Hexanal as a marker of oxidation flavour in sliced and uncured deli turkey with and without phosphates using rosemary extracts

Ability of commercial rosemary extracts (REs) alone and in combination with sodium tripolyphosphate (P) to inhibit lipid oxidation in uncured deli turkey (UDT) was examined via headspace hexanal and oxidation flavour. Sliced UDT was packaged (75% N₂/25% CO₂) and stored 13 weeks at 4 °C. Addition of P decreased hexanal 2.4-fold (P < 0.05) and increased mean pH of UDT from 5.94 to 6.30 (P < 0.05). Addition of water/lipid-soluble RE did not inhibit hexanal formation in UDT. Addition of water-soluble RE decreased hexanal 2.2-fold (P < 0.05). The combination of P and water-soluble RE decreased hexanal 33-fold (P < 0.05). The combination of P and water/lipid-soluble RE decreased hexanal ninefold (P < 0.05). Oxidation flavour was highest in UDT without added antioxidant> RE> P> RE+P (P < 0.05). Hexanal values were positively correlated with oxidation flavour scores throughout storage (P < 0.05). The combination of P with either RE was particularly effective at inhibiting lipid oxidation in modified atmosphere packaged UDT.     

液液萃取气相色谱法测定饮用水中有机氯农药

采用正己烷液-液萃取法提取,气相色谱法-电子捕获检测器测定饮用水中8种滴滴涕农药。结果表明8种滴滴涕农药的方法检出限为1.63μL~3.33μL回收率为82.1%~106.1%在1μL~100μL内质量浓度与峰面积呈良好的线性关系,相关系数均大于0.999。该方法操作简便、检出限低,准确度和精密度高,适用于饮用水中滴滴涕农药的分析。     

微波焙烤平欧榛子中挥发性成分差异性分析

香气物质是榛子炒食过程中质量评价的重要指标。本文采用顶空固相微萃取（HS-SPME）和气相色谱质谱联用（GC-MS）技术对生榛子和不同微波焙烤工艺条件下获得的榛子样品中挥发性成分进行差异性分析。结果显示,生平欧榛子检测出挥发性成分22种,低火（140 W,4 min）处理的平欧榛子检测出29种,中低火（210 W,4 min）处理的平欧榛子检测出30种,高火（350 W,4 min）处理的平欧榛子检测出47种;不同焙烤条件下的榛子样品中均检测到了吡嗪类挥发性成分,并且随着焙烤功率的增加吡嗪类和醛酮类挥发性成分的种类和含量均有明显的增加,而生榛子中不含有吡嗪类挥发性成分;通过OAV值筛选出11种香气成分,通过主成分分析出第一主成分和第二主成分的特征值为8.080和2.887,其累积贡献率达73.456%,99.705%,能够较好的代表原始数据所反应的信息,焙烤榛子的主要香气来源于吡嗪类、醛酮类物质。      

固相微萃取技术在食品风味分析中的应用

食品的风味是食品的典型特征之一,能够反映食品的质量与品质。进行风味分析需采用合适的分离分析技术,而提取方法极大地影响了分析结果的可靠性和准确性。固相微萃取(SPME)是一种无溶剂萃取技术,它集采样、萃取、浓缩、进样于一体,具有简单、快速、高效、无污染、便携、易于与其他仪器联用等优点,已被广泛应用于食品风味分析。本文综述了SPME技术在肉品、乳品、酒类、果蔬等食品风味分析上有代表性的应用研究,总结了食品风味分析所采用的萃取涂层和SPME与其他样品前处理技术的对比情况,重点分析了为提高SPME方法选择性、准确性和灵敏度所采取的措施,如衍生化SPME技术、萃取条件的优化方法、与多维色谱和电子鼻等分析仪器联用技术及SPME定量分析方法,并对SPME在食品风味分析上的发展趋势进行了探讨。     

超高压处理对黑莓酒香气成分的影响

运用超高压技术处理黑莓酒以期改善其香气品质,并采用固相微萃取与气相色谱-质谱联用对不同超高压条件处理的黑莓酒挥发性香气成分进行检测,探究超高压处理对黑莓酒香气成分的影响及作用机理.结果表明:经超高压处理的黑莓酒香气种类与未处理样品相同,但含量发生较大变化,200MPa处理20min的黑莓酒醇类、酯类和醛类无显著变化(p＞0.05),酸类减少了7.44％;600MPa处理20min的黑莓酒醇类、酯类分别增加了4.63％、13.38％,醛类、酸类无显著变化(p＞0.05);400MPa处理20min的黑莓酒醇类、酯类和醛类分别增加了4.89％、43.04％和1.12％,酸类减少了11.28％,整体香气趋向柔和、协调、饱满,达到改善黑莓酒香气品质的目的.     

A deep eutectic solvent based liquid phase microextraction for the determination of caffeine in Turkish coffee samples by HPLC-UV

ABSTRACT

A novel liquid-phase microextraction procedure for the determination and extraction of caffeine using a deep eutectic solvent based liquid-phase microextraction method (DES-LPME) was developed. A deep eutectic solvent consisting of choline chloride-phenol (1:3) and tetrahydrofuran as a dilution solvent were used for the extraction of caffeine from Turkish coffee samples. The quantitative recoveries were obtained when the DES volume was 400 µL, and the volume of tetrahydrofuran that was used as an emulsifier solvent was 800 µL. The limit of detection and the limit of quantification were found to be 0.12 and 0.40 µg mL^?1, respectively. Linear dynamic range was 0.5–100 µg mL^?1, and coefficient of determination (R²) was 0.9998. The relative standard deviation (RSD) was 2.20% when the standard solution concentration was 1.0 µg mL^?1. The fact that the determination coefficient obtained from the calibration curve was greater than 0.9998 gives information about the accuracy of the method. Also, in order to determine the accuracy of the developed method, selected coffee samples were spiked with 25 and 50 µg mL^?1 caffeine.     

SPME及其与GC/MS联用在我国烟草分析中的应用进展

概述了固相微萃取技术的发展、基本原理、萃取条件和GC条件的选择以及固相微萃取与气相色谱/质谱联用在我国烟草分析中的应用进展。     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry