Cardboard‐like off‐odour in yoghurt can negatively impact consumer acceptability. Herein, a method has been developed to analyse off‐odorants in yoghurt using headspace solid‐phase microextraction coupled with gas chromatography–mass spectrometry. Of 56 volatile organic compounds identified, 8 were active compounds responsible for cardboard‐like off‐odour, including 2, 2‐dimethyl‐propanoic acid and 3‐methyl‐2‐pentanone, which were newly identified in yoghurt. Hexanol and hexanal were found to be indicators of quality deterioration. The off‐odour may be caused by packaging materials and temperature changes during logistic activities. Overall, identifying off‐odorants can help producers to determine which part of the yoghurt‐producing process can be changed to avoid contamination.

Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze volatile flavor compounds of yogurt packaged in carton. Volatile flavor compounds of off-flavor yogurt were compared with that of fresh milk, unpackaged yogurt, non-off-flavor yogurt, and its packaging materials. Furthermore, volatile flavor substances from paper packaging materials were analyzed by migration assay. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to describe the changes of volatile compounds in different kinds of yogurt and to identify the potential markers associated with the off-flavor of yogurt. A total of 30 volatile flavor compounds were identified in two kinds of off-flavor yogurt. Importantly, three flavor compounds: Nonanal, 2-ethyl-1-hexanol, and d-limonene were not only detected in off-flavor yogurt, but also in paper packaging materials, which indicated that these substances from paper packaging materials have a certain contribution to off-flavor yogurt. Migration assay combined with VIP values showed that ethanol and ethyl acetate contributed can be considered as the other indicators for the monitoring of yogurt quality.

为探究回收聚乙烯的挥发性气味成分及其对总体气味的贡献,该文采用顶空固相微萃取/气相色谱-质谱联用技术(HS-SPME/GC-MS)对8种回收聚乙烯(PE)的挥发性成分进行提取和检测,通过检索NIST质谱库,结合保留指数对挥发性气味物质进行定性分析,最后利用相对气味活度值(ROAV)对其进行主体气味成分评价.萃取温度为80℃,平衡时间为30 min,萃取时间为40 min,萃取头为50/30μm DVB/CAR/PDMS,色谱柱为HP-5 MS(30 m×0.25 mm,0.25μm).结果表明,8种回收PE中共鉴定出47种挥发性气味物质,主要包括14种酯类、11种醇类、6种酮类、4种醛类、4种酚类、2种烷烃类、2种烯烃类、2种醚类、1种羧酸类和1种胺类,其中有31种共有成分.ROAV分析结果表明,壬醛、异佛尔酮、水杨酸戊酯、二苯醚、2-萘甲醚、苯酚和冰片是8种回收PE的主体气味物质.回收PE中的异味是限制其应用范围的重要因素之一,该研究可为回收PE的脱气除臭工艺改良提供理论依据.

建立一种顶空-气相色谱-质谱法结合保留指数分析食品包装用纸中挥发性气味成分的分析方法.采用顶空直接进样方式,经气相色谱-质谱上机检测,在美国国家标准与技术研究院(National Institute of Standards and Technology,NIST)质谱库检索的基础上,结合保留指数及气味物质谱库对挥发性气味物质进行定性分析,最后用面积归一法计算各物质的相对含量.结果表明,19种食品包装用纸中共鉴别出113种挥发性化合物,通过检索气味物质谱库,最终确定出36种挥发性气味物质,主要为醛类、羧酸类、酮类、烯烃类、呋喃类、醇类、酚类及含硫化合物共8大类.其中,主要气味物质包括糠醛、苯甲醛、2-戊基呋喃、乙酸、2-乙基-1-己醇、苯乙烯等.此方法可以快速、准确地鉴别出食品包装用纸中挥发性气味物质,提高了定性分析的工作效率;食品包装纸中挥发性气味物质可能会影响食品气味,需引起高度关注.

对15种餐盘纸中矿物油的含量进行检测,并对其中1种印刷有已知油墨的餐盘纸进行溯源分析.采用离线固相萃取前处理,以混合溶液(正己烷-乙醇(1∶1,V/V)).作为提取溶剂,经0.3％硝酸银硅胶固相萃取柱分离纯化,气相色谱-氢火焰离子化检测法进行定量,气相色谱-质谱法进行定性分析.结果 表明:网店购买的4种餐盘纸的矿物油含量普遍比快餐店中收集到的餐盘纸高,饱和烃矿物油的最高含量为3397.6 mg/kg,芳香烃矿物油的最高含量为374.6 mg/kg,均超过限量值.通过溯源分析发现,有印刷的餐盘纸中一部分矿物油来源于油墨.本方法的检出限和定量限分别为2.73 mg/kg和8.19 mg/kg,加标回收率为92.1％～115.1％,相对标准偏差为3.12％～11.85％,准确性高,实验操作方便,可用于食品接触用纸中矿物油的检测及溯源分析.

研究从市场上收集到的24种快餐包装纸中的矿物油向固体食品模拟物Tenax的迁移规律.在多个不同的迁移条件(40℃/0.5、1、2、3h,40℃/10 d和70℃/2 h),探究矿物油的迁移行为及其影响因素,以评价其安全性.选择正己烷-乙醇(1∶1,V/V)混合溶液对Tenax进行过夜萃取,采用质量分数0.3％硝酸银固相萃取柱对饱和烃矿物油(mineral oil saturated hydrocarbons,MOSH)和芳香烃矿物油(mineral oil aromatic hydrocarbons,MOAH)进行分离纯化,最后用气相色谱-氢火焰离子化检测法和气相色谱-质谱法分别进行定量和定性分析.结果 表明:随着温度的升高,多种快餐包装纸中矿物油向Tenax的迁移量也随之增加.涂蜡纸中MOSH迁移量均有所检出,其数值为110.49～615.40 mg/kg,而MOAH部分均未检出,这可能是因为涂蜡纸表面涂覆的石蜡层属于MOSH类,导致其MOSH部分的迁移量较高.网购餐盘纸和常规餐盘纸中MOSH迁移量约为其特定限量值(0.6 mg/kg)的10～400倍,MOAH的迁移量约为其特定限量值(0.5 mg/kg)的10～70倍,而使用优质胶印油墨的原生纤维餐盘纸均未超过其限量值.最后,通过对印有胶印油墨的原生纤维餐盘纸中矿物油进行溯源分析,发现经过迁移的矿物油一部分可能来源于其所用油墨,其他来源可能来自于回收纤维、黏合剂、添加剂和加工助剂等.

目的 研究4种印刷不同油墨的PET薄膜在酸性条件下26种化学元素的迁移行为.方法 采用电感耦合等离子体发射光谱(ICP-OES),测定铅、镉、铬等26种化学元素在PET薄膜中的初始含量;采用电感耦合等离子体质谱(ICP-MS)测定这26种化学元素向食品模拟物(体积分数为3％的乙酸)的迁移量.结果 铅、镉、铬等26种元素的迁移量随着温度和时间的增加而增大,并且均能达到各自的迁移平衡.ICP-OES方法的加标回收率为80.2％～109.7％,其相对标准偏差(RSD)为0.3％～12.9％;ICP-MS方法 的加标回收率为83.1％～118.6％,其相对标准偏差为0.7％～14.8％.结论 26种化学元素向体积分数为3％乙酸的最大迁移量均低于标准限量值.

A rapid and sensitive method for classification of virgin and recycled expanded polystyrene (EPS) food containers was developed using Fourier transform infrared spectroscopy (FTIR) and chemometrics. This method includes preparing a transparent film by dissolution, examining by FTIR and developing classification models. The degradation of EPS containers occurring during the recycling process was reflected by the carbonyl region of the infrared spectrum which was used as variables for multivariate data analysis. PCA was used to reduce the data dimension and view the sample similarities. Soft independent modelling of class analogy (SIMCA), partial least squares-discrimination analysis (PLS-DA) and linear discrimination analysis (LDA) were applied to construct three classification models. The best discrimination results were obtained by an LDA model, with all samples correctly classified. PLS-DA and SIMCA could not classify the recycled EPS samples with low levels of adulteration. When applying this method to commercially available EPS containers, about 45% of samples were shown to contain recycled polystyrene resins. It is concluded that the carbonyl region of the infrared spectra coupled with chemometrics could be a powerful tool for the classification of virgin and recycled EPS food containers.