Estimates of dietary exposure of children to artificial food colours in Kuwait

To assess the intake of artificial food colour additives by 5-14-year-old children in the State of Kuwait, a 24-h dietary recall was conducted twice on 3141 male and female Kuwaiti and non-Kuwaiti children from 58 schools. The determination of colour additives in 344 foods items consumed was performed using high-performance liquid chromatography with diode array detector. A comparison with the Food and Agriculture Organization and World Health Organization acceptable daily intakes (ADIs) was undertaken to evaluate the potential risk associated with the consumption of artificial colour additives by children in Kuwait. The results indicated that out of nine permitted colours, four exceeded their ADIs by factors of 2-8: tartrazine, sunset yellow, carmoisine and allura red. Further, follow-up studies to provide insight into potential adverse health effects associated with the high intakes of these artificial colour additives on the test population are warranted.     

一种测定蜂蜜中过氧化氢酶活性的改进方法

过氧化氢是蜂蜜的主要抑菌成分之一,其抑菌活性与蜂蜜中过氧化氢酶密切相关。过氧化氢酶在蜂蜜中普遍存在,建立测定方法对评价蜂蜜抑菌活性和内在质量有重要意义。实验参照Huidobro等人的方法,对蜂蜜中过氧化氢酶活性的测定方法进行了改进,并测定了5种单花种蜂蜜中过氧化氢酶的活性。结果表明,不同种类的单花种蜂蜜中过氧化氢酶活性存在较大差异,湖北荆州油菜蜜的过氧化氢酶活性最高,为(204.3±3.8)×10-3/(min·g),河北石家庄产的枣花蜜的酶活性最低,仅为(8.1±0.6)×10-3/(min·g)。中国蜂蜜中的过氧化氢酶的活性因蜂蜜种类、产地不同存在较大差异。     

Screening method for the detection of artificial colours in saffron using derivative UV-Vis spectrometry after precipitation of crocetin

A screening method for the detection of artificial colours (naphthol yellow, tartrazine, quinoline yellow, Sunset yellow, Allura red, amaranth, azorubine, Ponceau 4R and Red 2G) in saffron is described. The method involves removal of crocins by precipitation of crocetin (pH 0.1, 90°C) before adsorption of the artificial colours on polyamide SPE cartridges (pH 2). After washing with methanol, acetone and methanol, elution was done with a methanol:ammonia solution (95:5 v/v), and detection was performed by derivative spectrometry. Sample pretreatment changes the UV-Vis saffron extract profile in such a way that second derivative spectra can be used to identify the presence of added colours. Erythrosine, which was found to be pH dependent, could not be detected under the above conditions. The lowest detectable amount for each colour was strongly dependent on chemical structure. The recovery of carminic acid was very low possibly due to irreversible retention on the polyamide. This procedure can replace the current ISO TLC method (2003) and be used alternatively or in combination with HPLC procedures adopted in the same standard.     

Role of melanin and artificial hair color in preventing photo-oxidative damage to hair

This research is a multifaceted study which investigates not only the role of melanin in providing photostability to natural hair color and hair proteins, but also the claim that the presence of specific artificial colors in hair slows down the rate of photodegradation of hair proteins. In earlier studies, the extractability of protein from photodegraded hair was investigated and showed that many of the cleaved proteins could not be extracted because of photo‐oxidative cross‐linking. The current study investigates the effect of the amount of melanin in hair of different ethnicity and the presence of artificial hair colors on the extractability of the main classes of hair proteins. Furthermore, the data are used in the interpretation of the effect of these components in being able to prevent photo‐oxidative damage to hair proteins. When exposed to sunlight, hair undergoes changes in chemical, mechanical and morphological properties. The UVB and UVA regions of the solar spectrum are the most damaging to human hair. Of these two, the UVA region is predominant in the solar spectrum at low altitudes. Hair of different ethnicity responds differently to the damaging radiation of the solar spectrum, because of different amounts of melanin present in hair. Melanin absorbs the impinging radiation (especially at the lower wavelengths (254–350 nm), and converts it by some complex internal mechanism into heat. Because of this, melanin provides a photochemical protection to natural hair color and hair proteins and prevents their photodegradation. However, the melanin pigments act sacrificially and become themselves degraded in the process of protecting the proteins from light. As a result, this «protective» effect of the melanin pigments does not last during long‐term intense exposure, when, regardless of the amount of melanin in hair, most matrix, intermediate filament and high molecular weight hair proteins undergo photo‐oxidative cross‐linking into higher molecular weight species, and their extractability from hair decreases significantly. The goal of this study is to demonstrate how UV‐radiation affects natural and artificial hair color during long‐term exposures. Bright‐field and UV‐microspectrophotometry and an electrophoretic separation technique (SDS‐PAGE) were chosen as investigative techniques for these studies, because they are well‐suited to accurately and reproducibly investigate the initial properties of a specific hair sample and the changes in these properties as a result of long‐term light‐exposure. The goal of this paper is not to relate this to the content and type of melanin in hair. Electrophoresis, while not measuring the exact quantitative amount of protein extracted, is a semi‐quantitative method, where increases in brightness of the bands represent increased amounts of proteins that were extracted of that specific protein from hair. This electrophoretic study attempts to determine whether the presence of natural or artificial color in hair influences the protein extractability in unaltered hair and the photo‐oxidative cross‐linking during light‐exposure. The bright‐field microspectrophotometric study showed that high concentrations of melanin provide protection to the melanin itself and that they prevent loss of natural hair color during light‐exposure. However, neither large amounts of melanin in hair of different ethnicity, nor artificial hair colors (even a dye with an absorption in the UV region) provide protection to the hair proteins against photodegradation under the conditions used in this study. UV‐microspectrophotometry has suggested the formation of high levels of photo‐oxidized proteins as a result of light‐exposure. Electrophoresis revealed photo‐oxidative cross‐linking of most matrix, intermediate filament and high molecular weight hair proteins into their higher molecular weight analogues, rendering them less extractable due to their lowered diffusivity. Only very low levels of low molecular weight matrix proteins could be extracted.     

Ceramide binding to African-American hair fibre correlates with resistance to hair breakage

Repetitive hair-relaxing treatments often applied to African–American hair weaken the hair structure. Therefore hair breakage is a common feature of African–American hair and an important cause of hair loss. Recently, by analysing the lipids extracted from human hair, a fraction of free-ceramide was isolated in which sphinganine was predominant. This study shows that this sphinganine-derived ceramide (i.e. C18-dhCer) binds to African–American hair and protects it from weakening caused by chemicals. To show this binding, we used two methods: radioactivity detection with a microimager^TM and secondary ion mass spectrometry.
We evaluated the benefits of C18-dhCer on African–American hair fibre, relaxed by guanidine hydroxide, using a new method called the Break'in Brush Technique (BBT^®). This method determines the hair breakage resistance during a brushing. Using this technique, we have shown less breakage when applying a shampoo with ceramide.
The present study opens new prospects for the development of products able to increase the protection, provide better care and meet the needs of African–American hair thanks to the effect of ceramide binding.     

副溶血弧菌高灵敏免疫层析检测法的建立

目的建立一种简便、准确、高灵敏的检测副溶血弧菌的免疫层析方法。方法采用免疫层析结合纳米颗粒信号放大技术,利用间接法进行示踪标记:试纸条由粘贴在底板上的样品垫、含有副溶血弧菌检测抗体的结合垫2、含有荧光颗粒标记羊抗鼠IgG的结合垫1、含有检测线(捕获抗体)和质控线(羊抗鼠IgG)的硝酸纤维素膜和吸水纸组成。结果结合增菌培养,该方法的检测灵敏性为10~3 CFU/g,与大肠杆菌、霍乱弧菌、河弧菌、创伤弧菌、溶藻弧菌、拟态弧菌、沙门氏菌、金黄色葡萄球菌等无交叉反应。结论本研究所建立的检测方法具有高灵敏、特异、简便、快速等优势,具有潜在的实际应用价值。     

Development of a sensitive picrate method to determine total cyanide and acetone cyanohydrin contents of gari from cassava

The sensitivity of the normal picrate method for determination of total cyanide in cassava was increased tenfold using a small 1 cm² picrate paper, eluted using 0.5 mL instead of 5 mL of water as in the normal method. The absorbance was measured in a 2 mm cuvette in the spectrophotometer. The sensitive method was calibrated against the normal picrate method. The total cyanide content in mg HCN equivalents/kg sample = ppm, is calculated from the absorbance (A) by the equation ppm = A × 45.7 which is applicable from 0.1 to 50 ppm. A new method to determine acetone cyanohydrin was developed based on irreversible denaturation of linamarase in 0.1 M HCl at 30 °C for 1 h. Five gari samples from Mozambique gave a mean total cyanide content of 12 ppm (range 6–15 ppm) and mean acetone cyanohydrin content of 11 ppm (range 5–14 ppm). Acetone cyanohydrin liberates cyanide quantitatively in the human intestine.     

A highly sensitive automated technique for the determination of ammonium nitrogen

The catalytic action of nitroprusside on the phenol hypochlorite reaction has been utilised to design a more sensitive automated technique for determining ammonium nitrogen in soil extracts. The method gives reproducible results in close agreement with manual methods. Sensitivity is such that as little as 0.1 parts/ million of N in solution can be determined without the use of recorder range expansion.     

标准曲线法测敏感多酚

探讨了标准曲线法测定啤酒、果汁中敏感多酚的可行性。结果表明，单宁酸的浓度在0.05g／L～0．25g/L范围时，反应产物的浑浊度与单宁酸浓度成良好的线性关系。     

降低兔毛针织物缩水率的新工艺研究

提出了采用少量茧衣与兔毛纤维混纺,利用丝胶在热湿条件下会发生膨润溶解的特性,经特殊处理后丝胶溶解兔毛粘住,进而降低缩水率的新方法,试验结果表明,经处理的兔毛针织物缩水率显著降低。     

利用溶液缓冲能力测定龙眼汁饮料中原汁含量的方法研究

根据龙眼汁是一种缓冲溶液,其含量不同则缓冲能力大小不同,即由龙眼汁调配的龙眼汁饮料的溶液pH随添加的柠檬酸量的变化幅度不同,设计实验得出龙眼汁饮料的缓冲系数与其中龙眼汁含量的关系式,根据该关系式可以推算出龙眼汁饮料中龙眼汁的含量。     

A comparison of hand washing techniques to remove Escherichia coli and caliciviruses under natural or artificial fingernails

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P > 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P < or = 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.     

一种测定枸杞鲜果中总类胡萝卜素含量的方法

研究的目的是建立一种应用四氢呋喃-癸酸反胶束溶液作为样品萃取溶媒测定枸杞鲜果中总类胡萝卜素含量的方法。在实验中,比较了四氢呋喃、癸酸和四氢呋喃-癸酸反胶束溶液对枸杞鲜果中总类胡萝卜素的萃取效率,测定了四氢呋喃-癸酸反胶束溶液萃取玉米黄素酯的重复性和加样回收率,确定了样品萃取方法。同时测定玉米黄素酯在癸酸反胶束溶液中的吸光系数,建立了以四氢呋喃-癸酸反胶束溶液为样品液在UV-VIS上检测枸杞鲜果中总类胡萝卜素含量的方法。实验结果表明:四氢呋喃-癸酸反胶束溶液对枸杞鲜果样品具有良好的萃取效率和重复性(CV=6.24%)以及94.7%的玉米黄素棕榈酸双酯加样回收率。玉米黄素棕榈酸双酯在四氢呋喃-癸酸反胶束溶液中的吸光系数(A11%cm)为1221。可用来计算样品中的总类胡萝卜素含量。     

新型高灵敏赭曲霉毒素A间接竞争化学发光免疫分析法

建立了一种测定赭曲霉毒素A的新型高灵敏化学发光间接竞争酶联免疫分析方法。以酶标赭曲霉毒素A二抗上的辣根过氧化物酶催化过氧化脲氧化3-(4-羟苯基)丙酸,生成具有荧光的3-(4-羟苯基)丙酸二聚体。并利用乙腈介质中双[2,4,6-三氯苯基]草酸酯和过氧化脲在增强剂咪唑的作用下反应产生强化学发光,以发光强度确定待检物中赭曲霉毒素A含量。结果表明,在最佳条件下IC50为0. 55 ng/m L,在0. 05～6. 08 ng/m L范围内有良好的线性关系,最低检出限为0. 01 ng/m L。样品加标回收实验显示葡萄干和葡萄汁样品的平均回收率分别为84. 55%～91. 36%和73. 32%～87. 64%,批内与批间变异系数均小于10%,精密度良好。该新型化学发光方法检测赭曲霉毒素A时发光强度更大、发光时间更长,可用于食品中赭曲霉毒素A的高灵敏度痕量检测。     

A new rapid spectrophotometric method to determine the rosmarinic acid level in plant extracts

A novel spectrophotometric method to determine the amount of rosmarinic acid in unpurified methanol extracts of the plants was developed. Rosmarinic acid is a naturally occurring bioactive compound in plants as an ester of caffeic acid with 3,4-dihydroxyphenyl lactic acid. The developed method was based on the complexation of rosmarinic acid with Zr⁴⁺ ions, giving a maximum absorbance at 362 nm. The absorptivity coefficient at this wavelength was found to be ε₃₆₂ = 2.66 × 10⁴ L mol⁻¹ cm⁻¹. In fact, this method is also specified giving two more absorption bands in UV region at 299.5 and 263.5 nm besides 362 nm. In addition, the accuracy and sensitivity of the new developed method are compared with the direct UV and rosmarinic acid–Fe²⁺ complex spectrophotometric methods by using methanol extracts of 11 Salvia species. As a conclusion, the present method is faster, cheaper, and more selective than the conventional methods for rosmarinic acid.     

直接进样快速测定葡萄酒中白藜芦醇及其甙的HPLC方法

1 前言饮用红葡萄酒有益于健康的报道不断增加，这一方面是由于适量饮用酒精；更重要的是由于红葡萄酒中含有丰富的酚类物质。经国内外专家大量研究表明，酚类物质中的白藜芦醇及其葡萄糖甙具有很强的药理活性，这些药理活性包括：阻止LDL氧化、抗血小板凝聚、抑制肿瘤等作用。作为衡量红葡萄酒质量好坏的成分指标之一，如何将其准确测定就显的十分重要。至今国内外已建立了HPLC、GC/MS等多种测定白藜芦醇及其甙的方法，总结这些方法发现存在诸如样品处理方法复杂、分析所用时间较长、应用了复杂的梯度洗脱等影响分析精确度和准确度的…     

直读法测牛乳中蛋白质含量

建立了一种直观快速的测定方法以检测牛乳中蛋白质含量.对牛乳进行脱脂、水浴加热后加入一定量的蛋白质沉淀剂,离心分离,根据沉淀体积直接读取蛋白质含量.该法简便易行,在置信度大于90%时,置信区间为(8.72±0.43),RSD为4.75%.该方法快速准确,作为一种快速测量牛乳中蛋白质的方法,结果令人满意.     

A new high-throughput screening method to determine multiple dyes in herbs and spices

The unauthorised addition of colours to herbs and spices is a recurrent issue affecting food business operators. Such a practice aims at improving food visual attractiveness, masking poor product quality, and/or compensating for natural colour variation with the ultimate goal to increase profits. To detect this fraud, a new LC–MS/MS method was developed for screening 58 dyes in both herbs and spices. This extended list of targets was established based on requirements from international spices organisations, past issues identified by web scouting and by notifications from the European Rapid Alert System for Food and Feed (RASFF). The method is intended to quickly detect fraudulent addition of dyes with Screening Target Concentrations ranging from 0.1 to 2.5 mg/kg. Validation was performed according to the European Community Reference Laboratories Residues Guidelines 20/1/2010. False positive and false negative rates were below 5% for all analytes and applicability of the method was further demonstrated by analysing 117 samples collected worldwide. None of the surveyed dyes was found in herbs (n = 28, 16 varieties) whereas 6% of spice samples (n = 89, 21 varieties) was found contaminated with one or two dyes at levels ranging from 0.12 to 255 mg/kg. Four out of the nine detected compounds have never been reported in the RASFF, thus demonstrating the usefulness of this analytical approach.     

数字图像处理法测试织物起毛性能的阈值确定

提出了数字图像处理中动态自适应阈值确定方法，并就它在织物起毛测试中的处理效果与传统阈值确定方法的处理效果做了对比分析。