非线性化学指纹图谱在生乳掺杂鉴别方面的应用

生乳掺杂严重危害人民群众身体健康,但该现象屡禁不止,研究生乳掺杂鉴别方法迫在眉睫。本研究利用非线性化学指纹图谱技术,通过对待测生乳样本与标准生乳的非线性化学指纹图谱的直观形状差异比较、参数信息最大相对标准偏差计算、整体相似度计算的方式,实现对生乳中掺入的蔗糖、动物水解蛋白、过氧化氢、食盐的鉴别,为生乳掺杂鉴别提供新的思路和方法。     

用非线性电化学指纹图谱技术鉴别啤酒品种

以非线性化学指纹图谱技术鉴别啤酒种类。测定了11种啤酒的非线性化学指纹图谱,并通过指纹图谱直观特征及系统相似度模式识别对啤酒品种进行鉴别。结果表明,每种啤酒非线性化学指纹图谱的重现性良好,不同品种啤酒指纹图谱特征的差别仅决定于啤酒成分的种类和含量。参照同一品种啤酒指纹图谱共有模式的系统相似度在95.73%~99.62%之间,参照不同品种啤酒共有模式的系统相似度在52.65%~94.09%之间。品种鉴别准确度≥91.7%,平均准确度达到94.9%。利用非线性化学指纹图谱技术能较准确地鉴别啤酒的品种。该研究为啤酒品种鉴别提供了新的方法和研究思路。     

利用非线性化学指纹图谱技术鉴别啤酒生产中的大麦品种

利用非线性化学指纹图谱技术对两个不同品种大麦的快速准确鉴别评价进行研究.结果表明,利用非线性化学指纹图谱的直观信息、可量化信息以及系统相似度计算结果,均能很好地将不同大麦品种鉴别出来.非线性化学指纹图谱技术对啤酒行业的大麦品种鉴别提供了一种很好的方法.     

非线性化学指纹图谱鉴别天麻真伪及产地

目的在正交试验优化检测条件的基础上,采用非线性化学指纹图谱技术研究天麻(Gastrodia elata Bl.)的真伪及产地鉴别。方法收集吉林、湖南、四川、云南4个不同产地的天麻及紫茉莉根、大丽菊、蕉藕和马铃薯等天麻伪品,以天麻样本成分作为振荡底物,构建"硫酸+硫酸锰+溴酸钠+丙酮+样品成分"振荡体系,利用硫酸、硫酸锰、丙酮、溴酸钠和样品成分产生的非线性化学反应来测定天麻及其伪品的非线性化学指纹图谱,通过指纹图谱直观差异比较和系统相似度计算对天麻真伪及其道地性进行鉴别评价。结果样品用量为0.800 g,反应温度为50℃时,天麻非线性化学指纹图谱具有良好特征性和重现性。天麻和伪品非线性化学指纹图谱之间的特征差异大,可通过直观差异比较直接区分。不同产地的天麻指纹图谱相似,具有相同的振荡起伏规律,但振荡寿命、振荡幅度及振荡波数等有差异。利用系统相似度模式识别可对天麻的产地进行鉴别,同一产地的相似度均≥0.989,而不同产地天麻相似度均≤0.951,鉴别准确率达98.3%。结论本研究为天麻真伪鉴别及产地溯源提供了的一种新方法。     

基于非线性化学指纹图谱的羊乳广谱掺假检测研究

目前羊乳中发现的掺假物质种类繁多,而检测方法多为针对单一掺假物质的检测。本研究基于非线性指纹图谱技术构建非特异性的广谱掺假物质判定方法。本研究在测定32个纯山羊乳样品及添加5%、1%和0.1%不同浓度氯化钠、大豆蛋白胨、尿素和蔗糖羊乳样品的非线性指纹图谱基础上,对纯山羊乳与掺假羊乳的指纹图谱进行直观的比较和相似度比较。添加0.5%以上氯化钠或尿素的掺假样品和5%以上大豆蛋白胨或蔗糖的掺假样品与纯生鲜羊乳的指纹图谱明显不同,可判定为掺假羊乳。以纯羊乳样品最低相似度值为临界值,则含0.5%和1%蔗糖的掺假样品相似度值在临界值上下,其余掺假样品的相似度值均小于临界值83.4%。故对生鲜乳中添加以上四种掺假物质浓度大于5%的掺假行为通过指纹图谱的直观比较和相似度值比较均可判定为掺假,该方法可用于生鲜羊乳的掺假检测,一次检测即可排除多种掺假物质的存在。     

利用非线性化学指纹图谱技术鉴别评价茶饮料

通过向稳态体系“溴酸钠-硫酸锰-硫酸-丙酮”中加入不同的茶饮料,获得来自不同产家、不同品种的茶饮料的非线性化学指纹图谱,并对其进行相似度计算。非线性化学指纹图谱的直观信息、定量信息、相似度计算结果都能很好的将冰红茶从其他茶饮料中鉴别出来,且振荡寿命与检测用量有很好的函数关系。通过比较不同掺水量的茶饮料的非线性化学指纹图谱的参数信息,对茶饮料的质量进行评价。非线性化学指纹图谱技术可为茶饮料的鉴别和评价提供一种新的方法。     

基于指纹图谱和化学计量分析的鳕鱼肝油软胶囊掺假植物油鉴定

目的 建立一种基于脂肪酸气相色谱(gas chromatography, GC) 指纹图谱技术结合化学计量分析的鳕鱼肝油软胶囊中掺假植物油的鉴定方法。方法 采用GC法测定不同来源鳕鱼肝油软胶囊脂肪酸指纹图谱, 经拟合后构建对照指纹图谱, 并进行样品相似度评价。模拟制备鳕鱼肝油软胶囊中掺入不同种类、不同比例植物油的掺假样品, 以其中14个共有脂肪酸峰的相对峰面积作为数据源, 输入SIMCA-P数据分析软件进行主成分分析(principal component analysis, PCA)及掺假模型建立。结果 获得鳕鱼肝油软胶囊GC对照指纹图谱及三维掺假识别模型, 44批样品经相似度评价发现有2批拟似掺假植物油, 将拟似样品色谱数据标准化后导入SIMCA-P软件, 显示2批样品均掺了大豆油, 掺假比例约为15%和35%。结论 脂肪酸GC指纹图谱结合化学计量分析为鳕鱼肝油软胶囊中掺假植物油的鉴定提供一种可靠准确的检测手段, 可快速有效识别鳕鱼肝油掺假行为。     

指纹图谱在食品分析中的应用研究进展

指纹图谱技术是基于样品的某种特性,采用现代分析手段得到能够代表该样品特征的色谱、光谱以及其它图谱数据资料,从而进行成分鉴定及质量控制的一种可量化手段,具有快速、灵敏、方便等优点,不仅广泛应用于中药行业,在食品来源、品质检测和真伪鉴别方面也具有巨大的应用潜力。指纹图谱常用的技术手段有高效液相色谱法、气相色谱法、毛细管电泳法等色谱法,紫外光谱、红外光谱、荧光光谱等光谱法以及生物指纹图谱和非线性化学指纹图谱等,分析方法主要有化学模式识别和其它相似度评价方法。本文主要介绍了指纹图谱常用的技术手段和分析方法,综述了化学指纹图谱、生物指纹图谱和非线性化学指纹图谱等技术手段在食品产地与种类鉴别、掺假鉴别、名优产品的鉴别、批次一致性评价及品种选育等众多领域中的应用,同时对食品指纹图谱在未来的发展进行展望。     

非线性化学指纹图谱技术在食品掺假检测中的应用

利用非线性化学指纹图谱、色谱、质谱、酶联免疫、近红外、色谱-质谱联用等技术对调味品、饮料、啤酒大麦、蜂蜜、羊奶与牛奶等食品掺假进行检测和鉴别,通过比较,非线性化学指纹图谱技术是一种对样本进行整体分析或综合分析的一种新方法,拥有操作简单,无需样本处理和重现性好等优点。     

蓝莓汁有机酸高效液相色谱指纹图谱构建及其在掺假鉴定中的应用

根据蓝莓汁中有机酸的高效液相色谱(high performance liquid chromatography,HPLC)分析方法,利用"中药色谱指纹图谱相似度评价系统(V2.0)"建立蓝莓汁的有机酸HPLC指纹图谱,并通过相似度评价、主成分分析和聚类分析,对模拟掺假低价果汁(梨汁、苹果汁、杏汁和桃汁)和外源柠檬酸的蓝莓汁进行鉴别。结果表明:10个蓝莓汁样品的有机酸HPLC指纹图谱之间相似度均在0.950以上,与对照指纹图谱的相似度均在0.978以上,不同品种、不同产地的蓝莓果汁的指纹图谱具有很好的一致性,蓝莓果汁中添加其他果汁或柠檬酸可导致相似度降低;结合主成分分析和聚类分析等模式识别方法,可以实现对蓝莓汁与掺假低价果汁(梨汁、苹果汁、杏汁和桃汁)及外源柠檬酸样品的区分,而且掺假量越大,识别效果越好,而相似度评价仅能识别掺加量较高的样品。有机酸HPLC指纹图谱结合化学计量学分析,对于掺假蓝莓果汁具有较好的区分效果,可用于蓝莓汁掺假鉴定和质量控制。     

Reduction of milk and milk product wastage

The paper examines the assessment of waste control based on effluent monitoring and the results of a BOD test for 'milk equivalent' measurement are interpreted and evaluated. The importance of reliable flow measurement is stressed and a table is given showing wastage from various dairy operations and methods of reducing losses recommended.     

鲜乳及乳粉糊精掺假问题

目前,我国鲜牛（羊）乳及乳制品掺假是一个较为普遍的现象。鲜乳掺假会增加乳品加工企业的原料收购费及贮存、运输和加工成本,还严重威胁着产品质量,甚至决定着企业的生存和发展。俗话说“千里之堤,溃于蚁穴”,事实上,确有不少企业因无力控制乳原料掺假等等质量问题,在群雄逐鹿的乳品及冷饮市场竞争中不堪一击,不得不偃旗息鼓,被迫抱怨退出！而有的企业,则以低价倾销假冒伪劣乳制品的手段来打击竞争对手、占领市场,极大的破坏了乳品行业的利益,消弱了乳制品市场发展的后劲。然而,鲜乳及乳制品掺假不单是产品质量问题、企业声誉…     

毛细管电泳法对乳及乳制品中乳源蛋白的研究

采用毛细管电泳方法对原料乳、市售鲜奶、不同厂家的巴氏灭菌乳、不同厂家和产地超高温灭菌乳(UHT)、调味乳、乳酸饮料、复原乳、酸奶、奶粉中蛋白成分进行检测。选择聚乙烯醇涂层毛细管,采用柠檬酸缓冲体系,在紫外检测214nm、分离电压20kV条件下对乳及乳制品中的α一乳白蛋白(α-La)、β一乳球蛋白(β-Lg)、α-酪蛋白(α-CN)、β-酪蛋白(β-CN)和k-酪蛋白(k-CN)进行分离测定。结果表明:五种蛋白的含量在原料乳(巴氏灭菌乳、市售鲜奶)、UHT乳、酸奶、调味乳、乳酸饮料、复原乳中依次降低,而UHT乳含量随保质期的增加而减少,奶粉中蛋白质含量因其适应人群而有差异。乳及乳制品中蛋白质的含量与其存在形式、产地及加工工艺相关。     

Investigations on milk flow and milk yield from teats with milk flow disorders

The objective of this study was to investigate peak milk flow, average milk flow, and milk yield in teats with milk flow disorders. A total of 100 hard milking teats were studied in 97 cows. Teats with milk flow disorders were examined endoscopically. Quarter milk flow and quarter milk yield were examined with four Lactocorders attached to a quarter milking machine. Peak milk flow, average milk flow, and milk yield were measured in all teats of the udder before treatment of the affected teat, as well as 1 and 6 mo later. Teats with milk flow disorders were compared to all other teats of the same udder. Before treatment, peak milk flow from affected teats was 20%, average milk flow 14%, and milk yield 53% of the control teats, adjusted for other significant explanatory variables. Milk flow and milk yield increased after surgical treatment of the affected teats. Six months after treatment peak milk flow was 79%, average milk flow 76%, milk yield was 71% compared with control teats. We conclude from these findings that teat endoscopy and measuring quarter milk flow and milk yield with Lactocorders are useful tools for examining teats with milk flow disorders.     

山羊奶与牛奶和人奶营养成分的比较

对山羊奶、牛奶和人奶中蛋白质、脂肪、维生素、矿物质等主要营养成分进行了比较,分析了3种奶中主要营养成分的差别。通过比较发现,山羊奶在总体营养成分方面优于牛奶,更接近人奶。但山羊奶存在铁、叶酸和维生素B12含量较低以及羊奶膻味的问题,应在营养上对这方面加以重视。     

乳及乳制品加工中的美拉德反应

针对乳及乳制品在加工和储藏过程中由于发生美拉德反应不仅使乳制品的营养物质受到破坏，还产生对人体有害的物质，在很大程度上影响的乳制品的质量，对乳制品中美拉德反应的历程，产生的标志物及其测定方法等进行了的综述。     

乳中蛋白酶与UHT乳贮存中的胶凝现象

乳中的蛋白酶有2个主要的来源途径，乳中天然存在的蛋白酶和由某些微生物产生的蛋白酶，其中纤维蛋白溶酶和嗜冷菌产生的耐热性蛋白酶是存在于UHT乳中的主要蛋白酶，这些蛋白酶非常耐热，经UHT灭菌处理仍可存活。耐热性蛋白酶在UHT乳贮存中水解乳蛋白质从而导致了UHT乳的胶凝．简要介绍了纤维蛋白溶酶、嗜冷菌耐热性蛋白酶的性质、活性测定方法，论述了这些酶引起的UHT乳的胶凝性质、形成原因及影响因素，并提出了一些防止措施。     

Major advances in fresh milk and milk products: fluid milk products and frozen desserts

Major technological advances in the fluid milk processing industry in the last 25 yr include significant improvements in all the unit operations of separation, standardization, pasteurization, homogenization, and packaging. Many advancements have been directed toward production capacity, automation, and hygienic operation. Extended shelf-life milks are produced by high heat treatment, sometimes coupled with microfiltration or centrifugation. Other nonthermal methods have also been investigated. Flavored milk beverages have increased in popularity, as have milk beverages packaged in single-service, closeable plastic containers. Likewise, the frozen dairy processing industry has seen the development of large-capacity, automated processing equipment for a wide range of products designed to gain market share. Significant advancements in product quality have been made, many of these arising from improved knowledge of the functional properties of ingredients and their impact on structure and texture. Incidents of foodborne disease associated with dairy products continue to occur, necessitating even greater diligence in the control of pathogen transmission. Analytical techniques for the rapid detection of specific types of microorganisms have been developed and greatly improved during this time. Despite tremendous technological advancements for processors and a greater diversity of products for consumers, per capita consumption of fluid milk has declined and consumption of frozen dairy desserts has been steady during this 25-yr period.     

Nitrate-reducing microorganisms in milk products and human milk

The quantitative determination of nitrate-reducing microorganisms in food is important because of their role in the formation of N-nitroso compounds and methemoglobin. The total counts of microorganisms and the counts of nitrate-reducing microorganisms were assayed in various milk products and in human milk by the method of the most probable numbers using nitrate broth medium. The mean value and standard deviation of the nitrate-reducing microorganisms were the following: in pasteurized milk 3.4 +/- 1.1 log/ml (in spring and summer 4.2 +/- 1.1, and in winter 2.8 +/- 0.6 log/ml), in kefir "Tallinn' 2.9 +/- 1.1 log/ml, in fat kefir 2.9 +/- +/- 0.7 log/ml, in sour milk 3.9 +/- 0.5 log/ml, in fresh milk 4.6 +/- 0.6 log/ml and in human milk 2.7 +/- +/- 1.1 log/ml. The amount of nitrate-reducing microorganisms in pasteurized milk of the spring-summer period and in fresh milk was significantly higher than in human milk. The mean count of nitrate-reducing microorganisms in human milk is regarded as a maximum permitted count of these organisms in milk for bottle-fed sucklings. For them and for atrophic gastritis patients pasteurized or fresh milk should be boiled.     

N-acetyl-beta-D-glucosaminidase activity in whole milk and milk fractions

Experiment 1 was conducted to determine NAGase activity in skim, fat, and cell pellet fractions of foremilk and stripping milk from infection-free quarters. Changes in milk NAGase activity during a 12 h in vitro incubation were also determined. Eight cows, two quarters per cow, were used. One quarter of each cow received an intramammary infusion of oyster glycogen. N-Acetyl-beta-D-glucosaminidase activity was highest in stripping milk and in milk from infused quarters. The percentages of NAGase activity in skim, fat, and cell pellet fractions were 62.6, 22.4, and 12.6. The NAGase activity of milk incubated in vitro did not significantly change over time. Experiment 2 was conducted to determine if neutrophils lost NAGase activity during extravasation into milk. Leukocytosis was induced in infection-free quarters of five cows. The NAGase activities of peripheral neutrophils and milk neutrophils were not significantly different. Results from both studies suggest that the major source of milk NAGase is the mammary epithelial cell and that milk somatic cells contribute less than 15% of the total milk NAGase activity.