Facile SERS screening of melamine in bovine milk with 2D printed AgNPs/glass fabric filter paper as the flexible substrate

Melamine is one of the most frequently detected adulterants in dairy products.The current study proposes a surface-enhanced Raman spectroscopy(SERS)-based analytical tool for fast and reliable screening of melamine in bovine milk.A hand-held Raman spectrometer was used in conjunction with a substrate composed of silver nanoparticles(AgNPs)that was 2D printed onto glass fiber(GF)filter paper.Under optimized conditions,a sensitive and fingerprint-like signal at 674 cm^(-1) was obtained.The AgNPs/GF substrate exhibited high sensitivity to melamine in milk down to 1.9498×10^(-5)mg/mL,which is well below the USA and EU safety limits(2.5×10^(-3)mg/mL).Remarkably,the proposed technology was also highly reproducible,showing spot-to-spot and block-to-block variations below 3.3%and 4.9%at 674 cm^(-1) in Raman intensity,respectively.The characteristic peak intensity and concentration of melamine showed an acceptable linear relationship(R^(2)=0.9909)within the range of 0.0001-1 mg/mL.Overall,the method established in this study can provide an efficient and effective method for the quantitative target screening and detection of melamine in dairy products.

2DGE-coomassie brilliant blue staining used to differentiate pasteurized milk from reconstituted milk

Differentiating pasteurized milk and reconsti-tuted milk by scientific approach was necessary to defend consumer from economic fraud of wrong labeling. In this paper 2DGE (2 Dimen-sional Gel Electrophoresis)-coomassie brilliant blue staining method was employed and sig-nificant color intensity changing was observed among raw milk, pasteurized milk, UHT milk and reconstituted milk. For example, the intensity of 10 protein spots including casein and lac-toglobulin reduced more than two folds from pasteurized milk to reconstituted milk. However, DIGE (Differential Gel Electrophoresis) assay showed that the majority protein remained simi-lar level from pasteurized milk to reconstituted milk. Therefore the color fading of coomassie brilliant blue stained 2D gels may be due to other biochemical reaction, such as Maillard reaction, instead of protein degradation. Stability of 2DGE pattern was confirmed by running six gels of the same sample in parallel and software analysis showed that all proteins were at similar level. Two commercialized pasteurized milk samples and one reconstituted milk sample were tested by 2DGE-coomassie blue staining method and re-constituted milk could be easily identified.

Genetic Variants in the ELOVL5 but not ELOVL2 Gene Associated with Polyunsaturated Fatty Acids in Han Chinese Breast Milk

The present study was designed to examine the contributions of the fatty acid elongase （ELOVL） gene polymorphisms to the levels of polyunsaturated fatty acids （PUFAs） in breast milk. Two hundred and nine healthy Han Chinese mothers were included in the study. Carriers of minor alleles of SNPs （rs2397142 and rs9357760） in ELOVL5 were associated with higher levels of linoleic acid （LA）, dihomo-γ-linolenic acid （DGLA）, arachidonic acid （AA）, docosatetraenoic acid （DTA）, docosahexenoic acid （DHA）, while in rs209512 of ELOVL5 the carriers of minor alleles had lower levels of DTA compared to major homozygote alleles （P ranged from 0.004-0.046）, and genetically explained variability ranged from 3.2% for eicosapentaenoic acid （EPA） to 6.0% for LA. Our findings demonstrated that common variation in ELOVL5 gene encoding rate-limiting enzymes in the metabolism of PUFAs contribute to the PUFAs in breast milk.

A2β-酪蛋白牛奶和普通牛奶的体外消化特性和抗氧化能力评价

[目的]研究体外模拟胃肠消化对A2β-酪蛋白牛奶和普通牛奶的分子量分布及抗氧化能力的影响。[方法]以巴氏杀菌A2β-酪蛋白牛奶、超高温灭菌A2β-酪蛋白牛奶、巴氏杀菌普通牛奶、超高温灭菌牛奶为原料,通过INFOGEST 2.0对牛奶进行体外模拟胃肠消化,采用SDS-PAGE、高效液相色谱仪对体外模拟胃肠消化前后的牛奶样品进行分子量分析,并对体外模拟胃肠消化后各样品的抗氧化能力进行测定。[结果]在体外模拟胃肠消化后,4种牛奶的分子量主要分布于<1000 Da组分,A2β-酪蛋白牛奶小于500 Da组分的比例显著低于普通牛奶。超高温灭菌普通牛奶、超高温灭菌A2β-酪蛋白牛奶表现出较强的铁离子还原能力和1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力。[结论]本研究为各类牛奶产品的加工和功能特性提供基础数据。

基于MWCNTs和Co-Fe双金属普鲁士蓝类似物的电化学传感检测牛奶中的H_(2)O_(2)

该研究构建了钴铁普鲁士蓝类似物(Co-FePBA)和多壁碳纳米管(MWCNTs)修饰的无酶电化学传感器(NF/Co-FePBA/MWCNTs/GCE),Co-FePBA模拟过氧化氢酶对H_(2)O_(2)进行电催化还原,产生较强的电流响应,用于牛奶中H_(2)O_(2)的快速、灵敏电化学检测。在最优条件下,该传感器对H_(2)O_(2)的电流响应有较宽的线性范围(0.01~5.0 mmol/L),检出限(LOD,S/N=3)为0.52μmol/L。此外,该传感器具有较强的抗干扰能力和良好的重复性、重现性和稳定性,用于实际牛奶样品检测中回收率为91.3%~103%,相对标准偏差(RSD)≤2.7%(n=3)。该电化学检测方法可以实现牛奶中H_(2)O_(2)的低成本、简单、快速、高灵敏检测。

Appraisement on Contributive Ratio of Scientific and Technical Progresses in Milk Productive Enterprises by Model C^2GS^2

Scientific and technical progress has been the driving forces of enterprises development.Milk productive enterprises are developing faster and growing better.It is very important to measure the contributive ratio of scientific and technical progress in milk productive enterprises.And the appraisement could help to develop milk productive enterprises.The model C^2GS^2 was established to appraise the contributive ratio of scientific and technical progress in milk productive enterprises in the research.And the appraisement on the contributive ratio of scientific and technical progress in milk productive enterprises was made by the model.In the results of appraisement,science and technology play a main role in milk productive enterprises.It is shown that our milk productive enterprises are developed by scientific and technical progress while not by input of productive factors.

Cow milkα_(s1)-casein induces allergic responses in a mouse model of atopy

α_(s1)-Casein is a potential allergen to induce hypersensitivity in cow milk.We had identifiedα_(s1)-casein and its epitopes in previous studies.The present study aimed to evaluate the allergic mechanism ofα_(s1)-casein in a BALB/c mouse model.The levels of specific IgE,mast cell proteinase,histamine and cytokines in sensitized mice were determined,and the clinical and pathological observation were evaluated.Results showed that the levels of specific IgE,mast cell proteinase,histamine,IL-4,IL-5,IL-10 increased significantly with a dose-dependent trend.The local alveolar septum collapsed or thickened,and lymphatic foci were produced in the spleen and thymus,and the inflammatory cells infiltrated in small intestinal mucosa mesenchyme.In conclusion,the levels of specific IgE,mast cell proteinase,histamine,IL-4,IL-5,IL-10 and some inflammatory factors could possibly serve as allergic biomarkers ofα_(s1)-casein,however,additional studies on signal transduction and gene expression are necessary in future.

Simultaneous Determination of 2- and 3-MCPD Esters in Infant Formula Milk Powder and Edible Vegetable Oils by Gas Chromatography-Mass Spectrometry

Esters of 2- and 3-monochloropropane-1,2-diol (MCPD) are significative contaminants of processed edible oils used as foods or food ingredients. The aim of this study was to develop and validate a new method by GC-MS for the simultaneous quantification of 2 and 3-MCPD esters in infant milk powder and edible vegetable oils. The developed protocol included fat fraction in infant milk powder and edible vegetable oils samples was extracted and treated with sodium methylate-methanol to cleave the ester bonds of the 2- and 3-MCPD esters, moreover, standard samples of deuterium isotope-labeled 2- and 3-MCPD palmitic acid double esters and stearic acid double esters were used as the internal standards. Furthermore, this method was validated when it was applied to food products, concrete manifestation in its good accuracy (the recovery of MCPD esters ranged from 86% to 114%), high sensitivity (the LOD of 3-MCPD and 2-MCPD esters were 0.025 and 0.020 mg/kg, LOQ were 0.075, 0.060 mg/kg, respectively) and satisfactory repeatability (RSD below 6.8%) for all analytes. In the 150 commercial edible vegetable oils and infant formula milk powder samples, we obtained a preliminary profile of MCPD ester contamination.

2'⁃岩藻糖基乳糖功能及其微生物生产菌种构建研究进展

2'⁃岩藻糖基乳糖(2'⁃fucosyllactose,2'⁃FL)在人乳寡糖中含量最高,占比可达30%。2'⁃FL能够有效促进婴儿大脑发育、提高婴儿免疫力,对青少年、成年人、老年人也大有裨益,已被广泛应用于婴幼儿配方奶粉、功能性食品饮料及医疗辅剂中。微生物合成2'⁃FL具有易实现大规模生产、可使用廉价原料作为底物等优势。目前2'⁃FL最主要的工业生产菌种为大肠杆菌,其他食品安全级菌株如酿酒酵母、枯草芽孢杆菌等也陆续被改造用来生产2'⁃FL,并已取得一定成效。该文对2'⁃FL作用于人体的机制、应用领域及2'⁃FL合成菌种构建现状等进行综述,并对未来发展趋势进行展望。

代谢工程产2′-岩藻糖基乳糖的研究

人乳低聚糖(human milk oligosaccharide,HMO)是存在人母乳中的重要组成成分,与婴儿的健康和发育密切相关。2-岩藻糖基乳糖(2′-fucosyllactose,2′-FL)是HMO中含量最丰富的成分,具有显著的营养价值和药用价值,如促进婴儿大脑发育、提高婴儿免疫力等。现如今合成2′-FL的方法有直接提取、化学合成、酶促合成以及微生物发酵法,但前3种方法存在诸多限制及不足,微生物发酵法成为最有潜力的方法。该文对利用微生物进行改造从而提高2′-FL产量的研究进行了综述,以期为相关研究者提供参考。

气相色谱法测定婴幼儿配方乳粉中的1,3-二油酸-2-棕榈酸甘油三酯

目的建立气相色谱法测定婴幼儿配方乳粉中1,3-二油酸-2-棕榈酸甘油三酯(1,3-dioleyl-2-palmitoyl-glycerol,OPO)的方法。方法样品通过碱式水解处理,提取脂肪后,采用甘油三酯专用气相色谱柱进行分离,并使用氢火焰离子化检测器进行检测,结果采用外标法定量。结果OPO在0.02~1.00mg/m L质量浓度范围内具有良好的线性关系,相关系数(r^(2))为0.999。检出限与定量限分别为0.119 g/100 g和0.664 g/100 g,回收率为99.1%~100.1%,相对标准偏差小于5%。应用此方法对我国市售的36批次OPO强化婴幼儿配方乳粉进行检测,OPO含量为2.39~4.89 g/100 g,占标签标示值的60.7%~102.1%。这主要因为本方法检测的是OPO含量,而标签标示的是碳数为C52的甘油三酯的量。结论该方法成功实现了OPO与其他碳数为C52、饱和度不同的甘油三酯的气相色谱法基线分离,可对OPO单体进行精确的定性和定量分析,适用于婴幼儿配方乳粉中OPO的检测。

基于超高效液相色谱-串联质谱同时测定婴幼儿配方乳粉中2′-岩藻糖基乳糖和乳糖-N-新四糖

建立超高效液相色谱-串联质谱法(ultra-performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)同时测定婴幼儿配方乳粉中2′-岩藻糖基乳糖(2′-fucosyllactose,2′-FL)和乳糖-N-新四糖(lacto-N-neotetraose,LNnT)。样品经水提取,沉淀法除蛋白、针式水系滤膜净化,以乙腈和10 mmol/L甲酸铵水溶液(含0.1%甲酸,体积分数)为流动相,采用酰胺柱进行梯度洗脱,采用选择反应检测扫描模式(selective reaction monitoring,SRM)测定,外标法定量,稀释法评估溶剂效应、提取后添加法评估基质效应。结果表明,正离子模式下2′-FL和LNnT分别采用加合离子峰[M+NH^(+)_(4)]和[M+H^(+)]较好,梯度条件、流速优化后使得2′-FL和LNnT均能在8 min内完成洗脱,溶剂效应考察发现2′-FL和LNnT存在严重的溶剂效应,但在消除试验中发现在稀释20倍的情形下,50%乙腈甲酸铵水溶液作为净化样液的稀释溶剂可消除影响,线性范围考察发现2′-FL和LNnT线性范围分别为5.0~150.0 ng/mL和2.5~75.0 ng/mL,基质效应考察发现2′-FL和LNnT均不存在基质效应。方法验证表明,2′-FL和LNnT各项精密度正确度参数均满足国标要求,该方法适用于婴幼儿配方乳粉中2′-FL和LNnT的同时测定。

气相色谱—质谱法快速测定乳粉中2种单氯丙二醇

本文研究建立一种适用于乳粉中3-氯-1,2-丙二醇(3-MCPD)和2-氯-1,3-丙二醇(2-MCPD)的气相色谱-质谱联用(GC-MS)检测方法。样品经甲醇提取浓缩后,加入20%氯化钠溶液复溶,正己烷脱脂后无需进一步净化,通过乙酸乙酯萃取,并加入苯基硼酸作为衍生化试剂,浓缩后采用DB-5MS色谱柱(30 m×0.25 mm×0.25μm)分离,选择离子监测模式(SIM)下测定,内标法定量。结果表明,该方法在0~400μg/L范围内线性良好,相关系数(r^(2))均大于0.999;方法检出限(LODs)均为0.002 mg/kg,定量限(LOQs)均为0.005 mg/kg;在定量限、3-MCPD限量值及介于二者之间的3个浓度水平的平均回收率为96.3%~103.8%,相对标准偏差(RSD)为0.19%~8.36%。该方法操作简便、成本较低,且灵敏度好,准确性高,可为乳粉的风险监控提供技术支持。

婴配乳粉中2'-岩藻糖基乳糖和乳糖-N-新四糖含量离子色谱法检测

研究了离子色谱法同时测定婴配乳粉中2′-岩藻糖基乳糖和乳糖-N-新四糖的含量及影响因素。采用离子色谱柱分离,脉冲安培检测器检测和外标法定量分析等方法。通过对不同净化方式、酶解处理和洗脱条件等过程进行考察和优化,比较确定色谱条件和前处理条件对分离的影响,并就线性范围进行探讨。结果表明,优化后的方法线性关系良好,R^(2)>0.999;方法精密度好,相对标准偏差(n=7)<2.7%;方法准确度好,2′-岩藻糖基乳糖回收率为95.97%~103.38%,乳糖-N-新四糖回收率为100.09%~104.01%。该方法能对婴配乳粉中的2′-岩藻糖基乳糖和乳糖-N-新四糖同时测定,操作简单,具有良好的准确度和精密度,可为婴配乳粉质量监控方法提供参考。

ILC2细胞、肠道微生态与牛奶蛋白过敏关系的研究进展

2型固有淋巴细胞(ILC2)是一种免疫细胞,可分泌辅助性T细胞2,参与呼吸道过敏、蠕虫感染等疾病的发生发展。牛奶蛋白过敏(CMPA)是一种口服耐受建立失败而引起的多器官甚至全身过敏状态。受饮食方式和环境变化的影响,肠道微生态失衡导致儿童中CMPA的发生率逐年攀升。近年来对免疫相关细胞群体的研究表明,ILC2在肠道局部免疫中起重要作用。ILC2的激活和功能表达离不开肠道菌群产生的细胞因子和代谢物,未来对过敏肠道内ILC2的代谢组学研究,或将成为治疗CMPA的靶细胞。

婴幼儿配方奶粉中1,3-二油酸-2-棕榈酸甘油三酯的测定

[目的]建立气相色谱检测婴幼儿配方奶粉中1,3-二油酸-2-棕榈酸甘油三酯的含量。[方法]婴幼儿配方奶粉样品经温水溶解、氨水皂化、乙醚石油醚提取油脂,正己烷溶解,采用Agilent DB-1HT毛细管柱分离,通过与标准甘油三酯溶液对比确定出峰位置,采用内标法定量。[结果]方法定量限为0.008 mg/100 g,线性范围良好。低、中、高3个标准添加水平的回收率为81.1%~98.4%,相对标准偏差在2.89%~7.88%。对婴幼儿配方羊奶粉、牛奶粉基质样品中1,3-二油酸-2-棕榈酸甘油三酯的含量测定RSD≤3.03%。[结论]该方法操作过程简单、分析周期短、灵敏度高、重复性好,适用于测定婴幼儿配方牛奶粉、婴幼儿配方羊奶粉中1,3-二油酸-2-棕榈酸甘油三酯的含量,具有理想的定量效果及应用前景。

无锡地区人乳脂肪脂肪酸组成及sn-2位脂肪酸分布

采集无锡地区150例人乳样品,提取乳中脂肪后,采用气相色谱法对人乳脂肪中总脂肪酸及sn-2位脂肪酸进行测定。结果表明:人乳脂肪总脂肪酸中饱和脂肪酸含量较低,主要为棕榈酸,不饱和脂肪酸含量较高,主要为油酸和亚油酸。随着泌乳期的延长,中碳链饱和脂肪酸(C8∶0、C10∶0、C12∶0)及单不饱和脂肪酸(C16∶1)含量逐渐增加,而部分长碳链饱和脂肪酸及长碳链多不饱和脂肪酸如二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)含量明显下降。人乳脂肪中sn-2位脂肪酸组成中饱和脂肪酸含量约为70%,主要为棕榈酸。

驼乳对2型糖尿病小鼠肝脏损伤的保护作用

目的:探讨驼乳对2型糖尿病小鼠肝脏损伤的保护作用。方法:高糖、高脂联合链脲佐菌素(STZ)诱导2型糖尿病小鼠模型,将造模成功的小鼠随机分为模型组、病理组、驼乳组。灌胃4周后,检测各组小鼠血清中三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白(LDL-c)、高密度脂蛋白(HDL-c)、超氧化物歧化酶(SOD)和丙二醛(MDA),及肝组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和丙二醛(MDA)水平;采用HE染色光镜观察肝脏组织的病理变化。结果:与模型组相比,驼乳能有效缓解糖尿病小鼠的症状,明显降低血清TG、TC、LDL-c的水平。增加SOD、CAT的活力,降低MDA水平,并能改善肝脏的病理变化。结论:驼乳具有改善糖尿病小鼠肝脏功能,改善肝脏氧化应激和改善血脂代谢的作用,对2型糖尿病造成的肝脏损害具有一定的保护作用。

猪后海穴接种猪传染性胃肠炎疫苗对母乳及仔猪血清中IL-2含量的影响

应用放射免疫分析方法 ,测定比较了猪后海穴穴位免疫与常规口服、肌肉途径免疫猪传染性胃肠炎疫苗后 ,母猪初乳、常乳及免疫仔猪血清中 IL -2的含量。结果表明 ,初乳中 IL-2的含量以穴位免疫最高 ;常乳中 IL-2含量各种免疫途径基本一致 ,处于较低水平。仔猪免疫后 3d,血清中 IL-2含量 ,穴位免疫与口服免疫基本一致 ,但均高于肌肉免疫及对照 ;免疫后 7d,血清中 IL-2含量 ,穴位免疫高于口服、肌肉免疫。从免疫调节因子方面看出 。

骆驼奶对2型糖尿病防治作用试验研究

探讨骆驼奶对2型糖尿病预防和治疗作用。采用预防性灌胃骆驼奶后在造模和先造模再治疗性灌胃骆驼奶两种方法,分别与对照组、糖尿病模型组、牛奶组、盐酸二甲双胍组和驼奶与盐酸二甲双胍混合组比较,研究骆驼奶对由高脂饮食联合链脲佐菌素(Streptozotocin,STZ)诱发2型糖尿病模型小鼠的预防和治疗作用,并测定其空腹血糖(glucose)含量、血清超氧化岐化酶(superoxide dismutse,SOD)活性、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)活性、丙二醛(malon dialdehyde,MDA)含量及甘油三酯(triglyceride,TG)、总胆固醇(total cholesterol,TC)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)、低密度脂蛋白胆固醇(low density lipoprotein,LDL-C)的含量。结果表明:骆驼奶能显著降低2型糖尿病小鼠空腹血糖,增加其血清SOD、GSH-Px活性和HDL-C含量,降低血清MDA、TG、TC、LDL-C含量。因此,骆驼奶有较好的预防和治疗2型糖尿病的作用。