Determination of volatile compounds in apple pomace by stir bar sorptive extraction and gas chromatography-mass spectrometry (SBSE-GC-MS)

A method based on stir bar sorptive extraction combined with gas chromatography-mass spectrometry detection (SBSE-GC-MS) has been optimized with the aim of applying it to the analysis of apple pomace. The method allowed the identification of 124 volatile compounds after 3 h of extraction with a precision (RSDs) ranging between 2% (linalool) and 11% (ethyl hexanoate). Its use in analyzing varietal apple pomace revealed the interest of this substrate as regards its content in aromas. From a semi-quantitative point of view, the higher content in aldehydes and esters of the Blanquina variety is worth highlighting, as are the greater concentration of acids in the Clara variety and the higher content of terpenes and norisoprenoides in the Coloradona variety. In contrast, the Ernestina and Perico varieties presented the lowest levels of aromas. PRACTICAL APPLICATION: The analysis of varietal apple pomaces showed the importance of this type of waste in the food industry, both for its content in aromas such as for its use as substrate in biotechnological processes.     

Varietal and pre-fermentative volatiles during ripening of Vitis vinifera cv Nebbiolo berries from three growing areas

Flavour analysis of grape is a key step in quality evaluation. The Stir Bar Sorptive Extraction technique (SBSE, ‘Twister’®) was used to assess varietal and pre-fermentative volatile accumulation in ‘Nebbiolo’ berries, from véraison to harvest. Grapes were collected in three vineyards, representing different ‘crus’ in the cultivation areas of Barolo, Barbaresco and Roero (North–West Italy). Volatile constituents of grapes were identified and quantified by GC–MS.     

Determination of Selected Beer Flavours: Comparison of a Stir Bar Sorptive Extraction and a Steam Distillation Procedure

The aim of this work was focused on the comparison of two sample preparation procedures — a stir bar sorptive extraction (SBSE) followed by solvent back extraction and a well‐established distillation method followed by liquid/liquid extraction — for the simultaneous determination of some beer esters (isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, phenyl‐ethyl acetate, ethyl laurate, ethyl myristate, ethyl palmitate) and free fatty acids (caproic, caprylic, pelargonic, capric). Subsequent gas chromatographic analyses with flame ionization detection were used for the determination of these compounds. Both procedures were characterized by good linearity (correlation coefficients were higher than 0.9987). The relative standard deviations were found to be 2.1–7.3% for SBSE and 10–14% for the distillation technique with recovery 81–107% and 70–89%, respectively. Results obtained by these two procedures were in good correlation.     

Quantification of volatile compounds in Chinese soy sauce aroma type liquor by stir bar sorptive extraction and gas chromatography-mass spectrometry

BACKGROUND: Considering the important of aroma compounds on the quality of baijiu, stir bar sorptive extraction (SBSE) coupled with gas chromatography–mass spectrometry was applied to the aromas analysis of baijiu (Chinese liquor). RESULTS: Based on the results of optimization, a total of 76 volatile compounds were identified from 14 Chinese liquors, including 25 esters, 10 alcohols, 9 aldehydes and ketones, 8 aromatic compounds, 5 furans, 3 nitrogen‐containing compounds, 6 acids, 4 phenols, 3 terpenes, 1 sulfide‐containing compound, 1 lactone, and 1 acetal. By principal component analysis based on quantification results, 14 Chinese liquor samples could be classified into three groups. CONCLUSION: SBSE is a fast, simple, effective, and reliable method for extracting volatile compounds from Chinese liquor. The chemometrics approach revealed that LJ liquor with soy sauce aroma could exhibit more prominent sauce flavor through extending the time of storage, and its peculiar manufacturing practice was responsible for the soy sauce flavor. Copyright © 2011 Society of Chemical Industry     

Determination of Some Beer Flavours by Stir Bar Sorptive Extraction and Solvent Back Extraction

This work presents the development of a simple, rapid and low cost method for the determination of some beer flavours as esters such as isoamyl acetate, ethyl caproate, ethyl caprylate, phenyl acetate, ethyl caprate, phenylethyl acetate, ethyl laurate, ethyl myristate and ethyl palmitate using stir bar sorptive extraction (SBSE). The combination of this extraction technique with solvent back extraction and subsequent gas chromatographic analysis with flame ionisation detection was used for the determination of these compounds. The effects of different mixtures of organic solvents and the influence of sampling time and time of solvent back extraction were studied. An optimum procedure for the SBSE method was developed. The method had high repeatability (RSD 2.1–7.3%), good linearity (the correlation coefficients were higher than 0.9995 for quadratic fit over the concentration range from 0.015 to 30 mg/L) and acceptable recoveries (78–107%) and precision (RSD > 7.3%).     

自制吸附萃取搅拌棒结合气相色谱嗅觉计（GC/O）、气质联用仪（GC/MS）分析肉味香精呈香组分

采用自制吸附萃取搅拌棒对肉味香精呈香组分进行提取,利用热脱附仪进样,结合气相色谱嗅觉计联用（GC/O）、气质联用（GC/MS）双重定性方式,令组分富集率更高,检测结果更加真实、客观地反映出香精的香气组成。为高级香精的调配及仿香工作提供有力依据。实验仪器采用在色谱柱出口安装＂石英三通＂进行1∶1分流,样品被同时引入质谱和嗅觉计,避免了单一定性方法存在的不足。其中,两种方法共同检出的物质31种,仅GC/O检出的物质24种,仅GC/MS检出的物质26种。     

搅拌棒萃取-气相色谱-质谱法分析地表水中合成麝香及紫外线吸收剂

建立了搅拌棒萃取-溶剂解吸结合气相色谱-质谱法测定水样中16种合成麝香及2种紫外线吸收剂。实验优化了萃取温度、萃取时间、萃取体积、pH值、离子强度、溶剂解吸条件等参数,最终确定使用50 mL水样在40 ℃下搅拌提取4 h后,采用1.2 mL溶剂超声解吸后直接浓缩分析。该方法的线性范围为2~120 μg/L,线性相关系数大于0.996,各化合物的加标回收率在68.5%~126%之间,相对标准偏差范围为2.3%~14.9%,方法检出限在0.003~0.038 μg/L之间。应用该方法分析北京市内不同采样点的7个地表水样品,结果表明,佳乐麝香的检出率最高,浓度在0.003~0.337 μg/L之间。该方法操作简单、有机溶剂使用量少,可以实现分析测试快速、绿色的目的,能够用于实际水样中合成麝香和紫外线吸收剂的同时准确分析。     

Efficient multi-objective higher order mutation testing with genetic programming

It is said 90% of faults that survive manufacturer’s testing procedures are complex. That is, the corresponding bug fix contains multiple changes. Higher order mutation testing is used to study defect interactions and their impact on software testing for fault finding. We adopt a multi-objective Pareto optimal approach using Monte Carlo sampling, genetic algorithms and genetic programming to search for higher order mutants which are both hard-to-kill and realistic. The space of complex faults (higher order mutants) is much larger than that of traditional first order mutations which correspond to simple faults, nevertheless search based approaches make this scalable. The problems of non-determinism and efficiency are overcome. Easy to detect faults may become harder to detect when they interact and impossible to detect single faults may be brought to light when code contains two such faults. We use strong typing and BNF grammars in search based mutation testing to find examples of both in ancient heavily optimised every day C code.     

自制吸附萃取搅拌棒结合气相色谱嗅觉计、气质联用仪分析肉味香精呈香组分

采用自制吸附萃取搅拌棒对肉味香精呈香组分进行提取,利用热脱附仪进样,结合气相色谱嗅觉计联用（GC/O）、气质联用（GC/MS）双重定性方式,令组分富集率更高,且检测结果可以更加真实、客观地反映出香精的香气组成;为高级香精的调配及仿香工作提供重要依据.实验仪器采用在色谱柱出口安装＂石英三通＂进行1∶1分流,样品被同时引入质谱和嗅觉计,避免了单一定性方法存在的不足.其中,两种方法共同检出的物质31种,仅GC/O检出的物质24种,仅GC/MS检出的物质26种.     

新型样品前处理——搅拌棒吸附萃取技术及其在食品分析中的应用

综述了搅拌棒吸附萃取的萃取原理、萃取涂层、国内外发展状况,以及搅拌棒吸附萃取与其他分析技术联用在食品分析中的应用状况。