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     

Identification of tartary buckwheat tea aroma compounds with gas chromatography-mass spectrometry

Tartary buckwheat tea, which is an important and healthy product, has a distinct malty aroma. However, its characteristic aroma compounds have not been elucidated. The aims of present study were identification and quantification of its aroma compounds. The analyses were performed by gas chromatography-mass spectrometry (GC-MS) after 3 different isolation techniques. Seventy-seven compounds were identified. Among these compounds, 35 were quantified by available standards. The compounds with a high probability of contribution to the tartary buckwheat tea aroma (OAV ≥ 10) were as follows: 2,5-dimethyl-4-hydroxy-3(2H)-furanone, nonanal, 2,3-diethyl-5-methylpyrazine, benzeneacetaldehyde, maltol, 2,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine. Some nutritional and bioactive compounds were also identified in this study, such as linoleic acid, niacin, vanillic acid, 7-hydroxycoumarin, butylated hydroxytoluene. Practical Application: Tartary buckwheat, one type of buckwheat, has gained much attention from nutritionists and medical doctors in recent years. It is rich in rutin, quercetin, and other nutrients that are good for health. Tartary buckwheat-based product such as tartary buckwheat tea is an important and popular healthy product in China, Japan,South Korea, European countries as well as in American countries. It has a distinct malty aroma. The present study first identified and quantified of its aroma compounds. The results will draw attention to other researchers in food flavor and buckwheat filed.     

Differentiation of volatile aroma components in organically and conventionally produced apples by stir bar sorptive extraction combined with gas chromatography and EI/CI TOF mass spectrometry

Volatile aroma components and contents of organically and conventionally produced apples of the cultivars Elstar, Jonagold, Jonagored and Braeburn were studied. In three cultivars investigated, the aroma contents of organically produced apples were significantly lower (Elstar 16%, Jonagold 29%, Jonagored 68%). For Braeburn, no statistically significant difference was observed. In particular, the main aroma components were present at much lower concentrations in organically produced apples. In all apple cultivars, these were hexanal, trans-2-hexenal, 2-methylbutylacetate and hexylacetate. twenty-three aroma components were identified in total, in different relative ratios in the different apple cultivars: saturated esters, saturated and unsaturated aldehydes and alcohols. Some components identified in the conventionally produced cultivars were not present in the organically produced cultivars at all. The aroma components were extracted from juice freshly prepared from the apples by stir bar sorptive extraction (SBSE) technique and characterised by FID gas chromatography and EI/CI TOF mass spectrometry.     

SBSE-TDs-GC-MS测定白酒中酯类成分的方法研究

建立使用搅拌棒吸附萃取(SBSE)和热脱附系统(TDs)并结合气相色谱-质谱联用(GC-MS)测定白酒中酯类成分的分析方法.实验中对影响SBSE的因素(萃取时间、乙醇加入量和氯化钠加入量)及影响TDs的条件(脱附时间、脱附温度和CIS4进样口温度)进行了优化.在所得优化条件下采用外标法对白酒中的乙酯类成分进行定量测定,结果表明,白酒中酯类成分的检出限范围为8.1×10-4～9.3×10-2ng,加标回收率范围为72.4%～98.6%,6次测定的相对标准偏差小于10%.该方法具有很高的灵敏度和很好的重现性,可用于白酒中乙酯类成分的快速分析测定.     

苹果渣中多酚物质的福林法测定

以没食子酸为标准品研究了福林法测定苹果渣中多酚物质含量的适宜条件。结果表明,当福林试剂与10%Na2CO3体积之比1∶1,反应温度25℃,反应时间120min时,多酚含量在5～30μg范围内与吸光值呈良好的线性关系。测定方法的平均回收率为106.5%,RSD为0.49%,有较好的准确度和精密度。     

搅拌棒磁子萃取-热脱附-气相色谱质谱联用分析葫芦巴浸膏的挥发性成分

应用搅拌棒磁子萃取和热脱附系统,并结合气相色谱-质谱联用仪,测定了葫芦巴浸膏中的挥发性成分。从中鉴定出67个挥发性物质,主要成分为:1,2-丙二醇(38.83%)、苯乙酸苯乙酯(7.32%)、羟基丙酮丙二醇缩酮(5.33%)、芳樟醇(3.67%)、丙二醇单醋酸酯(3.54%)、异戊酸(2.75%)和2-乙酰基呋喃(2.06%)。此外,对葫芦巴浸膏的致香机理进行了探讨,研究为葫芦巴浸膏的品质控制和开发应用提供了技术依据。     

Effect of eugenol and guaiacol application on tomato aroma composition determined by headspace stir bar sorptive extraction

BACKGROUND: The present work was carried out because there is only a small amount of literature on how the volatile composition of tomatoes can be modified by the effect of exogenous substances in contact with tomato plants. This work studies how eugenol and guaiacol, either by foliar application and/or in the surrounding atmosphere, can affect the volatile composition of this fruit. An important work of this study was also conduced to validate the analytical method [headspace stir bar sorptive extraction–gas chromatography–mass spectrometry (HS‐SBSE‐GC‐MS)] to determine the composition of the volatiles in tomato. RESULTS: Analytical method validation parameters such as linearity, limit of detection, limit of quantification, and recovery proved that this method is suitable for the analysis of tomato volatiles. Their eugenol and guaiacol content changed, with an increase of 200 and 35 times, respectively, when foliar treatment was used, and an increase of 10, in both cases, when plants were in contact with the contaminated atmosphere. As consequence of the treatments other volatile compounds changed considerably. CONCLUSION: For first time, a HS‐SBSE‐GC‐MS method was successfully validated for the study of volatiles in tomatos. Results suggests that exogenous compounds in contact with the plants, such as eugenol and guaiacol, can be absorbed changing the global volatile composition of fruits, which could produce a negative or positive effect in their aroma. © 2012 Society of Chemical Industry     

Determination of flavour compounds in beer using stir‐bar sorptive extraction and solid‐phase microextraction

The analysis of volatile compounds in beer is important for quality control in the brewing industry. In this study, stir‐bar sorptive extraction (SBSE) and solid‐phase microextraction (SPME), two solvent‐less enrichment techniques, were applied in combination with gas chromatography flame ionization detection (GC/FID) for the determination of four flavour compounds (isoamyl acetate, ethyl hexanoate, benzaldehyde, myrcene) in beer. Limits of detection, linearity and repeatability of both methods were determined using standard ethanol solutions, while accuracy was determined by conducting recovery tests on commercial beer samples. Both methods were characterized by high linearity (r > 0.996) and repeatability (RSD = 1.76–10.66%). When both methods were compared, higher recoveries were obtained by SBSE, with limits of detection 1.8–2.8 times lower compared with SPME. In the analysis of commercial beer samples using both methods, SBSE analysis resulted in higher recoveries, therefore demonstrating promise for the analysis of beer volatiles. Copyright © 2015 The Institute of Brewing & Distilling     

微波法提取苹果渣中多酚的工艺研究

以乙醇作为提取溶剂,研究了微波法提取苹果渣中多酚的工艺条件。主要探讨了溶剂浓度、微波功率、提取时间、料液比、物料颗粒等因素对多酚提取的影响,结果表明,微波法从苹果渣中提取多酚的最佳工艺条件为乙醇浓度60%、物料颗粒40目、液料比1∶10、微波功率350W、提取时间90s,此条件下从苹果渣中提取的多酚浓度可达245.31mg/100g,明显优于回流提取法和超声波提取法。     

Determination of synthetic phenolic antioxidants in soft drinks by stir-bar sorptive extraction coupled to gas chromatography-mass spectrometry

The synthetic phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) were pre-concentrated by stir-bar sorptive extraction and thermally desorbed (SBSE-TD) before analysis by GC-MS. Several parameters affecting the derivatisation step and both SBSE extraction and thermal desorption were carefully optimised. When the analyses of BHA and TBHQ in their acetylated, silylated and underivatised forms were compared, the best results were obtained when the in-situ derivatisation procedure with acetic anhydride was employed. Quantification was carried out using carvacrol as the internal standard, providing quantification limits of between 0.11 and 0.15 ng ml^?1, depending on the compound. Recovery assays for samples spiked at two concentration levels, 1 and 5 ng ml^?1, provided recoveries in the 81–117% range. The proposed method was applied in the analysis canned soft drinks and the analytes were found in five of the 10 samples analysed.     

纤维素酶提取苹果渣黄酮及抗氧化研究

研究了纤维素酶提取苹果渣黄酮的工艺条件及抗氧化活性。结果表明,与传统化学法相比,纤维素酶法提取苹果渣黄酮较好,黄酮提取率从0.43%提高到0.56%。对酶法提取工艺进行优化,得到最佳工艺条件为:纤维素酶浓度0.2%,pH=5.2,酶解温度60℃,酶解时间40min。在最佳条件下,纤维素酶法所得黄酮的提取率可达到1.26%,为化学法黄酮提取率的2.93倍。并对提取的黄酮进行羟自由基清除实验,发现酶法与化学法提取黄酮的成分清除能力相似,表明两种方法提取黄酮物质结构可能一样。     

响应面法优化超声波辅助提取苹果渣低聚糖的工艺

以苹果渣为原材料,在单因素实验的基础上,通过Box-Behnken实验设计以及响应面分析法,研究超声时间、料液比、乙醇体积分数和超声温度对苹果渣低聚糖得率的影响。优化后的最佳工艺参数为超声时间35 min、料液比1∶17（g/m L）、乙醇体积分数80%、超声温度43℃,在此实验条件下,苹果渣低聚糖实际得率为13.23%。结果表明,响应面分析法对超声波辅助提取苹果渣低聚糖的工艺优化合理可行,为其开发利用提供了理论支持。      

响应曲面法优化苹果渣可溶性膳食纤维提取工艺

以苹果渣为原料,采用酸水解法从苹果渣中提取可溶性膳食纤维。借助响应面设计分析,考察盐酸质量分数、料液比、浸提时间、浸提温度对可溶性膳食纤维提取率的影响。结果表明,各因素对提取率影响均显著。求解回归方程得到最佳工艺条件为:盐酸质量分数2.0%、液料比17mL/g、浸提时间65min、浸提温度78.2℃,此时可溶性膳食纤维的提取率可达到17.68%。     

固相萃取-气质联用法测定苹果中甲胺磷、地虫磷、甲基对硫磷和对硫磷的残留量

目的建立一种经固相萃取,以气相色谱-质谱法(gas chromatography-mass spectrometer,GC-MS)测定苹果中甲胺磷、地虫磷、甲基对硫磷和对硫磷残留量的方法。方法采用乙腈提取,石墨化碳/氨基复合固相萃取柱对苹果中的甲胺磷、地虫磷、甲基对硫磷和对硫磷进行净化,氮吹浓缩后利用气质联用仪测定其农药残留量。结果 4种有机磷农残在20~200μg/L线性范围内关系良好,相关系数(r~2)均大于0.995,检出限和定量限分别为1.4~3.5μg/kg和5.1~9.8μg/kg,当添加浓度为10~50μg/kg,回收率为81.2%~112.5%,测量结果RSD(n=5)在5.3%~13.7%之间。结论本法干扰低、快速高效,适合苹果中的甲胺磷、地虫磷、甲基对硫磷和对硫磷的残留量的测定。     

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。     

苹果渣中结合酚不同提取方法的研究

在最优条件下,以结合态酚类物质的种类和含量为指标,比较碱法、酶法和酸法对苹果渣中结合态酚类物质的提取效果。采用单因素实验对提取条件进行优化,HPLC-DAD法分别检测游离态酚和结合态酚中单体酚的种类和含量。结果表明:在温度为40℃下,选择碱降解时间为4 h,Na OH浓度为3 mol/L;酸降解时间为15 h,甲醇/浓硫酸浓度为13∶1（v/v）;酶降解时间为24 h,单宁酶酶活为1000 U。苹果渣中酚类物质主要是金丝桃苷、绿原酸、根皮苷、儿茶素、槲皮素、根皮素、没食子酸、原儿茶酸和咖啡酸。儿茶素、槲皮素、根皮素、没食子酸、原儿茶酸和咖啡酸主要以结合态的形式存在,没食子酸、原儿茶酸、咖啡酸和根皮素通过酶法提取的含量最高,分别为16.122、18.574、13.030、69.934μg/g;儿茶素和槲皮素通过酸法提取的含量最高,分别为148.909、66.396μg/g。酶法水解和酸法水解比碱法水解更适用于提取苹果渣中的结合态酚类物质。      

Determination of polycyclic aromatic hydrocarbons in edible seafood by QuEChERS-based extraction and gas chromatography-tandem mass spectrometry

A high-throughput analysis of polycyclic aromatic hydrocarbons (PAHs) in edible seafood using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) based extraction and gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed and validated in 4 seafood matrices--crab, finfish, oyster, and shrimp. The extraction employs QuEChERS with dispersive solid phase extraction (dSPE) using cleanup sorbent that includes C18. The acetonitrile extract is partitioned into hexane and analyzed by GC-MS/MS. The procedure was validated by spike recovery experiments of 15 parent and 5 substituted PAHs at 5ppb and 25 ppb levels in the 4 matrices. Recoveries were 71%-130% with RSDs less than 14%. The limit of quantitation (LOQ) for benzo[a]pyrene are 0.4-2.5 ppb depending on matrix. For all 15 parent PAHs the LOQs are less than 10% of the Levels of Concern established by the U.S. Food and Drug Administration. Good recoveries were also achieved in aged spikes at 5 ppb level in oyster and shrimp. Method accuracy was further evaluated by analyzing NIST Standard Reference Material 1974b. Ten of 14 incurred PAHs corresponding to the parent compounds in the present study fell within the control limits established by the National Oceanic and Atmospheric Administration. Using the present method approximately 20 samples every 24 h can be analyzed with confirmation. PRACTICAL APPLICATION: The presented analytical method could be used for seafood safety assessments to examine petroleum contaminant levels in edible seafood after an oil spill. The method is fast and sensitive.     

苹果渣可溶性膳食纤维提取工艺的研究

研究采用了酸性及碱性提取法从苹果渣中制备可溶性膳食纤维,利用正交试验设计确定了最佳提取工艺条件,提取酸溶性膳食纤维的最佳工艺条件是pH1.0、温度90℃、液料比15∶1(mL/g)、反应时间60min提取率为17.49%;碱溶性膳食纤维的最佳工艺条件是温度90℃、碱液浓度2.0%、反应时间60min、液料比2∶1(mL/g),提取率可达16.93%。     

气相色谱-质谱法同时测定食用油中的35种增塑剂

建立同时测定食用油中35种增塑剂的固相萃取-气相色谱-质谱(SPE-GC-MS)分析方法。采用乙腈萃取食用油中待测组分,经过硅胶/N-丙基乙二胺固相萃取(SPE)净化,乙腈淋洗后,氮吹浓缩至1 m L;再经DB-5MS色谱柱程序升温分离,选择离子监测模式(SIM)定性,外标法定量。食用油中35种增塑剂方法检出限为0.02~0.15 mg/kg;平均回收率为64.2%~129.6%;相对标准偏差RSD小于18.4%;线性范围:0.1~5.0 mg/L,相关系数≥0.9975。方法稳定、可靠,适用于食用油中多种类增塑剂的同时分析。