含有汽车用乙烯基树脂和橡胶防护剂的聚硅氧烷

含有汽车用乙烯基树脂和橡胶防护剂的聚硅氧烷@兰云军!蓝博工作室     

LC-UV and LC-MS analysis of food and drink products containing kava

A method for the determination of six kava lactones, methysticin, dihydromethysticin, kawain, dihydrokawain, yangonin and desmethoxyyangonin, in solid foods and beverages has been developed. Solid samples were prepared using methanol extraction, while beverages were extracted using a separate solid phase extraction (SPE) method. After sample preparation, the extracts were analysed using LC-UV or atmospheric pressure photoionization (APPI) LC-MS in the positive mode. Using the method, 10 beverage products, two chocolate products, three unbrewed tea products, three dietary supplements and a drink mix product were analysed. The results obtained using the LC-UV were comparable to those obtained using APPI-LC-MS for most products. Using the SPE method in conjunction with LC-MS, individual kava lactones were detected in drink products at ppb concentrations. Concentrations of total kava lactones ranged between 135-0.035 mg per serving in the food and beverage products tested and between 40-61 mg per serving for the dietary supplement products tested. Results of these analyses as well as extraction efficiency and reproducibility data are reported.     

Alkylphenol and bisphenol A levels in rubber products

Levels of p-t-butylphenol (PTBP), p-t-octylphenol (PTOP), p-nonylphenol (NP) and bisphenol A (BPA) in rubber products in food-contact use, infant-related use and other uses are reported. Of 60 rubber products tested, PTOP was found in three in a concentration range of 2.2-37 μg g^-1, and NP in 15 in a concentration range of 2.6-513 μg g^-1. PTBP and BPA were not found in any sample. PTOP and NP were not detected in any infant-related sample, regardless of the material type. In contrast, among the samples with food contact and with other uses, the percentages containing PTOP or NP were 33 and 43%, respectively. A migration test was performed on eight samples containing NP and used in food-contact environments. The migration level of NP from spatulas to n-heptane was 0.83-1.52 μg ml^-1. The average migration rates to water, 20% ethanol and n-heptane were 0.03, 0.7 and 6.6%, respectively.     

High-performance liquid chromatographic analysis of biogenic amines in pharmaceutical products containing Citrus aurantium

A reverse-phase (RP)-HPLC method is reported for determining L-tyrosine, p-octopamine, synephrine, tyramine and hordenine as chemical markers of the species Citrus aurantium in raw material, dry extracts and phytotherapeutic herbal formulations. Using RP-HPLC with diode array detection (DAD) and gradient elution, the amines were determined in 12 different products from different Brazilian states labelled as containing C. aurantium. The presence of the amines was confirmed by mass spectrometry using electrospray ionisation (ESI-MS/MS). This RP-HPLC method allowed the separation of the amines from complex mixtures containing caffeine, ephedrine, salicin and other raw materials (e.g. Garcinia camboja, Phaseolus vulgaris, Caralluma fimbriata, Cassia nomane, Ephedra sp. and Cordia ecalyculata). The method proved useful and selective for inspecting herbal medicines containing p-synephrine and structural analogues. The herbal products analysed had a p-synephrine content ranging from 0.005 to 4.0% (w/w).     

茶叶有机氯及菊酯类农药检测方法的改进

茶叶有机氯及菊酯类农药残留检测样品净化处理中 ,通过利用真空减压抽滤装置 ,建立一种快速、简便、经济的检测方法 ,可大大缩短样品处理时间 ,提高工作效率     

Heat-induced changes in dairy products containing sucrose

The aim of the present work was to analyse the influence of the variables reaction temperature, casein–sucrose ratio and pH, on the kinetic parameters of gelation reactions, the gelation time and the functionality of casein micelles in concentrated milk systems containing sucrose.     

Residual chemicals in natural rubber products for food contact use

The residues of additives and other chemicals were investigated by GC/MS in natural rubber products for food contact, which included nipples, packing, gloves and a net for ham. The packings and gloves contained 980-6,570 micrograms/g of vulcanization accelerators, such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate (EZ), zinc di-n-buthyldithiocarbamate (BZ) and 2-mercaptobenzothiazole. Some samples contained BHT, Irganox 1076 and Yoshinox 2246R as antioxidants; dibutyl phthalate and di(2-ethylhexyl) phthalate as plasticizers; and palmitic acid, stearic acid, palmitamide, stearamide and hydrocarbons as lubricants. Two unknown peaks were identified as stigmasterol and beta-sitosterol, and others were estimated to be fucosterol, oryzanol and alpha-sitosterol. These sterols are widely distributed in plants, so their origin was presumed to be the rubber plants. The sterols were detected at a level of 340-2,940 micrograms/g in all natural rubber samples. A migration test was carried out for some samples. No chemicals were released into water, 4% acetic acid or 20% ethanol at 60 degrees C for 30 min, though BHT, Yoshinox 2246R, EZ, BZ and sterols were released into n-heptane at 25 degrees C for 60 min.     

Preservative systems containing essential oils in cosmetic products

The aim of this study was to evaluate the antimicrobial activity of selected essential oils ( Laurus nobilis , Eucalyptus globulus and Salvia officinalis ), both alone and in combination, in cosmetic preparations characterized by an increasing risk of microbial contamination, i.e. an O/W skin cream, a hydrogel and a non-alcoholic hydrolyte. Their potential synergistic effect in combination with the usual cosmetic preservatives at low concentrations (up to 200-fold less than usual) was also investigated.     

Residual chemicals in silicone rubber products for food contact use]

The residues of additives and other chemicals in 23 kinds of silicone rubber products for food contact use, including nipples, packing and spatulas, were investigated by GC/MS. The packing and spatulas contained 80-480 micrograms/g of BHT, 60-5,830 micrograms/g of di(2-ethylhexyl) phthalate (DEHP), and 60-80 micrograms/g of dibutyl phthalate, while the nipples contained no additives. All of the samples contained 15 to 20 peaks of polydimethylcyclosiloxanes. Dodecamethylcyclohexasiloxane (D6) to tetratriacomethylcycloheptadecasiloxane (D17) were confirmed, and other larger siloxanes up to pentacontamethylcyclopentacosasiloxane (D25) were estimated. A rough estimate of the total cyclosiloxane content was 3,310-14,690 micrograms/g. They might be mainly unreacted materials or by-products, and some of them might be additives. Based on the migration test, no chemicals were released into 20% ethanol at 60 degrees C for 30 min, though DEHP and the polydimethylcyclosiloxanes were released into n-heptane at 25 degrees C for 60 min.     

Chemical and sensory changes of different dairy products during storage in packages containing nanocrystallised TiO2

The chemical changes of three types of cheese, yoghurt and kefir were evaluated during storage in packages containing TiO₂ with two different compositions of the mixed anatase–rutile phase. The influence of TiO₂ packaging during storage on titratable acidity and fat content and on the external aspect was investigated. Fourier Transformed Infrared Spectroscopy (FTIR) analyses were performed to establish whether the TiO₂ penetrated the food during storage. The results showed that the TiO₂ nanoparticles deposited on polyethylene surface significantly decreased acidity and fat content of the investigated cheese and yoghurt types. During storage in TiO₂ nanopackages, the change in chemical parameters is accentuated as the content of rutile grows from 2.8% to 6.9%. The sensory evaluation revealed that the dairy products stored for 11 days in TiO₂ nanopackages present similar colour, texture and flavour with that of the references; the samples stored in polyethylene film were found to be unacceptable.     

肉制品发色剂的改良

随着人民生活水平的提高,我国的肉和肉制品的消费量逐年增加,肉制品工业已成为食品工业的重要组成部分.肉和肉制品的种类繁多,在许多肉制品的生产工艺中,盐腌是一个重要环节,其目的有：防腐保存,稳定肉色,提高保水性和粘结性,改善风味和口感等.在盐腌时,需要加入食盐及多种辅料或添加剂,其中发色剂是不可缺少的.     

面制品及糕点中含铝食品添加剂的测定

以乙二胺四乙酸二钠溶液为提取剂,选择性提取面制品及糕点中含铝食品添加剂残留铝,提取液酸化后用ICP-MS测定,实现了面制品及糕点中添加剂残留铝的准确测定。考察了超纯水、氢氧化钾溶液、硝酸溶液(2%)、EDTA二钠溶液及草酸溶液对食品中添加剂残留铝的提取效果和选择性,研究了EDTA二钠提取剂浓度、提取时间、提取温度及振摇时间间隔对添加剂残留铝提取效率的影响。结果表明,最佳提取条件为EDTA二钠提取剂浓度300μg/mL、提取时间30min、提取温度90℃、振摇时间间隔10min。对海苔麻花及蛋糕分别进行50mg/kg、100mg/kg两种梯度加标,加标回收率为98.0%~100.5%,相对标准偏差为1.36%~2.58%,方法检出限为0.026mg/kg,定量限为0.087mg/kg。     

Assessment of the reproductive-endocrine disrupting potential of chlorine dioxide oxidation products of plant sterols

This study examined the hypothesis that chlorine dioxide bleaching used in pulp and paper production causes the formation of reproductive-endocrine disrupting compounds from plant sterols. This was tested by conducting a laboratory simulation of the chlorine dioxide oxidation of two plant sterols, beta-sitosterol and stigmasterol. Oxidation products of the plant sterol beta-sitosterol were purified and identified and found to be cholestan-24-ethyl-3-one, 4-cholestene-24-ethyl-3-one, and 4-cholestene-24-ethyl-3,6-dione. The first two compounds were found in a number of pulp and paper effluents and biosolids. The sterols and their oxidation products were tested in vitro using bioassays for androgenicity and estrogenicity. A 28 d in vivo bioassay was employed to examine masculinization in female mosquitofish. In vitro bioassays revealed little estrogenic activity in the parent sterols or in mixtures of their oxidation products. Androgenic activity as measured by the androgen receptor binding bioassay was in the order of 19-96 microg/g testosterone equivalents but with no increase or decrease with chlorine dioxide oxidation. The mosquitofish bioassay did not show significant masculinization for any of the preparations tested. A number of androstane steroids were identified in the sterols tested, however, those compounds could only account for a small fraction of the androgenic activity in the sterols. It was clear that the parent sterols were not themselves acting as androgens in the bioassays used. This study indicated that chlorine dioxide oxidation of sterols produced predominantly oxidized sterols that were not likely to act through androgenic or estrogenic mechanisms.     

改良动物性食品中脂肪酸组成

一、动物性食品中脂肪酸的分类 根据动物体内脂肪酸代谢途径不同,其所含脂肪酸共分３类。 （１）饱和、单不饱和脂肪酸系列,代谢过程为： 碳水化合物与蛋白质一饱和脂肪酸（１６：０,１８：０）→ （动物脂肪） 单不饱和脂肪酸（１６：１,１８：１） （动物脂肪、橄榄油、菜籽油） （２）亚油酸（ｎ—６）系列,代谢过程为： 亚油酸（ＬＡ, １８： ２, ｎ－６）→γ－亚麻酸（１８： ６, ｎ—６） （谷物、大豆、玉米中丰富）（海藻如螺旋藻中） →双高－γ－亚麻酸 （２： ３, ｎ－６）→花生四烯酸 （ＡＡ,２０：４ ｎ－６） （…     

Characteristics of solidified products containing radioactive molten salt waste

The molten salt waste from a pyroprocess to recover uranium and transuranic elements is one of the problematic radioactive wastes to be solidified into a durable wasteform for its final disposal. By using a novel method, named as the GRSS (gel-route stabilization/solidification) method, a molten salt waste was treated to produce a unique wasteform. A borosilicate glass as a chemical binder dissolves the silicate compounds in the gel products to produce one amorphous phase while most of the phosphates are encapsulated by the vitrified phase. Also, Cs in the gel product is preferentially situated in the silicate phase, and it is vitrified into a glassy phase after a heat treatment. The Sr-containing phase is mainly phosphate compounds and encapsulated by the glassy phase. These phenomena could be identified by the static and dynamic leaching test that revealed a high leach resistance of radionuclides. The leach rates were about 10(-3) - 10(-2) g/m2 x day for Cs and 10(-4) - 10(-3) g/m2 x day for Sr, and the leached fractions of them were predicted to be 0.89% and 0.39% at 900 days, respectively. This paper describes the characteristics of a unique wasteform containing a molten salt waste and provides important information on a newly developed immobilization technology for salt wastes, the GRSS method.     

Identification of extractable substances from rubber nettings used to package meat products

Ten meat nettings were sampled from four different suppliers in the Netherlands. These meat nettings consisted both of natural rubber and of vegetable fibres. Nitrosamines were extractable up to 2 mg kg -1 netting, the nitrosamine being N -nitrosodibenzylamine. The nitrosatable substances found were precursors of N -nitrosodimethylamine and N -nitrosodibenzylamine and were extracted up to 0.4 mg kg -1 nettings. Considering the ratio of meat netting and foodstuff, the extractable amount of nitrosamines and nitrosatable substances does not raise concern for public health. The meat nettings were also screened for other potential migrants. Extractable amounts of several alkanes, alkenes, acids, antioxidants, plasticizers and sterols were found. Several of these extracted substances are not allowed in the Netherlands, although some are authorized in other countries. Several substances, however, have not been evaluated for use in food-contact materials and therefore the possible risk to public health is unknown.     

Sunless tanning products containing dihydroxyacetone in combination with a perfluoropolyether phosphate

It is well known that the shelf-life of products containing dihydroxyacetone (DHA) is quite unsatisfactory, and that in this area the adjustment to an acidic pH is the way usually recommended to improve DHA stability. The adoption of this rule, however, is a challenge for the cosmetic chemist not only because of the risks of skin irritation, but also because of the strong limitations in the choice of the acidic agent. It occurs that the use of either hydroxy-acids and phosphoric acid/phosphate buffers has the opposite effect on the one intended. Recently, a perfluoropolyether phosphate (PFPE phosphate) was introduced as a new acidic agent to lower the pH without increasing the skin irritation. Starting from a rationale based on this potential, we investigated sunless tanners containing PFPE phosphate and DHA. We monitored the ageing of sunless tanners with and without PFPE phosphate, by visual observation and instrumentation (pH measures and (1)H-NMR spectroscopy). Furthermore, to evaluate whether the substances produced from the DHA degradation are potential irritants, patch tests on volunteers were used to check the safety and indirectly the stability of the compositions. In conclusion, our investigations on the guidelines to formulate DHA-containing sunless tanners: confirmed that the pH is a key parameter in formulating these compositions; proved that PFPE phosphate is a safe and compatible ingredient to lower the pH; gave some evidence of the critical importance of thickeners; suggested a strategy based on multifunctional agents to minimize the ingredients.     

Mid-FTIR在乳制品分析中的应用

乳制品是几大类食品之一,有关乳制品的分析也是人们比较感兴趣的研究方向。随着经济的发展和消费需求的提高,乳制品分析手段亟需改进和发展。近年来,国内外学者针对这个方向作了大量工作,而FTIR(傅里叶红外光谱)分析法以其优越性成为乳制品分析中的佼佼者。文章初步概括其在乳制品分析中的研究,重点介绍了在乳蛋白功能性质影响、乳制品评价标准的建立、加工控制、营养评价及质量分析方法的研究进展。     

氨纶产品定量分析探讨

采用不同的预处理方法和不同定量分析方法研究分析氨纶产品定量实验产生的偏差。通过试验比较得出在氨纶产品定量分析过程中,预处理在样品非纤维物质含量较高的情况下尤显重要。     

Tannin analysis of food products

Phenolic substances occur primarily in fruits and vegetables and in the seeds of certain pigmented cultivars of sorghum, millets, and legumes. One of the major difficulties encountered in polyphenol research is the lack of a standard quantitative method for the analysis of phenolics that would be suitable for a wide range of seeds, forage crops, and food products and under a variety of experimental conditions. Some methods measure "total phenol", which may not be a true index of the nutritional quality of foods and thus does not distinguish polyphenols of nutritional concern from other low-molecular-weight phenols that also occur naturally in these products. Tannic acid (a hydrolyzable gallotannin) is commonly used as a "reference standard", but this may be a questionable practice since its biological properties differ from those of tannins of flavonoid origin. Polyphenols of cereals and legumes are predominantly of the latter type. Also, commercially available tannic acid has been shown to be a mixture of four phenolic compounds, the relative proportions of which vary with the samples. Thus, the choice of a suitable standard for tannin analysis is also important. The quantitative extraction of the condensed tannins from plant tissue is always difficult, since it may be complexed to a carbohydrate or protein matrix which could be quite insoluble due to a high degree of polymerization. The literature on tannin methodology is diverse and at times conflicting. Currently available methods for tannin analysis range from simple colorimetric, UV spectrophotometric, chromatographic, and enzymic to more sophisticated and expensive nuclear magnetic resonance (NMR) techniques. None of these methods of analyses is completely satisfactory nor can it be applied to different food products with the same degree of success. This review covers physical and chemical methods for tannin analysis of different food products, the problems in analysis and interpretation of data, and future research needs in this area.