不同熟化方法对紫色马铃薯挥发性风味物质形成的影响

利用顶空固相微萃取和气相色谱质谱联用技术,对不同熟化方式的2种紫色马铃薯(杭引1号、紫罗兰)挥发性风味物质进行分析,结果表明:1)癸醛为蒸熟马铃薯主体挥发性风味化合物;癸醛,香叶基丙酮为煮熟马铃薯主体挥发性风味物质,微波烘烤的马铃薯主要挥发性风味物质有香叶基丙酮、2,2,4-三甲基-1,3-戊二醇二异丁酸酯;烘烤马铃薯主要挥发性风味物质有癸醛、香叶基丙酮、2,4-二叔丁基苯酚、1-吡咯烷-1-环己烯。2)熟化加热方式的不同,马铃薯产生的挥发性风味化合物的种类丰富程度也不同,烘烤熟化处理马铃薯产生的挥发性风味物质种类最丰富,分别为8种(杭引1号)、21种(紫罗兰);微波烘烤马铃薯检测出挥发性风味物质种类最单调,分别为2种(杭引1号)、4种(紫罗兰)。3)2个品种之间既有共有风味物质,又有独有的风味物质。     

不同类型腐乳中挥发性风味成分比较分析

采用同时蒸馏萃取(SDE)和顶空固相微萃取(HS-SPME)两种方法提取红方、青方、白方3种腐乳中挥发性风味成分。并用气相色谱-质谱(GC-MS)联用对挥发性物质进行鉴定,结果显示共鉴定出179种挥发性物质,SDE法和HS-SPME法分别鉴定出114种和102种。红方腐乳含量较高的挥发性风味物质包括硬脂酸乙酯、4-乙烯基-2-甲氧基苯酚、3'-甲氧基苯乙酮、丁香酚、十四酸乙酯、十五酸乙酯、辛酸乙酯、乙醇、棕榈酸乙酯、2,4,6-三羟基苯甲醛、α-石竹烯等;白方腐乳中含量较高的挥发性风味物质包括茴香脑、辛酸乙酯、2,2,4-三甲基-1,3-戊二醇二异丁酸酯、油酸乙酯、亚油酸乙酯等,其中茴香脑是白方腐乳的特征风味物质之一;青方腐乳中含量较高的挥发性物质有吲哚、苯酚、丁酸丁酯、亚油酸乙酯、丁酸丙酯、2,4-二叔丁基苯酚、油酸乙酯、棕榈酸乙酯、苯乙醇、桉叶油醇等,其中吲哚是青方腐乳的特征风味物质之一。     

Isolation and identification of some unknown substances in disposable nitrile-butadiene rubber gloves used for food handling

In Japan, disposable gloves made from nitrile-butadiene rubber (NBR) are frequently used in contact with foods. In a previous paper, we investigated substances migrating from various gloves made of polyvinyl chloride, polyethylene, natural rubber and NBR. Zinc di-n-butyldithiocarbamate (ZDBC), diethyldithiocarbamate (ZDEC) used as vulcanization accelerators, di(2-ethylhexyl)phthalate (DEHP) used as a plasticizer and many unknown compounds that migrated from NBR gloves into n-heptane were detected by GC/MS. In this paper, six unknown compounds were obtained from one kind of NBR glove by n-hexane extraction and each was isolated by silica gel chromatography. From the results of NMR and mass spectral analysis of the six unknown compounds, their structures are proposed as 1,4-dione-2,5-bis(1,1-dimethylpropyl)cyclohexadiene ( 1 ), 2-(1,1-dimethylethyl)-4-(1,1,3,3-tetra methylbutyl)phenol ( 2 ), 2,6-bis(1,1-dimethylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol ( 3 ), 2,4-bis(1,1,3,3-tetramethylbutyl)phenol ( 4 ), 2-(1,1-dimethylethyl)4,6-bis(1,1,3,3-tetramethylbutyl)phenol ( 5 ) and 2,4,6-tris(1,1,3,3-tetramethylbutyl)phenol ( 6 ). Compound 1 was observed in five of the seven kinds of NBR gloves, and compounds 2-4 and 6 , which are not listed in Chemical Abstract (CA), were present in four kinds of gloves.     

GC-MS法测定白酒接触塑料材料中非邻苯类塑化剂TXIB的迁移量

该研究采用液液萃取结合气相色谱-质谱(GC-MS)法建立了白酒接触用塑料材料中2,2,4-三甲基-1,3-戊二醇双异丁酸酯(TXIB)迁移量的测定方法.方法采用食品模拟物对常见塑料材料样品进行迁移试验后,得到模拟浸泡液,选择正己烷作为萃取溶剂对模拟浸泡液进行萃取,萃取溶剂体积为2 mL,震荡萃取时间为1 min,萃取液...     

甘薯黑斑病拮抗细菌抑菌性能及抑菌物质鉴定

甘薯采后由病原菌引起的腐烂损失严重，其中由长喙壳菌（Ceratocystis fimbriata）侵染所导致的黑斑病是甘薯采后主要病害之一。本研究对前期筛选到的对长喙壳菌有较强拮抗作用的菌株解淀粉芽孢杆菌（Bacillus amyloliquefaciens）JK和克雷伯氏杆菌（Klebsiella pneumoniae）GK进行抑菌性能分析，同时采用气相色谱-离子迁移谱（GC-IMS）和气相色谱-质谱联用（GC-MS）技术对两株拮抗菌的体外挥发性抑菌成分进行了分析。结果表明:用两株拮抗菌JK和GK的菌液熏蒸甘薯果实，延缓了黑斑病发病时间，显著（P<0.05）抑制了病斑的扩展。两株菌所产的挥发性气体成分主要有酮类、烷类、醇类、酯类、醛类等，其中异辛醇（1-Hexanol, 2-ethyl-）、己醛（Hexanal）、2-壬酮（2-Nonanone）和2,2,4-三甲基-1,3-戊二醇二异丁酸酯（2,2,4-Trimethyl-1,3-pentanediol diisobutyrate）对甘薯长喙壳菌具有较强的抑制作用。选择两种安全气体成分己醛和2-壬酮按照1:1比例混合，在200 μL/L时可以完全抑制长喙壳菌的生长。该研究为拮抗微生物在果蔬采后的应用提供了参考和依据。     

Occurrence of 2,2,4-trimethyl–1,3-pentanediol monoisobutyrate (Texanol®) in foods packed in polystyrene and polypropylene cups

After simultaneous distillation–extraction (SDE) of foods packed in polystyrene (n = 77) and polypropylene cups (n = 42) from 61 different suppliers, coupled capillary gas chromatography–mass spectrometric (HRGC–MS) analyses indicated the presence of diastereomers of 2,2,4-trimethyl–1,3-pentanediol monoisobutyrate (TMPD-MIB; Texanol®), a known coalescent of paints and printing inks. The contaminant was found in 55 and 50% of the polystyrene and polypropylene packed samples, respectively. Amounts ranged 1.2–64.5 µg kg^?1 in polystyrene cups (average 25.1 µg kg^?1) and 0.9–45.7 µg kg^?1 in polypropylene cups (average 10.8 µg kg^?1). The origin of Texanol® in the printed plastic cups was demonstrated by separate HRGC–MS analysis, showing amounts in the higher µg kg^?1 range. In addition, the presence of two pairs of enantiomers, both found to be racemic by enantioselective multi-dimensional gas chromatography–mass spectrometry (enantio-MDGC–MS), excluded it being of natural origin. The detection limit of overall procedure (DLOP) and the reliable quantification limit (RQL) were 0.2 and 0.9 µg kg^?1, respectively. As the diester, 2,2,4-trimethyl–1,3-pentanediol diisobutyrate (TXIB), is on the EU list of regulated substances (restricted to single-use gloves only) with a migration limit of 5 mg kg^?1 in food and is metabolised rapidly by hydrolysis, the observed migration of the monoester Texanol® at the µg kg^?1 level poses no risk of adverse effects.     

Migrants from disposable gloves and residual acrylonitrile]

Disposable gloves made from polyvinyl chloride with and without di(2-ethylhexyl) phthalate (PVC-DEHP, PVC-NP), polyethylene (PE), natural rubber (NR) and nitrile-butadiene rubber (NBR) were investigated with respect to evaporation residue, migrated metals, migrants and residual acrylonitrile. The evaporation residue found in n-heptane was 870-1,300 ppm from PVC-DEHP and PVC-NP, which was due to the plasticizers. Most of the PE gloves had low evaporation residue levels and migrants, except for the glove designated as antibacterial, which released copper and zinc into 4% acetic acid. For the NR and NBR gloves, the evaporation residue found in 4% acetic acid was 29-180 ppm. They also released over 10 ppm of calcium and 6 ppm of zinc into 4% acetic acid, and 1.68-8.37 ppm of zinc di-ethyldithiocarbamate and zinc di-n-butyldithiocarbamate used as vulcanization accelerators into n-heptane. The acrylonitrile content was 0.40-0.94 ppm in NBR gloves.     

Estrogenic activities of chemicals related to food contact plastics and rubbers tested by the yeast two-hybrid assay

Food contact plastics and rubbers possibly contain many kinds of chemicals such as monomers, oligomers, additives, degradation products of polymers and additives, and impurities. Among them, bisphenol A, nonylphenol, benzylbutyl phthalate, styrene oligomers and hydroxylated benzophenones have been reported to possess estrogenic activities. In this study, other chemicals related to food contact plastics and rubbers, and their metabolites induced by the S9-mixture were tested for their estrogenic activities using the yeast two-hybrid assay. Among the 150 chemicals, 10 chemicals such as bis(4-hydroxyphenyl) methane, 4-cyclohexylphenol, 4-phenylphenol, 4,4'-isopropylidenediphenol alkylphosphite, two type of styrenated phenol (including mono type), tris(nonylphenyl) phosphite, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone and 2,4-diphenyl-4-methyl-1-pentene, their metabolites and the metabolites of 6 other chemicals, such as 2-(phenylmethyl) phenol, styrenated phenol (di and tri type), 1-(N-phenylamino)naphthalene, 4-tert-butylphenylsalicylate, nonylphenol ethoxylates and 2-methyl-6-tert-butylphenol, displayed estrogenic activities. All of them contained a phenol group in their chemical structures or formed one easily by hydrolysis or metabolism. However, most of the chemicals related to food contact plastics and rubbers, and their metabolites did not show any estrogenicity.     

Sensory and analytical evaluations of paints with and without texanol

Perception of odor can figure prominently in complaints about indoor air,yet identification of the responsible compound(s) is often difficult. For example, paint emissions contain a variety of odorous volatile organic compounds (VOCs) which maytrigger reports of irritation and upper respiratory health effects. Texanol ester alcohol (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), a paint coalescing agent, is frequently associated with the "persistent, characteristic odor" of water-based paint. To evaluate the sensory impact of Texanol, naive (unfamiliar with paint constituents) and experienced (familiar with paint constituents) subjects evaluated the odor properties of paints with and without Texanol. VOC emissions from neat paint and paint applied to gypsum wallboard were collected via solid-phase microextraction and analyzed by gas chromatography/ mass spectrometry and gas chromatography/olfactometry. Regardless of subjects' prior experience, aromatic hydrocarbons and oxygenated compounds, introduced from other paint additives and not Texanol, were most commonly associated with paint odor. However, quantitative sensory techniques demonstrated that addition of Texanol to paints led to an overall increase in the perceived intensity of the coating. The combined use of these techniques proved to be an effective methodology for analyzing the structure of paint volatiles and their sensory properties and holds promise for solving many odorous indoor air problems.     

Determination of Henry's law constants of phenols by pervaporation-flow injection analysis

A novel dynamic nonequilibrium technique for the determination of Henry's law constant (HLC) of phenols based on pervaporation-flow injection (PFI) is described. A linear relationship between HLC and the amount of phenol measured by a detector in the acceptor line of a PFI system was demonstrated. This relationship was constructed using five frequently encountered phenols (phenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,3-dimethylphenol) and used for the determination of the HLC of three other phenols (2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol). The HLC of all eight phenols were also determined by the single equilibrium static technique (SEST). Fairly good agreementwas observed between both techniques regarding the HLC of 2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol. On the basis of the results obtained, it was concluded that the PFI technique offers considerable advantages over SEST in terms of precision, speed, labor intensity, and possibilities for automation.     

Survey of plasticizers in polyvinyl chloride toys

Plasticizers in 101 samples of polyvinyl chloride (PVC) toys on the Japanese market were surveyed. No phthalates were detected in designated toys, though bis(2-ethylhexyl)phthalate, diisononyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisodecyl phthalate and benzyl butyl phthalate were detected in more than half of other toys. 2,2,4-Tributyl-1,3-pentanediol diisobutylate, o-acetyl tributyl citrate, adipates and diacetyl lauroyl glycerol, which are alternative plasticizers to phthalates, were detected. The results of structural analysis confirmed the presence of di(2-ethylhexyl)terephthalate, tributyl citrate, diisononyl 1,2-cyclohexanedicarboxylate and neopentyl glycol esters; these have not previonsly been reported in Japan. There appears to be a shift in plasticizers used for designated toys from phthalates to new plasticizers, and the number of different plasticizers is increasing.     

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.     

Removal of chlorophenols using industrial wastes

Development of inexpensive adsorbents from industrial wastes for the treatment of wastewaters is an important area in environmental sciences. Blast furnace slag, dust and sludge from steel plants, and carbon slurry from fertilizer plants after their treatment have been utilized as inexpensive adsorbents for the removal of phenols, which are an important class of pollutants as they are highly toxic. The characterization of the four adsorbents prepared has shown that the carbonaceous adsorbent prepared from carbon slurry possesses high porosity and maximum surface area (380 m2/g) as compared to the other three adsorbents (4-28 m2/g). The adsorption of four phenols (phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol) on these adsorbents is parallel to their porosity and surface area order. The uptake of the phenols on carbonaceous adsorbent is substantial and found to be 17.2, 50.3, 57.4, and 132.5 mg/g for phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol, respectively. The detailed adsorption studies on carbonaceous adsorbent have indicated that the adsorption process follows the Langmuir isotherm, is first order, and is pore diffusion controlled. As adsorption of phenols on prepared carbonaceous adsorbent is significant, its performance has been evaluated with respect to standard activated charcoal. The results indicate that the phenols removal efficiency of carbonaceous adsorbent is about 45% to that of a standard activated charcoal sample. Thus, the carbonaceous adsorbent can be used for the removal of phenols as a low-cost alternative (approximately 0.1 U.S. dollars/kg) to activated charcoal.     

Removal of chlorophenols from wastewater using red mud: an aluminum industry waste

Removal of toxic substances from wastewaters using low-cost alternatives to activated carbon is an important area in environmental sciences. Efforts have been made to convert red mud, an aluminum industry waste, into a low-cost potential adsorbent, and the final material has been used for the removal of phenol, 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol from wastewater. It is pertinent to mention that phenol and chlorophenols are highly carcinogenic and an priority class of pollutants which needs to be removed from effluents before discharge into water bodies. 2,4-Dichlorophenol and 4-chlorophenol are sorbed by the developed adsorbent up to 94-97%, while the removal of 2-chlorophenol and phenol was up to 50-81%. The removal of phenols and its derivatives was achieved up to 98% by column experiments at a flow rate of 0.5 mL/min. The order of removal was 2,4-dichlorophenol > 4-chlorophenol > 2-chlorophenol > phenol, and the removal takes place through a particle diffusion mechanism. The adsorption was found to be endothermic in nature and follows both Langmuir and Freundlich models. Estimation of the phenols was carried out by capillary electrophoresis, and the adsorbent has been successfully tried for the removal of chlorophenols from a wastewater. The developed process is very useful, economic, rapid, and reproducible for the removal of phenols.     

Determination of 2,4,6-tri-tert-butylphenol and related compounds in foods

An analytical method has been developed for the determination of 2,4,6-tri-tert-butylphenol (TTBP) in foods. TTBP was determined by GC/MS (SIM) after extraction from food samples using a steam distillation technique. The developed method was able to determine simultaneously 2,4-di-tert-butylphenol (2,4-DTBP), 2,6-di-tert-butylphenol (2,6-DTBP), 3,5-di-tert-butylphenol (3,5-DTBP) and 2,4-di-tert-pentylphenol (2,4-DTPP). The method was applied to analyze the residues of the 5 phenolic compounds in 101 food samples purchased from markets. TTBP was found in some samples of meat, liver and fish (muscle) at the levels of trace (tr)-0.50 ng/g, tr and tr-1.83 ng/g, respectively. 2,4-DTBP was found in some samples of vegetables, meat, liver, fish (muscle) and fish (viscera) at the levels of 1.4-10.6 ng/g, 2.7-26.4 ng/g, tr-34.2 ng/g, tr-21.6 ng/g and tr, respectively. 2,6-DTBP was found in some samples of fish (muscle) and fish (viscera) at the levels of tr-3.9 ng/g and tr, respectively. 3,5-DTBP and 2,4-DTPP were not found in any of the analyzed samples.     

主链含柔性链的聚酰亚胺的制备及其在纺织品中的探索性应用

以1,2-双(4-氨基苯氧基)乙烷、1,3-双(4-氨基苯氧基)丙烷、1,4-双(4-氨基苯氧基)丁烷三种主链含柔性链的二胺单体和3,3,′4,4′-二苯醚四羧酸二酐进行缩聚反应,制得聚酰胺酸溶液,涂层于芳纶1414基布。对经聚酰亚胺处理后织物的力学性能、热性能及防紫外辐射性能进行测试,结果表明强力有所降低,热性能稍有提高,防紫外辐射性能有了显著提高。     

Antioxidants and their migration into food simulants on irradiated LLDPE film

Effects of γ-irradiation on residual and migration levels of antioxidants, tris-(2,4-di-tert-butylphenyl) phosphite (Irgafos 168) and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076), and their radiolysis products were investigated in the linear low density polyethylene (LLDPE) packaging samples treated at doses from 0 to 200 kGy. The content of Irgafos 168 was not detected in 5 kGy treated samples and the content of Irganox 1076 decreased by 34.9% from the initial level in 10 kGy treated samples. The radiolysis products, 2,4-di-tert-butylphenol (2,4-DTBP), 1,3-di-tert-butylbenzene (1,3-DTBB), and toluene were identified and their concentrations gradually increased as the irradiation dose increased. Migration of Irgafos 168 from the LLDPE pouch into food simulants, distilled water, acetic acid (4 ml/100 ml distilled water) or ethanol (20 ml/100 ml distilled water), was not detected at dose levels up to 200 kGy while that of the Irganox 1076 was detected in a decreasing mode with increasing dose.     

Selective trace level analysis of phenolic compounds in water by flow injection analysis--membrane introduction mass spectrometry

Flow injection analysis coupled with membrane introduction mass spectrometry (FIA-MIMS) with on-line derivatization is shown to allow fast, accurate, nearly interference-free, and sensitive (low microgram/L) quantitation of phenolic compounds in water. On-line FIA derivatization of the phenolic compounds is performed by acetic anhydride acetylation in a K2CO3-buffered alkaline medium. The phenol acetates so formed efficiently permeate a silicone membrane and are directly transferred to the mass spectrometer, in which they are analyzed with selectivity and high sensitivity via selected ion monitoring. FIA-MIMS analysis was performed for aqueous solutions of phenol, 2-methylphenol, 4-chlorophenol, 4-chloro-3-methylphenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol, and detection limits in the 0.5-20 micrograms/L (ppb) range were observed for an analytical frequency of six samples/h. FIA-MIMS for phenolic compound analysis is considerably less time-consuming and labor intensive than most chromatographic methods based on liquid-liquid extraction and preconcentration procedures and is therefore applicable for on-line and in-situ monitoring of phenols in wastewaters and in the environment. FIA-MIMS employing acetic anhydride derivatization is also virtually free of interferences since it combines chemical, membrane, and enhanced MS selectivity; hence quantitation of phenolic compounds can be performed in the presence of congeners.     

Simultaneous analysis and exposure assessment of migrated bisphenol analogues,phenol, and p-tert-butylphenol from food contact materials

ABSTRACT

A simple, rapid, and novel liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was developed and validated to determine levels of eight bisphenol analogues (A, S, F, B, P, AF, AP, and Z), phenol, and p-tert-butylphenol migrated from food contact material (FCM) into food simulants. Method validation showed acceptable values in terms of linearity, precision, and accuracy. The limits of detection and quantification were 0.53–29.6 and 1.77–29.6 μg L^?1, respectively. Water, 4% acetic acid, 50% ethanol, and n-heptane were employed as food simulants for the migration tests, and the proposed method was applied to 234 articles of 11 FCMs including polycarbonate, polyethersulfone, polypropylene, and polyethyleneterephthalate, obtained from domestic markets and manufacturers in Korea. Only phenol was found in the FCMs poly(cyclophexane-1,4-dimethylene terephthalate), polylactide, and thermoplastic polyurethane. Eight bisphenol analogues and p-tert-butyl phenol were not found in any samples. Using the obtained migration results, the estimated daily intake (EDI) of phenol was calculated. Exposure assessments were carried out to compare the EDI with the tolerable daily intake (TDI), showing a low percentage (0.18%) of the TDI reported. This is the first study to examine eight bisphenol analogues and two phenols simultaneously in FCMs using the LC-MS/MS.     

基于主成分分析和HS-SPME-GC-MS技术综合评价不同品种芒果品质特性

为表征台农、象牙和金煌三种芒果的品质特性,本文通过测定其主要品质指标,利用主成分分析法(PCA),构建芒果主要品质综合评分模型,并采用HS-SPME-GC-MS技术对其挥发性风味物质进行分析,综合评价其品质。结果表明,金煌的可溶性固形物、总糖含量和糖酸比最高,分别为19%、24.18 mg/g和10.86;台农的V_C和总酚含量最高,分别达9.52 mg/100 g和1.03 mg/g;主成分分析结果表明,台农的综合得分最高,其次为金煌,象牙的综合得分最低。HS-SPME-GC-MS技术从三种芒果中共检测出116种挥发性风味物质,主要包括烯烃类、酚类和醛类等8类物质。台农和象牙的挥发性化合物以烯烃类为主,相对含量分别为45.52%和58.12%,金煌中以酚类物质为主,相对含量为56.88%。通过ROAV分析法共确定了15种关键风味化合物,其中台农和象牙香气贡献最大的物质为(E,Z)-2,6-壬二烯醛,金煌香气贡献最大的是3-己烯醛。台农呈柑橘香、甜香等芳香气味,象牙具有黄瓜香特征风味,而金煌含有特殊的木香气味,该风味主要由2,4-二叔丁基苯酚所贡献。综合分析认为,台...