顶空固相微萃取结合GC-O与GC-MS技术鉴定可可粉中特征风味化合物

利用顶空固相微萃取(HS-SPME)结合GC-O与GC-MS技术鉴定可可粉中的特征致香成分,鉴定出有39种化合物参与构成可可风味,分别是:7种醛、3种醇、3种酮、8种酯、2种酸、4种吡嗪、2种胺以及其他一些特殊的挥发性物质。其中具有典型可可风味(坚果,可可香)的关键化合物有3种,分别为2,5-二甲基吡嗪、2,3,5-三甲基吡嗪以及2,3,5,6-四甲基吡嗪。     

A kinetic study on extraction and transformation phenomena of phenolic compounds during red wine fermentation

The aim of this work was both to model the kinetics of the extraction and transformation of phenolic compounds during fermentation and to propose an index to compare fermentation procedures. Six lots of Sangiovese grapes from five vineyards were used for red wine fermentation tests on lab and industrial scale during 2005 and 2006 vintages. Total phenol index, colour parameters, anthocyanin and pigmented polymer contents were measured during fermentations as variables related to phenolics. Microvinifications performed during vintage 2005 were used to model the evolution of total phenol index at 280 nm, malvidine content, colour parameter a* and pigmented polymer content during fermentation. Vinifications performed during vintage 2006 were used to validate the models. A specific adimensional number, called equivalent index, was set up to specify the operating conditions of red wine fermentation being a function of the extraction and transformation phenomena of phenolic compounds.     

HS-SPME-GC-MS分析发芽糙米储藏过程中挥发性成分的变化

以水分含量为(14±0.5)％的发芽糙米为原料,取1 kg装入聚乙烯(PE)袋(15 cm×20 cm)密封后分别在湿度(65±3)％的4℃和35℃条件下储藏6个月.采用顶空固相微萃取(HS-SPME)和气相色谱-质谱联用(GC-MS)对4℃和35℃储藏及新鲜的发芽糙米中的挥发性物质进行提取、鉴定与分析.结果表明:发芽糙米挥发性成分主要有烃类、醛类和酯类,其次是醇类和酸类;随着储藏时间的延长,发芽糙米挥发性成分发生明显变化;4℃与35℃储藏下的发芽糙米挥发性成分种类、含量有差异性;在35℃下储藏的发芽糙米中的挥发性成分种类含量较4℃下有显著性增加.储藏6个月之后,变化较明显的挥发性成分有十六烷、十八烷、己醛、n-十六酸、2-乙基-1-己醇、乙酸乙酯.     

超声波辅助-顶空固相微萃取-气相色谱法测定葡萄酒中痕量2,4,6-三氯苯甲醚

建立了超声波-顶空固相微萃取-气相色谱检测葡萄酒中的痕量木塞污染物——2,4,6-三氯苯甲醚（TCA）的方法。试验结果表明,该方法有良好的线性关系,相关系数为0.999 89,方法定量限为0.5 ng/L,相对标准偏差RSD在1.98%～5.32%之间,加标回收率为89.0%～103.2%。该方法操作简便、快速、准确度高、重现性好,适用于普通实验室对葡萄酒中痕量TCA残留的检测。     

Characterisation of volatile compounds in an alcoholic beverage produced by whey fermentation

An alcoholic beverage (35.4% v/v ethanol) was produced by distillation of the fermented broth obtained by continuous whey fermentation with a lactose-fermenting yeast Kluyveromyces marxianus. Forty volatile compounds were identified in this drink by gas chromatography. Higher alcohols were the most abundant group of volatile compounds present, with isoamyl, isobutyl, 1-propanol, and isopentyl alcohols being found in highest quantities (887, 542, 266, and 176 mg/l, respectively). Ethyl acetate had the highest concentration (138 mg/l) among the esters. Besides higher alcohols and esters, other components, including aldehydes, acids and terpenes were also identified in the whey spirit. Considering that the quality of an alcoholic beverage can be evaluated by the relation between isoamyl alcohol/2-methyl-1-propanol and 2-methyl-1-propanol/1-propanol, which have to be higher than unity, it was concluded that a novel spirit of acceptable organoleptic characteristics can be produced by cheese whey continuous fermentation with K. marxianus.     

顶空固相微萃取结合气质联用分析沙葱中挥发性成分

沙葱是一种生长于荒漠地带的野生蔬菜,具有独特的气味。为了确定其挥发性成分,实验采用顶空固相微萃取技术（HS-SPME）对其挥发性成分进行萃取,然后用气相色谱质谱联用（GC-MS）进行检测。结果表明,共检测到24种化合物,在DVB/CAR/PDMS、PDMS/DVB、PA三种固相萃取头中,DVB/CAR/PDMS型号的萃取头萃取效果最佳;沙葱中主要挥发性成分是:2-己烯醛（27.74%）、甲基-2-烯丙基三硫醚（25.70%）、二甲基三硫化物（13.62%）、烯丙基甲基二硫醚（9.94%）、二烯丙基二硫（7.23%）,占总成分的84.23%,其中2-己烯醛在沙葱中首次报道。      

菠萝皮渣糯米果酒发酵过程中主要成分变化研究

以菠萝皮渣和糯米为原料,进行糯米果酒发酵,并采用相关国标检测方法、液相色谱（LC）及气相色谱质谱联用（GC-MS）法,分析菠萝皮渣糯米果酒在发酵过程中可溶性固形物、酒精度、有机酸、挥发酸和香气成分等成分变化。结果表明：发酵过程中糖度迅速降低、酒精度升高后维持稳定,pH值在3.50～3.80之间,呈先降后升趋势,酸度先降低直至陈酿后期轻微升高。有机酸含量在发酵过程中总体呈下降趋势,草酸、酒石酸含量逐渐降低,柠檬酸、苹果酸、丙酮酸、乳酸含量先降后升,琥珀酸和乙酸呈上升趋势。果酒中挥发酸含量不断下降,第60天甲酸、乙酸含量分别为0.30 mg/L和0.26 mg/L。菠萝皮渣糯米果酒中共检测出88种香气成分,其中41种酯类、22种醇类、10种酸类和15种其他类,发酵过程中乳酸乙酯、乙酸异戊酯、2-甲基丁酸乙酯、正己酸乙酯、辛酸乙酯、乙酸苯乙酯、癸酸乙酯、月桂酸乙酯和十六酸乙酯含量较高,相对含量在0.27%～20.57%。     

基于顶空固相微萃取-气质联用分析燕麦黄酒与藜麦黄酒的挥发性成分

通过顶空固相微萃取结合气相色谱-质谱联用技术对燕麦与藜麦黄酒进行挥发性成分分析,共鉴定出挥发性成分86种,其中藜麦黄酒57种,燕麦黄酒55种,有26种是两种黄酒共有的。藜麦黄酒的挥发性物质组成为芳香族(64.09%,15种)、醇类(29.36%,7种)、酯类(4.37%,13种)、其他类(2.18%,22种)。燕麦黄酒的挥发性成分组成为(芳香族43.77%,14种)、醇类(27.39%,6种)、酯类(22.66%,15种)、其他类(6.18%,22种)。两种黄酒的含量较高的组分均为苯乙醇与异戊醇,同时在挥发性成分中均检测到具有抗氧化能力的物质,可以推测两种黄酒可能有抗氧化活性。     

基于顶空固相微萃取-气质联用分析燕麦黄酒与藜麦黄酒的挥发性成分

通过顶空固相微萃取结合气相色谱-质谱联用技术对燕麦与藜麦黄酒进行挥发性成分分析,共鉴定出挥发性成分86种,其中藜麦黄酒57种,燕麦黄酒55种,有26种是两种黄酒共有的。藜麦黄酒的挥发性物质组成为芳香族（64.09%,15种）、醇类（29.36%,7种）、酯类（4.37%,13种）、其他类（2.18%,22种）。燕麦黄酒的挥发性成分组成为（芳香族43.77%,14种）、醇类（27.39%,6种）、酯类（22.66%,15种）、其他类（6.18%,22种）。两种黄酒的含量较高的组分均为苯乙醇与异戊醇,同时在挥发性成分中均检测到具有抗氧化能力的物质,可以推测两种黄酒可能有抗氧化活性。      

HS-SPME-GC-O-MS联用法分析红枣发酵饮料易挥发性成分条件的优化

以红枣发酵饮料为研究对象,利用顶空固相微萃取和气相色谱-嗅闻-质谱联用法分析其易挥发性成分并对其进行了分析,对影响固相微萃取操作条件的萃取头、萃取温度、萃取时间、样品用量、平衡时间和解吸时间进行系统的优化,旨在建立一种分析红枣发酵饮料易挥发性成分的方法,并通过嗅闻检测结合气味活度值和香气强度值确定红枣发酵饮料的特征风味成分,采用草酸二乙酯做内标对特征风味成分进行了含量测定。结果表明:选用50/30μm DVB/CAR/PDMS固相微萃取头、Rtx-WAX色谱柱、样品用量8.0 m L/20.0 m L样品瓶、加盐量3.00 g、萃取时间70 min、萃取温度70℃、平衡时间20 min、解吸时间3 min,分析红枣发酵饮料易挥发性成分,共检出114种组分,确定结构96种,占总易挥发性成分总量的98.86%;气味活度值及香气强度值分析结果表明:乙酸乙酯、戊酸乙酯、己酸乙酯、2-辛酮、2-十一酮、乙酸-2-苯乙酯、苯丙酸乙酯、6-甲基-5-庚烯-2-酮、苯甲醛和3-羟基-2-丁酮为红枣发酵饮料的特征风味成分。      

顶空-固相微萃取与气质联用法分析草菇中的香味成分

本文以享有“中国蘑菇”之称的草菇为原料，采用碳分子筛-聚二甲基硅氧烷（CAR／PDMS）涂层的固相微萃取头分别萃取新鲜草菇和干草菇蒸馏后的挥发性成分，并通过气质联用仪分析鉴定了其主要的香味成分。结果表明，固相微萃取有效地吸附了草菇中的挥发性成分，经NIST质谱数据库和文献对照，分别从干草菇和新鲜草菇中检测出48和29种成分，其中八碳化合物是最要的风味主体。     

苹果酸-乳酸发酵对威代尔冰酒香气的影响

以酒精发酵与苹果酸-乳酸发酵同时进行的威代尔冰酒为实验组,以单一酒精发酵的冰酒为对照,采用液相色谱（LC）、顶空固相微萃取（HS-SPME）和气相色谱-质谱联用（GC-MS）技术,对有机酸含量和挥发性香气成分进行定性定量检测,同时进行感官评定,探究苹果酸-乳酸发酵对威代尔冰酒香气的影响。结果表明,苹果酸-乳酸发酵能使冰酒中苹果酸含量降低26%,乳酸含量增加50%,显著提高冰酒中脂肪酸乙酯类（34.71%）和萜类香气物质含量（15.2%）（P＜0.05）,显著降低戊醇等高级醇类含量（12.19%）（P＜0.05）,提高冰酒的花香、果香、焦糖香,显著降低化学味。感官分析结果表明,苹果酸-乳酸发酵能增加冰酒中的果香、花香,降低冰酒酸度,提高糖酸平衡感,从而提高其整体接受度。     

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.     

Inhibition of spoilage lactic acid bacteria by lysozyme during wine alcoholic fermentation

The efficacy of lysozyme against indigenous lactic acid bacteria (LAB) and four inoculated spoilage LAB cultures was investigated in laboratory scale Chardonnay winemaking trials (at pH 3.8). These LAB cultures included Lactobacillus kunkeei, Lactobacillus brevis, Pediococcus parvulus , and Pediococcus damnosus . Three concentrations of lysozyme were used: 0, 125 and 250 mg/L. Alcoholic fermentation of the grape juice was carried out at 20±0.5°C using Saccharomyces cerevisiae . Lysozyme did not have any negative impact on yeast growth and sugar reduction. This enzyme was found to be very effective in inhibiting the growth of all four LAB cultures investigated. Under the given experimental conditions, as high as an 8 log cell reduction was obtained for some of the strains. The acetic acid production by L. brevis and L. kunkeei was significantly reduced in the treatments with 125 and 250 mg/L lysozyme added ( P < 0.01). The effect of lysozyme on the cells of the LAB cultures was examined under a scanning electron microscope. It is evident that lysozyme had a detrimental impact on the cells of these cultures. Based on these observations, it is concluded that lysozyme may be a useful tool for winemakers to control the growth of spoilage LAB and to reduce the production of volatile acids. The addition of lysozyme may also prevent the increase of volatile acidity during stuck/sluggish alcoholic fermentation. This tool is particularly useful in high pH wines where SO₂ is less effective.     

Analysis of volatile compounds of pineapple wine using solid-phase microextraction techniques

An analytical procedure based on headspace solid-phase microextraction (HS-SPME) method combined with GC–MS was developed for the extraction and quantification of volatile compounds from pineapple wine. Different sample preparation (SPME fibre type, addition of sodium chloride, extraction time and temperature) were evaluated to optimise the method. For the final method, 8 ml of pineapple wine were placed in a 15 ml headspace vial with addition of 1 g of NaCl; a polydimethylsiloxane SPME fibre was used for extraction at 30 °C for 30 min with continuous stirring. The volatile compounds have shown a good linearity in the range of concentrations studied with regression coefficients higher than 0.98, and the reproducibility expressed as relative standard deviation ranged from 4.2% (2-phenylethyl acetate) to 7.1% (ethyl benzoate). The values obtained for detection and quantification limits were low enough to permit the determination of volatiles in pineapple wine. Using this method, 18 volatiles were identified, including 13 esters, 4 alcohols and one acid. Ethyl octanoate, ethyl acetate, 3-methyl-1-butanol and ethyl decanoate were the major constituents. A tentative study to estimate the contribution of the identified compounds to the aroma of the wine, on the basis of their odour activity values (OAV), indicated that the compounds potentially most important to pineapple wine included ethyl octanoate, ethyl acetate and ethyl 2-methylpropanoate.     

红树莓果酒主发酵工艺的优化

本文对二氧化碳浸渍法酿造红树莓果酒的主发酵工艺进行了系统的研究。以野生红树莓为原料,安琪高活性葡萄酒用干酵母为发酵菌种,残糖质量分数、酒精度、总酸和感官评价分数为指标;在单因素实验基础上,采用L9(34)正交优化实验,探究出红树莓果酒酿造的最佳主发酵工艺为:pH2.7、发酵温度22℃、初糖质量分数23%、酵母接种量4%。在此工艺条件下主发酵6d,得到红树莓果酒:残糖10.11g/L(以葡萄糖计),酒精度12.0%vol,总酸17.22g/L(以柠檬酸计),感官评分为75.83±3.06;红树莓果酒呈酒红色,澄清透明,有光泽,味纯正爽怡,有清雅果香与和谐酒香。      

Fruit wine produced from cagaita (Eugenia dysenterica DC) by both free and immobilised yeast cell fermentation

The aims of this work were to elaborate a fruit wine from cagaita (Eugenia dysenterica DC) pulp and to compare the fermentations conducted with free and with Ca-alginate immobilised cells. Two strains of Saccharomyces cerevisiae (UFLA CA11 and CAT-1) were tested and four fermentation batches were performed, in triplicate, at 22 °C for 336 h: UFLA CA11 in free and immobilised cells and CAT-1in free and immobilised cells. Fermentation time and ethanol production were influenced by the yeast strain and by the cell status, with immobilised cells of UFLA CA11 and CAT-1 fermenting faster (4 days and 8 days, respectively) than UFLA CA11 and CAT-1 free cells (10 days and 12 days, respectively). Ethanol content (g/L) was slightly higher when the fermentation was conducted with free cells (94.63 and 94.94 for UFLA CA11 and CAT-1, respectively) than with immobilised cells (86.82 and 87.21 for UFLA CA11 and CAT-1, respectively). The beverage from CAT-1 free cells showed the highest concentration of higher alcohols (82,086.12 ??/L), whereas the lowest concentration (37,812.17 ??/L) was found in the beverage from immobilised UFLA CA11. The ethyl ester concentration ranged from 1511.42 ??/L (CAT-1 free cells) to 2836.34 ??/L (UFLA CA11 free cells). According to the sensory evaluation, the fruit wine acceptability was greater than 70% for colour, flavour and taste for all cagaita beverages.     

Concentration of volatile compounds in Chardonnay wine fermented in stainless steel tanks and oak barrels

The influence of the type of container used in alcoholic fermentation on the formation of volatile compounds in wine from Chardonnay variety was studied. To do so, must from Chardonnay variety was fermented in both stainless steel tanks and in new Nevers oak barrels. The results obtained showed that wine fermented in barrels had a greater concentration of higher alcohols and esters than wine fermented in tanks. Concentration of isoamyl acetate, ethyl hexanoate, ethyl octanoate and ethyl decanoate was four times higher in wine fermented in oak barrels than in wine fermented in stainless steel tanks. With regard to the concentration of acids, a greater concentration of medium-chain fatty acids (C6:0–C10:0) was noticeable in wine fermented in oak barrels. Given that these acids are toxic for the yeasts, they may be responsible for the slower fermentation rate of wine fermented in oak barrels.