Rapid Screening of 26 Organophosphorus Pesticides in Fresh Milk by Ultra Liquid Chromatography Coupled With Quadrupole-Time of Flight Mass Spectrometry

[Objectives]A rapid screening and analysis method for 26 organophosphorus agrochemicals in fresh milk was established using ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry.[Methods]Raw milk was extracted with acetonitrile solution containing 0.2%formic acid by volume,and purified with a Dikma ProElut QuECHERS solid phase extraction cartridge.Target compounds were separated on a Waters ACQUITY UPLC HSS T3 chromatographic column(2.1 mm×50 mm,1.8μm)with methanol-water solution as a mobile phase for gradient elution,and through scanning with an electrospray ion source in positive ion mode,26 kinds of organophosphorus agrochemicals could be accurately qualitatively determined within 10 min.[Results]When using formic acid acetonitrile with a volume fraction of 0.2%,there were more types of detected compounds and a greater recovery;and using B cartridge could effectively eliminate the interference of non-polar substances such as phospholipids,achieve higher number of detected compounds than those of A and C,and well separate the 26 kinds of agrochemical residues.[Conclusions]This study provides a reference method for the rapid screening of agrochemical residues in dairy cows in the future.

Impact of Bacterial and Somatic Cells Content on Quality Fresh Milk in Small-Scale Dairy Farms in Kosovo

The basic goal of this research was to determine the impact of the presence of bacterial (CFU) and somatic cells count content (SCC) in quality of fresh milk in some small cattle farms in Kosovo. The survey was based on existing standards for milk quality in Kosovo placed under administrative guidance MA-no. 20/2006. The study was based on fresh milk analysis of 150 farms performed during the period September-December 2012, which was obtained in 9 different localities (collection points) of the Kosovo. Our study reveals that CFU and SCC in fresh milk were significantly affected by a number of factors, as: sampling period (repetition), locality, breed, and time of sampling (evening or/and morning). According to the results for CFU and SCC, there were big differences between the farms (milk collection points) included in the study (P < 0.0403) and (P < 0.0293). The results show that small size breed like Busha and its crosses tend to be less exposed to SCC/mL in milk (72.840) and (293.592), compared to Black Holstein (613.462), Simmental (521.519) and Brown Swiss (418.44). Milk produced in evening tended to be of better quality (259.854 CFU/mL) compared to the one from morning milking (576.689 CFU/mL). Fresh milk quality analyzed in the third repetition was better for about 33.3% compared with the repletion first. For CFU and SCC, the analyses show that about 74.7% and 64.7% of milk produced belongs to extra quality, while lower quality of milk of category three is 12.0% and 23.3%, respectively. Considering that about 85% of milk produced in Kosovo comes from small-scale dairy farms, the current study sets out that small-scale milk production system cannot be neglected by interest parties in dairy sector and needs permanent following up and improvement.

Evaluation of Moisturizing Efficacy of A Fresh-Milk Cream

The moisturizing effect of a fresh-milk cream after single and long-term application was studied by the combination of subjective and instrumental methods.The purpose of this study was to evaluate the moisturizing efficacy of fresh milk as a moisturizer in skin care products.Thirty female subjects aged 18~55 years were enrolled and a randomized,double-blind,placebo-controlled comparison study was applied in this research.The stratum corneum water content and transdermal water loss on the cheek,and VISIA-CR images of the whole face were recorded after using the samples.The subjective evaluation of the subjects were also collected.The results showed that the fresh milk cream played a significant role in increasing the water content of facial stratum corneum,improving the transdermal water loss and skin redness compared with the base formula without fresh milk.It indicated that fresh milk can be added to skin care products as a moisturizing agent,which can replenish moisture and enhance the skin barrier function.

Reducing Efficiencies of the Commonly Used Heat Treatment Methods and Fermentation Processes on Aflatoxin M1 in Naturally Contaminated Fresh Cow Milk

The reducing efficiencies of the commonly used heat treatment methods and fermentation processes on aflatoxin M1 (AFM1) in Nigeria were investigated. Seventy samples of fresh cow milk from both conventional and traditional dairy cattle herds were collected and analyzed for the determination of AFM1 using Cobra-cell incorporated high performance liquid chromatography. Of these analyzed samples, 56 (80.0%) tested positive for AFM1 out of which 3 milk samples with high AFM1 concentrations were selectively pooled and subjected to varied conditions of heat treatments and fermentation processes using both indigenized and exotic strains of lactic acid bacteria (Lactobacillus bulgaricus + Streptococcus thermophilus and L. rhamnosus and L. plantarum) as starter cultures respectively. Both processes used either singly or combined, demonstrated high degrees of reducing effects on AFM1 levels. Sterilization of the milk at 121?C and 80?C under the same condition of time (15 - 20) min showed significant reduction of up to 58.8% (p 0.05) in the level of AFM1 when compared with the initial mean AFM1 concentration of the untreated fresh milk. The situation was however different around the boiling temperature of 100?C at which point the level of AFM1 reduction was found to be inconsistent. The indigenized combined strains showed some slight margins of AFM1 reduction in the proportions of (20.5, 30.8 and 43.9)% over and above that of the exotic strains (17.4, 30.0 and 41.1)% in 12 h, 48 h and 72 h of fermentation respectively. Generally, fermentation alone showed lower reduction of AFM1 in milk from 24.5% to 43.9% compared with the reducing activities of (35.4 to 58.8)% when heat-treated milk samples were subsequently subjected to varied fermentation conditions.

Study on Fresh Yam Fermented Milk Technology

[Objective] The aim was to study the fermentation of yam and lactic acid bacteria. [Method] Taking fresh yam as main materials, optimized wheat, skimmed milk and white sugar as auxiliary materials, the lactic acid bacteria developed into healthy drinks with unique flavor. The ratio of raw materials, the best conditions for hydrolysis of malt, lactic acid fermentation process conditions, such as product formulations were studied. [Result] The best conditions for the yam malt enzyme dosage was 21.0%,malt dosage 1.4%, reaction temperature 68 ℃, hydrolysis time 60 min; optimal fermentation process to increase milk production 2.4% , fermentation temperature 38 ℃, fermentation time 7.0h, inoculums size 5.0%. [Conclusion] The fresh yam tastes fresh, sour and sweet. The natural white ram is of high quality.

Quantification of theophylline or paracetamol in milk matrices by high-performance liquid chromatography

A simple, accurate and sensitive high-performance liquid chromatography （HPLC） method was developed, validated and applied to the determination of either theophylline or paracetamol in milk-based samples. The method allowed drug quantification in fresh and powdered milk with a relatively short run time of analysis and it was also successfully applied to the quantification of the drugs in solid dosage forms intended for pediatric use. Moreover, the main significant advantages over other published works are the simplicity of the sample preparation, reduced assay time and sample loss. The method meets the International Conference on Harmonization guideline for analytical methods validation regarding specificity, linearity, accuracy, precision, specificity and robustness as required by health authorities and applied by industry while designing and marketing new drug products. The technique encompasses the separation of the analytes with a reverse phase C18 column under isocrafic conditions and UV detection at 272 nm and 243 nm, respectively, for theophylline and paraeetamol. The lower limit of quantification for both drugs was determined as 0.2 μg/mL and the between-batch accuracy was 99.7%. This HPLC method allows quantification of theophylline and paracetamol in milk matrices and it can be applied in the design, development and production of milk-based pediatric dosage forms.

规模奶牛场提高奶牛乳蛋白含量的营养调控技术综述

优质生鲜乳是人体获取优质蛋白的重要来源,评价生鲜乳质量优良的关键指标是其中乳蛋白含量的高低。为满足大众对生鲜乳的需求,规模化奶牛养殖场逐渐增多,但问题也随之而来。由于奶牛养殖数量较多,若不进行科学的养殖饲喂管理,极易导致乳蛋白含量低下,质量降低,不利于奶及奶制品后期加工及售卖。因此,提高生鲜乳中乳蛋白含量至关重要。本文综合概述影响生鲜乳乳蛋白含量的因素,介绍提高乳蛋白含量的措施,以提升规模化奶牛养殖场中奶牛的乳蛋白含量,促进养殖业健康发展。

纳米保鲜型食品新鲜度指示材料的制备及其应用

随着食品包装在食品品质安全中扮演越来越重要的角色,新鲜度指示材料已成为当下的研究热点。一方面可以阻隔微生物的进入,有效抑制微生物的滋生和繁殖,确保食品包装内部环境的稳定性,进而改变食品品质;另一方面,它可以监测并指示包装内部的环境变化反馈食品品质信息。本文以食品级高分子材料高直链玉米淀粉(HAMS)、聚乙烯醇(PVA)为主要原料,负载复合型pH指示剂MR-BB(甲基红与溴百里酚蓝混合物),利用超声分散法将高抑菌性的纳米二氧化钛(nano-TiO_(2))分散于其中,同时利用交联剂甘油、疏水剂尿素,构建高分子三维立体网状结构,优化其物化性质。用溶液聚合和流延成膜的方法制备具有p H响应性的纳米保鲜-食品新鲜度指示材料(AFIF)。综合各项基础性能可知,高直链玉米淀粉和PVA添加量的体积比为7∶3,甘油添加量为2%,尿素添加量为2%。构筑牛奶新鲜度下降的环境模型(二氧化碳气氛),通过数据对比和优化AFIF膜的p H响应性的灵敏度及其准确性,可知MR-BB最佳体积比为1∶2,最佳添加量为6%。对AFIF膜的抑菌性能以及对市售牛奶的保鲜性能进行分析,当nano-TiO_(2)的添加量为0.15 g时(每100 mL膜液),抑菌率可高达80%左右。实际应用结果表明,常温贮藏时,非抗菌型AFIF膜组在36 h后液态奶失去可食用价值,而AFIF膜包装的牛奶仍保持较好的品质,直到72 h,该组液态奶失去食用价值,此时AFIF膜对变质牛奶的检出时间为3 min 35 s,膜颜色由蓝绿色(初始)转变为深黄色,初始变色面积为10%(膜面积为9 cm^(2)),变色完成时间为33 min 31 s,色差值可达5.91。AFIF膜对市售液态牛乳具有明确的保鲜和新鲜度指示功能。

鲜牛奶品质参数的动力学特性研究及货架期预测

目的为了研究鲜牛奶的品质参数变化规律,建立鲜牛奶的货架期模型。方法对鲜牛奶的脂肪、蛋白质、pH值和酸度在不同贮藏时间和温度内的变化进行分析,通过食品化学反应动力学方程和阿伦尼乌斯方程对鲜牛奶品质参数进行动力学特性研究。结果鲜牛奶中脂肪、蛋白质、pH值在贮藏期内呈下降趋势,酸度呈上升趋势。4℃能减缓鲜牛奶pH值的下降和酸度的上升。结论酸度能很好地表达鲜牛奶品质的变化过程,并且通过化学反应动力学特性研究得到了鲜牛奶酸度的活化能和基于酸度的鲜牛奶的货架期模型。

高效液相色谱-质谱法测定生鲜乳中氯霉素的方法研究

建立高效液相色谱-串联质谱法测定生鲜乳中氯霉素残留的方法。对GB 29688—2013《牛奶中氯霉素残留量的测定液相色谱-串联质谱法》中的测定方法进行优化。量取生鲜乳适量,加氯霉素-D_(5)内标工作液,经乙腈萃取后,5000 r/min离心,过OASIS Prime HLB柱,将所过溶液氮气吹干,水复溶,取下层水溶液层过0.22μm水系滤膜。将C_(18)柱作为液相色谱柱,按V_((乙腈))∶V_((水))=60:40体积比等度洗脱。结果表明,氯霉素在0.2~10.0μg/kg范围内有较好的准确度,相关系数均大于0.99,方法检测限0.05μg/kg,定量限都为0.2μg/kg,3个加标浓度(0.2、1.0、10.0μg/kg)的氯霉素的平均回收率为85.5%~116.0%,相对标准偏差为1.23%~8.16%。试验结果完全符合国家标准检测要求,适用于生鲜乳中氯霉素定性定量快速检测。

不同底物激活的乳过氧化物酶系统对生牛乳保鲜效果的影响

乳过氧化物酶系统(Lactoperoxidase System,LPS)是新鲜生牛乳中的天然抗菌活性体系。本文在深入研究LPS相关文献的基础上,开展实验比较不同底物激活的乳过氧化物酶(LP)+硫氰酸盐(SCN^(-))+过氧化氢(H_(2)O_(2))系统和乳过氧化物酶(LP)+卤化物(I^(-))+过氧化氢(H_(2)O_(2))系统对延长生牛乳保质期的有效性。结果表明,LP+SCN^(-)+H_(2)O_(2)系统和LP+I^(-)+H_(2)O_(2)系统均能有效延长生牛乳在室温下的保质期,LP+I^(-)+H_(2)O_(2)系统对生牛乳保质期的延长效果更加显著。

Effect of Bacterial Content and Somatic Cell Count on Sheep Milk Quality in Kosovo

The main objective of this study was to analyze the effect of bacterial content (CFU) and somatic cell count (SCC) in milk quality in sheep (Ovis aries) farms according to the existing standards for fresh milk quality in Kosovo. A total of 2256 milk test day records from 379 Bardhoka (BAR), Sharri sheep (SHA), Kosovo sheep (KOS) and Balusha (BAL) ewes in eight herds across the country were collected and analyzed through a period April-October 2010. The general linear model and Duncan’s test were used to analyze the effect of different variables on presence of CFU and SCC in fresh milk. The effect of all variables was considered as a fixed. The overall results show that farm (P 0422), respectively, had a significant effect on presence of SCC. For CFU farm (P 0422) and breed (P 1211.17 to 6425.76 CFU/mL and 846.07 to 2043.15 SCC/mL milk, respectively. Although the rate of fresh milk contamination with SCC tends to be relatively low compare with CFU, by all means both variables should not be underestimated bearing in mind that a high rate of them on fresh milk are negatively correlated with farmer’s profit, consumer food safety and overall animal health.

Establishment and Optimization of HPLC-MS/MS for Detection of Progesterone Residue in Raw Milk

In order to establish an HPLC-MS/MS method for detecting progesterone in raw milk,raw milk was extracted with methanol,and then determined by HPLC-MS/MS after the purification with a C18 solid phase extraction column. Qualitative determination was performed according to retention time and selective ion abundance ratio,and quantification was performed by external standard method. The results showed that progesterone had a good linear relation in the range of0. 1-5. 0 ng/ml,with a correlation coefficient of 0. 999 9. The detection limit of the established method was 0. 02 μg/kg,and the quantification limit was0. 04 μg/kg. In the standard addition range of 0. 1-5. 0 ng/ml,the recovery ranged from 79. 6% to 105. 1%,with relative standard deviation≤8. 9%. Compared with the industry standard,the detection limit and the quantification limit of the established method are significantly reduced,and the sensitivity of the method is enhanced,so this method is suitable for the detection of progesterone residue in fresh milk in pastures.

冻藏条件对牦牛原料乳品质的影响

牦牛乳因其营养价值丰富、风味独特而逐渐受到消费者关注。然而,因牦牛的泌乳期短、产奶量偏低,在贮存保鲜等方面存在诸多问题。本研究将牦牛原料乳在不同冻藏条件贮存180 d,分别在30 d、90 d、180 d时测定其新鲜度、蛋白质特性、脂肪特性和感官评价等的变化,探究冻藏条件对牦牛乳在贮存期间品质的影响。结果显示,与新鲜原料乳比较,各组牦牛乳在冻藏30 d内的菌落总数及嗜冷菌数量显著下降(P<0.05);冻藏至90 d时,各组微生物数量有所增加,-20℃及-40℃组中牦牛乳的酸度、蛋白水解度、脂肪氧化度以及脂肪球的聚集程度和颗粒大小显著增加(P<0.05),而乳的热稳定性、可溶性蛋白含量显著下降(P<0.05),-80℃组只有蛋白含量发生显著变化;当原料乳冻藏至180 d时,各组乳的品质进一步降低,其中-40℃组的显著优于-20℃的冻藏组,电子舌分析结果也显示在-40℃冻藏条件下的牦牛乳中酸、涩及苦的味感值优于-20℃冻藏组,而-80℃组乳的品质则显著优于前两者。

北京和河北地区生鲜乳中重金属铅含量的风险监测

目的:调查北京和河北地区生鲜乳和牧场投入品中重金属污染情况。方法:针对北京和河北地区养殖场分布情况,采集这两个地区35家牧场的生鲜乳样和北京地区3家规模牧场中饲料、生产用水等投入品样,开展铅污染状况的风险监测。结果:北京地区3家牧场的52份饲料样品铅的含量未超出标准限量要求,6份用水样品未检出铅的含量,饲料和用水合格率均为100%;北京和河北地区奶牛养殖场35份生鲜乳合格率为100%。结论:北京地区牧场投入品的安全性较好,北京和河北地区的生鲜乳无明显受重金属铅的污染,通过本文不仅了解北京和河北地区生鲜乳中铅污染水平,同时也为制修订标准、风险预警和风险评估提供了参考数据。

GC-MS法测定不同地区生鲜牛乳中的脂肪酸组成及含量

[目的]比较分析不同地区生鲜牛乳中的脂肪酸种类和含量。[方法]于2019年5月—2020年3月,从河南省、河北省、山西省各选取1个规模化奶牛养殖场,按照四个季节分别采集健康奶牛生鲜乳样,每个地区采集12份,3个地区共36份。使用GC-MS法进行脂肪酸的提取和甲酯化,利用CP-WAX 52 CB毛细管色谱柱和质谱联用分析仪进行脂肪酸种类和含量分析。通过与37种脂肪酸甲酯混合标准品的保留时间比对和NIST05谱库检索对脂肪酸进行定性分析,脂肪酸含量通过面积归一化法进行计算。[结果]从河南省采集的生鲜牛乳中共检出28种脂肪酸,其中,饱和脂肪酸15种,癸酸甲酯、月桂酸甲酯、肉豆蔻酸甲酯、硬脂酸甲酯、棕榈酸甲酯5种饱和脂肪酸的含量较高,占检出脂肪酸总含量的57.03%;检测到不饱和脂肪酸13种,多数含量较低,只有油酸/反油酸甲酯含量较高,占检出脂肪酸总含量的32.26%。从河北省以及山西省采集的生鲜牛乳中均检出30种脂肪酸,但其组成略有不同;2个省份生鲜牛乳的脂肪酸含量检测结果与河南省生鲜牛乳的检测结果相似,饱和脂肪酸含量占检出脂肪酸总含量的比例均在60%左右。河北省生鲜牛乳中的油酸/反油酸含量为39.80%,在3个地区中最高。3个地区的生鲜牛乳中均未检测到反亚油酸甲酯、γ-亚麻酸甲酯、顺-15-碳烯酸甲酯、芥酸甲酯、顺-4,7,10,13,16,19-二十二碳六烯酸甲酯。[结论]3个地区生鲜牛乳中的脂肪酸含量都比较丰富,以饱和脂肪酸为主,所有脂肪酸中以油酸/反油酸含量最高,但脂肪酸组成及含量也存在一定的地区差异。

ICP-MS测定宁夏生鲜乳中多种矿物质元素

本研究采集宁夏12个养殖重点县区114个牧场的荷斯坦奶牛混合奶罐奶样,利用电感耦合等离子体质谱仪测定生鲜牛乳中钙、铁、锌、硒等9种矿物质元素含量,对其差异性进行评价,探明宁夏牛奶富硒富锌富钾富铜的显著特异性品质,为“宁夏牛奶”品牌创建、标准化生产提供技术支撑。

生乳新鲜度评价指标研究进展

牛奶是最接近完美的食物,也是微生物生长繁殖的绝佳培养基。生乳在离开母体的那一刻便开始逐步走向腐败,其品质降低和风味变差,甚至危害人们的健康。本文综述了生乳腐败过程、新鲜度评价指标及相应的检测方法,为探索生乳新鲜度评价指标和检测方法提供理论参考。

乙基纤维素/蓝莓花青素浸泡型标签对牛奶新鲜度的指示

目的旨在研发一款可浸泡在液体中的食品级牛奶新鲜度指示标签,让消费者简单方便且直观地了解牛奶的实时品质。方法以乙基纤维素为聚合物基材,蓝莓花青素为pH敏感染料,吐温80和甘油为增塑剂制备出标签。通过比色分析、溶胀率、迁移测试、接触角、傅里叶变换红外光谱分析、扫描电镜(SEM)对指示标签进行表征,再将标签用于牛奶新鲜度监测,探究牛奶菌落总数、pH与指示标签总色差的关系。结果花青素添加量为乙基纤维素质量分数10%的指示标签在pH缓冲液中的指示效果最佳;乙基纤维素和花青素通过氢键较好地结合使标签耐水性较好,可浸泡于液体中;迁移测试证明标签与牛奶接触不会造成安全问题;牛奶菌落总数、pH值与指示标签总色差存在相关性。结论花青素添加量为乙基纤维素质量分数10%的指示标签在新鲜牛奶中显示为浅紫色,在变质牛奶中显示为粉色。该浸泡型指示标签在指示牛奶新鲜度上有良好应用价值和开发前景。

鲜乳中添加肉桂精油对其货架品质的影响

为研究肉桂精油(Cinnamon Essential Oil)对鲜乳货架期的影响,本试验选择新鲜生乳作为研究对象,利用不同浓度(0.0、0.5、1.0、1.5、2.0 mg/L)的CEO对鲜乳进行处理,研究在4℃条件下,鲜乳中pH、吉尔涅尔度、丙二醛、超氧化物歧化酶、菌落总数、色度及质构特性随储藏时间的变化情况。结果表明:鲜乳贮藏至第4天时,添加0.5 mg/L CEO的鲜乳吉尔涅尔度显著低于2.0 mg/L的CEO组(P<0.05),添加2.0 mg/L CEO的鲜乳的MDA含量和菌落总数显著低于对照组(P<0.05),且各试验组鲜乳的pH值均低于鲜乳正常pH值范围(pH=6.4~6.8)。添加1.5 mg/L CEO组鲜乳中,吉尔涅尔度、MDA值以及菌落总数显著低于对照组及其它浓度的处理组(P<0.05),SOD值、色度和质构特性显著高于对照组(P<0.05)。此外,随着贮藏时间的增加,1.5 mg/L CEO组中鲜乳的pH值由第2天的6.58迅速降低至第4天的6.26,吉尔涅尔度由第2天的14.70°T迅速升高至第4天的19.00°T,且增幅显著(P<0.05)。在整个试验期间,添加精油各组中鲜乳的pH值均显著高于对照组(P<0.05)。由以上结果可知,CEO可抑制鲜乳中微生物繁殖,可作为一种鲜乳的保鲜剂进行应用开发,本试验推荐鲜乳中CEO的最佳添加量为1.5 mg/L。