微波条件下二苯甲酮与1-羟基环己基苯基甲酮从微波纸向Tenax中的迁移规律

采用高效液相色谱法(HPLC)对不同微波100、250、440、600W条件下二苯甲酮(BP)和1-羟基环己基苯基甲酮(HCH)从微波纸向脂肪类模拟物Tenax中的迁移规律进行研究。在此基础上,将微波加热的迁移结果与常用恒温迁移实验方法的结果进行比较。结果表明:BP在微波250W和440W时的最大迁移率几乎相同,而HCH在微波440W和600W时最大迁移率几乎相同,且微波条件下的最大迁移率小于常用恒温条件下的最大迁移率。除了功率的作用,温度和所做功对BP和HCH的迁移也有影响,且相比常用恒温加热的迁移实验,微波加热能加快BP和HCH在脂肪类物质中迁移行为的发生,但最大迁移率降低。     

食品包装纸中的饱和烃矿物油向食品模拟物Tenax的迁移和安全评估

研究食品包装纸中饱和烃矿物油(MOSH)向食品模拟物Tenax的迁移,考虑了不同类型包装纸在不同温度下(25℃、40℃、100℃)的迁移行为,并采用毒理学关注阈值(TTC)的方法对MOSH进行安全评估。结果表明:温度一定时,厚度和克重是影响食品包装纸中MOSH迁移的重要因素,厚度和克重越小,MOSH的迁移率越大;在一定条件下,温度越高,MOSH达到迁移平衡的时间越短(100℃,100 min;25℃,8 d),迁移率越大(100℃,24.81%;25℃,7.82%)。所测定的包装纸中MOSH达到迁移平衡时的迁移量,都明显超过了JECFA规定的特定迁移量0.6 mg/kg,容易发生迁移的MOSH主要集中在C16~C18和C23~C26,均属于容易在人体内蓄积的中低粘度矿物油。TTC评估结果表明:主要发生迁移的MOSH烃类经Cramer分类均属于Class I,从四种食品包装纸中迁移到Tenax的MOSH,估计每日摄入量(EDI)均明显高于对应的TTC阈值(1.8 mg/person·day),需要引起关注。     

高温下白卡纸中二苯甲酮和1-羟基环己基苯基甲酮向食品模拟物质的迁移

研究了在70℃和90℃下,采用直接浸泡法使白卡纸中的固化剂二苯甲酮（BP）和1-羟基环己基苯基甲酮（HCH）向水、3%乙酸、15%乙醇、50%乙醇、95%乙醇等食品模拟物质迁移,采用高效液相色谱仪（HPLC）分别检测迁移后模拟物质中的迁移量。结果表明两种固化剂在0.64⁴0mg/L的质量浓度范围内呈良好线性,相关系数不小于0.9995。温度越高,迁移时间越长,迁移量也越大;随着乙醇浓度的增高,BP、HCH的迁移量也增加;对于3%乙酸,BP和HCH迁移率最小。      

高压液相色谱法测定食品接触材料水性模拟液中2,4-二羟基二苯甲酮

目的 探讨高压液相色谱法测定食品接触材料水性模拟液中2,4-二羟基二苯甲酮的方法。方法 食品接触材料经水、10%乙醇(v/v)、20%乙醇(v/v)、50%乙醇(v/v)以及3%乙酸(w/v)5种不同水性模拟液提取后, 以Agilent HC-CN为分析柱, 甲醇: 水(55: 45, v/v)为流动相, 经UV检测器(?=290 nm) 进行定量分析。结果 5种不同水性模拟液中2,4-二羟基二苯甲酮在0.5~10.0 mg/L浓度范围内线性关系均良好(r=0.9999), 检测限(S/N=3)均为0.02 mg/L。在低、中、高3个不同添加水平下进行加标回收实验, 2,4-二羟基二苯甲酮的平均回收率为84.0%~96.9%, RSD(n=6)为0.85%~4.60%。结论 本方法简单、快速、准确, 完全能够满足食品接触材料日常检验的需要。     

高效液相色谱-串联质谱法测定纸质包装材料中米氏酮、对二甲氨基二苯甲酮及2-异丙基硫杂蒽酮的迁移量

为测定纸质包装材料中米氏酮、对二甲氨基二苯甲酮及2-异丙基硫杂蒽酮的迁移量,建立了磁固相萃取-高效液相色谱-串联质谱检测法(MSPE-HPLC-MS/MS)。该方法采用溶剂热还原法制备了Fe3O4磁性亚微米粒子,以其为固相萃取材料,并以Agilent Eclipse AAA柱为分析柱,甲醇和水溶液为流动相,正离子模式下测定,流量为0.5 mL/min。对磁固相萃取中影响米氏酮、对二甲氨基二苯甲酮及2-异丙基硫杂蒽酮的主要萃取因素(包括磁性纳米粒子用量、洗脱溶剂和体积、PH值)进行了考察。结果表明:米氏酮等3种物质在0.5～50 ng/mL范围内线性关系良好(r>0.999),最低定量限均为0.5 ng/mL,检测限为0.2 ng/mL,3种物质的添加回收率为78.3～92.1%,相对标准偏差小于7.4%,所建立的方法简单、快速、灵敏度高,适用于纸质包装材料中米氏酮、对二甲氨基二苯甲酮及2-异丙基硫杂蒽酮在实际样品中的残留分析检测。     

阳离子型微乳液对铅-二溴羟基苯基 荧光酮增敏作用的研究

研究了在溴化十六烷基三甲铵／正戊醇／正庚烷／水组成的阳离子型微乳液介质中铅与二溴羟基苯基荧光酮（ＤＢＨ－ＰＦ）的显色。在 ＰＨ９．５ ＮＨ３－ＮＨ４Ｃl缓冲体系中, Ｐb2+与 ＤＢＨ－ＰＦ形成 １：２紫红色配合物,＝１．０１１０５Ｌ／mol／Ｃm, ｐb2+浓度在０－９ ｇ／２５ml范围内服从比尔定律／方法用于牙膏、人发以及粮食中铅的测定,结果令人满意。     

3-甾酮-9α-羟基化酶的C-1，2位脱氢和C-9位羟基化双重特性的研究

目的 验证来自新金分枝杆菌（Mycobacterium neoaurum) NRRL B-3805的3-甾酮-9α-羟基化酶（KSH）是否具有C-9位羟基化和C-1,2位脱氢功能。方法 将ksh基因中的加氧酶组分kshA395和还原酶组分kshB122分别在大肠杆菌（Escherichia coli, E. coli) BL21（DE3）中进行异源表达,以4-雄烯-3,17-二酮（4-AD）为底物,分别用KshA395、KshB122以及两者等比例混合对其进行酶催化反应。通过对反应体系优化构建pET28a-kshB-kshA等融合质粒,对KSH的双组分酶进行共表达,并以4-AD为底物进行酶催化反应。结果 KshA395和KshB122均对4-AD表现出脱氢功能,产物为1,4-雄二烯-3,17-二酮（ADD）,未出现羟基化作用;等比例混合的KSH双组分酶在催化4-AD过程中,前期表现出强烈的C-9位羟基化作用,后期羟基化功能关闭,转为C-1,2位脱氢功能。KSH的双组分融合蛋白,包括KshB122-MBP-KshA395、MBP-KshB122-MBP-KshA395、MBP-KshB122-KshA395,在催化4-AD前期表现出C-9位羟基化作用,后期转变为C-1,2位脱氢作用;而KshB122-KshA395仅表现出C-1,2位脱氢作用,未表现出羟基化作用。结论 在甾醇降解途径中,KSH可以同时承担羟基化及脱氢功能,且先在C-9位羟基化,随后在C-1,2位脱氢,导致甾醇母核B环打开。     

聚酰胺/聚丙烯蒸煮袋中2,4-二氨基甲苯和4,4’-二氨基二苯甲烷向酸性食品模拟物的迁移分析

采用液相色谱-三重四极杆串联质谱（liquid chromatography-triple quadrupole tandem mass spectrometry,LC-MS/MS）法,测定尼龙/聚丙烯（polyamide/cast polypropylene,PA/CPP）蒸煮袋中2 种初级芳香胺（primary aromatic amines,PAAs）物质2,4-二氨基甲苯（2,4-diaminotoluene,2,4-TDA）和4,4’-二氨基二苯甲烷（4,4’-diaminodiphenylmethane,4,4’-MDA）向4%乙酸食品模拟液的迁移量,并研究不同热处理及杀菌方式（巴氏杀菌、蒸、煮、高温灭菌、紫外杀菌）对蒸煮袋中这2 种物质向4%乙酸食品模拟物中迁移的影响。实验结果表明：LC-MS/MS检测2,4-TDA和4,4’-MDA迁移量的检出限均不大于0.02 μg/kg,定量限均不大于0.05 μg/kg,满足欧盟标准中对于PAAs限量的检测要求。在此基础上,研究发现除紫外杀菌对2,4-TDA和4,4’-MDA的迁移无显著影响外,巴氏杀菌、蒸、煮、高温灭菌均会促进PA/CPP蒸煮袋中2,4-TDA和4,4’-MDA向4%乙酸溶液的迁移,迁移量随着迁移温度的升高显著增加（P＜0.05）。根据迁移结果可知,在对蒸煮袋包装的食品进行杀菌处理时,紫外和巴氏杀菌是相对安全的处理方式;另外,在对蒸煮袋包装的食品进行加热时,相比煮,蒸是更为安全的一种加热方式。而在121 ℃高温灭菌15 min条件下,2 种PA/CPP样品袋中4,4’-MDA的迁移量分别达到2.733 μg/kg和3.113 μg/kg,均高于欧盟正在修订的对单个PAAs的迁移限量（0.002 mg/kg）,具有潜在的食品安全风险。可见,当利用PA/CPP蒸煮袋包装食品时,不同热处理方式对胶黏剂中PAAs的迁移量及食品安全的影响值得重点关注。     

Effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax® and modelling hereof

The aim of this study was to investigate the effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax®. Kinetic migration investigations were carried out with three relative humidities in the interval between 39% and >73%. All investigations were carried out at a constant temperature of 34°C. It was found that the migration of benzophenone after more than 30 days was 4.8 times higher at a relative humidity of 64%–71%, and 7.3 times higher at a relative humidity of >73%, compared with that at a relative humidity of 39%–49%. Diffusion and partition coefficients were derived from the results by using a software for modelling migration in multilayer materials. Both the diffusion coefficient and the partition coefficient, between paperboard and Tenax®, decrease with increasing relative humidity. The experimental results were correctly modelled only when the paperboard was regarded as a one-layer system as compared with a two-layer system: where the main part of the paperboard (B1) has a high diffusion rate and a thin part of the paperboard (B2) in contact with the foodstuff has a lower diffusion rate.     

胶束增敏光度法测定黑色食品中锗

研究了黑色食品的溶解方法,对不同的消解方法进行了对比试验,并对高压消解的最佳条件进行了探讨。建立了在H2SO4介质中,采用CTMAB-OP胶束增敏,锗-苯基荧光酮显色,并对最大吸收波长、显色时间、显色剂用量、酸用量、表面活性剂用量等影响因素进行了探讨。在λmax=507 nm,0～20μg/50 mL内符合朗白比尔定律,ε=1.31×105L.mol-1.cm-1。该方法具有良好的选择性、抗干扰性、重现性和稳定性,操作简单方便、无需分离,可直接用于黑色食品中痕量锗的测定。     

植物乳杆菌代谢产物抑菌机制与应用研究进展

植物乳杆菌(Lactobacillus plantarum,Lp)是一种多功能乳酸菌,属于乳酸菌的同型发酵菌,其代谢可产生有机酸、小分子肽、过氧化氢等生物活性物质,常用于发酵的乳制品、肉制品、蔬菜等.Lp及其代谢产物具有良好的抑菌作用,对革兰氏阴性菌和革兰氏阳性菌均有抑制效果,Lp代谢产生植物乳杆菌细菌素和苯乳酸能有效...     

Migration of fluorochemical paper additives from food-contact paper into foods and food simulants

Fluorochemical-treated paper was tested to determine the amount of migration that occurs into foods and food-simulating liquids and the characteristics of the migration. Migration characteristics of fluorochemicals from paper were examined in Miglyol, butter, water, vinegar, water-ethanol solutions, emulsions and pure oil containing small amounts of emulsifiers. Additionally, microwave popcorn and chocolate spread were used to investigate migration. Results indicate that fluorochemicals paper additives do migrate to food during actual package use. For example, we found that microwave popcorn contained 3.2 fluorochemical mg kg^-1 popcorn after popping and butter contained 0.1 mg kg^-1 after 40 days at 4°C. Tests also indicate that common food-simulating liquids for migration testing and package material evaluation might not provide an accurate indication of the amount of fluorochemical that actually migrates to food. Tests show that oil containing small amounts of an emulsifier can significantly enhance migration of a fluorochemical from paper.     

胶束增敏光度法测定食品中的铝

建立以胶束增敏分光光度法测定面制食品中铝的含量.采用CTMAB-OP增敏,铝一苯基荧光酮显色,铝络合物的最大吸收峰位于560 nm,其吸光度与铝的含量在一定浓度范围内成正比.结果表明,吸光度与铝在0~5 ug/25 mL浓度范围内呈良好线性关系,符合比尔定律,相关系数r=0.997 1,回收率在99.75%~104.1...     

Non-visible print set-off of photoinitiators in food packaging: detection by ambient ionisation mass spectrometry

Direct analysis in real time coupled to time-of-flight mass spectrometry (DART/TOF-MS) was used to detect the non-visible set-off of photoinitiators on the food contact surface of three different packages. The samples were intentionally under-cured to provoke set-off. Twelve commercially available photoinitiators were included in the ink formulations including α-amino-, morpholino, and α-hydroxy benzophenones, thioxanthones, aryl-phosphine oxide and three polymeric versions of these. Major colours of the packages’ prints were analysed, as well as the specific areas of the inner surface in contact with them. Larger quantities of photoinitiators were detected on the food contact areas in contact with the darker colours of the images. Speed-cure 7005 and 4-phenylbenzophenone were the compounds most susceptible to set-off in each of the samples by DART response. An identification protocol for unknown set-off compounds was tested, resulting in the set-off detection of diethylene glycol ethers, erucamide and acrylates, and confirmed by solvent extraction GC-MS analysis. Finally, DART/TOF-MS was scanned across transects of the food contact side of packages to map the presence of photoinitiators. Higher photoinitiator signals were observed in patterns corresponding to the printed image, suggesting DART/TOF-MS might “image” print set-off.     

Migration of silver from commercial plastic food containers and implications for consumer exposure assessment

Food storage containers with embedded silver as an antibacterial agent promise longer durability of food. For risk assessment the release of this silver into the stored food and resulting human exposure need to be known. For the purpose of exposure assessment, silver migration from commercial plastic containers with declared content of ‘nano-’ or ‘micro-silver’ into different food simulants (water, 10% ethanol, 3% acetic acid, olive oil) was quantitatively determined by ICP-MS and the form of the released silver was investigated. The highest migration of silver was observed for the acidic food simulant with 30 ng silver cm^?2 contact surface within 10 days at 20°C. In a second and third use cycle, migration dropped by a factor of up to 10, so that the maximum cumulated release over three use cycles was 34 ng cm^?2. The silver release over time was described using a power function and a numerical model that simulates Fickian diffusion through the plastic material. The released silver was found to be in ionic form, but also in the form of silver nanoparticles (around 12%). Consumer exposure to the total amount of silver released from the food containers is low in comparison with the background silver exposure of the general population, but since natural background concentrations are only known for ionic silver, the exposure to silver nanoparticles is not directly comparable with a safe background level.