛋白质组学及其在乳及乳制品中的应用前景进行了总结与展望,为应用蛋白质组学技术深入研究乳及乳制品提供了理论依据。     

乳制品质量快速检测原理与技术研究进展

乳制品是鲜奶以及所有以奶为主要原料加工制成的产品的总称,乳制品的安全问题是全球关注的热点。为了对乳制品质量进行监控,目前已有的检测标准和方法需要在实验室进行,检测环境条件要求较高,周期较长。研究并开发灵敏、准确、便捷的检测方法十分必要。近年来,一系列新的乳制品质量快速检测技术已经被广泛应用,本文主要介绍了电子学、光谱学和生物学检测技术的原理及其在乳制品质量检测应用中的优缺点,同时展望了乳制品质量检测技术的发展方向,旨在为乳制品质量检测技术的进一步发展提供资料参考和思路。     

蒙古族传统乳制品奶皮子和奶豆腐的工艺研究及营养价值分析

奶皮子和奶豆腐是蒙古族的两种传统特色乳制品。研究了奶皮子和奶豆腐的加工工艺,并对两种制品的营养成分进行分析,为进一步研制开发民族乳制品提供一定的理论依据。     

概述乳制品加工中产生的生物活性肽

乳蛋白是许多生物活性肽的重要来源,主要的乳蛋白源生物活性肽有阿片样肽、降血压肽、免疫刺激肽、抗血栓肽和酪蛋白磷酸肽.文章对这些活性肽进行了介绍,并对乳制品(发酵乳和干酪)中的活性肽进行了讨论.乳制品中含有活性肽证明通过外源酶或微生物的作用可以将活性肽从乳蛋白中释放出来,这些肽的存在将促进乳制品的加工和消费.     

A Sensitive and Robust Method for Direct Determination of Lipolytic Activity in Natural Milk Environment

Microbial lipases may be produced during milk storage and processing. This can lead to organoleptic changes in the corresponding dairy products. Thus, monitoring of lipase activity in milk is desirable. Turbidity of milk prevents a direct photometric measurement of lipase activity using chromophore- or fluorophore-based assays. Laborious pretreatments or alternative analytical methods normally have to be used. With the method for the determination of lipolytic activity (MeDeLi) proposed here, it is possible to measure lipase activity directly in the natural milk utilizing tailored fluorometric substrates. Only a defatting step is carried out initially for the MeDeLi. Then, the conversion of added lipase substrate is carried out in the unmodified milk without addition of any solutions or any enzyme extraction procedure which may influence the enzyme activity. Thereafter, the milk sample is treated with two solutions to remove the turbidity of milk by dissolution. A valid and sensitive fluorometric measurement is then possible. The applicability of the MeDeLi was demonstrated in comparison with tests published previously: The limit of detection for lipolytic activity measured by MeDeLi was the lowest, with 41 pkat/mL. Raw milk, milk products, and spoiled milk samples were also investigated with the MeDeLi.     

Adhesion of fermented diary products to packaging materials. Effect of material functionality,storage time,and fat content of the product. An empirical study

In this empirical study, we have shown that adhesion of dairy products such as fermented milk and yoghurt on packaging materials is dependent on the product contact time to the surface. Approximately 10% of all fermented milk products remain on the inside of today’s packaging material. The viscosity of the product seems to have a major effect on how much product that will be adhered to the surface. The initial adhesion (the first 24 h) of product to material surface shows significant discrepancies whereas on longer time scales (days) it seems to be rather constant and independent of the fat content in the fermented milk or the material polarity. This effect would be explained by the fact that both fat and proteins show strong amphiphilic behaviors. By using FT-IR/ATR measurements it is concluded that the deposit on the surface contains proteins.