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在牛奶的营养成分中，蛋白质含量是衡量牛奶质量的核心指标。因此，文章探索两种牛奶中蛋白质含量的检测方法。为比较凯氏定氮法和杜马斯燃烧法测定牛奶中蛋白质含量的准确性，对市面上出售的3种牛奶样品（即全脂纯牛奶、脱脂纯牛奶、发酵乳）进行测定。并讨论了牛奶样品温度对蛋白质含量测定结果的影响，结果表明，牛奶样品的温度对凯氏定氮法、杜马斯燃烧法的蛋白质检测结果没有显著影响。随后，使用凯氏定氮法与杜马斯燃烧法测定了这3种牛奶中蛋白质含量，试验结果显示，这两种方法均能准确测定牛奶样品中的蛋白质含量，检测结果存在显著差异（P <0.05）。3种牛奶中的蛋白质含量对比为全脂纯牛奶>脱脂纯牛奶>发酵乳。凯氏定氮法测定结果的相对误差均小于杜马斯燃烧法的相对误差，这表明凯氏定氮法比杜马斯燃烧法的准确度略高。 相似文献
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蛋白质是牛奶中最主要的营养成分之一,无论是育种工作还是评定牛奶品质都要测定牛奶中蛋白质含量。而测定乳蛋白的方法通常采用凯氏定氮法和乳蛋白测定仪测定,前者方法繁琐,使用的仪器、药品较多,所需时间长;后者仪器价格高,普及率低。为此,我们特介绍德国采用的简单易行、可靠性较高的乳蛋白测定法——索恩生氏(Soerensen)测定法。一、原理:牛奶中的蛋白质是由氨基酸组成。氨基酸具有两性性质,其分子中同时存在着羧基和 相似文献
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《畜牧与兽医》2014,(10):38-40
旨在建立一种简单、快速、可靠的测定牛奶中叶黄素含量的方法。牛奶样品经皂化、蛋白酶解后、正己烷提取,然后经色谱柱分离测定,外标法定量。使用正相硅胶柱(4.6 mm×250 mm,5μm),以正己烷∶乙酸乙酯∶异丙醇=65∶30∶5为流动相,检测波长446 nm。该方法加标回收率为94.8%96.3%,相对标准偏差(RSD)为0.7%,并具有良好的准确度和精密度。应用此方法,测得每100 mL牛奶中叶黄素的含量在0.5196.3%,相对标准偏差(RSD)为0.7%,并具有良好的准确度和精密度。应用此方法,测得每100 mL牛奶中叶黄素的含量在0.510.62μg之间,是一种准确测定牛奶中叶黄素的方法。 相似文献
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针对水牛奶脂肪含量高、蛋白质颗粒大,易导致水牛奶产品质地较硬、细腻度差、酸香味不足等问题,本文通过单因素试验和Box-Behnken中心组合设计筛选了水牛奶发酵乳的发酵剂和工艺配方,并对产品理化和卫生安全指标进行了检测。结果表明,保加利亚乳杆菌:嗜热链球菌:植物乳杆菌=2:1:3、菌种添加量4%、糖添加量8%、发酵时间6h时,水牛奶发酵乳的组织细腻,呈均匀乳白色,酸香味浓郁且具有丰富的营养价值,脂肪含量达到4.04%,蛋白质含量达到3.31%,乳酸菌含量为3.3x107CFU/m L,卫生指标符合标准。本研究旨在为水牛奶发酵乳生产加工提供参考依据。 相似文献
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本试验旨在建立特异检测牛奶蛋白质含量的ELISA方法。利用提纯酪蛋白免疫试验动物,获得针对酪蛋白的多克隆抗体;利用棋盘格试验确定抗原抗体的最佳作用浓度,并优化各步骤反应条件;根据标准样品建立牛奶中蛋白质含量的定量ELISA检测方法,并对该方法的特异性、敏感性、检测范围及重复性进行评价。通过试验确定封闭液为1% BSA,37 ℃孵育120 min;血清抗体工作浓度为1∶12000稀释,37 ℃孵育90 min;酶标二抗最适浓度为1∶3000稀释,37 ℃孵育30 min。牛奶酪蛋白检出范围为0.063~0.500 μg/mL;该方法具有良好的特异性、敏感性、重复性,回归率范围为97.6%~123%。成功建立了牛奶蛋白含量的定量ELISA检测方法。 相似文献
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本试验旨在研究在低蛋白质饲粮中添加蛋氨酸对梅花鹿仔鹿生长性能及血清生化指标的影响。选取24头健康的梅花鹿仔鹿,随机分成3组(Ⅰ、Ⅱ、Ⅲ组),每组8个重复,每个重复1只。Ⅰ组饲喂蛋白质水平为14.16%的饲粮,Ⅱ组饲喂添加了0.16%蛋氨酸的蛋白质水平为12.46%的低蛋白质饲粮,Ⅲ组饲喂添加了0.12%蛋氨酸的蛋白质水平为12.46%的低蛋白质饲粮。饲养试验于2015年10月2日开始,至2015年10月24日结束。为了测定其生长性能,在试验开始和结束时对仔鹿进行称重;为了测定其血清生化指标,在试验结束时进行采血。结果表明:各组梅花鹿仔鹿的增重、平均日增重、料重比均差异不显著(P0.05);各组梅花鹿仔鹿血清中总蛋白(TP)、球蛋白(GLOB)、尿素氮(UN)、葡萄糖(GLU)含量及丙氨酸氨基转移酶(ALT)、天冬门氨酸氨基转移酶(AST)、碱性磷酸酶(AKP)活性均差异不显著(P0.05);Ⅲ组血清中白蛋白(ALB)含量显著高于Ⅰ组(P0.05)。由此得出,与蛋白质水平为14.16%的饲粮相比,在蛋白质水平为12.46%的低蛋白质饲粮中添加0.16%蛋氨酸对梅花鹿仔鹿的生长性能及血清生化指标均无显著影响,说明在本试验范围内利用低蛋白质饲粮添加蛋氨酸代替高蛋白质饲粮是可行的。 相似文献
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Near infrared spectroscopy for biomonitoring: cow milk composition measurement in a spectral region from 1,100 to 2,400 nanometers 总被引：2，自引：0，他引：2
The potential of near infrared spectroscopy (NIRS; 1,100 to 2,400 nm) to measure fat, total protein, and lactose content of nonhomogenized milk during milking and the influence of individual characteristics of each cow's milk on the accuracy of determination were studied. Milk fractions were taken during milking, twice per month, for 6 mo. Samples were taken every 2nd and 4th wk at the morning and the evening milkings. Teatcups were removed at each 3 L of milk yield as determined with a fractional sampling milk meter. A total of 260 milk samples were collected and analyzed with an NIRSystem 6500 spectrophotometer with 1-mm sample thickness. Partial least squares (PLS) regression was used to develop calibration models for the examined milk components. The comparison with the reference method was based on standard error of cross validation (SECV). The obtained SECV varied from .107 to .138% for fat content, from .092 to .125% for total protein, and from .066 to .096% for lactose content, and the accuracy of the reference method (AOAC, 1990, method No 972.16) was .05% for all measured milk components. The obtained models had lower SECV when an individual cow's spectral data were used for calibration. The reduction of SECV for each cow's individual calibration, when compared with SECV for the set of all samples, differed with the different constituents. For fat content determination, the reduction reached 22.46%, for protein 26.40%, and for lactose 31.25%. This phenomena was investigated and explained by principle component analysis (PCA) and by comparing loading of PLS factors that account for the most spectral variations for each cow and the measured milk components, respectively. The results of this study indicated that NIRS (1,100 to 2,500 nm, 1-mm sample thickness) was satisfactory for nonhomogenized milk compositional analysis of milk fractions taken in the process of milking. 相似文献
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von Tavel L Kirchhofer M Doherr MG Kaufmann T Kuepfer U Eicher R 《DTW. Deutsche tier?rztliche Wochenschrift》2005,112(12):443-4, 446-8
Different methods to evaluate the nutritional and metabolic status in dairy herds are available. The aim of this study was to evaluate three different methods to assess the energy status of the herd: 1) the calculation of the energy balance of the herd with a new method based on the Swiss standard calculations, 2) the "efficiency of the feeding management" based on milk yield and milk protein content (%) obtained from DHI data, and 3) the percentage of cows per herd with an average milk yield (16-25 kg/day), but a low milk protein (< 3.2 %). The study included data from 47 farms enrolled in the herd reproduction survey program of the University of Berne, with a total of 653 cows included in one winter period. A correlation could only be seen between methods two and three. It is concluded that it is insufficient only to calculate the ration as an estimation of the energy status of the herd. A rough calculation of the ration is necessary to have an idea on the energy density. But the calculated ration seems to be considerably different from the amount of energy and nutrients of the diet finally absorbed by the cow. As the ingested ration is relevant for milk production and animal health, the relationship between milk yield and milk protein content as well as the percentage of cows with milk protein < 3.2% are considered to provide good information about the efficiency of the feeding management in dairy herds. 相似文献
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22～25日龄羔羊对两种不同营养水平代乳粉消化性的研究 总被引：1，自引：0，他引：1
将18只滩羊(♂)×小尾寒羊(♀)的杂交F1代羔羊随机分为3组,A组哺喂1号代乳粉(低营养水平),B组哺喂2号代乳粉(高营养水平),C组随母羊自然哺乳,进行了60d的饲养试验。羔羊22～25日龄采用全收粪法收集粪样,测定代乳粉的表观消化率。结果表明:1号、2号两种不同营养水平的代乳粉干物质、粗蛋白、粗脂肪、粗纤维、钙和磷的表观消化率中除粗脂肪分别是74.20%、80.99%,差异显著(P<0.05),无氮浸出物分别是63.57%、50.44%,差异极显著(P<0.01)外,其余项目差异均不显著(P>0.05)。 相似文献
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试验旨在分析内蒙古生鲜乳中氨基酸含量、乳蛋白营养价值及其在不同地区的差异，为生鲜乳营养品质评定提供理论依据。选取内蒙古呼伦贝尔市、锡林郭勒盟、乌兰察布市、赤峰市、呼和浩特市、兴安盟、通辽市7个代表地区，采集同一季节70批次奶罐奶，用于分析内蒙古生鲜乳中17种氨基酸含量，并用FAO（2011）推荐的最新氨基酸评分模式评价乳蛋白营养价值，同时比较地区差异。结果表明：内蒙古生鲜乳中氨基酸总量为3.117%，其中谷氨酸含量最高（0.593%），其次是脯氨酸、亮氨酸、赖氨酸，甘氨酸和胱氨酸含量最低（0.060%和0.061%）。内蒙古生鲜乳中必需氨基酸（EAA）构成比例及氨基酸评分均高于FAO/WHO理想蛋白质标准和模式。内蒙古不同地区生鲜乳氨基酸含量存在较大差异，主要表现为：与赤峰市生鲜乳中氨基酸含量相比，锡林郭勒盟生鲜乳中EAA、非必需氨基酸（NEAA）和总氨基酸（TAA）的含量优势明显（P<0.05），呼伦贝尔市生鲜乳中缬氨酸、赖氨酸、组氨酸、甘氨酸、丙氨酸的含量较高（P<0.05），呼和浩特市生鲜乳中亮氨酸、赖氨酸、组氨酸、丙氨酸、天冬氨酸和酪氨酸含量相对较高（P<0.05），其他几个盟市差异不显著（P>0.05）。综合上述试验结果，内蒙古生鲜乳中乳蛋白为优质蛋白，其中锡林郭勒盟、呼伦贝尔市和呼和浩特市生鲜乳氨基酸营养价值相对较高。 相似文献
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利用傅里叶变换红外光谱法（FTIR）结合软独立模式分类法（SIMCA）对不同类别的牛奶进行识别。通过对光谱数据基线校正和Savitzky-Golay平滑处理后,在3100～850cm-1光谱区域,利用留一交互验证法建立获得主成分分析（PCA）最优模型。在α=5%显著水平下,最优模型对纯牛奶、低乳糖奶、低脂奶和高蛋白奶的识别率分别为80%、80%、100%和80%,拒绝率分别为93%、100%、100%和93%。表明FTIR结合SIMCA可成为快速识别牛奶类别的有效方法。 相似文献
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饲料蛋白质组分对泌乳奶牛乳脂率和乳蛋白的影响 总被引：2，自引：0，他引：2
本试验研究采用粗蛋白质相同而蛋白质组分水平不同的四种日粮(日粮粗蛋白质中瘤胃未降解蛋白质(RUP)比例由35.9%逐步提高到40.9%,其他营养成分基本保持一致),选择32头处于中产水平的荷斯坦奶牛,根据产奶量、胎次和泌乳日龄按配对法随机分为四组,研究了不同蛋白质组分水平的日粮对奶牛乳脂率、乳蛋白率和乳蛋白质产量的影响规律。结果表明,粗蛋白质相同而蛋白质组分水平不同的日粮对奶牛乳脂率、乳蛋白率和乳蛋白产量没有显著的影响(P>0.05),但乳脂率有下降的趋势,乳蛋白产量有增加的趋势。 相似文献
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本方法在《GB 5009.6—2016食品安全国家标准 食品中脂肪的测定》中第三法碱水解法的基础上进行改良,使用改良后的方法测定不同样品的脂肪含量,变异系数CV在0.26%~1.73%之间;同时用该方法参加第三方的能力验证,结果满意,其准确度结果的偏差为1.89％~3.90%,符合《GB/T 27404—2008 实验室质量控制规范 食品理化检测》的要求。改良后的方法为抽提步骤使用具塞量筒替代抽脂瓶;蒸干步骤使用烧杯替代脂肪接收瓶,称量步骤用脂肪的体积比来换算脂肪的质量,可用于日常牛乳中脂肪的检测。 相似文献
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P. Slagsvold B. Laksesvela K. Flatlandsmo N. Krogh T. L. Ulstein N. Ek T. Landsverk 《Acta veterinaria Scandinavica》1977,18(2):194
Increasing the lactose content of different milk replacers or milk diets by approx. 30 % of the dry matter increased the frequency of diarrhoea the first 10–12 days in young calves on all occasions in 5 experiments comprising 120 calves. For all diets taken together, this effect was highly significant. Total daily intakes of lactose amounted to 200–480 g. When lactose was given on top of the milk rations, the growth rate increased significantly, whereas the growth rate was usually insignificantly reduced when lactose replaced other nutrients in milk diets or milk replacers, their levels of protein and fat becoming low. Albumin and total protein in blood plasma were significantly lower when the dietary protein level was low. Milk replacers with 20 or 40 % whey powder, replacing skim milk powder, performed equally well, but gave significantly less growth than the old-fashioned feeding of whole milk-skim milk. Intake of hay and barley and a number of clinical and histological or pathological parameters did not vary consistently with dietary level of whey powder or lactose. Feeding whole milk all the time resulted in low intake of hay and barley and poorly developed forestomachs, but high dressing-out %. Substituting soya for part of the skim milk powder in milk replacers gave abomasal content with no curds. In most cases, pH in the rumen appeared to be nearly up to neutral until the calves ate ground barley, about 1 month old. 相似文献