西红柿中营养素定性检测的实验探究

利用常用仪器、微型实验及相应物质的特效反应,对西红柿中所含的营养素进行了定性检测,结果显示：西红柿中含有蛋白质、维生素、铁、镁、钙、磷、钾。引导学生把化学知识运用于生活。     

芹菜中营养素的实验探究

采用常规的研磨、脱色、过滤方法对芹菜做预处理。利用常用仪器、微型实验,对芹菜中所含营养素进行定性检测。实验结果表明：芹菜中含有蛋白质、维生素、铁、镁、钙、磷、草酸。此外,芹菜叶中还含有钾,在此实验条件下不能确定芹菜茎中是否含有钾。芹菜叶中含有的营养素远大于芹菜茎,在食用芹菜时不应将芹菜叶丢掉,应利用化学知识来提高生活质量。     

Mn(V)的定性检验及试管实验的条件优化

探讨了在实验室制备MnO43-的反应条件,并利用紫外可见吸收光谱定性检验了制备的MnO43-离子,同时提出了一个在试管实验里迅速制备和检验MnO43-的方法.本实验可用于大学普通化学实验教学中,帮助学生更加直观地认识Mn(V).     

Mn(Ⅴ)的定性检验及试管实验的条件优化

探讨了在实验室制备MnO34-的反应条件,并利用紫外可见吸收光谱定性检验了制备的MnO34-离子,同时提出了一个在试管实验里迅速制备和检验MnO34-的方法。本实验可用于大学普通化学实验教学中,帮助学生更加直观地认识Mn(Ⅴ)。     

茶叶中铁、钙及蛋白质的定性检验

通过探究茶叶中的营养物质,使学生深刻理解化学与生活的密切联系.用水浸泡茶叶,取其浸泡液与浓硝酸反应,能明显检出茶叶中的蛋白质;取其浸泡液在碱性条件下与钙试剂反应,能检出茶叶中的钙;用3 mol/L左右的盐酸浸泡茶叶,取其浸泡液与饱和硫氰酸钾溶液反应,能检出茶叶中的铁.     

氯水性质检验的微型实验设计

采用以双通管为主体的复合微型实验装置,4 min 内完成了氯水的制备、氯水颜色的观察、氯水的萃取、氯气与水反应产物H+与Cl-的检验、氯水漂白性的实验。     

碘的升华及性质检验微型实验探究

对碘的升华及性质检验进行微型一体化的实验,操作简单,现象明显,试剂用量少,克服了现行高中化学课本中碘升华实验的弊端,同时实现其性质的检验,符合定性实验的要求,有利于提高教学效果及普及学生单人实验.     

高师生探究松花蛋中营养素及铅的实验设计

为了让高师生体验探究学习,掌握探究方法、发展实验设计和探究能力,以适应新课程对教师的需要,利用常用仪器、微型实验,用盐酸处理试样后,检测到松花蛋的蛋白和蛋黄中都含有维生素、钙、锌、镁、铁、磷,蛋白中还含有铅。     

用生活用品检验海带与食盐中碘的研究

中学教材中在检验海带中的碘元素时,先要灰化海带,再用各种化学试剂与方法鉴别,操作繁琐且不易得出准确结果。用生活中易得的白醋浸泡海带,然后用双氧水氧化其浸出液,可迅速地判断出所购买的海带的真假。用此浸出液还可进一步检验食盐中的碘元素,方便快捷。     

高效液相色谱法测定牛奶中的氯霉素残留

建立牛奶中氯霉素残留的高效液相色谱测定方法。牛奶样品用乙腈提取,超声离心后采用液相色谱柱分离,外标法定量。色谱条件:Agilent ZORBAX SB-C18柱(4.6mm×250mm,5μm),流动相:甲醇-水(40∶60,V/V),波长:278nm,流速0.8mL.min-1。线性范围为0.1～10.0 mg·L-1,相关系数R2为0.9995,最低检测限为0.009 mg·L-1。平均回收率在93.0%～97.3%之间,相对标准偏差在3.67%～5.25%之间(n=6),该方法简便、准确,适用于牛奶中氯霉素的检测。     

高师生实验探究洋葱中挥发性化学物质

利用实验室一般仪器,对洋葱中挥发性化学成分如含硫化合物、醇类、醛类、羧酸进行了定性检测,旨在让高师生体验探究学习,掌握探究方法,发展实验设计和探究能力。     

Detection of Ovine or Bovine Milk Components in Commercial Camel Milk Powder Using a PCR-Based Method

Food ingredient adulteration, especially the adulteration of milk and dairy products, is one of the important issues of food safety. The large price difference between camel milk powder, ovine, and bovine milk powder may be an incentive for the incorporation of ovine and bovine derived foods in camel milk products. This study evaluated the use of ordinary PCR and real-time PCR for the detection of camel milk powder adulteration based on the presence of ovine and bovine milk components. DNA was extracted from camel, ovine, and bovine milk powder using a deep-processed product column DNA extraction kit. The quality of the extracted DNA was detected by amplifying the target sequence from the mitochondrial Cytb gene, and the extracted DNA was used for the identification of milk powder based on PCR analysis. In addition, PCR-based methods (both ordinary PCR and real-time PCR) were used to detect laboratory adulteration models of milk powder using primers targeting mitochondrial genes. The results show that the ordinary PCR method had better sensitivity and could qualitatively detect ovine and bovine milk components in the range of 1% to 100% in camel milk powder. The commercial camel milk powder was used to verify the practicability of this method. The real-time PCR normalization system has a good exponential correlation (R² = 0.9822 and 0.9923) between ovine or bovine content and Ct ratio (specific/internal reference gene) and allows for the quantitative determination of ovine or bovine milk contents in adulterated camel milk powder samples. Accuracy was effectively validated using simulated adulterated samples, with recoveries ranging from 80% to 110% with a coefficient of variation of less than 7%, exhibiting sufficient parameters of trueness. The ordinary PCR qualitative detection and real-time PCR quantitative detection method established in this study proved to be a specific, sensitive, and effective technology, which is expected to be used for market detection.     

Proteomics Analysis Reveals Altered Nutrients in the Whey Proteins of Dairy Cow Milk with Different Thermal Treatments

Thermal treatments of milk induce changes in the properties of milk whey proteins. The aim of this study was to investigate the specific changes related to nutrients in the whey proteins of dairy cow milk after pasteurization at 85 °C for 15 s or ultra-high temperature (UHT) at 135 °C for 15 s. A total of 223 whey proteins were confidently identified and quantified by TMT-based global discovery proteomics in this study. We found that UHT thermal treatment resulted in an increased abundance of 17 proteins, which appeared to show heat insensitivity. In contrast, 15 heat-sensitive proteins were decreased in abundance after UHT thermal treatment. Some of the heat-sensitive proteins were connected with the biological immune functionality, suggesting that UHT thermal treatment results in a partial loss of immune function in the whey proteins of dairy cow milk. The information reported here will considerably expand our knowledge about the degree of heat sensitivity in the whey proteins of dairy cow milk in response to different thermal treatments and offer a knowledge-based reference to aid in choosing dairy products. It is worth noting that the whey proteins (lactoperoxidase and lactoperoxidase) in milk that were significantly decreased by high heat treatment in a previous study (142 °C) showed no significant difference in the present study (135 °C). These results may imply that an appropriately reduced heating intensity of UHT retains the immunoactive proteins to the maximum extent possible.     

铝热反应实验的微型化设计

分析了教科书中铝热反应演示实验设计存在的问题,基于微型实验设计理念,对铝热反应实验装置和引燃剂进行了改进,实现了实验药品用量少、成功率高、绿色环保的目的。     

探究化学高考中增加学生实验操作测试的必要性与可行性

探讨在高考中增加学生实验操作测试,有效引导各个学校及教师在教学过程中重视化学实验,从高考的功能性、课程的国际化、国外的经验、配套政策等方面分析了高考中增加学生实验操作测试的必要性与可行性。     

巧用具支试管改进化学实验

巧用具支试管改进了“钠与硫酸铜溶液的反应”“氢氧化亚铁的制备”“铜与浓硫酸反应”等实验,不仅节约药品、操作简便、快捷,而且现象明显,既适合教师演示实验,更利于学生开展探究实验。     

An Integrative Approach of an In Vitro Measurement of the Digestibility of Triacylglycerols of Human Milk

Several studies have been published regarding the effect of different factors on the digestion of milk lipids, considering their natural structural arrangement as milk fat globules and the efficiency of the digestive enzymes in the lipolysis of such complex structures. During digestion, the lipolytic products are dispersed in vesicles and micelles, which are the source for absorption of digested lipids. Therefore, it is necessary to consider the isolation of the micellar phase from the digesta to appropriately determine the amounts and classes of lipids which are bioaccessible. This study presents an integrative approach that included an isolation procedure to separate the micellar fraction from undigested and non-micellar parts, and the distribution of digested milk lipids in micelles determined directly through chromatographic techniques. Four groups of five full term mothers donated colostrum or mature milk. Two sets of samples were analyzed directly (raw), and two sets were pasteurized and then analyzed. Our data revealed that the profile of digested milk lipids is different depending on the lactation period and processing stage, while the carbon atom number distribution of the digested triacylglycerols in the micellar fraction provides a substantial information regarding the acylglycerols species that are less available for absorption.     

钠在氯气中燃烧的微型实验

简要介绍了一种取用金属钠的简便方法,利用气体实验微型装置设计了钠在氯气中燃烧的微型实验,包括氯气的制取、收集、钠在氯气中燃烧以及尾气的吸收等操作方法和技巧,并指出了实验关键和安全注意事项。     

Milk-Compositional Study of Metabolites and Pathogens in the Milk of Bovine Animals Affected with Subclinical Mastitis

Bovine milk is an important food component in the human diet due to its nutrient-rich metabolites. However, bovine subclinical mastitis alters the composition and quality of milk. In present study, California mastitis testing, somatic cell count, pH, and electrical conductivity were used as confirmatory tests to detect subclinical mastitis. The primary goal was to study metabolome and identify major pathogens in cows with subclinical mastitis. In this study, 29 metabolites were detected in milk using gas chromatography–mass spectrometry. Volatile acidic compounds, such as hexanoic acid, hexadecanoic acid, lauric acid, octanoic acid, n-decanoic acid, tricosanoic acid, tetradecanoic acid, and hypogeic acid were found in milk samples, and these impart good flavor to the milk. Metaboanalyst tool was used for metabolic pathway analysis and principal component estimation. In this study, EC and pH values in milk were significantly increased (p < 0.0001), whereas fat (p < 0.04) and protein (p < 0.0002) significantly decreased in animals with subclinical mastitis in comparison to healthy animals. Staphylococcus aureus was the predominant pathogen found (n = 54), followed by Escherichia coli (n = 30). Furthermore, antibiotic sensitivity revealed that Staphylococcus aureus was more sensitive to gentamicin (79.6%), whereas Escherichia coli showed more sensitivity to doxycycline hydrochloride (80%).