Characterization of the odor-active volatiles in citrus Hyuganatsu (Citrus tamurana Hort. ex Tanaka)

The volatile components of Hyuganatsu (Citrus tamurana Hort. ex Tanaka) peel oil, isolated by cold-pressing, were investigated by chemical and sensory analyses. According to chemical analysis by GC and GC-MS, limonene (84.0%) was the most abundant compound, followed by gamma-terpinene (6.9%), myrcene (2.2%), alpha-pinene (1.2%), and linalool (1.0%). Monoterpene hydrocarbons were predominant in Hyuganatsu peel oil. The odor-active volatiles in Hyuganatsu flavor were studied by GC-olfactometry and omission tests. The characteristic flavor was present in the oxygenated fraction. Flavor dilution (FD) factors of the volatile flavor components of the Hyuganatsu cold-pressed oil were determined by aroma extraction dilution analysis (AEDA). Furthermore, relative flavor activity was investigated by means of FD factor and weight percent. Ten kinds of odor compounds having Hyuganatsu-like aroma were detected by AEDA: limonene, linalool, octanol, neral, neryl acetate, tridecanal, trans-carveol, cis-nerolidol, trans,trans-farnesyl acetate, and trans,trans-farnesol. Linalool and octanol were regarded as the most odor-active or key compounds of Hyuganatsu aroma. Diluted solutions of linalool and octanol of approximately 2 ppm gave a fresh and fruity aroma note similar to Hyuganatsu flavor.     

Character impact odorants of Citrus Hallabong [(C. unshiu Marcov x C. sinensis Osbeck) x C. reticulata Blanco] cold-pressed peel oil

The volatile components of Hallabong ([C. unshiu Marcov x C. sinensis Osbeck] x C. reticulata Blanco) cold-pressed peel oil were quantitatively and qualitatively determined by use of two internal standards with GC, GC-MS, and GC-olfactometry. According to instrumental analysis by GC and GC-MS, limonene (90.68%) was the most abundant compound, followed by sabinene (2.15%), myrcene (1.86%), and gamma-terpinene (0.88%). Flavor dilution (FD) factors of the volatile flavor components from Hallabong peel oil were determined by aroma extract dilution analysis. Furthermore, relative flavor activity was investigated by means of FD factor and weight percent. The highest FD factors were found for citronellal and citronellyl acetate, and delta-murollene showed a higher relative flavor activity. Results of sniff testing of the original oil and its oxygenated fraction revealed that citronellal, cis-beta-farnesene, and citronellyl acetate were regarded as the character impact odorants of Hallabong peel oil, and citronellal gave the most odor-active character of Hallabong aroma.     

Characteristic odor components of kumquat (Fortunella japonica Swingle) peel oil

This study was conducted to determine the composition of kumquat (Fortunella japonica Swingle) cold-pressed peel oil and to determine which volatile components are primarily responsible for the aroma of this oil. Eighty-two compounds were identified in the oil by GC and GC-MS. The major compounds were limonene (93.73%), myrcene (1.84%), and ethyl acetate (1.13%). Flavor dilution (FD) factors and relative flavor activities (RFA) of volatile constituents were evaluated by aroma extract dilution analysis with gas chromatography-olfactometry (GC-O). Camphene, terpinen-4-ol, citronellyl formate, and citronellyl acetate showed high FD factors (>/=5) and RFA (>20). Citronellyl formate and citronellyl acetate were regarded as the characteristic odor components of the kumquat peel oil from the results of FD factor, RFA, and GC-sniffing. Citronellyl acetate is considered to be the odor component most similar to kumquat by organoleptic evaluation with GC-O.     

Changes of the volatile profile and artifact formation in Daidai (Citrus aurantium) cold-pressed peel oil on storage

The chemical changes and artifact formation in daidai (Citrus aurantium L. var. Cyathifera Y. Tanaka) cold-pressed peel oil upon storage at 20, 5, and -21 degrees C for 3, 6, and 12 months were investigated using capillary gas chromatography (GC) and GC-MS. Major changes occurred in the oil stored at 20 and 5 degrees C. No changes were found at -21 degrees C. Monoterpene hydrocarbons decreased from 98.0 to 66.4% upon 12 months at 20 degrees C, while sesquiterpene hydrocarbons and alcohols increased from 0.1 to 2.4% and from 0.3 to 7.9%, respectively. Notable decreases of germacrene D, myrcene, linalyl acetate, and limonene occurred. Prominent increases of cis-carveol, trans-beta-farnesene, trans-p-2,8-menthadien-1-ol, linalool, and beta-caryophyllene were found. Thirty-four artifact compounds constituting 17.0% of the total volatile compounds were formed upon 12 months at 20 degrees C. The artifacts consisted of 13 alcohols (6.0%), five carbonyl compounds (5.3%), seven esters (4.9%), three epoxides (0.4%), four hydrocarbons (0.3%), and two unidentified. The prominent artifact compounds were (+)-carvone, trans,trans-farnesyl acetate, sabinene hydrate, 1-octen-3-ol, cis,cis-farnesyl acetate, and dihydrocarveol acetate. The results could be applied for monitoring and control of the flavor quality of daidai essential oil and related products.     

基于HS-SPME-GC-MS法比较瓢鸡和盐津乌骨鸡不同部位挥发性风味成分

为了研究优质地方鸡种瓢鸡和盐津乌骨鸡不同部位的主体风味成分,以300日龄瓢鸡和盐津乌骨鸡的胸肌和腿肌作为试验对象,利用顶空固相微萃取(HS-SPME)技术提取,采用气相色谱质谱联用(GC-MS)技术分离和鉴定鸡肉中的挥发性物质,结合相对活度值(ROAV)确定主体风味活性物质。结果表明,鸡肉样品中共检出76种挥发性化合物,主要包括醛类、醇类、酮类、酯类、酸类、烃类化合物,不同品种不同部位之间挥发性风味物质的组分和含量存在差异。瓢鸡主体风味物质由2-甲基丁醛、戊醛、己醛、庚醛、辛醛、反-2-辛烯醛、壬醛、1-辛烯-3-醇、辛烷构成;盐津乌骨鸡主体风味物质主要由2-甲基丁醛、己醛、壬醛、1-辛烯-3-醇构成。主体风味物质对不同部位不同品种鸡肉样品的贡献程度不同,其中醛类化合物对鸡肉的整体风味贡献最大。本研究结果为瓢鸡和盐津乌骨鸡的风味特性研究和开发利用提供了理论依据。     

Volatile constituents of redblush grapefruit (Citrus paradisi) and pummelo (Citrus grandis) peel essential oils from Kenya

The volatile constituents of cold-pressed peel essential oils of redblush grapefruit (Citrus paradisi Macfadyen forma Redblush) and pummelo (Citrus grandis Osbeck) from the same locality in Kenya were determined by GC and GC-MS. A total of 67 and 52 compounds, amounting to 97.9 and 98.8% of the two oils, respectively, were identified. Monoterpene hydrocarbons constituted 93.3 and 97.5% in the oils, respectively, with limonene (91.1 and 94.8%), alpha-terpinene (1.3 and 1.8%), and alpha-pinene (0.5%) as the main compounds. Sesquiterpene hydrocarbons constituted 0.4% in each oil. The notable compounds were beta-caryophyllene, alpha-cubebene, and (E,E)-alpha-farnesene. Oxygenated compounds constituted 4.2 and 2.0% of the redblush grapefruit and pummelo oils, respectively, out of which carbonyl compounds (2.0 and 1.3%), alcohols (1.4 and 0.3%), and esters (0.7 and 0.4%) were the major groups. Heptyl acetate, octanal, decanal, citronellal, and (Z)-carvone were the main constituents (0.1-0.5%). Perillene, (E)-carveol, and perillyl acetate occurred in the redblush grapefruit but were absent from the pummelo oil. Nootkatone, alpha- and beta-sinensal, methyl-N-methylanthranilate, and (Z,E)-farnesol were prominent in both oils.     

Volatile Profiles of 13 Foxtail Millet Commercial Cultivars (Setaria italica Beauv.) from China

The volatile components from 13 commercially valuable foxtail millets from China were investigated by means of gas chromatography–mass spectrometry combined with simultaneous distillation extraction. A total of 52 volatile compounds were identified in all of the samples: 19 aldehydes, 5 alcohols, 10 ketones, 9 hydrocarbons, 6 benzene derivatives, and 3 others. Here, 23 common constituents were found in all samples. Aldehydes were the predominant volatile components in various cultivars. The importance of each volatile was assessed on the basis of odor thresholds and odor activity values (OAVs). Here, 35 volatile compounds were described using aroma character, and 24 volatile compounds were found to be odor‐active compounds. Another 11 common constituents were found in all samples. The components with the highest OAVs in most cultivars were (E )‐2‐nonenal and (E,E )‐2,4‐decadienal. Most of the other aldehydes also had high OAVs. Some of the ketones, alcohols, benzene derivatives, and other compounds were found to contain an odor‐active compound in several cultivars of foxtail millet. Principal component analysis was employed to evaluate the differences among cultivars. The results demonstrated that the volatile profile based on the OAVs of aroma compounds enabled good differentiation of most cultivars.     

Change in the flavor of black tea drink during heat processing.

Heat processing during canning is responsible for the change in flavor of black tea infusion. The quantitative change in the volatile components of the black tea infusion during heat processing is not sufficient for explaining the sensory evaluation. In this study, application of aroma extract dilution analysis using the volatile fraction before and after black tea (Darjeeling) samples were heat processed resulted in the detection of 10 odor-active peaks for which flavor dilution (FD) factors changed. Seven potent odorants were identified from these peaks by gas chromatography-mass spectrometry. Among these components, 3-methylbutanal (stimulus), methional (potato-like), beta-damascenone (sweet), dimethyl trisulfide (putrid), and 2-methoxy-4-vinylphenol (clove-like) showed the highest FD factors after heat processing of the black tea sample. Therefore, these odorants were the most important components involved in changing the black tea odor during heat processing. In addition, the precursor of beta-damascenone in black tea infusion was investigated, and 3-hydroxy-7,8-didehydro-beta-ionol was determined to be one of the beta-damascenone-generating compounds for the first time.     

6种食用芳香植物挥发性成分的GC-MS/GC-O分析

挥发性成分是芳香植物具有多样风味及香气性能的物质基础。为研究常见可食用芳香植物的挥发性成分及其风味特性的异同,构建特色芳香植物风味数据库,利用气相色谱-质谱联用技术分析经顶空法萃取的6种食用芳香植物（薄荷、藿香、罗勒、丁香罗勒、香薷及密花香薷）的挥发性成分,经气相嗅辨仪对其挥发性成分进行香气描述分析,对比研究6种芳香植物挥发性成分的异同及香气性能的差异。结果表明：6种芳香植物香气主要由萜烯类、醇类、酮类、醛类成分组成,含有少量的酯类、杂环类及芳香族类化合物,多具有辛辣、刺激、樟脑样香气及清新的柠檬、柑橘风味。薄荷中以具花香和柠檬样香气的香叶醇、香茅醇及柠檬醛、香叶醛含量较多;藿香中以左旋薄荷酮及草蒿脑为主,具木香及大茴香似香气特征;罗勒中丙烯酸酯和芳樟醇是其主体成分,辛辣味突出,花香显;而丁香酚成就了丁香罗勒的主体风味,似丁香花香,具辛辣香气;香薷中以具柠檬样香气的D-柠檬烯、柠檬醛、γ-萜品烯为主,柠檬醛和香叶醛为密花香薷的主体成分,整体偏辛辣,花香透,伴柠檬样清新香气。不同的挥发性成分,以一定的比例及含量组成呈现了芳香植物的特征香气。研究结果可为特色芳香植物的品种选育、香气品质提升及风味性能的研究提供科学数据参考。     

食盐对鸡汤挥发性风味物质的影响

为探究食盐对鸡汤品质和挥发性风味物质的影响,以武定鸡与狄高鸡杂交系F₁为研究对象,采用料水比1∶3、炖煮时间2 h进行炖煮鸡汤,通过顶空固相微萃取(SPME)和气相色谱-质谱联用(GC-MS)方法检测不同食盐添加量对鸡汤中挥发性风味物质的影响。结果表明,随着食盐添加量的增加,鸡汤风味成分增多,其中,鸡汤中含量较高的挥发性风味物质主要为醛类物质和醇类物质,醛类物质主要为己醛、庚醛、壬醛、2-庚烯醛、正辛醛、反式-2-辛烯酸等,醇类物质主要为正辛醇和庚醇。感官评价结果显示,当食盐添加量为2%时,鸡汤感官评分最高,且挥发性风味物质组成较为丰富。因此,当料水比1∶3,炖煮2 h,食盐添加量为2%时,鸡汤的品质和食用最佳。本研究结果为探究食盐对鸡汤产品的挥发性成分提供了研究方法和科学依据。     

Volatile constituents of wild citrus Mangshanyegan (Citrus nobilis Lauriro) peel oil

Volatiles of a wild mandarin, Mangshanyegan (Citrus nobilis Lauriro), were characterized by GC-MS, and their aroma active compounds were identified by aroma extract dilution analysis (AEDA) and gas chromatography-olfactometry (GC-O). The volatile profile of Mangshanyegan was compared with those of other four citrus species, Kaopan pummelo (Citrus grandis), Eureka lemon (Citrus limon), Huangyanbendizao tangerine (Citrus reticulata), and Seike navel orange (Citrus sinensis). Monoterpene hydrocarbons predominated in Mangshanyegan, in particular d-limonene and β-myrcene, which accounted for 85.75 and 10.89% of total volatiles, respectively. Among the 12 compounds with flavor dilution factors (FD) = 27, 8 oxygenated compounds, including (Z)- and (E)-linalool oxides, were present only in Mangshanyegan. The combined results of GC-O, quantitative analysis, odor activity values (OAVs), and omission tests revealed that β-myrcene and (Z)- and (E)-linalool oxides were the characteristic aroma compounds of Mangshanyegan, contributing to the balsamic and floral notes of its aroma.     

电子鼻结合HS-SPME-GC-MS分析辐照对甲鱼预制菜挥发性风味成分的影响

为了探究辐照对甲鱼预制菜挥发性风味成分的影响,采用0、4.7、7.1、9.9 kGy剂量⁶⁰Co-γ射线辐照处理甲鱼预制菜,通过感官评定并利用电子鼻结合顶空固相微萃取-气相色谱-质谱联用技术(HS-SPME-GC-MS)分析辐照前后挥发性风味成分的变化。结果表明,5 kGy以内剂量辐照对甲鱼预制菜的感官品质无明显影响,高于5 kGy会影响其气味和滋味,进而可能产生异味。辐照对甲鱼预制菜特征气味引起的差异主要表现在传感器响应值较高的芳香成分和有机硫化物、氮氧化合物、甲烷、醇类和醛酮类物质,利用主成分分析(PCA)和线性判别分析(LDA)能够有效区分经不同剂量辐照处理的甲鱼预制菜。4.7 kGy组与对照组气味差异较小,7.1、9.9 kGy组与对照组差异相对较大。不同剂量辐照后甲鱼预制菜挥发性成分的种类增加,醛类、酸类相对含量降低,烃类、芳香族类、酮类、酯类相对含量升高,醇类、含氮含硫及杂环类相对含量先降低后升高。相对气味活度值(ROAV)分析结果表明,壬醛、癸醛、辛醛、己醛、庚醛、1-辛烯-3-醇和2-戊基呋喃是甲鱼预制菜的关键风味成分,苯甲醛、苯乙醛、(E,E)-2, 4-癸二烯醛对其风味具有重要修饰作用。辐照后辛醛、己醛、1-辛烯-3-醇对甲鱼预制菜总体风味的贡献率降低,庚醛、2-戊基呋喃的贡献率先降低后增加,苯乙醛的贡献率增加并成为关键风味成分。因此,建议采用不超过5 kGy剂量的⁶⁰Co-γ射线辐照处理甲鱼预制菜,在杀菌的同时最大限度保持其原有风味。本研究结果为辐照技术在甲鱼预制菜杀菌保鲜中的应用提供了科学依据。     

Determination of key aroma compounds in the crumb of a three-stage sourdough rye bread by stable isotope dilution assays and sensory studies

An investigation of the volatile fraction of a freshly prepared sourdough rye bread crumb by means of the aroma extract dilution analysis (AEDA), followed by identification experiments, revealed 22 flavor compounds in the flavor dilution (FD) factor range of 128 to 2048. Quantitations performed by stable isotope dilution assays (SIDA) and a calculation of odor activity values (OAV; ratio of concentration to odor threshold) revealed the following as contributors to the overall crumb flavor: 3-methylbutanal (malty), (E)-2-nonenal (green, fatty), (E,E)-2,4-decadienal (fatty, waxy), hexanal (green), acetic acid (sour, pungent), phenylacetaldehyde (honey-like), methional (boiled potato-like), vanillin (vanilla-like), 2,3-butandione (buttery), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (spicy), and 2- and 3-methylbutanoic acid (sweaty). Using either citrate buffer, starch, or deodorized crumb as model matrixes, the typical malty and sour rye bread crumb flavor was reproduced by adding a mixture of 20 reference odorants in the "natural" concentrations as quantitatively determined in the fresh crumb.     

Comparison of volatiles of cultured and wild sea bream (Sparus aurata) during storage in ice by dynamic headspace analysis/gas chromatography-mass spectrometry

Cultured and wild sea bream were compared for differences in their volatile components over a 23 day storage period in ice. A total of 60 compounds in cultured and 78 compounds in wild sea bream were tentatively identified (in addition to this, there were 23 unknowns in cultured and 29 unknowns in wild sea bream volatiles). These included aldehydes, ketones, alcohols, aromatics, terpenes, furans, sulfur-containing compounds, an acid, and miscellaneous compounds. Although selection of best fish is a subjective matter, more aldehydes, ketones, aromatics, and terpenes were found in wild sea bream as compared to that of its cultured counterpart. Both sea bream samples exhibited complex volatile profiles over the entire storage period. The combination of several classes of volatile compounds, dependent upon their concentrations and odor thresholds, is responsible for the distinctive and unique flavor of fresh cultured and wild sea bream. Relative concentrations of several compounds (trimethylamine, piperidine, methanethiol, dimethyl disulfide, dimethyl trisulfide, 1-penten-3-ol, 3-methyl-1-butanol, and acetic acid) increased continually throughout the storage period, and these may have the potential to be used as indicators of sea bream quality.     

采用气相色谱-离子迁移谱分析黄大茶加工过程挥发性成分

茶叶加工对茶叶香气的形成至关重要。为了研究黄大茶加工过程中香气成分的组成及变化规律,采用气相色谱-离子迁移谱(Gas Chromatography-Ion Mobility Spectrometry,GC-IMS)技术对黄大茶加工过程的挥发性成分进行分析。定性分析、鉴定茶叶挥发性成分,构建黄大茶加工过程挥发性成分的差异谱图,并以鉴定的挥发性成分对黄大茶加工过程进行主成分分析。共鉴定出挥发性成分40种,主要有醇类、酮类、醛类、酯类和杂环类化合物。杂环类和醛类化合物是黄大茶挥发性成分的主体部分,且杀青之后,杂环类化合物的含量随着加工过程的进行逐渐增加,醛类化合物的相对含量在初烘之后呈现显著性增加,而醇类及酮类挥发性成分的相对含量在初烘之后显著性降低(P0.05)。具花香的氧化芳樟醇只在初闷之前的样品中得到鉴定,在鲜叶中的含量最高,达21.98%,而1-辛烯-3-酮及苯乙酮只在初烘之后的样品中得到鉴定。通过GC-IMS的指纹图谱可知,苯甲醛、2,5-二甲基呋喃、糠醛及二甲基二硫等挥发性成分构成了经"拉老火"工序的黄大茶的特征峰区域。在一定程度上,主成分分析能够将黄大茶加工过程样品进行区分,表明气相色谱-离子迁移谱分析可为黄大茶加工过程的判别区分提供可能。相较于传统的茶叶挥发性成分检测分析技术,气相色谱-离子迁移谱具有快速、高效、绿色环保的特点。研究结果提供一种新的茶叶挥发性成分的检测分析方法,同时为茶叶加工过程监测及品质控制等提供了一定参考依据和理论基础。     

烫漂时间对香椿嫩芽颜色及挥发性风味成分的影响研究

为了研究香椿嫩芽烫漂过程中颜色热降解规律及挥发性风味成分的变化,分别采用分光光度法和光电反射光度法对香椿嫩芽叶绿素含量和色差进行测定,同时利用顶空固相微萃取及GC-MS联用技术对不同烫漂时间下香椿嫩芽的挥发性成分进行鉴定,并对各种处理后的风味物质进行主成分分析。结果表明,香椿嫩芽叶绿素降解和绿色损失均属于一级动力学反应,且叶绿素的减少与绿色损失相关性较好,呈极显著水平。烫漂后香椿嫩芽挥发性成分种类增多,含硫类等呈刺激性气味的化合物相对含量减少,烯类等呈柔和气味增加,提升了香椿的香味品质。综合颜色及挥发性成分随烫漂时间的变化规律,确定最佳烫漂时间为30s。主成分分析结果显示,第1、第2和第3主成分累积贡献率达98.742%,能够较好的代表原始数据所反应的信息。第1主成分包含噻吩类、烯类、醇类和醛类,贡献率大小为噻吩类烯类醇类醛类;第2主成分包含酮类和其它类,贡献率大小为酮类其它类;第3主成分为烃类。本研究结果为香椿嫩芽精深加工过程中颜色和风味的控制提供了理论依据。     

Repellent constituents of essential oil of Cymbopogon distans aerial parts against two stored-product insects

The screening for bioactive principles from several Chinese medicinal herbs showed that the essential oil of Cymbopogon distans aerial parts possessed strong repellency against the booklouse, Liposcelis bostrychophila , and the red flour beetle, Tribolium castaneum . A total of 36 components of the essential oil were identified by GC and GC-MS. trans-Geraniol (16.54%), (R)-citronellal (15.44%), (+)-citronellol (11.51%), and α-elemol (9.06%) were the main components of the essential oil followed by β-eudesmol (5.71%) and (+)-limonene (5.05%). From the essential oil, four monoterpenes were isolated by bioassay-guided fractionation. The compounds were identified as limonene, citronellol, citronellal, and trans-geraniol. Geraniol and citronellol were strongly repellent against the booklouse, L. bostrychophila, whereas citronellal and limonene exhibited weak repellency against the booklouse. Geraniol and citronellol exhibited comparable repellency against the booklouse relative to the positive control, DEET. Moreover, geraniol and citronellol exhibited stronger repellency against the red flour beetle than DEET, whereas the two other compounds showed the same level of repellency against the red flour beetle compared with DEET.