大蒜中大蒜素含量简便测定法

采用一种快速简便的分光光度法测定大蒜中的大蒜素含量.研究测定过程中半胱氨酸反应浓度、反应时间、反应温度及反应体系pH值等因素对测定结果的影响.优选出最佳测定条件,提高测定的准确性和重现性.     

鸡蛋新鲜度评价方法研究现状

综述鸡蛋新鲜度评价方法的研究现状.目前评价方法主要有破坏性测定、无损测定及其他方法,破坏性测定包括感官评价和理化指标测定,无损测定包括红外光谱及荧光光谱,其他方法包括微波传感器测定及生物超弱发光测定等.     

利用SM400型吸烟机测定卷烟阴燃速率

介绍了一种利用SM400型吸烟机测定卷烟阴燃速率的方法.实验结果表明,该方法具有提高实验效率、操作简便和测定结果准确、重复性好的优点.可以同时进行20支卷烟的阴燃测定.对测定过程中易出现的问题及解决方法进行了说明.     

超高效液相色谱快速检测葡萄酒中5种合成着色剂

采用超高效液相色谱同时测定葡萄酒中5种人工合成着色剂(柠檬黄、苋菜红、胭脂红、日落黄、赤藓红).采用ACQUITYUPLC(R)BEHC18色谱柱分离,以甲醇-20mmol/L乙酸铵水溶液为流动相进行梯度洗脱.利用每种色素最大可见吸收波长,在检测过程中变化波长测定各个着色剂以消除杂质干扰,在428nm测定柠檬黄,520nm测定苋菜红,509 nm测定胭脂红,483nm测定日落黄,528 nm测定赤藓红.结果表明,该法简便、快速、重现性好、回收率高.     

电位溶出法同时测定茶叶中的铅、铜

目前测定食品中铅、铜常用原子吸收法.本文提出用电位溶出法同时测定茶叶中的铅、铜.该方法仪器设备简单,容易普及推广,它通过电积富集,把低浓度的离子富集,提高了灵敏度.样品经过湿法消化,适当稀释可直接测定,本法可同时测定茶叶中的铅、铜含量,方法简单、快速、灵敏度高、重现性好,具有很好的实用性.     

电子鼻测定香精气味过程中测定参数的研究

用电子鼻对不同种类的香精进行测定,旨在寻求一组最佳的测定参数.通过单因素试验时测定过程中不同影响因素进行考察,运用正交试验找出最佳测定参数.结果表明,浓度0.15%、清洗时间70 s、测样时间60 s、进气量350 mL/min为最佳参数组合.     

粮食脂肪酸值自动测定方法与应用

目前我国测定粮食脂肪酸值的标准方法有GB5510-1985<粮食脂肪酸值的测定>、GB/T15684-1995<谷物碾磨制品-脂肪酸值的测定>,二者都是通过观察指示剂的颜色变化,判定滴定终点.由于操作者对颜色变化的判断存在较大的主观性,往往使终点判定不准确.我国粮食行业迫切需要一种能自动测定粮食脂肪酸值的方法,消除人为因素影响,实现脂肪酸值测定的自动化.本文针对粮食脂肪酸值测定,探讨采用微机控制自动滴定、记录数据,判断滴定终点,处理数据,使测定过程自动化的方法.     

空白实验及测试条件对纤维素酶活测定的影响

以Chose推荐的滤纸酶活力测定程序为基础,考察了空白实验、滤纸种类、缓冲体系对酶活力测定的影响.研究结果表明,常规的100℃沸水浴灭酶活并不彻底,残留酶活形成的空白值会导致测定结果产生较大的负偏差.建立了一种简便可靠的空白实验方法:以底物空白与酶液空白的算术和作为总空白值处理,其酶活测定偏差小于2%.并指出应在规范的测试条件下测定酶活,其测定结果才具有可比性,因滤纸以及缓冲体系也会影响测定结果.     

超高效液相色谱-串联质谱法测定乳饮料中香兰素的不确定度评定

采用液相色谱-质谱法对乳饮料中香兰素进行不确定度评定.通过整个测定过程建立不确定度测定模型来确定影响不确定度的主要来源,并对各不确定度分量进行合成和扩展,最终建立液相色谱-质谱法测定乳饮料香兰素的不确定度评定方法.结果表明,影响乳饮料中香兰素测定的主要来源为称样量、样品定容、测定浓度、测定重复性和提取回收率,其测定结果...     

利用NIR技术快速测定豆浆晶中蛋白质和糖分

使用Perten公司近红外测定仪和所提供的软件,开发了测定豆浆晶中蛋白质和糖分的定标曲线.测定结果表明近红外仪测定结果与实验室常规方法测定结果相关性大于0.98,两者测定结果差异蛋白质为0.26%、糖分为0.38%,说明利用近红外技术可以快速、准确地测定豆浆晶中蛋白质、和糖分的含量.     

国内外肉制品中食品添加剂硝酸盐和亚硝酸盐的标准管理探讨

目的 探讨肉制品中食品添加剂硝酸盐和亚硝酸盐的标准管理。方法 通过对国际食品法典以及美国、加拿大、欧盟、澳新、日本、韩国和中国肉制品中硝酸盐和亚硝酸盐食品添加剂标准规定的分析,结合风险评估、监测结果和食品中毒事件数据分析的情况,探讨相关标准未来的发展方向。结果 从生产加工过程控制、终产品检测可操作性或进出口口岸检测便利性的角度出发,美国、加拿大、澳新选择制定最大添加量,日本和韩国选择制定最大残留量,欧盟则根据具体食品产品,选择制定最大添加量或最大残留量。我国在食品添加剂标准中采用了添加量和残留量兼顾策略的同时,在污染物限量标准中规定了食品中N-二甲基亚硝胺的限量。膳食暴露评估显示硝酸盐和亚硝酸盐作为食品添加剂对膳食暴露贡献较低,对公众食品安全风险较低。结论 虽然目前标准中保留硝酸盐和亚硝酸盐最大添加量和残留量的做法符合过程控制原则和实际监管需求,但仍建议继续开展关于食品加工工艺改进和替代品的研究,同时也要继续加强对消费者和餐饮业者食品安全教育,减少误食误用引起的食物中毒。     

Evaluation of fruit authenticity and determination of the fruit content of fruit products using FT-NIR spectroscopy of cell wall components

An analytical procedure using Fourier transform near infrared (FT-NIR) spectroscopy and chemometrics with multivariate techniques for the rapid determination of the fruit authenticity and for the quantification of the fruit content was developed, based on the cell wall constituents (alcohol-insoluble residue, AIR, and hemicellulose, HC). The contents of rhamnose, fucose, arabinose, xylose, mannose, galactose, and glucose in the hemicellulose fraction of apricots, peaches, and pumpkins determined by gas chromatography were used as references. Furthermore, spectral information was correlated with the fruit content and the gravimetric data obtained from sequential fractionation of the alcohol-insoluble residue. Samples of self-made and commercial apricot and peach fruit preparations, jams, and spreads were included in the investigations. Hemicellulose from 109 samples and AIR from 92 samples was recorded, and principal component regression was used to create calibration models relating chemical and gravimetrical reference values to spectral data. The calibration models provided a good predictability in comparison with the results obtained by reference methods. Good agreement was also obtained for the prediction of the neutral sugar composition of the HC and the fruit content from the AIR. FT-NIR spectroscopy allowed a rapid, accurate and non-destructive assignment of specified fruit from spectral data of the HC fraction and the AIR. Thus, FT-NIR could be applied for investigations on quality control complementing, or even replacing, gas chromatography as the most widespread method for the determination of neutral sugars. Furthermore, preliminary investigation on classification of fruit blends was performed. The probability of belonging to a specific fruit was significantly lowered or precluded for samples with fraudulent admixture like peach or pumpkin to apricot, or pumpkin to peach.     

物流运输对鱼类肌肉品质影响研究进展

现代物流运输技术高速发展,呈现智能化、信息化和高效化的趋势。通过物流运输可满足国内外消费者对鱼类产品多样性的需求,实现渔业资源优化配置。肌肉是鱼体主要食用部分,其品质直接影响产品加工适应性和经济价值。本文将鱼类产品分为鲜活、冰鲜和冷冻三大类,首先概述鱼类物流运输的方式、网络图和特点;其次,从营养价值、组织结构、风味特点、感官品质及物理性质五方面对鱼肌肉品质进行评价,并总结测定方法;最后,论述物流运输过程中温度、时间、包装等主要因素对鱼肌肉品质的影响。     

Copper in grape and wine industry: Source,presence, impacts on production and human health,and removal methods

Heavy metals are of particular concern in grape and wine processing, especially copper. The sources of copper are diverse, including vineyard soil, copper-containing pesticides on the fruit surface, copper wine-making equipment, and exogenous addition in winemaking. Copper has potential risks to human nerves, metabolism, and others. It can inhibit yeast growth, delay fermentation, and also mediate oxidation reactions, which has a huge impact on the nutritional quality and sensory quality of fresh wine and aged wine. It is therefore crucial to detect, quantify, and remove copper from grapes and wine. However, the copper situations in the wine industries of various countries are complicated and diverse, and the existing forms of copper are quite different, which makes the research challenging. This review summarizes and analyzes the existence and influence of copper in the wine industry by analyzing the sources of, the current situation regarding, and the detection and removal methods for copper in wine. With the study, a better understanding of copper's impact on wine production will be gained, facilitating further control of copper in wine and helping the wine industry grow.     

纺织品前瞻性制备技术及应用研究现状与发展趋势

随着纺织行业各领域的高速发展,纺织产业不断迭代升级,通过革新逐步实现从量变到质变的转化,实现高质量发展。通过介绍由1,3-丙二醇、乳酸等生物基材料为代表的纤维素原料在合成生物学等领域进行的革新,使纤维基体在分子结构、维度、性能、智能化以及应用等方面突破极限;结合目前纺织行业发展趋势,从未来纺织品的成形与制造技术、应用领域及新型产品等方面进行了分析和展望,以期在未来会有更为成熟的一体化制备方法和成形技术,使纺织产品不仅能应用于日常生活领域也能应用于极限领域,为开拓更广阔的市场提供新思路。     

酸汤子面团对发酵面包品质的影响

以不同地区采集的酸汤子面团为研究对象，采用高通量测序技术测定其微生物多样性，并利用此酸汤子面团发酵面包制品，分析面团中主要菌属所占比例与面包品质的相关性。结果表明：在采集的11 种酸汤子面团中共鉴定出6 种乳酸菌属，分别为Lactobacillus、Leuconostoc、Lactococcus、uncultured Streptococcaceae、Pediococcus、Streptococcus，鉴于多数样品中检测出Lactobacillus，推测其为酸汤子样品细菌优势菌属；鉴定出7 种酵母菌属，分别为Candida、Pichia、Dipodasous、Zynosaccharomyces、Naumovozyma、Metschnikowia、Sugiyamaella，鉴于Candida、Pichia在多数样品中被检测出，推测其为酸汤子样品真菌优势菌属。酸汤子面团中乳酸菌和酵母菌总含量高，且酵母菌含量越高，则面包产品硬度、胶黏性、咀嚼性越低，贮藏期间硬度变化和水分变化越小，面包品质越好。     

花生中重金属含量的影响因素及其来源

为分析花生中重金属含量的影响因素及其来源,进行产地及品种田间模型试验,采集花生、土壤及降水样品,测定样品中7种重金属的含量.结合单因素方差分析、多因素方差分析和Pearson相关性分析,解析产地、品种及其交互作用对花生中重金属含量的影响,探究重金属含量与种源土壤和降水中重金属含量的关系.结果显示,花生中Ni、Cd和Tl...     

Stitch in Time: The Fabric of Contemporary Life

Abstract

Ebira-speaking people inhabit a region to the south-west of the confluence of the Niger and Benue rivers in Nigeria. The social environment is dominated by Islam, with a Christian minority. Nevertheless, in the late 1960s, when I began the research drawn upon in this article, much of the pre-Islamic/pre-Christian ritual tradition remained intact; and all three religions presuppose a continuity of human existence beyond death. Yet the question of what persisted, and how, beyond the corpse and the grave remained unanswered in local metaphysics; and none of the Ebira words used for “body” or “person” were used of the deceased. Rather, the link between living and dead, enacted in rite and performance, was manifested by means of cloth; for the one index of that continuity was a textile woven by local women of hand-spun cotton with indigo and white stripes, one pattern for the corpse of a man, and another for a deceased woman. This kind of cloth would be draped around the doorway of a house signifying the presence of the deceased, and later it would be taken down and used to wrap the corpse for burial. The lineage of the deceased's mother supplied the cloth, this constituting one of the means whereby relationships between lineages subsisted. The only other use for this kind of cloth, and then only if striped as for a man, was in the clothing of masked performers. It was as if people entered the world of the dead and returned, re-embodied in masquerade, wearing the same kind of cloth; and it was this, more than any other single aspect of social practice, that manifested the continuity between living and dead. Masked performers also enabled access to a healing energy determined by (male) ancestral precedent. Indeed, masquerade was an aesthetic, structuring, therapeutic, and cognitive locus of much of Ebira social practice, a locus in which a form of textile was essential in the gathering together of ideas-and-practices wherein the relationship between living and dead was constru(ct)ed.     

Transverse fingernail curvature in adults: a quantitative evaluation and the influence of gender, age, and hand size and dominance

The nail plate's convex shape in both the longitudinal and transverse directions is thought to contribute to its mechanical rigidity, and overcurvature can be a symptom of local and/or systemic disorders. Although a number of methods to measure the longitudinal nail curvature have been proposed, evaluation of the transverse nail curvature has been largely limited to visual estimation of overcurved nail plates. The aim of this study was therefore to measure the transverse curvature of healthy adult fingernail plates and thereby provide a baseline range for 'normal curved' nail plates. In addition, the influence of gender, age, hand size and hand dominance on the transverse fingernail curvature was investigated. The transverse fingernail curvature in 92 men and 90 women (aged 21-90 years) was measured using a set of radius gauges, and the nail plate curvature was expressed as the radius of a circle whose curve most closely approximated that of the nail plate. ANOVA was used to investigate the influence of digit nature on curvature, whereas general linear model was used to assess the influence of gender, age, and hand length, breadth and dominance on transverse nail curvature. Subsequently, the influence of hand dominance and age was further examined by paired t-test and ANOVA, respectively. In this study, baseline values for the transverse nailplate curvature of the thumb, index, middle, ring and little fingers are presented. The thumbnail is the flattest, followed jointly by the index and middle fingernails, then the ring fingernail and finally the little fingernail. Transverse nail curvature is influenced by a person's gender, age, hand dominance and hand width, but not by hand length. Thus, nails are flatter in the dominant hand, in men, in older individuals and in those with wider hands.