原料乳中铵盐掺假检测方法

通过向原料乳中人为添加定量铵盐测试试剂,研究原料乳中铵盐掺假物质定性检测的方法。实验结果表明,该方法用于检测原料乳中铵盐质量分数在0．025％以上,具有良好的可操作性,同时方法操作简单,结果便于观察,适用于在养殖、收购、乳制品企业等进行原料乳质量验收检验。     

原料乳中尿素掺假检测方法的研究

研究原料乳中尿素含量的定性检测,结果表明,该方法用于检测原料乳中“尿素”含量在0.5g/L以上具有良好的可操作性,同时方法操作简单,结果便于观察,适用于在养殖、收购、乳制品企业等进行原料乳质量验收检验.     

原料乳硫氰化物掺假定性检测方法

研究原料乳中硫氰化物掺假物质定性检测的方法,通过向原料乳中人为添加定量硫氰化物,在酸溶液中硫氰酸根与三价铁离子反应生成可溶于水及乙醚的血红色化合物,根据样品中硫氰酸根含量的多少,所显示的颜色不同。通过颜色反应判定原料乳中是否添加硫氰化物掺假物质。实验结果表明,该方法用于检测原料乳中硫氰化物质量分数在0．005％以上,具有良好的可操作性,同时方法操作简单,结果便于观察,适用于乳制品企业进行原料乳质量验收检验。     

电导率法检测原料乳掺假的方法研究

研究了使用电导率法检测原料乳中掺假的方法,根据乳中掺入电解质时电导率有显著增大、掺乳非电解质时电导率有显著减小的特性,使用电导率仪测定待检乳样的电导率,根据一定温度下电导率值与该温度下正常乳样的电导率对比,有显著差异的判定为乳样中有掺假物。此法具有成本低廉,操作方便快捷,检验时间短等特点,为快速定性检测方法,可以在线应用,适用于乳品企业进行原料乳掺假的快速检测。     

原料乳中铵盐与氟乙酰胺掺假定性检测方法

研究了原料乳中铵盐与氟乙酰胺掺假定性检测方法,通过对铵盐与氟乙酰胺检测过程中的取样量、药品加入量、结果判定时间的整合.结果表明,用于检测原料乳中铵盐质量分数在0.025％以上具有良好的重现性,同时方法操作简单,结果准确,适用于乳品企业进行原料及产品中铵盐含量的检测.     

原料乳及乳粉中水解蛋白掺假检测方法的改进

为了监控原料奶和奶粉中是否掺有水解蛋白,采用人为添加水解蛋白到原料乳和奶粉中的方法,使用硝酸汞沉淀除去乳酪蛋白,其中水解蛋白不会被除去,与饱和苦味酸产生沉淀反应的方法进行准确性和检出限的验证,对原料乳和奶粉中水解蛋白检测方法进行改进,满足对阳性样品的分级判定。该方法对原料乳的最低检出量0．05％,对奶粉的最低检出量为0．5％。     

原料奶中尿的掺假定性检测方法

研究了原料乳中尿的检测方法,尿中含有肌酐,在pH值为12的条件下,肌酐与苦味酸反应生成红色或橙红色的复合苦味酸肌酐,通过颜色的变化判断鲜乳中是否有尿的存在.结果表明,该方法用于检测原料乳中尿含量在4％以上含量具有明显的颜色变化,同时方法操作简单,结果判定较直观.适用于乳品企业进行尿定性的检测.     

原料奶中蔗糖掺假的检测方法

通过人为的向原料乳中添加一定量的蔗糖进行测试,检测结果表明,该方法可以快速的测定出掺假乳,同时操作简单,结果便于观察,适用于养殖、收购、乳制品企业等进行原料乳质量验收的检验.     

铁盐法定量检测原料乳中硫氰酸盐

研究原料乳中硫氰酸钠定量检测方法,原料乳样品经过蛋白沉淀后,向滤液中加入铁盐溶液,样液的颜色变化与硫氰酸盐掺入量有关,通过样液的吸光度计算出硫氰酸盐含量。通过对标准溶液线性关系、检出限、回收率、重复性的验证,以及与离子法的对比实验,结果表明,该方法用于检测原料乳中硫氰酸根质量浓度在30mg/L 以下具有良好的线性、回收率、重现性,方法操作简单、结果准确,适用于乳品企业进行原料乳质量检验。     

原料乳及乳粉中糊精掺假的检测方法

研究了原料乳及乳粉中糊精含量的检测方法,样品通过离心除去牛乳中脂肪,在加入沉淀试剂除＋去蛋白、肽和低聚糖等干扰物质,制备澄清透明待测乳清液,加入无水乙醇使糊精结晶形成悬浊液,该悬浊液的吸光度与糊精掺入量有关。通过吸光度换算出糊精质量浓度。结果表明,该方法用于检测原料乳及复原乳中糊精质量浓度在O．025g／100mL以上具有良好的重现性和回收率,同时方法操作简单,结果准确,适用于乳品企业进行原料及产品中糊精质量浓度的检测。     

Simultaneous detection for adulterations of maltodextrin,sodium carbonate,and whey in raw milk using Raman spectroscopy and chemometrics

To achieve rapid on-site identification of raw milk adulteration and simultaneously quantify the levels of various adulterants, we combined Raman spectroscopy with chemometrics to detect 3 of the most common adulterants. Raw milk was artificially adulterated with maltodextrin (0.5–15.0%; wt/wt), sodium carbonate (10–100 mg/kg), or whey (1.0–20.0%; wt/wt). Partial least square discriminant analysis (PLS-DA) classification and a partial least square (PLS) regression model were established using Raman spectra of 144 samples, among which 108 samples were used for training and 36 were used for validation. A model with excellent performance was obtained by spectral preprocessing with first derivative, and variable selection optimization with variable importance in the projection. The classification accuracy of the PLS-DA model was 95.83% for maltodextrin, 100% for sodium carbonate, 95.84% for whey, and 92.25% for pure raw milk. The PLS model had a detection limit of 1.46% for maltodextrin, 4.38 mg/kg for sodium carbonate, and 2.64% for whey. These results suggested that Raman spectroscopy combined with PLS-DA and PLS model can rapidly and efficiently detect adulterants of maltodextrin, sodium carbonate, and whey in raw milk.     

综合型传感器阵列对掺杂生乳的识别

以钯、铂、金、钛、钨和银6种自制电极组为工作电极,与Ag/AgCl参比电极和铂对电极组成非选择性传感器组,再结合pH电极、电导率电极和钠度计电极3种选择性电极组成综合型传感器阵列,连接到电化学工作站和安装SPSS统计学软件电脑后,构成生乳掺杂检测系统。对荷斯坦牛生乳及掺杂不同浓度尿素和三聚氰胺,碳酸氢钠的样本乳、陈放乳、巴氏乳、酸败乳采用电化学方法进行检测,获得开路电位、交流阻抗谱、微分脉冲伏安数据,非选择性与选择性传感器组数据分别采用模式识别法进行计算,并获得各被测样本与生乳标准数据库的欧氏距离,再以不同权重得出综合欧氏距离,通过图表得到表达。结果表明,非选择性传感器阵列组对掺杂生乳具有良好的判别能力,在此基础上构建的加装有选择性传感器的综合型传感器阵列对掺杂的甑别效果优于前者。      

Determination of chlorine ions in raw milk by pulsed amperometric detection in a flow injection system

Chloride ion concentration in milk was determined by pulsed amperometric detection in a flow injection system. Results showed that the Au electrode lost 3 electrons at 1.10 V and formed chloroaurate ions (AuCl₄^?) by combining with chloride ions, after which AuCl₄^? was partly reduced to Au at 0.6 V. Based on the electrochemical process, a triple waveform with detection potential of 1.15 V, detection time of 150 ms, oxidation potential of 1.4 V, oxidation time of 550 ms, reduction potential of 0 V, and reduction time of 400 ms was applied to the Au electrode for detecting chloride ion concentration in milk. The approach is rapid and automatic and features a detection limit of 0.005 g/L. The relative standard deviation obtained by 60 repetitive injections reached 1.48% at 2 g/L of NaCl. The method developed using the Au electrode without modification was used to analyze the chloride ion concentration in raw milk without preprocessing. The method showed good agreement with potentiometric titration.     

免疫学检测羊乳中掺入牛乳成分

由于营养、价格和原料等原因，市场上在羊乳中掺入牛乳的现象常有发生。针对这种乳源性掺假陆续产生了多种检测方法，本文主要综述了以ELISA为主的免疫学快速检测方法。     

Use of MALDI-TOF MS technology to evaluate adulteration of small ruminant milk with raw bovine milk

Detection of adulteration of small ruminant milk is very important for health and commercial reasons. New analytical and cost-effective methods need to be developed to detect new adulteration practices. In this work, we aimed to explore the ability of the MALDI-TOF mass spectrometry to detect bovine milk in caprine and ovine milk using samples from 18 dairy farms. Different levels of adulteration (0.5, 1, 5, 10, 20, 40, 60, and 80%) were analyzed during the lactation period of goat and sheep (in May, from 60 to 90 d in milk, and in August, from 150 to 180 d in milk). Two different ranges of peptide-protein spectra (500–4,000 Da; 4–20 kDa) were used to establish a calibration model for predicting the concentration of adulterant using partial least squares and generalized linear model with lasso regularization. The low molecular weight part of the spectra together with the generalized linear model with lasso regularization regression model appeared to have greater potential for our aim of detection of adulteration of small ruminants' milk. The subsequent prediction model was able to predict the concentration of bovine milk in caprine milk with a root mean square error of 11.4 and 17.0% in ovine milk. The results offer compelling evidence that MALDI-TOF can detect the adulteration of small ruminants' milk. However, the method is severely limited by (1) the complexity of the milk proteome resulting from the adulteration technique, (2) the potential degradation of thermolabile proteins, and (3) the genetic variability of tested samples. Additionally, the root mean square error of prediction based only on one individual sample adulteration series can drop down to 6.34% for quantification of adulterated caprine milk and 6.28% for adulterated ovine milk for the full set of concentrations or down to 2.33 and 4.00%, respectively, if we restrict only to low concentrations of adulteration (0, 0.5, 1, 5, 10%).     

生乳体细胞数检测方法的研究

研究了酯酶分析法检测生乳中体细胞数的方法。对不同样品体细胞计数,拟合了三段标准曲线,分别对应不同的体细胞数,相关系数分别为0.9376,0.9484,0.9633,0.9556。对拟合的标准曲线进行精密度和准确度分析,方法变异系数均小于10%,与直接镜检法无显著差异。结果表明,酯酶分析法是生乳中体细胞数快速检测的有效方法,而且可以应用在奶牛乳房炎的诊断方面。     

水牛乳及其乳制品中掺入牛属动物乳源的检测方法研究进展

综述了电泳、色谱、免疫化学、DNA技术等在掺假水牛乳检测中的研究进展及各自优劣,旨在为我国开展类似研究提供理论依据。     

生乳细菌总数检测仪测定生乳细菌总数的应用

以还原法为理论基础,研制生乳细菌总数检测仪进行生乳细菌总数快速检测,以克服经典还原法目测比色主观性强的缺点,而且检测结果可以定量表示。该仪器连续检测加入试剂后的生乳样品颜色(RGB),通过数理统计分析,采用斜率法以R值斜率表示样品颜色的变化速度。研究以标准平板计数法(SPC法)为标准,建立了R值斜率与菌落总数之间的标准方程,经验证生乳细菌总数检测仪检测结果与SPC法检测结果差异不显著。与流式细胞仪比较,在与SPC法的相关性、运行成本及便携性等方面具有一定优势。     

高效液相色谱法分析原料乳和奶粉中三聚氰胺

建立了二极管阵列检测器-高效液相色谱测定原料乳及奶粉中三聚氰胺的方法。奶粉样品经三氯乙酸超声提取,乙酸铅沉淀蛋白,三氯甲烷除去脂肪和非极性杂质,PROELUTPXCSPE阳离子交换固相萃取小柱进一步除去样品基质干扰,氨化甲醇洗脱。实验对色谱分离条件进行了优化,三聚氰胺的质量浓度在1.0～100.0μg/mL范围内与色谱峰面积呈良好的线性关系,回归方程为y=89.763x-113.72,相关系数为R2=0.9988。加标回收率为90.5%～105.0%,相对标准偏差(RSD)小于4.0%。该方法简单、快速,结果准确可靠。     

原料奶干物质快速测定方法

以直接干燥法和GB5409-85公式计算法为依据,采用甲醛滴定法测定原料奶的干物质质量浓度。结果表明,三种方法测定结果十分接近(P>0.05),回归关系为Y=0.35514(V1-V0)N 6.24762(r=0.9312,P<0.01)。经验证,用回归公式估测牛奶干物质质量浓度与回归标准误差比较相差0.24%;甲醛法操作简单,费用低,省时省力,是一种快速、准确、实用的常规性原料奶干物质快速检测方法。