顶空气相色谱-质谱联用法分析灵芝发酵物中的挥发性物质

采用顶空-气相色谱-质谱联用法对灵芝发酵物的风味物质进行了定性和定量测定。结果表明,灵芝发酵物中至少含有31种风味物质。对其中21种主要成分进行了鉴定,这些物质大多是酮类、醇类和内酯类化合物。所有物质中4,5-二氢-3,5-二甲基-2-呋喃酮的含量最高,达64.12%。此外,3-戊烯-2-酮和戊基乙烯基原醇是已知的食品香料成分。结果有助于初步理解灵芝发酵物产生清淡香味的原因。     

虫药蜣螂对灵芝发酵物风味组成的影响

采用顶空-气相色谱-质谱联用对虫药蜣螂和添加蜣螂发酵后的灵芝发酵物的风味物质进行了测定,进而分析了添加蜣螂对灵芝发酵物风味组成的影响。结果表明,虫药蜣螂和灵芝发酵物(添加蜣螂)中分别含有40和30多种风味物质。添加蜣螂发酵后,灵芝发酵物跟对照相比新出现了5种风味物质,分别为苯甲醛、α-松油醇、苯乙醇、唑苯并噻和桃金娘烯醇。其中α-松油醇、苯乙醇和唑苯并噻是蜣螂中的风味成分,苯甲醛和桃金娘烯醇为新产生成分。所有5种风味物质均为食品香料物质。蜣螂中其它风味成分经灵芝发酵转化或降解后,未出现在灵芝发酵物中。因此,添加蜣螂发酵对灵芝发酵物的风味无不良影响。结果还提示灵芝细胞可生物转化或降解虫药蜣螂中的部分风味物质。     

9 种海洋硅藻挥发性成分的比较分析

采用顶空固相微萃取气相色谱一质谱联用技术,通过SIMCA．P分析软件,对硅藻门下处于生长平台后期的9种海洋硅藻的挥发性成分进行比较分析研究。结果表明：在平台后期硅藻的挥发性成分中,醛类物质的含量和种类占据了很大的优势,壬醛、2,4-辛二烯醛、2-己烯醛、2-壬烯醛、2,4-庚二烯醛等是硅藻挥发性成分的主要构成物质,十四烷、十五烷、1-十五烯、十六烷等烷烃类是硅藻中含量仅次于醛类物质的挥发性成分,3,5-辛烯基-3-酮等短链酮类和1-辛烯基-3-醇是硅藻中含量较高的酮类和醇类物质,9种硅藻中均检测二甲基硫的存在。差异性较大的挥发性物质主要有壬醛、8-十七碳烯、1-戊烯．3．酮、1-己烯-3．醇、2,6-二甲基一苯酚,它们决定了不同的硅藻有着各自不同的风味。研究结果表明这些挥发性物质对硅藻的饵料价值、养殖生物的肉质风味、水环境的异味形成有着重要意义。     

南瓜5个品种果肉的挥发性成分分析

为了解南瓜（Cucurbita sp.）果实中的特征风味物质,采用顶空固相微萃取气质联用（HS-SPME-GC-MS）技术对5个品种（‘新美玉’、宝丰’、‘金磨盘’、‘健宝’和‘东升’）果肉的挥发性成分和含量进行测定并进行主成分分析。结果表明,从5个品种南瓜果肉中共检测出68种挥发性成分,以醇类、醛类和烃类为主,其中壬醛、正己醛、反,反-2,4-庚二烯醛、顺-壬-3-烯-1-醇和正己醇等化合物为南瓜果肉的主要风味物质。主成分分析表明,南瓜5个品种果肉的风味差异化合物主要有9种,其中十一醛和反-2-壬烯醛为‘健宝’和‘东升’的特征风味物质;1,9-壬二醇是‘宝丰’的标志性风味物质;‘金磨盘’和‘新美玉’因3-壬炔-1-醇相对含量较高而区别于其他品种。因此,特征挥发性物质为南瓜品种改良和品质评价提供参考。     

药用昆虫蜣螂对灵芝发酵和抗小鼠肝癌活性的影响

采用液体深层发酵方式,研究了药用昆虫蜣螂对灵芝细胞生长、关键活性产物发酵动力学和抗小鼠肝癌活性的影响。结果表明,药用昆虫蜣螂在各添加浓度下对灵芝的细胞生长均无显著促进作用;但在添加量为5g/L时,对灵芝多糖和灵芝三萜的发酵动力学有显著影响(P<0.05),在发酵第7天时,灵芝总多糖和总三萜的产量分别达到2.81g/L和539.0mg/L(对照组分别为2.25g/L和428.2mg/L)。小鼠体内抗肝癌结果表明,灵芝对照发酵物的抑癌率为41.61%,灵芝-蜣螂配合物的抑癌率为42.24%;而补加蜣螂发酵后的灵芝加蜣发酵物的抑癌率高达57.21%,与灵芝对照发酵物的抑癌率相比,提高了37.49%。研究表明,采用昆虫蜣螂补料-分批发酵后,灵芝发酵物抗小鼠肝癌的活性得到显著增强。     

脱皮与不脱皮青稞酿造营养黄酒风味差异的研究

以青稞为原料酿造新型黄酒,为研究原料脱皮与否对新型黄酒风味的影响,利用气相色谱质谱联用(GC-MS)测定脱皮青稞黄酒、不脱皮青稞黄酒及青稞麸皮中挥发性和半挥发性风味物质。结果表明未脱皮青稞黄酒中香气物质总量为71 134.67μg/L;脱皮青稞酿造黄酒香气物质含量较少为39 208.99μg/L。挥发性香气成分在含量上差异主要来源于,3-甲基丁醇、苯乙醇、2-甲基丙醇。通过香气活力值OVA分析发现,对两种青稞黄酒香气贡献的较大的物质种类均为辛酸乙酯、乙酸异戊酯、苯乙醇和苯甲醛,贡献值的大小有差异。对麸皮挥发性风味成分分析发现,青稞黄酒中香气成分均是通过微生物作用产生,麸皮中富含的苯丙氨酸、缬氨酸和亮氨酸通过代谢产生苯乙醇、2-甲基丙醇、3-甲基丁醇,是造成两种青稞黄酒中挥发性风味物质差异的主要原因。研究表明青稞麸皮对黄酒风味的形成有积极意义。     

花生中香味成分的研究与分析

笔者通过分析花生中香味成分化合物来对花生中香味成分进行研究。采用的方法为固相微萃取法,此法可以萃取出烘烤花生中的各种风味物质,根据实验我们可以看出:烘烤花生中挥发性的化合物中FD因子的最大值为256,并且FD因子排在前三位(FD因子>64)的在实验中检测出有10种已知的化合物和3种未知的化合物,实验结果显示:已知的化合物分别为:3-甲基丁醛(巧克力味)、2-甲基丁醛(焦糖味)、2-(2-羟乙基)-3-甲基-4-噻唑(鱼腥味)、2,5-二甲基吡嗪(烘烤坚果味)、2,6-二甲基吡嗪(烘烤坚果味)、乙基吡嗪(爆米花味)、2-乙基-5-甲基吡嗪(草味,坚果味)、呋喃醛(生土豆味)、3-乙基-2,5-二甲基吡嗪(咖啡味)、苯乙醛(甜芳香味)等。通过本次的实验,可以得出结论:2,5-二甲基吡嗪、乙基吡嗪等吡嗪类和醛类化合物是花生中香味的主要成分,对花生散发香味的贡献最大,酮类化合物对花生的风味贡献率较醛类来讲较低。     

奥利亚罗非鱼胶原蛋白酸解液美拉德反应产物风味成分分析

以奥利亚罗非鱼鱼皮中胶原蛋白酸解液和葡萄糖为主要基质进行美拉德反应,采用氨基酸自动分析仪和GC-MS分析了游离氨基酸组成和主要风味成分。结果表明,酸解后游离氨基酸完全符合胶原蛋白特有的氨基酸组成,且风味氨基酸占59.77%。此外鉴定出19种风味成分,其中包括乙酸乙酯(30.34%)、2,3-二羟基丙醛、柠檬烯、1,1-乙二醇二乙酸酯、己二酸二丁酯、二乙二醇丁醚醋酸酯、苯甲酸乙酯、2-乙酰基吡咯等。     

基于GC-IMS技术的不同红火蚁监测诱饵的风味成分分析

探讨不同红火蚁Solenopsis invicta Buren监测诱饵的风味成分,以期获得优化诱饵配方的科学依据。本文采用顶空气相色谱-离子迁移谱法分析不同红火蚁监测诱饵在60℃下的气味指纹图谱,并通过主成分分析法分析其风味物质的差异。结果共鉴定出93个信号峰和87种挥发性化合物,载体物质(CK)中具有较高强度峰的化合物包括3种苯、2种醇、3种酮、2种酯、4种醛、1种呋喃和1种烯;自主配制的诱饵(JR、ZR、JZ)的风味组成相似,较高强度峰的化合物包括2种醇、1种酸、12种醛和1-8桉叶素等;市售火腿肠(HT)中的3种烯、10种酮、1种苯、5种醛、1种呋喃、3种醚、7种醇和4种酯是具有较高强度峰的化合物。主成分分析表明,CK、HT与自主研发的诱饵聚集距离较远,三者均单独聚为一类,相互风味成分区别较大。综上所述,JR、ZR和JZ诱饵中醛类物质较多,而HT中酮类与醇类物质较为丰富。上述诱饵的风味成分分析结果能为研发精准高效的红火蚁监测专用诱饵提供重要信息。     

基于顶空-气相色谱-离子迁移谱法研究干燥方式对小米椒挥发性风味物质的影响

本研究采用顶空-气相色谱-离子迁移谱(HS-GC-IMS)技术对经热风干燥、红外干燥、真空冷冻干燥和自然晾晒4种干燥方式处理的小米椒进行挥发性风味物质分析。结果表明:这4种干燥方式获得的小米椒中共鉴定出挥发性风味物质39种,其中酯类9种、醛类10种、醇类10种、呋喃类2种、吡嗪类3种、酮类3种、有机酸类2种;小米椒干燥后的主要风味物质为酯类、醛类和醇类化合物。主成分分析(PCA)和热图聚类结果表明:相比于真空冷冻干燥与自然晾晒,热风干燥与红外干燥的挥发性风味物质具有较高的相关性;而与热风干燥和红外干燥相比,真空冷冻干燥与自然晾晒间的差异较大;干燥过程中部分挥发性风味物质间具有较强的相关性,如酯类和醇类、醇类和醛类等,其通过化学反应可实现风味物质间的转化。干燥方式对挥发性风味物质种类影响较小,热风干燥、红外干燥、真空冷冻干燥、自然晾晒的小米椒挥发性风味物质种类分别为39、37、36、34种。然而,干燥方式对小米椒挥发性风味物质的含量有明显的影响。与真空冷冻干燥和自然晾晒相比,热风干燥和红外干燥处理的样品中酯类、呋喃类和吡嗪类物质含量较高,而在真空冷冻干燥和自然晾晒处理的样品中醛类物质含量高于热风干燥和红外干燥。总之,相比于其他干燥方式,热风干燥与红外干燥对丰富干制小米椒的风味具有积极的影响。本研究将为干制小米椒的加工及风味品质调控提供理论依据。     

Studies on Cereals

Five carbonyl compounds were found in the vapour of cooked rice, of which acetaldehyde, and n-caproaldehyde were identified from their retention times in gas chromatography and by their infrared spectra. Propionaldehyde or acetone, methylethylketone, and n-valeraldehyde were tentatively identified. The mechanisms of the formation of these carbonyl compounds were discussed from the view-point of Strecker degradation and lipid oxidation.

When stored rice (40°C, two months) was cooked, the stale flavor (komai-shu) was clearly detected by sensory test. Direct gas chromatographic analysis of head space vapors over cooked rice showed three main peaks which corresponded to propionaldehyde or acetone, n-valeraldehyde and n-caproaldehyde. On the other hand, the content of linoleic and linolenic acids of the rice decreased during storage at 40°C. This means that the unsaturated fatty acids autoxidized during storage and gave rise to carbonyl compounds responsible for the stale flavor of cooked rice.     

Volatile production by Aspergillus versicolor as a possible cause of odor in houses affected by fungi

Aspergillus versicolor, which has been isolated from several mould affected houses was shown by laboratory studies under axenic conditions to produce several specific volatile compounds on water agar. These compounds were not produced by the fungus when grown on a rich malt extract medium or on several synthetic media. The volatile compounds were analysed by GC-MS. The majority of the peaks represented aromatic compounds. A non-aromatic substance which previously has been revealed by us among prominent volatile compounds sampled from building materials from so-called mould houses was produced only on water agar. According to a comparison with the mass spectrum and retention time of pure reference compound this compound is ethylhexanol, a compound not previously reported as a mould metabolite. The presence of this compound was correlated with pungent odor in the cultures.     

Lactones in the Flavor of Heated Pork Fat

Pork fat was heated at 160~170°C for 3 hr under bubbling with air, and the volatile compounds were collected in the cold trap. After the acidic compounds were removed from the volatile compounds by extraction with 3% aqueous sodium carbonate solution, lactones were obtained from the nonacidic compounds by saponification. Gas chromatographic analyses of lactones were carried out on the PEG-20M and Apiezon L packed columns, and then each lactone was fractionated by repeated gas chromatography. Each isolated lactone was identified by infrared spectrometry, and also three major lactones were identified by mass spectrometry. Consequently, γ-C₅—C₁₂ and δ-C₉, δ-C₁₀, δ-C₁₂ and δ-C₁₄ lactones were found in the flavor of heated pork fat. Gamma-lactones, especially γ-C₇, γ-C₈ and γ-C₉, were predominant in the flavor, and unsaturated lactones were not detected. Mechanisms for the formation of the lactones were discussed.     

Volatile Flavor Compounds of Boiled Buckwheat Flour

Volatile flavor compounds of boiled buckwheat flour were collected using a Likens and Nickerson apparatus type and were fractionated into acidic, weak acidic, basic and neutral fractions. The neutral fraction was further fractionated by silica gel column chromatography. All fractions were analyzed by gas chromatography and gas chromatography-mass spectrometry.

Two hundred and nine compounds were thus identified. Among them, 168 were newly identified as volatile flavor compounds of buckwheat flour; special note is made of 2-(1′-ethoxyethyl)pyrazine and 2-(1′-ethoxyethyl)-5-methylpyrazine being found which are compounds previously unreported in any literature.     

Studies on Flavor Components in Soybean

Volatile neutral fraction of flavor components in raw soybean was investigated. Ground raw soybean was packed in a glass column, warmed at about 50°C by a water-jacket column, and swept with nitrogen gas. Volatile materials swept out were trapped in bottles dipped in ice-water, solid carbon dioxide-acetone and liquid nitrogen in this order, and were submitted to gas chromatography. The peaks corresponding to basic and carbonyl compounds were eliminated by treating the original volatile materials with 2, 4-dinitro-phenylhydrazine in phosphoric acid, and the residual peaks were compared with authentic alcohols and esters.

Methanol, ethanol, 2-pentanol, isopentanol, n-pentanol, n-hexanol and n-heptanol were found as alcohols, and n-pentanol acetate was found as an ester. Other methods of identification of alcohols were carried out by introducing these into 3, 5-dinitrobenzoate derivatives, which were investigated by thin-layer and paper chromatographies.

Isopentanol, n-hexanol and n-heptanol were considered to be important factors among the volatile neutral components, which gave green bean-like odor to soybean.     

软儿梨果酒发酵过程中挥发性风味物质变化分析

软儿梨是西北地区特有的一种“冻果”产品,酸甜可口、果香浓郁,是酿造果酒的上乘原料。为明确果酒发酵过程中果香的保留情况,并探究发酵时间的延长对软儿梨果酒品质的影响,以青海省民和县软儿梨冻果为原料,基于带皮渣发酵工艺,先采用顶空固相微萃取（solid?phase microextraction, SPME）,再结合气相色谱?质谱联用技术（gas chromatography?mass spectrometry, GC?MS）对原汁（0 d）、前发酵（7、14、28 d）、后发酵（100 d）3个不同时期样品中挥发性风味物质进行了动态跟踪分析,并结合相对气味活度值（relative odor activity value,ROAV）和主成分分析（principal component analysis,PCA）法分别探讨了软儿梨果酒原果香味保留情况和后发酵时间的延长对果酒风味的影响。结果显示：整个发酵过程共检出88种挥发性化合物,其中酯类33种、醇类29种、酸类6种、萜烯类7种以及13种其他类化合物,且风味物质的总含量随发酵的进行呈先上升后略有下降的趋势。ROAV结果表明：软儿梨原汁关键风味物质共8种,分别是丁酸乙酯、己酸乙酯、2?甲基丁酸乙酯、正辛醇、大马士酮、芳樟醇、丁香酚和癸醛;其中果香物质己酸乙酯、正辛醇、芳樟醇、丁香酚和大马士酮在果酒发酵中得到了很好的保留,是决定软儿梨果酒风味的关键物质。主成分分析表明：发酵初期主要的香气贡献物质是具有水果香的丁酸乙酯、3?羟基丁酸乙酯、2?甲基丁酸乙酯;发酵100 d时,乙酸乙酯、α?松油醇、柠檬烯和芳樟醇对香气贡献较大,这些香气化合物共同赋予软儿梨果酒幽香清雅、馥香浓郁的独特风味品质。研究获得了软儿梨果酒关键风味物质及其在不同发酵阶段特征风味物质的变化规律,可为研发高品质软儿梨果酒产品、改进软儿梨果酒发酵工艺提供理论支撑和参考。     

In Situ Analysis of Metabolic Characteristics Reveals the Key Yeast in the Spontaneous and Solid-State Fermentation Process of Chinese Light-Style Liquor

The in situ metabolic characteristics of the yeasts involved in spontaneous fermentation process of Chinese light-style liquor are poorly understood. The covariation between metabolic profiles and yeast communities in Chinese light-style liquor was modeled using the partial least square (PLS) regression method. The diversity of yeast species was evaluated by sequence analysis of the 26S ribosomal DNA (rDNA) D1/D2 domains of cultivable yeasts, and the volatile compounds in fermented grains were analyzed by gas chromatography (GC)-mass spectrometry (MS). Eight yeast species and 58 volatile compounds were identified, respectively. The modulation of 16 of these volatile compounds was associated with variations in the yeast population (goodness of prediction [Q²] > 20%). The results showed that Pichia anomala was responsible for the characteristic aroma of Chinese liquor, through the regulation of several important volatile compounds, such as ethyl lactate, octanoic acid, and ethyl tetradecanoate. Correspondingly, almost all of the compounds associated with P. anomala were detected in a pure culture of this yeast. In contrast to the PLS regression results, however, ethyl lactate and ethyl isobutyrate were not detected in the same pure culture, which indicated that some metabolites could be generated by P. anomala only when it existed in a community with other yeast species. Furthermore, different yeast communities provided different volatile patterns in the fermented grains, which resulted in distinct flavor profiles in the resulting liquors. This study could help identify the key yeast species involved in spontaneous fermentation and provide a deeper understanding of the role of individual yeast species in the community.     

Identification of 4,5-Dimethyl-3-hydroxy-2(5H)-furanone (Sotolon) and Ethyl 9-Hydroxynonanoate in Botrytised Wine and Evaluation of the Roles of Compounds Characteristic of It

Two new components of botrytised wine were identified: 4,5-dimethyl-3-hydroxy-2(5H)-furanone (Sotolon) and ethyl 9-hydroxynonanoate. Sotolon, the key substance of cane sugar aroma, was identified as the sugary flavor substance of botrytised wine by means of gas chromatography-mass spectrometry after column chromatographic separation on DEAE-Sephadex and silica gel. Ethyl 9-hydroxynonanoate was identified by chemical ionization and electron impact mass spectrometry. To evaluate the role of 17 volatile and 5 nonvolatile compounds characteristic of botrytised wine, these compounds were added to a normal wine. This produced a sweet, honey-like flavor similar to that of botrytised wine. The importance of Sotolon and the role of each group of flavor substances in producting this flavor was clarified by omission tests.