牛奶中青霉素含量的快速检测

在1 ml待检牛奶中加入3滴Benedict试剂,煮沸5 min.根据试样中颜色变化,判断牛奶中青霉素含量.青霉素含量为(80～100)×10-6显红色,(50～70)×10-6显红黄色,(30～40)×10-6显橘黄色,(10～20)×10-6显浅橘黄色,(5～9)×10-6显正黄色,(0～4)×10-6显黄色.     

牛奶中青霉素类残留微生物学快速检测方法问世

华中农业大学的“牛奶中青霉素类残留微生物学快速检测方法及试剂盒研究”成果11日在武汉通过了农业部鉴定。这项“十五”国家科技攻关项目子课题填补了国内空白，整体技术水平达到国际先进，预期具有良好的社会效益和经济效益。     

牛奶掺杂及其快速检测方法介绍

为促进我国乳品工业的稳步发展,逐步提高乳制品的质量,维护消费者的切身利益,解决乳制品的原料牛奶掺杂问题已提到行业有关部门及加工企业的议事日程。一、我国牛奶掺杂情况据我国奶牛业协会和中国消费者协会1988年对哈尔滨、广州、上海、西安等八大城市49个点的联合调查情况表明:目前牛奶掺杂的情况是严重的。如某市两家乳品厂收     

牛奶中β-内酰胺类抗生素残留的快速检测方法

将微生物方法与仪器分析方法相结合，用嗜热脂肪芽孢杆菌作为指示菌，通过“阻抗分析仪”的自动检测、分析，根据DT时间的产生，判断牛奶中抗生素的残留情况。结果表明，该方法操作简单、快捷，灵敏度高、结果易判断，全部检测过程可在2～3h内完成。本方法检测牛奶中青霉素G的检测限可达3μg／kg。     

时间分辨荧光免疫层析快速检测牛奶中地塞米松

目的 建立基于时间分辨荧光微球对牛奶中的地塞米松残留进行快速检测的方法,并对该方法性能进行评估。方法 使用地塞米松抗体标记时间分辨荧光微球,分别采用湿法和干法制备检测试纸条,比较两种方法的灵敏度,同时确定微球的最佳抗体标记量,并对试纸条的重复性、检测灵敏度进行评估。结果 以20μg抗体/mg微球的标记量,湿法制备的试纸条检测灵敏度更佳。该方法重复性检测中变异系数(coefficientof variation, CV)为8.2%,地塞米松溶液的检出限为0.07 ng/mL,检测牛奶中地塞米松的半抑制浓度(half maximal inhibitory concentration, IC50)为0.24 ng/mL。结论 该方法具有测试简单、灵敏度高等特点,制备的试纸条可满足牛奶中地塞米松残留的检测要求。     

胶体金免疫层析法快速检测牛奶中环丙沙星残留

针对牛奶中恩诺沙星的代谢物环丙沙星残留的问题,该研究开发一种胶体金试纸条快速检测牛奶中的环丙沙星残留。研究制备环丙沙星包被抗原,对环丙沙星抗体进行表征,优化胶体金标记条件,选用最佳标记pH和最佳蛋白添加量,以硝酸纤维素膜为固相载体,环丙沙星包被抗原为检测带(T带),羊抗兔二抗为质控带(T带)。依据免疫竞争法原理,建立胶体金免疫层析试纸条快速检测牛奶中环丙沙星的方法,方法检出限为6.25 ng/mL,对牛奶样品的检出限为12.50 ng/mL。样品前处理方法简单,在10 min内即可目测判断结果。     

大米加工精度检测方法研究进展

加工精度显著影响大米产率和营养,但是加工精度的检测方法众多且尚未统一。本文整理了科学研究和市场贸易中常用的检测方法,通过分析这些方法的原理将它们系统归为重量表征法、外观表征法和糠层成分表征法三大类,并比较了各类方法的优缺点,为大米加工精度的测定方法研究提供理论依据。开展用仪器识别米粒外观的研究将促进大米加工精度检测方法的发展。      

牛奶质量安全快速检测新技术

<正> 在经济全球化背景下,牛奶制品也已步入全球化时代。人口众多的中国经济快速发展,中国牛奶制品进出口贸易总量的变化对国际奶类食品贸易影响越来越大。中国奶类食品质量与安全得到政府的高度重视。随着人们生活质量的提高,奶类人均消费量增长加快,国民的食品安全意识明显增强。国际上也对中国各类出     

蔬菜硝酸盐快速检测方法的研究

以常见叶菜大白菜、小白菜、小油菜、波菜、芹菜为试材,依据NO3-与二苯胺在酸性介质(浓硫酸)中的显色反应,设计了一种建立在目视比色法基础之上,进行比色的一种快速检测叶菜中NO3-含量的方法。这种方法测定时间短、操作简便、快速,无需特殊处理和昂贵的仪器,用于半定量分析,准确度、精密度、灵敏度满足要求。     

Effect of preservatives on milk composition determination

The main objective of our study was to determine the effect of different concentration of four different preservatives, potassium dichromate, Azidiol, Bronopol and Microtabs II, on the results of laboratory analyses of milk using mid-infrared spectrometry. The final concentrations of the preservatives in the raw cows' milk samples were 0.005%, 0.01%, 0.05%, 0.1%, 0.5% and 1% respectively. We analysed unpreserved, fresh bulk raw cows' milk 2 and 24 h after milking. The effect of preservatives on the composition of the milk was studied 24 h after preservation. The experiment was replicated 10 times. Each experiment was carried out after the calibration of the mid-infrared spectrophotometer using calibration samples preserved with 0.02% Bronopol. We found that the concentration of the preserving agent had a significant effect (P < 0.005) on the results of the laboratory analyses; therefore, the proper concentration of preservative has to be used for routine sample preservation.     

奶粉中乙二胺四乙酸铁钠的检测方法及其稳定性研究

研究了奶粉中乙二胺四乙酸铁钠(NaFeEDTA)的检验方法。利用NaFeEDTA与H2O2形成紫红色络合物的反应,建立了奶粉中的NaFeEDTA的快速定性鉴别方法。对前处理条件进行考察后,利用NaFeEDTA解离产生的Fe3+与硫氰酸铵的反应,建立了奶粉中的NaFeEDTA的定量检测方法,方法回收率为86.1%～93.2%。用该方法对强化奶粉储藏过程中NaFeEDTA的含量进行检测发现,在光照或避光储藏90d后,NaFeEDTA含量无明显变化。     

电导微生物技术快速测定原料乳菌落总数的研究

从乳品电导率微生物学的角度研究了快速测定原料乳菌落总数的原理。向计算机(MALTHUS计算软件)中一一对应输入平皿菌落计数值的log值与检测时间，当输入50组以上数据时曲线自动生成。将电导测定方法与常规方法测定结果相比较，结果较理想。电导率微生物检测提供了传统微生物测试所不能比拟的优点。结果表明，该方法具有快速测定、方便、资料自动搜查、允许样品随时插入测试的优点，原料奶得以更快速的监测，适合用于原料乳的微生物指标的质量控制。     

Bradford法测定牛奶中蛋白质含量

采用Bradford法与传统的凯氏定氮法测定牛奶中蛋白质含量并进行比较,Bradford法方便快捷,成本低廉。通过试验对比验证,添加的尿素或者三聚氰胺对测定无影响,与微量凯氏定氮法比较,两者的结果有相关性。     

考马斯亮蓝G-250法快速测定牛乳中的蛋白质

依据考马斯亮蓝G-250与蛋白质结合呈现蓝色，在595nm波长下的吸光度与蛋白质含量呈正比，制作出标准曲线。研究了最佳实验条件，成功地建立一个牛乳中蛋白质快速测定的方法，具有简单、快捷、易行等特点。结果表明该方法精密度高，RSD为1．70％，结果准确，相对误差较小，回收率98．2％-100.3％。     

近红外光谱分析技术快速测定儿童高钙奶粉理化指标的研究

从化学计量学角度研究了近红外光谱技术测定儿童高钙奶粉理化指标的原理。使用多元线性回归法分别建立了近红外检测的儿童高钙奶粉水分、蛋白、脂肪、乳糖和蔗糖的快速测定模型。将近红外法测定结果和标准方法测定结果进行比较,结果吻合理想。近红外光谱法具有分析快速、操作方便、节约检测成本的优点,非常适合用于奶粉生产过程中的质量控制。     

高效液相色谱法测定乳及乳粉中氮氨菲啶

以乙腈-甲酸氨提取样品中氮氨菲啶,应用反相高效液相色谱-可见光检测器,外标法定量,测定了乳及乳粉中氮氨菲啶的质量浓度.氮氨菲啶质量浓度在0.050～1.0 mg/L范围内呈良好线性关系,r=0.9992,平均加标回收率为87.5%～96%,CV=2.13%～7.53%,该方法简便,准确,重现性好,可用于乳及乳粉中氮氨菲啶质量浓度的测定.     

Genetic determination of fatty acid composition in Spanish Churra sheep milk

The objective of this study was to estimate the genetic variation of ovine milk fatty acid (FA) composition. We collected 4,100 milk samples in 14 herds from 976 Churra ewes sired mostly by 15 AI rams and analyzed them by gas-liquid chromatography for milk fatty acid composition. The studied traits were 12 individual FA contents (proportion in relation to the total amount of FA), 3 groups of fatty acids [saturated fatty acids (SFA), monounsaturated FA (MUFA), and polyunsaturated FA (PUFA)], and 2 FA ratios (n-6:n-3 and C18:2 cis-9,trans-11:C18:1 trans-11). In addition, percentages of fat and protein and daily milk yield were studied. For the analysis, repeatability animal models were implemented using Bayesian methods. In an initial step, univariate methods were conducted to test the hypothesis of the traits showing additive genetic determination. Deviance information criterion and Bayes factor were employed as model choice criteria. All the studied SFA showed additive genetic variance, but the estimated heritabilities were low. Among unsaturated FA (UFA), only C18:1 trans-11 and C18:2 cis-9,cis-12 showed additive genetic variation, their estimated heritabilities being [marginal posterior mean (marginal posterior SD)] 0.02(0.01) and 0.11(0.04), respectively. For the FA groups, only PUFA showed significant additive genetic variation. None of the studied ratios of FA showed additive genetic variation. In second multitrait analyses, genetic correlations between individual FA and production traits, and between groups of FA and ratios of FA and production traits, were investigated. Positive genetic correlations were estimated among medium-chain SFA, ranging from 0 to 0.85, but this parameter was close to zero between long-chain SFA (C16:0 and C18:0). Between long- and medium-chain SFA, estimated genetic correlations were negative, around −0.6. Among those UFA showing significant additive genetic variance, genetic correlations were close to zero. The estimated genetic correlations among all the investigated FA, milk yield, and fat and protein percentages were not different from zero. Our results suggest that low additive genetic variation is involved in the determination of the FA composition of milk fat in Churra sheep under current production conditions, which results in low values of heritabilities.