Comparison of isolation methods for the determination of buckwheat volatile compounds

Five different isolation techniques were combined with gas chromatographic–mass spectrometric determination of aroma compounds from buckwheat: dynamic headspace (DHS) with cryotrapping or sorbent trapping, solid-phase microextraction (SPME), headspace sorptive extraction (HSSE), solvent extraction (SE) and simultaneous distillation–extraction (SDE). Optimisation of each technique is presented, as well as comparison of the chemical profiles obtained by them. Solvent extraction with methanol resulted in the isolation of rather polar and less volatile compounds and was deemed least suitable for the odour-active compounds. Only SPME with DVB/CAR/PDMS fibre was suitable for the isolation of highly volatile compounds in a wider polarity range. DHS extracted the smallest number of compounds, but with the comparable chemical profile as obtained by SDE, which was chosen as the most suitable technique to obtain the aroma compounds of cooked buckwheat. The applied isolation techniques are complementary in their ability to extract a representative aroma profile of buckwheat.     

The profile in polyphenols and volatile compounds in alcoholic beverages from different cultivars of mulberry

Abstract: Mulberry fruits have different chemical compositions because of cultivar variation. In this study, polyphenol profile and volatile composition of alcoholic beverages produced from different mulberries of Da 10, Hongguo 2 hao, and Hongguo 1 hao were investigated. Statistically significant differences were detected in the chemical composition of the analyzed alcoholic beverage samples. The beverage of Da 10 possessed the highest content of total phenols, total flavonoids, and total anthocyanins, which was determined by spectrophotometry analysis, contrarily Hongguo 1 hao beverage showing the lowest. Phenolic acids and flavonols were analyzed by high performance liquid chromatography analysis. Protocatechuic acid was the main phenolic acid in all analyzed alcoholic beverage samples, and its concentration ranged from 8.20 mg L^?1 (Hongguo 1 hao beverage) to 29.98 mg L^?1 (Da 10 beverage). High level of flavonols was found in both Da 10 and Hongguo 2 hao beverage samples, whereas Hongguo 1 hao beverage sample was characterized with lower level of flavonols. Furthermore, volatile compounds were analyzed by solid phase microextraction‐gas chromatography mass spectrometry analysis. The amount of esters varied widely among the 3 alcoholic beverage samples. The concentration of aliphatic alcohols in Hongguo 2 hao and 1 hao beverage samples was higher than Da 10 sample, whereas Da 10 beverage sample contained more aromatic alcohols than the others. Hongguo 1 beverage sample showed the highest concentration of acetic acid. This study demonstrated that quantitative differences of phenolic compounds and volatile compounds among cultivars were significant, which highly affected the quality of alcoholic beverage from mulberry. Practical Application: Mulberry fruits had different chemical compositions because of cultivar variation. The analyzed Da 10 cultivar of mulberry appeared to be a good raw material for alcoholic beverage‐making because of its high level of total sugar and acidity. This study demonstrated that alcoholic beverages from mulberry contain high amounts of polyphenols. These bioactive compounds may act synergistically to promote health, and reduce risk factors of chronic diseases.     

Study of methods for the extraction of volatile compounds from fermented grape must

The main objective of the present study was to analyze the volatile compounds extracted from fermented grape musts by two extraction methods in order to characterize the samples. The purge and trap system provided the necessary sensitivity for the analysis of low-boiling point compounds, such as acetaldehyde and ethyl acetate, and the liquid–liquid extraction method allowed for the analysis of a great number of medium to high boiling point volatile compounds, such as phenylethyl alcohol, hexanoic and octanoic acids, ethyl hexanoate and ethyl octanoate. Ethyl propionate and propyl acetate, extracted by the liquid–liquid method, characterized the sample of grape must fermented by Kloeckera apiculata. The sample of grape must fermented by Pichia membranaefaciens was characterized by 2-propanol and 2-hexanone, extracted by the purge and trap system and liquid–liquid method, respectively. These results show that the purge and trap/dynamic headspace system and liquid–liquid extraction method are complementary in the determination of the aroma profiles of fermented grape musts and characterization of the samples.     

Trace metal concentrations in distilled alcoholic beverages and liquors in Nigeria

The concentrations of 12 metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn, Ca, Mg and K) in 13 classes of alcoholic beverages were determined by atomic spectrometry after HNO₃/H₂O₂ digestion. The mean concentrations of metals (µg mL^?1) in these alcoholic beverages varied in the ranges 0.01–0.04, 0.02–0.24, 0.04–0.13, 0.01–0.28, 0.01–0.77, <0.001–0.12, 0.28–1.48, 0.004–0.33, 0.10–1.02, 1.43–162.86, 0.26–25.46 and 0.49–322.58 for Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn, Ca, Mg and K respectively. The concentrations of metals found in these particular alcoholic beverages were below the International Statutory Limits for metals in alcoholic beverages. The estimated daily intake of the metals based on a per capita consumption of 3.6 L per annum pure alcohol was <3% of the tolerable daily intake of each metal. The individual and combined target hazard quotients of the metals were <1, indicating no long‐term health concerns from the consumption of these alcoholic beverages based on their metal content alone. Copyright © 2014 The Institute of Brewing & Distilling     

不同萃取方法提取青稞老酵馒头挥发性成分的比较

该研究采用顶空固相微萃取（HS-SPME）法和同时蒸馏萃取（SDE）法提取青稞老酵馒头样品中的挥发性风味物质,采用气相色谱-质谱（GC-MS）法对其进行检测,比较不同提取方法对青稞老酵馒头挥发性成分的提取效果。结果表明,两种方法提取物中共检测到91种挥发性化合物,共同检出成分为7种。其中HS-SPME法提取物中共检测到63种,以醇类、醛类、烯烃类为主;SDE法提取物中共检测到35种,以醇类、醛类、酮类、酯类、羧酸类为主。两种方法提取的青稞老酵馒头挥发性风味物质差异明显,且HS-SPME法提取物中检测出的挥发性风味物质数量高于SDE法。说明两种方法各有优劣,相互补充,结合分析可为青稞老酵馒头挥发性成分的鉴定提供更全面、完整的信息。     

饮料酒中挥发性酚类物质分析方法研究进展

挥发性酚类化合物是饮料酒的香味组成部分,对于酒的闻香、口味及稳定性等方面均具有重要的作用.有研究者认为,4-乙基苯酚(4-EP)和4-乙摹愈创木酚(4-EG)这2种挥发性酚,其在酒中的总浓度小于400μg/L时,为酒的风味贡献了辛香、烟香韵和革香韵;当其总浓度了大于620μg/L时,会使酒中产生腥异味,掩盖酒的香味.因此对酒中挥发性酚类物质的分析测定一直是研究的课题.目前饮料酒中挥发性酚的测定,主要采用各种样品前处理过程结合气相色谱或液相色谱的方法.随着先进仪器和设备的使用,样品前处理过程不断简化,饮料酒中挥发性酚的分析和测定正逐步向着简单、快速、准确度高的方向发展.文中综述了饮料酒中挥发性酚类物质分析方法的研究进展.     

Classification of distilled alcoholic beverages and verification of adulteration by near infrared spectrometry

Near-infrared (NIR) spectrometry and chemometric methods of classification were used to classify and verify adulteration of 69 samples of alcoholic beverages (whiskey, brandy, rum and vodka). The characterization of the drinks was accomplished by chemometric models based on principal component analysis and soft independent modelling of class analogy elaborated for each different group. Alcoholic beverages adulterated with 5% and 10% (v/v) of water, ethanol or methanol were analyzed and used to verify the models capacity of prediction. Besides, actual samples with suspicions of adulteration were analyzed by gas chromatography and used to test the chemometric models which were able to predict the adulteration in the actual samples. The proposed method was successfully applied in the verification of alcoholic beverages adulteration with 100% of correct prediction at 95% of confidence level. The absence of reagents, low sample consumption, high sampling throughput and good predictive ability enables the developed methodology to be applied as a screening analysis to verify adulteration of the alcoholic beverage, that is, a prior step used to condition the sample to a deeper analysis only when a positive result for adulteration is obtained by the proposed method.     

Variability of odour thresholds for some compounds in alcoholic beverages

In a study of the distribution of sources of variation in the interpretation of odour-threshold judgements, 16 aroma compounds in alcoholic beverages were examined by variance analysis and factor analysis at concentration levels corresponding to positive responses amounting to 50% and 75%. For the determination of threshold values, the concentration level corresponding to 50% positive responses was observed to be the better of these two alternatives from the aspect of statistical points and psychophysical responses. The detection threshold values in 9.45 % (by wt.) alcohol-water solution are mainly dependent upon the differences between the substances themselves, and the variation between subjects remains insignificant. Nevertheless, the odour-stimulating process caused by a compound can vary, despite the responses for all the groups of compounds being considered the same in regard to these threshold values.     

马铃薯及其蒸馏酒香气成分的鉴定

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Comparison and evaluation of volatile oils from three different extraction methods for some Thai fragrant flowers

Several tropical flowers have distinctive fragrances which are very appealing to use in perfumery, cosmetics and spa. However, to obtain a ‘natural fragrance’ from the flower is a challenge as the scent could change during the extraction process. The aim of the study is to find the suitable procedure for extraction of volatile oils from some Thai fragrant flowers. Three different methods: hydrodistillation, solvent extraction and enfleurage methods have been applied for the extraction of volatile oil from Jasminum sambac L. Aiton; Oleaceae (jasmine). The quantities and quality of jasmine volatile oils obtained from the different tested methods were compared. The solvent extraction method using 95% ethanol provided the greatest level of oil yield. However, sensory evaluation using preference test showed that the scents of the volatile oils from solvent extraction using diethyl ether and from enfleurage method were the closest to the fresh flowers compared with the volatile oils obtained from other methods. Their chemical constituents were analysed using gas chromatography coupled with mass spectrometer. Both volatile oils were then evaluated using a triangle discrimination test. From the triangle test, we found that 14 panellists from the total of 36 could not distinguish between the scents of jasmine oil from enfleurage and fresh jasmine flowers whereas only one panellist could not distinguish between the scent of jasmine oil from the solvent extraction and fresh jasmine flowers. These results suggest that the scent of the volatile oil obtained from the enfleurage method was the closest to fresh flowers compared with that obtained from other methods. This method was then successfully applied for extraction of volatile oils from three other Thai fragrant flowers, Michelia alba DC.; Magnoliaceae, Millingtonia hortensis L.; Bignoniaceae and Hedychium coronarium J. Konig; Zingiberaceae.     

酒精饮料中氨基甲酸乙酯检测方法研究进展

氨基甲酸乙酯是一种多位点致癌物,酒精饮料中含有微量的氨基甲酸乙酯.概述了国内外酒精饮料中检测氨基甲酸乙酯含量的方法;阐述了检测方法中的样品前处理方法、质谱检测选择性离子控制模式、检测方法的国际合作研究及我国氨基甲酸乙酯检测方法,并展望了未来该领域研究的发展趋势.     

饮料酒中氨基甲酸乙酯检测方法研究进展

氨基甲酸乙酯存在于黄酒、葡萄酒等酒精类饮料中,对人体具有潜在致癌作用,已被国际癌症研究机构确定为2A级致癌物。随着我国居民生活水平不断提高,酒精类饮料的消费量日趋上升,导致人均氨基甲酸乙酯的暴露量也日益上升,但是我国目前仍未对饮料酒中氨基甲酸乙酯做出限量标准。自从1985年加拿大报道了酒中有较高的氨基甲酸乙酯含量后其检测方法备受兲注,本文介绍了用于检测饮料酒中氨基甲酸乙酯的常用方法如气相色谱法、气相色谱质谱联用法、高效液相色谱法、薄层色谱法、傅里叶变换近红外光谱法等,幵简述了其特点及应用。以期能为饮料酒中氨基甲酸乙酯检测方法的发展提供参考,同时,我国应尽快对饮料酒中氨基甲酸乙酯做出限量标准以保障饮料酒行业快速、健康发展,保护我国居民健康。     

Comparison of methods for the isolation of thermotolerant Campylobacter from poultry

Human campylobacteriosis has become the major cause of foodborne gastroenteritis in industrialized countries. Although there have been numerous studies investigating the prevalence of Campylobacter in animals and raw meat, sensitive and low-cost detection methods are needed to implement effective control measures during primary production and to use as tools in risk assessment studies. Thermophilic Campylobacter spp. in naturally contaminated (n = 64) and inoculated (n = 16) broiler samples were detected using two International Organization for Standardization (ISO)-approved methods. Both enrichment broths (those of Preston and of Park and Sanders) were inoculated with (i) Campylobacter jejuni ATCC35921, (ii) boneless breast from broilers, (iii) boneless breast rinse solution, (iv) boneless breast rinse solution inoculated with C. jejuni ATCC35921 before centrifugation, and (v) boneless breast rinse solution inoculated with C. jejuni ATCC35921 after centrifugation. The results indicated that the Park and Sanders broth was superior to the Preston broth for recovery of Campylobacter spp., and no significant differences (P > 0.05) were found between ISO (meat pieces) and modified ISO (centrifuged chicken rinse solution) methods for the detection of Campylobacter spp.     

HS-SPME-GC-MS分析玫瑰香葡萄中挥发性物质的萃取条件优化

原料选自宁夏贺兰山东麓玉泉营6年生玫瑰香,设置平衡时间分别为5 min、10 min、15 min,解吸时间分别为4 min、5 min、6 min,萃取温度分别为20 ℃、30 ℃和40 ℃,吸附时间分别为30 min、40 min和50 min,用顶空固相微萃取（HS-SPME）法对玫瑰香葡萄果实的挥发性物质进行萃取,以建立适宜于玫瑰香葡萄果实挥发性物质的气相色谱-质谱联用技术（GC-MS）分析方法。结果表明,萃取玫瑰香果实挥发性物质的最适萃取条件为平衡时间10 min,解吸时间5 min,萃取温度30 ℃,吸附时间40 min。在此优化萃取条件下,得到的挥发性物质的数量和响应强度较高,检测出玫瑰香果实的主要挥发性物质有芳樟醇、橙花醚、玫瑰醚、橙花醇、香叶醇、辛酸乙酯、柠檬醛、酞酸二甲酯、棕榈酸甲酯、正辛基醚等。     

姜辣素不同提取方法的比较研究

对姜粉中姜辣素提取的不同方法进行了比较研究。分别采用了回流法、微波辅助法和超声波辅助法3种不同方法进行了提取。其中超声波辅助法的提取率最高,达到7.28mg/g。     

辣椒碱不同提取方法的比较研究

文章对辣椒碱提取的不同方法进行了比较研究.采用了有机溶剂法、碱性乙醇法、超声波法、酶法及超临界流体法5种不同方法进行了提取.与其它方法相比,碱性乙醇法不仅提取时间短,提取率高,而且操作方便,适合大规模生产应用.     

一种萃取酒醅中低沸点挥发性成分的方法

分别采用水蒸汽蒸馏（SD）法、超声辅助溶剂萃取（UASE）法和蒸馏-微溶剂萃取（SD-MSE）法从浓香型白酒酒醅中提取挥发性成分,利用峰面积归一化法测定各成分的相对含量,通过对挥发性成分的气相色谱-质谱连用/自动化退卷积系统（GC-MS/AMDIS）对比分析。结果表明,SD、UASE及SD-MSE法分别鉴定出42种、71种、60种挥发性成分。SD、UASE及SD-MSE法分别测得的醇、酸、酯的相对含量分别为1.34%、6.61%、21.67%;1.03%、39.28%、37.42%;3.96%、9.97%、64.97%。由此可知,SD法对酸、酯的提取效果劣于另两种方法,UASE法对酸类物质萃取效果更佳,SD-MSE法对酯类物质的萃取效果更佳。和UASE法相比,SD-MSE法节约了大量溶剂,减少了样品转移次数,且待测液澄清透明,是一种适宜萃取糟醅中低沸点成分的方法。     

A novel technique for rapid extraction of volatile organohalogen compounds from low permeability media

A new method for rapid extraction of Volatile Organic Compounds (VOC) from low permeability, unconsolidated geologic media such as clayey soil has been developed and tested using trichloroethylene (TCE) as the model compound. The technique is based on a combination of sonication and mechanical agitation of the samples. The sample vials, mounted in a special holder attached to an orbital shaker, were immersed in an ultrasonic bath during extraction. The extracts were analyzed by gas chromatography with electron capture detection (GC-ECD). The method was validated using clay samples from a TCE-contaminated industrial site by comparing TCE recoveries to those obtained by the standard methanol extraction. In all cases, the recoveries obtained with the new method were the same or better than the recoveries obtained with the reference method. The extraction time was shortened from 5 days with the standard method to less than 2 h with the new method. The new technique makes it possible to analyze a large number of samples in a short time, without the need for sample preservation and prolonged storage. It has good potential for on-site analysis to facilitate decisions while field investigations are in progress.     

酒精度快速测定仪测定饮料酒酒精度

利用酒精度快速蒸馏仪和酒精度快速测定仪测定分析了饮料酒的酒精度。验证了蒸馏过程中不同酒类的最佳馏出液质量,系统分析了该方法对饮料酒酒精度的测定准确性、精密度、适用性与不确定度。方法对不同酒精度的酒精度标准参比溶液以及15～25℃之间不同温度的酒精度标准参比溶液的测定结果均与参考值一致,无差异(P 0. 05)。利用该方法与密度瓶法同时对不同酒精度的蒸馏酒、发酵酒的酒精度进行测定,二者测定结果一致,无差异(P 0. 05),且酒精度快速测定仪的测定精密度(SD≤0. 01%vol)优于密度瓶法。酒精度快速测定仪可在20 s内完成酒精度的精确测定,操作简单、时效性强、重复性好,可广泛用于饮料酒企业生产指导,品控检测以及相关检测机构的日常检验。