食品接触材料中荧光增白剂VBL和APC的迁移规律研究

采用高效液相色谱法,以VBL和APC为标准物质建立了对食品包装材料中荧光增白剂的定量检测的方法。并对食品接触材料中荧光增白剂VBL和APC在纯水、乙酸、乙醇和正己烷等4种食品模拟物中的迁移规律进行了研究,研究荧光增白剂VBL和APC迁移溶出量与食品接触介质、p H、浸泡温度和处理时间等因素的关系。结果表明,荧光增白剂VBL和APC在4种食品模拟接触物中的迁移量都是VBL溶出量较多,并且随着浸泡液p H、浸泡液温度、处理时间的增加,荧光增白剂VBL和APC的迁移溶出量都出现增加的趋势。     

纳米银-聚乙烯复合包装中银对2 种抗氧化剂向食品模拟物迁移的影响

探究纳米银-聚乙烯复合包装中纳米银成分的存在对2 种抗氧化剂（Irganox1076和Irgafos168）向食品模拟物迁移规律的影响。将含有抗氧化剂的聚乙烯包装膜和同时含有抗氧化剂与纳米银的复合包装膜裁成正方形若干,分别浸泡于正己烷和体积分数95%乙醇溶液2 种食品模拟物中,密封后在20、40 ℃以及70 ℃条件下进行迁移实验。食品模拟物中2 种抗氧化剂的加标回收率在79.3%～108.0%之间,相对标准偏差在0.7%～5.3%之间。2 种抗氧化剂的迁移会随着迁移温度的升高以及迁移时间的延长而增加直至达到迁移平衡,且其在正己烷模拟物中的迁移量大于在体积分数95%乙醇模拟物中的迁移量;含纳米银聚乙烯塑料比不含纳米银聚乙烯塑料中的抗氧化剂向食品模拟物中的迁移量小,表明纳米银成分的存在可以抑制包装中的抗氧化剂向食品模拟物中的迁移。     

食品包装PE材料中荧光增白剂迁移规律的分析

以PE塑料薄膜为研究对象,采用高效液相色谱法研究食品包装塑料材料中荧光增白剂在纯水、乙酸、乙醇、植物油4?种不同模拟物中的迁移规律,研究荧光增白剂溶出量与食品接触介质、乙酸质量浓度、乙醇体积分数、浸泡温度以及处理时间等因素的关系。结果表明：纯水基质食品模拟物对香豆素类荧光增白剂有一定溶解性,酸性食品模拟物相比于水模拟物有更强的溶解性,而含醇类食品模拟物和脂肪类食品模拟物对大部分荧光增白剂都具有较好的溶解效果;荧光增白剂的溶出量随着乙酸和乙醇含量的增加而增加;较高的温度对塑料包装材料中荧光增白剂的迁移溶出具有显著影响,并且随着接触时间的延长,塑料包装材料中的荧光增白剂向食品中迁移的可能性也不断增大。     

PVC塑料食品包装中的2种荧光增白剂迁移规律研究

以食品包装的PVC塑料为研究对象,采用高效液相色谱法研究食品包装材料中荧光增白剂在纯水、3%乙酸、10%乙醇、橄榄油4种不同模拟物的迁移规律,于一定时间吸取少量浸泡液,研究迁移行为与食品模拟物、浸泡时间、温度、荧光增白剂的初始浓度、材料厚度等参数的关系。试验结果表明,荧光增白剂只在脂肪类食品模拟物迁出;迁移率和迁移量随温度升高而增加;材料厚度增加,迁移量增大,迁移率降低;荧光增白剂初始浓度越高,则迁移量越大,迁移率越低。     

荧光分光光度法测定餐巾纸中荧光增白剂特定迁移量

建立了基于荧光分光光度法对直接接触口腔的餐巾纸向蒸馏水模拟物的特定迁移量的测量方法。餐巾纸中迁移出的被分析物迁移至模拟物中,采用外标法进行定量。目标分析物在0.01～0.5 mg/L内线性关系良好（R² > 0.999）。3个加标水平（加标水平分别为25、50和100 μg）的回收率在97.9％～102.3％之间,相对标准偏差（RSD）小于8.0％, 检出限（LOD）为0.0012 mg/dm²。该方法准确、灵敏,适用于餐巾纸中荧光增白剂特定迁移量的测定。实际普查市面上10种品牌17个餐巾纸样品显示：荧光增白剂特定迁移量检出率为41.2%;荧光增白剂特定迁移量范围0～0.0061 mg/dm²。     

聚乳酸抗菌包装中麝香草酚在食品模拟物中迁移规律

研究麝香草酚/聚乳酸包装材料中的抗菌剂麝香草酚在食品模拟物中的迁移行为。在4、10、20、30 ℃条件 下分别将麝香草酚/聚乳酸包装材料浸入蒸馏水溶液、体积分数4%乙酸溶液、正己烷溶液、体积分数10%乙醇溶液 中,通过紫外分光光度法测定食品模拟液中麝香草酚迁移量,分析温度和食品模拟物对麝香草酚迁移量的影响,在 实验数据基础上,采用Piringer方程建立麝香草酚迁移模型,分析验证迁移模型的合理性。结果表明：麝香草酚迁 移量随着迁移温度升高和迁移时间延长而逐渐上升直至平衡,且在4 种食品模拟物中麝香草酚的迁移量大小顺序为： 正己烷＞10%乙醇＞4%乙酸＞蒸馏水;根据幂律方程发现麝香草酚的迁移机制符合Fick扩散定律,且迁移方程扩散系 数随迁移温度升高而增大,分配系数与之相反;Piringer方程能够较好地描述麝香草酚迁移行为。在迁移实验的基础 上构建数学模型,进一步完善基于聚乳酸食品包装材料的迁移理论,以期更好地预测食品包装中麝香草酚的迁移。     

食品包装材料中双酚A迁移量的测定

建立采用高效液相色谱法对塑料食品包装材料中双酚A向食品模拟物迁移量的检测方法。使用4种食品模拟物：水、质量分数为4%乙酸溶液、体积分数30%的乙醇溶液和脂肪类模拟物(正己烷、异辛烷和橄榄油)。结果表明,双酚A在与食品塑料包装接触过程中,无论在何种情况下都会向食品模拟物中迁移,尤其向醇类模拟物中迁移最严重;在温度超过60℃时,双酚A向食品模拟物中的迁移率骤增;在微波加热条件,高火700W功率时双酚A向食品模拟物中的迁移速率最快。该方法检测限为0.3ng/mL,线性范围为0.5～100ng/mL,线性相关系数为0.9997,回收率在92.0%～102.4%之间,相对标准偏差≤2.84%(n=5)。     

竹木筷中过氧化氢在食品模拟物中迁移量的测定及其迁移规律的研究

目的:建立过氧化氢在不同食品模拟物中的测定方法,研究竹木筷中过氧化氢在不同食品模拟物中的迁移量及其迁移规律。方法:应用分光光度法测定过氧化氢,以不同食品模拟物（水基非酸性食品模拟物、水基酸性食品模拟物、酒精类食品模拟物、油基食品模拟物）中过氧化氢的质量对吸光度建立标准曲线,以相关系数、准确度和精密度为考察指标进行方法学验证;以食品模拟物的种类、迁移时间、迁移次数和迁移温度为考察因素,初步探索竹木筷中过氧化氢在食物模拟物中的迁移规律。结果:不同食品模拟物中过氧化氢建立的标准曲线相关系数均大于0.999,加标回收率范围84%~113%,加标平行样品间相对偏差（RSD）均小于10%。相同条件下,竹木筷中过氧化氢在油基模拟物中的迁移量最小;竹木筷中过氧化氢迁移存在一段快速迁移释放过程,而后转换为长时间缓慢迁移释放;过氧化氢的迁移为长时间反复迁移过程,试验至第8次仍有过氧化氢的迁移;随着温度的升高,过氧化氢迁移量会显著增加。结论:分光光度法测定竹木筷中过氧化氢在食品模拟物中迁移量准确可靠;市场部分竹木筷在不同食品模拟物中存在不同程度的过氧化氢迁移检出;其迁移规律为长时间,反复迁移的过程,增加温度可显著提高迁移速度;100 ℃煮沸处理可有效降低竹木筷中的过氧化氢的再迁移量。     

铝塑复合食品包装中的铝向食品模拟物的迁移研究

建立了基于电感耦合等离子体质谱法（ICP-MS）,铝塑复合食品包装中的铝向食品模拟物迁移量的测定方法。采用两种食品模拟物（3%（w/v）乙酸、水）,利用迁移机使食品模拟物与铝塑食品包装材料单面接触,在温度27±2、45、70℃下进行迁移实验,采用电感耦合等离子体质谱仪对食品模拟物中的铝元素进行测定,得出迁移规律。随着迁移时间的延长,铝的最大迁移量都在增加;在实验温度区间,随着温度的升高,铝的迁移量也随之增加至迁移平衡。本方法适合用于铝塑复合食品包装中的铝向3%（w/v）乙酸溶液和蒸馏水两种食品模拟物迁移后的检测。      

气相色谱/质谱法测定PVC在油性介质中增塑剂ATBC迁移的分析研究

建立了气相色谱/质谱法测定PVC瓶盖密封垫中ATBC增塑剂在油性模拟物中迁移量的检测方法。该方法以正己烷作为油性食品模拟物,采用超声提取法提取PVC瓶盖密封垫中的乙酰柠檬酸三丁酯(ATBC)增塑剂,利用气相色谱/质谱法对其进行定性、定量分析。该方法在1mg/L～200mg/L范围内有很好的线性关系,相关系数为0.9973;准确度和精密度试验中,平均回收率为95.8%～105.2%,相对标准偏差RSD%为1.03%～4.72%。该方法为研究就柠檬酸酯类增塑剂在油性食品中的迁移提供了一定的参考。     

纸页干燥过程中树脂迁移现象的研究

探讨采用迁移阻碍剂（明矾和聚乙烯醇）来减少纸页中的树脂迁移，并提供一种简单，快捷的方法来评价树脂迁移的效果。结果表明添加明矾比添加聚乙烯醇更能有效地防止树脂迁移。     

涤纶织物产生风印的根本原因及解决办法

分析涤纶织物产生风印的根本原因,并详细探讨了产生风印后的挽救措施及如何从根本上避免风印的产生。     

Chocolate Swelling during Storage Caused by Fat or Moisture Migration

Abstract: Quantification of swelling in dark chocolate subjected to fat or moisture migration was conducted using a new method based on confocal chromatic displacement sensor. The nondestructive method allowed for the height profile of dark chocolate samples to be scanned with a sensitivity of ± 2.8 μm. By performing multiple scans on each sample prior to and after being subjected to fat or moisture migration, the induced swelling could be quantified. Applying the new method on confectionery systems revealed that fat and moisture migration generate different swelling behavior/kinetics in dark chocolate during storage. Moisture migration resulted in a rapid swelling once a water activity of 0.8 was reached in the chocolate, probably by interaction and absorption of moisture by the particulate solids. Fat migration also affected the swelling behavior in chocolate, possibly by inducing phase transitions in the continuous cocoa butter phase. Migrating fat also proved to induce a more pronounced swelling than the same amount of absorbed moisture which further consolidated that the observed swelling caused by fat or moisture migration is a result of significant different mechanisms.     

Survey of the migration of melamine and formaldehyde from melamine food contact articles available on the UK market

The migration of melamine and formaldehyde, monomers used in the production of melamine-ware food contact articles, has been determined from 50 retail articles purchased in the UK. The food simulant 3% aqueous acetic acid was used as this is the most aggressive simulant towards melamine plastics. The test conditions used were repeated exposure to the simulant for 2 hours at 70°C, since the articles were all intended for general use including contact with hot foods and beverages. Melamine migrated from 43 of the 50 samples tested and formaldehyde migrated from all 50 samples. Directive 2002/72/EC specifies migration limits for both of these monomers in foods and food simulants. Melamine is restricted by a specific migration limit (SML) of 30 mg/kg (equivalent to 5 mg/dm²) and formaldehyde, along with hexamethylenetetramine expressed as formaldehyde, is restricted by a total (T) SML(T) of 15 mg/kg (equivalent to 2.5 mg/dm²). In all cases the migration of melamine was much lower than the SML for this monomer. The migration of formaldehyde exceeded the SML(T) for 5 of the 50 samples tested. The failure to comply with the SML(T) was accompanied by a number of visible surface effects including discolouration and/or pitting of the simulant contact surface and cracking of the articles. Similar surface effects were observed when one of the samples was exposed to fruit juice which confirmed the suitability of the exposure conditions and 3% acetic acid as a simulant for the articles tested. The ratio of specific migration to overall migration was consistent with, but did not prove, the hypothesis that high formaldehyde migration could be due to the use of excessive hexamethylenetetramine in the polymer formulation. All illegal products were voluntarily removed from the market by the product suppliers.     

学校食堂在用密胺和不锈钢餐具检测及风险分析

目的 通过对学校食堂在用密胺和不锈钢餐具进行检测分析,并参照相关国际标准与国家标准对检测结果进行分析,以评估学校食堂在用密胺和不锈钢餐具的风险状况,为建立风险防范措施及优化现行标准提供理论依据。方法 本次检测通过对密胺餐具中甲醛迁移量、三聚氰胺迁移量;对不锈钢餐具中铅迁移量、砷迁移量、镉迁移量和镍迁移量六项指标,对食堂抽取的100批次密胺在用餐具和100批次不锈钢在用餐具样品进行风险分析。结果 本次研究共发现在用问题餐具共72批次,占比36.0%。其中在用问题密胺餐具55批次,占密胺餐具总量的55.0%;问题不锈钢餐具17批次,占不锈钢餐具总量的17.0%。密胺餐具不合格项目主要为甲醛和三聚氰胺(4%乙酸,水)的迁移量超标,不锈钢餐具不合格项目主要为铅、镉元素的迁移量超标。结论 食堂应制定密胺餐具相应的使用管理规范,设定密胺餐具的使用年限为1年以内,同时规范餐具的消毒、清洗等操作,从而有效地降低甲醛和三聚氰胺的迁移风险;应加强不锈钢餐具原料供应链管理,从源头降低风险。     

A new insight into the dynamics of fibre migration in ring spinning

Fibre migration in yarns is thought to take place in the spinning triangle (ST), where high tensioned edge fibres tend to compete for a low tension state by displacing inner fibres outwards to occupy the core position – the tension mechanism. The angular alignment of fibres in the drafted roving – the geometric mechanism – is also considered to contribute to this movement. Although there is an understanding of the mechanisms of fibre migration, the outward movement of core fibres, from a low to high tension state and through a thick web of gripped fibres – moving inwards – has not been fully understood. In this study, we have attempted to reanalyse the classical migration mechanism from a new perspective and establish its relationship with a real ST using a new reflective imaging technique. The study findings suggest that pre-twist region in the ST, which is generally considered to be stable at one location, shows a rather dynamic oscillatory movement – a result of continuous change in ST tension profile. Spinning trials were conducted to confirm a relationship between pre-twist movement and degree of fibre migration.     

水分经非织造纤维类多孔介质蒸发时的几个物理参数测定

非织造材料是农业上用作覆盖物的一种重要材料 ,水分经这一材料蒸发时 ,涉及到复杂的热质同时传递现象。提出了一种试验方法和计算途径 ,对几种非织造纤维材料 ,可获得其在水分蒸发状态下表面的传质系数和传热系数。     

Impact of pre-crystallization process on structure and product properties in dark chocolate

Dark chocolate microstructures with different structure densities, i.e., close-packing of the fat crystal lattice, and homogeneity i.e., evenness and connectivity of the fat crystal network, were created by β_VI-seeding or conventional pre-crystallization with various degrees of temper and were evaluated with respect to storage stability. The structure characterization was conducted by measuring the strength of the cocoa butter crystal network with traction tests combined with DSC melting curves. Subsequent storage stability was evaluated with DigiEye technique for fat bloom development and gravimetrical techniques for fat/moisture migration. The two pre-crystallization processes generated significantly different structures and storage stability. Well-tempered β_VI-seeding resulted in a dense and homogenous chocolate structure directly after solidification, which was optimal in order to retard fat bloom and fat migration. However, a too high structure density generated heterogeneous structures with reduced ability to withstand fat bloom. A lower structure density exhibited optimal resistance against moisture migration.     

密胺餐具中甲醛迁移行为的研究

研究了浸泡液类型、浸泡温度、浸泡时间、剪切程度、微波加热时间等五种试验条件对美耐皿餐具中甲醛迁移量的影响,探讨了甲醛单体迁移行为的规律。结果表明,甲醛单体在酸性溶液中更易迁出;在高于80℃时甲醛含量呈现突跃式增长;甲醛迁移量与浸泡时间呈现良好的正比线性关系;样品剪切得越细,浸泡接触面积越大,甲醛迁移量越高;微波炉内加热时间较长时（大于15min）,甲醛迁移量明显增加。