Occurrence of N-nitrosodiethanolamine (NDELA) in cosmetics from the Dutch market

N-Nitrosamines as carcinogens in general pose a potential health risk. Since 1992, legal guidelines that restrict the occurrence of N-nitrosamines in cosmetics have been operational in the European Union. Problem issues are NDELA (N-nitrosodiethanolamine) and NMPABAO (2-ethylhexyl 4-(N-nitroso-N-methylamino)benzoate). Data available on the NDELA content of Dutch samples date back to the early 1980s and those for NMPABAO are lacking. For the determination of NDELA in cosmetics, a method based on capillary gas chromatography (GC) without derivatization and online chemiluminescence detection with a Thermal Energy Analyser (TEA) has been developed and validated. The sample is diluted with water, adsorbed onto a kieselgur column and eluted with n-butanol. The extract is transferred to a silica gel column which is eluted with acetone. The eluate is dried and re-dissolved in dichloromethane. The final extract is analysed for NDELA by GC-TEA. The average recovery for NDELA is 99%, range 86-112% (n = 4) and the limit of quantification is 5.3 mug kg(-1). The GC-TEA method was used to determine the NDELA content of 48 cosmetics including gels, shampoos, cremes, milks, conditioners and foams. All determinations were done in duplicate, and for every 10 cosmetics a recovery experiment and a blank determination were performed. The results of these quality assurance experiments were within the performance characteristics of the method developed. In 1996, a content of NDELA above the limit of quantification of 5.3 mug kg(-1) was measured in four out of the 48 cosmetics. Based on these results, a more selective survey was carried out. Now a NDELA content above the limit of quantification was measured in seven out of 25 sampled and analysed cosmetics.     

A screening procedure for total N-nitroso contaminants in personal care products: results of collaborative studies undertaken by a CTPA Working Group

A modified procedure for the determination of total N -nitroso compounds in personal care products was evaluated in collaborative studies organized through the UK Cosmetic Toiletry and Perfumery Association (CTPA). The method offers a true 'totals'determination in that a solution of the whole sample is analysed. Samples are dissolved/suspended in water or aqueous THF, and nitrite/nitrite ester interferences are removed by prior treatment with sulphamic acid. The treated test solution is denitrosated in a single reaction with HBr/acetic acid, in refluxing n -propyl acetate, and 'total' N -nitroso compounds are determined in a chemiluminescence reaction of the released nitric oxide with ozone. The use of a propyl acetate denitrosation solvent and of higher concentrations of HBr have improved both the sensitivity (routine limit of determination at 10 μgkg^-1) and water tolerance of the method. The method was shown to recover N -nitrosamines quantitatively, and to be sufficiently repeatable and reproducible to be used as a screening technique for N -nitroso compounds in personal care products.     

Effect of selected Hofmeister anions on functional properties of protein isolate prepared from lablab seeds (Lablab purpureus)

Effects of selected Hofmeister anions, namely Na₂SO₄, NaCl, NaBr, NaI, NaClO₄ and NaSCN, on the functional properties of a protein isolate prepared from lablab seeds (Lablab purpureus) were investigated. The results of water absorption capacity indicated that highest water absorption was recorded in solutions of Na₂SO₄, and the lowest in NaSCN solutions. Reduction in water absorption capacity followed the Hofmeister series in the order Na₂SO₄ > NaCl > NaBr, NaI > NaClO₄ > NaSCN. Protein solutions prepared in chaotropic (NaI, NaClO₄, NaSCN) salts had better foam capacity, foam stability, emulsifying activity and emulsion stability than solutions prepared with kosmotropic salts (Na₂SO₄, NaCl, NaBr). The results also indicate that increase in foam capacity and stability followed the Hofmeister series in the order Na₂SO₄ < NaCl < NaBr, NaI < NaClO₄ < NaSCN. When least gelation concentration (LGC) was used as the index of gelation capacity, at various salts concentrations, the lowest LGC were observed in NaSCN and the highest LGC in protein solutions prepared with Na₂SO₄. Copyright © 2005 Society of Chemical Industry     

淀粉系列高吸水树脂的研究概况

高吸水性树脂是一种新型的功能高分子材料,由含强亲水性基团的单体经过适度交联使其能够吸收上百倍甚至上千倍的水。本文从吸水机理、聚合方法、影响因素及树脂的性能等方面综述了淀粉系列高吸水树脂的研究概况,并且介绍了淀粉接枝共聚高吸水树脂在生理卫生、医疗器械、土木建筑、农业、食品等方面的应用。     

Water sorption and the plasticization effect in wafers

Wafers are low moisture food products whose crunchiness or crispness is considered a primary textural attribute, highly affected by the product's physical state (glassy or rubbery). The water activity–water content–glass transition relationships for commercial wafers are reported, using Gordon and Taylor's equation to model the water plasticization effect and also Brunnaver‐Emmett‐Teller (BET) and Guggenheim‐Anderson‐DeBoer (GAB) sorption models. BET monolayer moisture content was 6.2% and the moisture limit to fit this model was about 11.5%. Critical water activity and critical water content for the glass transition of the product at 20 °C were 0.591 and 0.118 (mass fraction) respectively. Abrupt changes in the mechanical product properties, evaluated from a three‐point bend test, could be observed at these limits. Moisture levels between 6 and 11% give rise to a glassy state matrix in the product and so to acceptable product crispness. Below this range, the glassy matrix seems to turn fragile and, above this range, the product becomes rubbery.     

Effect of precooking time and drying temperature on the physico-chemical characteristics and in-vitro carbohydrate digestibility of taro flour

Achu is a thick porridge obtained by cooking and pounding taro (Colocasia esculenta) corms and cormels in a mortar. This study was undertaken with the objective of producing precooked taro flour that can be used in the preparation of achu. Taro slices were precooked to times of 0, 20, 45 and 90 min and dried in an air convection oven at varying temperatures of 50, 60, 70 or 80 °C before milling into flour which was then analysed for its water absorption capacity (WAC), water solubility index, emulsion activity and stability, bulk density, foam capacity and least gelation concentration (LGC). Achu made from the flours were equally analysed for their relative penetrometric index, bulk density and colour. The results showed that precooking induced significant (P<0.05) decrease in foam capacity, penetrometric index, and increase in LGC, emulsion stability and WAC. The drying temperature also induces significant reduction in emulsion capacity and stability, penetrometric index, and increase in LGC, WAC. Long precooking time (>45 min) and drying temperature (>60 °C) induced significant reduction of the in-vitro carbohydrate digestibility of taro achu.     

A method for the determination of N-nitrosoalkanolamines in cosmetics

A method für the determination of N-nitrosoalkanolamines in cosmetics and toiletries is described. The ingredients used in their manufacture N-nitroso-bis-(2-hydroxyethyl)amine (N-nitrosodiethanolamine, NDELA) and N-nitroso-bis-(2-hydroxy-propyl)amine (NBHPA) are almost exclusively the contaminants. The method has therefore been modified for their determination. N-Nitroso-(2-hydroxy-ethyl)-(2-hydroxypropyl)amine is used as the internal standard. After dilution with water, the cosmetic is adsorbed onto a kieselguhr column and extracted with n-butanol. The extract is brought to dryness, re-dissolved in chloroform/acetone (5 + 1) and transferred to a silica gel column. The column is washed and eluted with acetone. The eluate is dried and the residue is treated with N-methyl-N-trimethylsilyl-heptafluorobutyramide. Trimethylsilyl (TMS)derivatives of N-nitrosoalkanolamines are determined by gas-chromatography with a thermal energy analyzer (TEA). Recovery of the internal standard is 95% and the determination limit is 5 micrograms/kg, Repeated analyses of a foam bath, spiked with 30 micrograms/kg NDELA, gave an average content of 32 micrograms/kg NDELA (variation coefficient 8.8%; n = 10). In order to avoid artefact formation during the clean-up process, kieselguhr containing 50% sodium ascorbate has to be used when cosmetics containing free dialkanolamines are analyzed.     

Analysis of pharmaceuticals in water by isotope dilution liquid chromatography/tandem mass spectrometry

A method has been developed for the trace analysis of 15 pharmaceuticals, four metabolites of pharmaceuticals, three potential endocrine disruptors, and one personal care product in various waters. The method employs solid-phase extraction (SPE) and liquid chromatography/tandem mass spectrometry (LC-MS/MS), using electrospray ionization (ESI) in both positive and negative modes. Unlike many previous LC-MS/MS methods, which suffer from matrix suppression, this method uses isotope dilution for each compound to correct for matrix suppression, as well as SPE losses and instrument variability. The method was tested in five matrices, and results indicate that the method is very robust. Matrix spike recoveries for all compounds were between 88 and 106% for wastewater influent, 85 and 108% for wastewater effluent, 72 and 105% for surface water impacted by wastewater, 96 and 113% for surface water, and 91 and 116% for drinking water. The method reporting limits for all compounds were between 0.25 and 1.0 ng/L, based on 500 mL of sample extracted and a final extract volume of 500 microL. Occurrence of the compounds in all five matrices is also reported.     

Influence of nitrite addition and gas permeability of packaging film on the microflora in a sliced vacuum-packed whole meat product under refrigerated storage

Three batches of cured, smoked and cooked pork loins were prepared without nitrite and with 100 or 200 ppm nitrite. The product was sliced, vacuum packed and stored at 2°C, 5°C and 10°C. Part of the product was packed in a conventional film, a polyamide/polyethylene film, and part of it in two films with lower gas permeabilities. Nitrite inhibited the growth of Brocothrix thermosphacta and Enterobacteriaceae at all temperatures. This resulted in a lower growth rate and/or lower maximum counts. Reducing the gas permeability of the film in the absence of nitrite did not influence the growth of B. thermosphacta. An effect of increasing anaerobic conditions was, however, seen in conjunction with 100 pprn added nitrite at both 5°C and 10°C. The Gram-positive cocci were not affected by the addition of nitrite but were soon overgrown by the competing flora. The insensitivity of the lactic-acid bacteria to nitrite and microaerophilic conditions resulted in these bacteria constituting a larger proportion of the total flora in batches with nitrite and/or packaging films with reduced oxygen permeabilities.     

Substitution of nitrite by sorbate and the effect on properties of mortadella

Investigation of substitution of nitrite by sorbate in mortadella involved preparation of the product with nitrite–sorbate combinations and controls of nitrite and sorbate alone. The results revealed that mortadella samples made with sorbate alone were not sensorily acceptable and had the highest TBA values. Mortadella prepared with nitrite alone was acceptable in all respects but showed the highest percentage of nitrite losses during storage. Nitrite–sorbate combinations were not significantly different with regard to color, flavor, and overall acceptability, compared to nitrite alone. These combinations showed lower TBA values. The study also demonstrated the importance of refrigerated storage for mortadella. Overall, the results indicated that complete nitrite replacement by sorbate is not possible in mortadella, but partial replacement with sorbate is acceptable.     

Relative importance of nitrite oxidation by hypochlorous acid under chloramination conditions

Nitrification can occur in water distribution systems where chloramines are used as the disinfectant. The resulting product, nitrite, can be oxidized by monochloramine and hypochlorous acid (HOCl), potentially leading to rapid monochloramine loss. This research characterizes the importance of the HOCl reaction, which has typically been ignored because of HOCl's low concentration. Also, the general acid-assisted rate constants for carbonic acid and bicarbonate ion were estimated for the monochloramine reaction. The nitrite oxidation reactions were incorporated into a widely accepted chloramine autodecomposition model, providing a comprehensive model that was implemented in AQUASIM. Batch kinetic experiments were conducted to evaluate the significance of the HOCl reaction and to estimate carbonate buffer rate constants for the monochloramine reaction. The experimental data and model simulations indicated that HOCl may be responsible for up to 60% of the nitrite oxidation, and that the relative importance of the HOCl reaction for typical chloramination conditions peaks between pH 7.5 and 8.5, generally increasing with (1) decreasing nitrite concentration, (2) increasing chlorine to nitrogen mass ratio, and (3) decreasing monochloramine concentration. Therefore, nitrite's reaction with HOCl may be important during chloramination and should be included in water quality models to simulate nitrite and monochloramine's fate.     

香辛蔬菜苦藠粗提液对亚硝酸盐的清除作用

研究苦藠在不同实验条件下对亚硝酸盐的清除能力。选择苦藠粗提液不同的预热温度、pH 值、用量及反应时间进行单因素试验,并在此基础上进行正交试验,以探明清除效果随反应条件所发生的变化。结果表明：高温预热很必要,在苦藠自然pH 值下清除率可达50% 以上;pH 值对清除率影响极显著,pH2.0、11.0mL 的粗提液,反应10min,清除率达到82.7%。以芥菜为对象,设置①预煮后浸于苦藠粗提液中(模拟烹饪),7℃冷藏,以去离子水浸泡为对照,观察芥菜中亚硝酸盐的积累;②鲜叶去污染后PE 包装置于40℃条件下(模拟高温贮运环境),检测叶片亚硝酸盐的变化。贮存达13d 时,两种浸泡液中芥菜亚硝酸盐的积累都较缓慢,苦藠液中芥菜亚硝酸盐含量始终低于对照,提示煮沸、低温、添加苦藠均有抑制亚硝酸盐形成的能力;40℃条件下,前4d 中,亚硝酸盐含量虽略增但均很低,其后亚硝酸盐含量跃增,第6 天时达到356.4mg/kg,2.0mL 苦藠粗提液在第1、6天的清除率分别为21.1% 和5.9%。     

等离子体活化水作为解冻介质对牛肉杀菌效能及品质的影响

目的:研究低温等离子体活化水（plasma-activated water,PAW）作为解冻介质对牛肉微生物安全及生鲜品质的影响。方法:采用射频等离子体发生装置,处理水量为300 mL,以高压电源处理时间（40、60、80、100、120 s）为试验因素,制备不同处理时长的PAW。将放置至常温（25 ℃）的PAW作为冷冻牛腱子肉的解冻介质,以介质与样品4:1的质量比例静置浸泡解冻10 min,测定牛肉和解冻介质中的菌落总数、亚硝酸根含量、pH,及牛肉保水性（汁液损失率、持水力）、脂质氧化和蛋白质流失状况。结果:随着等离子体活化水制备时间的延长,其减菌效果显著增强（P<0.05）,解冻后牛肉中的菌落总数可降低0.91 lg (CFU/g)。将等离子体活化水作为解冻介质可显著增强牛肉的持水力（P<0.05）,汁液损失率最多可降低1.83%,脂质氧化程度可降低0.0944 mg/kg,蛋白流失可减少0.085 mg/mL,牛肉经解冻后,亚硝酸根含量最高为3.38 mg/kg,仍小于定量限,解冻后肉品pH最大仅增加0.06,即该解冻方式并不会对牛肉的亚硝酸根、pH产生显著影响（P<0.05）。本研究为低温等离子体活化水在肉制品解冻方面的应用提供了一定的理论依据和数据参考。     

Development and Validation of a Method for Determination of Residual Nitrite/Nitrate in Foodstuffs and Water After Zinc Reduction

An environmentally friendly and cost-effective spectrophotometric method to analyze nitrate and/or nitrite was developed. The method is based on reduction of nitrate with zinc powder (instead of the cadmium or enzymes used in the standard methods approved by ISO/CEN). The initial nitrite concentration and total nitrite after reduction are determined by the very sensitive and widely used diazotization-coupling Griess reaction. A single-laboratory validation was applied in five different matrices (vegetable, meat product, baby food, dairy product, and surface water). The results show that the new method fulfills the international criteria for precision and recovery. The limit of detection for several matrices, calculated using fortified samples, ranged from 3 to 5 mg/kg for both nitrite and nitrate. Furthermore, the results obtained were in good agreement with those obtained using the CEN method (HPLC) and the ISO method (Cd reduction).     

Development of a Reference Measurement Procedure and Certified Reference Material for the Determination of Hydroxyproline in Meat

The concentration of trans-4-hydroxy-l-proline has been traditionally employed as an estimate of collagen content in meat to assess meat quality. Conventional methods use chemical derivatization followed by UV–visible detection. However, complexity of the matrix may cause interferences due to lack of specificity and consequently bias quantification. On the contrary, liquid chromatography (LC) separation coupled to mass spectrometry (MS) detection overcomes these limitations, giving more accurate results. This study describes the development and validation of an exact matching-isotopic dilution mass spectrometry method for the determination of hydroxyproline in meat hydrolysates in the certification of a candidate meat reference material (CRM LGC7154). The method is not biased by changes in method conditions or by matrix load. Hydroxyproline concentrations and relative uncertainties for quality control samples revealed good agreement with the certified values. A mean hydroxyproline concentration of 1.78?±?0.28 g/kg (k?=?2) was found for the CRM LGC 7154 material.     

食品中甜蜜素气相色谱方法测定的研究

采用组校准数据处理方法,建立食品中甜蜜素(环己基氨基磺酸钠)准确定量气相色谱方法。甜蜜素在酸性介质中与亚硝酸钠反应生成环己醇亚硝酸酯,气相色谱法测定食品中甜蜜素发现,测定的反应产物有2个色谱峰,目前通常认为第一个峰为环己醇亚硝酸酯,第二峰为环己醇,并以第一峰作为主产物峰定量计算甜蜜素含量。但是主产物峰会随着时间和反应条件变化逐渐转变为副产物峰,试验发现用主峰进行定量造成检测结果极其不准确。通过大量试验数据与CNAS比对结果验证,采用主副产物峰面积之和进行数据处理,能准确测定食品中甜蜜素含量。甜蜜素在0.01～0.6mg/mL范围内线性关系良好,相关系数r=0.9995;该方法的检出限为0.005mg/mL,试样中5个添加水平回收率为97.4%～103.6%,方法精密度和准确度高,分离度好,能很好地避免样品中各种成分的干扰。     

自控风干和添加发酵剂对缠丝兔理化及微生物特性的影响研究

采用人工气候箱设定恒定温度、湿度和风速,模拟自然发酵环境,添加复合发酵剂（戊糖片球菌、木糖葡萄球菌、肉色葡萄球菌、清酒乳杆菌、汉逊德巴利酵母菌）0.25 g/kg加工缠丝兔,研究了对产品理化及微生物特性的影响。结果显示,与传统自然风干法比较,新工艺对水分含量和水分活度无显著性影响,但可加快产品p H的下降,且产品最终p H在可接受范围。产品亚硝酸盐、N-二甲基亚硝胺、N-二乙基亚硝胺和组胺分别为110.75、2.23、21.50、26.25μg/kg,而传统加工组为158.37、4.92、52.15、42.12μg/kg。微生物检测结果的差异主要是与发酵肉制品特有感官和风味特性的形成密切相关的乳酸菌和微球菌,新工艺产品为8.25×106、6.33×106CFU/g,远高于传统产品的4.25×105、1.37×105CFU/g。采用自控风干和添加微生物发酵剂显然可在一定程度上降低亚硝酸盐、亚硝胺和组胺等有害物的含量,提升产品安全性。      

玫瑰花提取液对发酵香肠品质的影响

为探究发酵香肠制作过程中玫瑰花提取液(玫瑰液)部分取代亚硝酸盐的可行性,按照半干发酵香肠的加工工艺制备5组发酵香肠:添加10％玫瑰液组(T1)、添加80 mg/kg NaNO2组(T2)、10％玫瑰液+80 mg/kg NaNO2组(T3)、150 mg/kg NaNO2组(PC)、空白对照组(NC),将5组发酵香肠冷...     

等离子体活性水对生鲜黄鱼杀菌效果及品质的影响

为开发适用于生鲜鱼肉的新型杀菌方法,本文采用等离子体射流装置分别处理去离子水(1000 mL)1、2和3 min,制备三种等离子体活性水,以肠炎沙门氏菌菌液(10⁸ CFU/mL)为菌体模型,研究活性水的抗菌活性及时效,并对活性水中长效杀菌物质进行测定。采用三种等离子体活性水分别处理表面接种肠炎沙门氏菌的黄鱼片,测定黄鱼表面残留肠炎沙门氏菌数量,并研究其对鱼肉色泽、pH、脂质氧化、亚硝酸盐含量、持水力、气味及味感的影响。结果表明:处理3 min的等离子体活性水表现出最强的抗菌活性,对肠炎沙门氏菌的杀菌率达99.91%,其抗菌活性最高能维持8 h,这主要由于亚硝酸根在酸性条件下分解形成的具有较强杀菌活性的NO·和NO₂·。采用等离子体活性水处理对鱼肉表面肠炎沙门氏菌的杀菌率最高达92.41%,有效抑制鱼肉储藏过程中的腐败,且不会对鱼肉的色泽、pH、脂质氧化、亚硝酸盐含量、持水力、气味以及味感造成显著影响而破坏鱼肉品质。     

可降解亚硝酸盐植物乳杆菌在广式腊肠发酵中的应用

目的:以可降解亚硝酸盐的植物乳杆菌为发酵剂,分析探讨广式腊肠制作中使用该发酵剂的产品特征。方法:研究两株植物乳杆菌分别对2%氯化钠和300mg/kg亚硝酸钠的耐受性,以及在MRS培养基中降解亚硝酸盐的能力。并以其中一株植物乳杆菌为发酵剂加入广式腊肠中,测定不同发酵时间产品的pH值、水活度以及乳酸菌、霉菌和大肠菌的生长情况,与对照组进行比较,研究该发酵剂对发酵腊肠产品特征的影响。结论:将具有良好耐盐和耐亚硝酸盐能力,同时对亚硝酸盐具有较强降解能力的H1菌作为发酵剂加入腊肠后,降低了腊肠的pH值,同时对有害菌有明显的抑制效果,说明所选植物乳杆菌具有较好的环境适应性并显示出强大的酸化潜力,能通过抑制肠杆菌科的生长,提高微生物的安全性。因此,H1菌有望成为一种具有生物安全性的本土发酵剂。