Comparison of fermented soybean paste (Doenjang) prepared by different methods based on profiling of volatile compounds

Abstract: In this study, 2 different extraction methods, namely solvent‐assisted flavor evaporation (SAFE) and solid‐phase microextraction (SPME), were employed to investigate the comprehensive volatile profile of Doenjang (one of Korean fermented soybean pastes) efficiently. Quantitatively, major volatiles of Doenjang isolated by SAFE were 3‐methylbutanoic acid, butanoic acid, 3‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one (maltol), ethyl 2‐methylbutanoate, 2‐methylpropanoic acid, tetramethylpyrazine, and 4‐ethyl‐2‐methoxyphenol, while ethanol, ethenylbenzene, ethyl benzoate, ethyl linoleate, ethyl acetate, ethyl butanoate, tetramethylpyrazine, and ethyl 2‐methylpropanoate extracted by SPME. In addition, volatile profiling that applied principal component analysis to gas chromatography‐mass spectrometry datasets allowed Doenjang samples that had been prepared using different traditional and commercial methods to be discriminated, and the volatile compounds that contributed to their discrimination were assigned. The major volatiles that were related to differentiation of traditional and commercial Doenjang samples were 2‐pentylfuran, 4‐ethylphenol, dihydro‐5‐methyl‐2(3H)‐furanone, butanoic acid, pyrazines (for example, 2‐ethyl‐5‐methylpyrazine and 2,3‐dimethylpyrazine), esters (for example, ethyl 4‐methylpentanoate and diethyl succinate), maltol, dimethyl disulfide, 2‐ and 3‐methylbutanal, hexanal, 4‐vinylphenol, and ethanol.     

Changes in volatile compounds of pickled mustard tuber (Brassica juncea var. tsatsai) during the pickling process

This study was carried out to determine the changes of volatile compounds composition during pickled mustard tuber production. The samples were collected at different pickling stages from the traditional industry production way in Chongqing, China. Gas chromatography–mass spectrometry were performed after simultaneous distillation and extraction. The results showed that ITC (isothiocyanates) possessed the highest relative percentage area (RPA) 78.87%, followed by sulphide compounds with RPA of 14.48%. Main volatile compounds that determined were allyl ITC, dimethyl trisulphide, (2-isothiocyanatoethyl)-benzene, n-Hexadecanoic acid and linolenic acid ethyl ester, which were responsible for the hot and pungent flavour of pickled mustard tuber. The sulphides, acids, aldehydes, alcohols, phenols, esters, nitriles and heterocyclic compounds increase with pickling time but ITC increase at the first and second pickling stage, then start to decrease in the last pickling stage. It was also demonstrated that more than 60-day pickling time was necessary for the formation of the typical aroma notes.     

Characterization of volatile compounds from Daqu‐a traditional Chinese liquor fermentation starter

Daqu is a fermentation starter and substrate complex that is used to initiate the solid fermentations for the production of Chinese liquor. The aroma of Daqu is one of the most important factors that influence the flavour of Chinese liquor. To further study the aroma of Daqu, volatile compounds in ten Daqu samples were extracted by headspace solid‐phase microextraction (HS‐SPME) and analysed by gas chromatography–mass spectrum (GC‐MS). The samples were pre‐equilibrated at 50 °C for 10 min and extracted with stirring at the same temperature for 30 min prior to injection into a GC‐MS. A total of 75 volatile compounds were characterised by GC‐MS, including twelve alcohols, eleven esters, eight acids, nine aromatic compounds, four phenols, two furans, fourteen nitrogen‐containing compounds and fifteen aldehydes and ketones. By a principal component analysis (PCA), the ten Daqu samples could be classified into three groups according to their origins and, in particular, the production technologies.     

Changes in volatile aroma compounds of pineapple (Ananas comosus) during freezing and thawing

Changes in the volatile aroma compounds of pineapple (Ananas comosus) during freezing and thawing were compared against fresh samples to determine the effect of freezing on pineapple flavour. An HS‐SPME–GC–MS analysis showed that the Smooth Cayenne pineapple variety had nineteen volatile compounds, in four classes of compounds including fourteen esters, two hydrocarbons, two sulphur‐containing compounds and one lactone. The main characteristic volatile compounds of the fresh pineapple were methyl hexanoate, ethyl hexanoate, ethyl 3‐methylthiopropanoate and 1‐(E,Z)‐3,5‐undecatriene. Freeze–thaw cycles were associated with the loss of some volatile aroma compounds, particularly the esters which were found to be the main characteristic of fresh pineapples. The freezing and thawing process was found to cause damage to the pineapple tissues due to ice recrystallisation and dehydration which lead to the reduction of volatile aroma compounds.     

罐罐肉加工与贮藏过程中挥发性物质变化的研究

为了探明雅安罐罐肉挥发性物质的变化规律,本研究以不同加工与贮藏阶段的罐罐肉为对象,用同时蒸馏萃取结合气相色谱/质谱法对挥发性化合物进行分析。结果显示,罐罐肉在加工与贮藏过程中共检测出120种挥发性物质,醇、醛、酮、烃、酰胺、酯是主要成分,其中以己醛和2,4-癸二烯醛为主的醛类物质相对含量最高（最高达64.42%）。在加工过程中醛、酮、酯显著增加,并检测出酰胺类物质。在贮藏过程中醇、醛、酮的相对含量整体呈现下降趋势,烃类、酰胺类、酯类和其他化合物的相对含量整体呈上升趋势,并新产生了（2E）-2-十一碳烯醛、甲酸己酯、（Z）-9-十八烯酸酰胺和2-戊基呋喃等物质。      

新疆焉耆盆地产区4种甜白葡萄酒中挥发性香气成分分析

为了研究焉耆盆地产区甜白葡萄酒的挥发性香气成分,延伸该产区甜白葡萄酒的产业链,该实验采用顶空固相微萃取（HSSPME）结合全二维气相色谱-飞行时间质谱（GC×GC-TOFMS）检测了新疆焉耆盆地产区的4种甜白葡萄酒中的香气成分,并对分析结果进行主成分分析（PCA）。结果表明,新疆焉耆盆地产区4种甜白葡萄酒中共检测出103种香气成分,其种类相似,但含量有差别,酯类和醇类物质总含量在各样品中均占80%以上。通过PCA初步确定了焉耆盆地产区4种甜白葡萄酒中各自的特征香气化合物,且4种甜白葡萄酒挥发性香气成分之间的得分关联度较小,构成了甜白葡萄酒独特的风味特征。     

百里香精油挥发性成分的研究

采用同时蒸馏与萃取法提取百里香精油,经气相色谱及色谱/质谱联用系统分析,并依据各成分的保留指数,鉴定出62种挥发性成分,其中有26种碳氢化合物、14种醇类物质、6种醛类物质、6种酯类物质、2种酚类物质、6种醚类物质和2种酮类物质。主要成分是百里酚、伞花烯、γ-萜品烯等。     

泸型酒酿造过程中各层酒醅挥发性物质变化规律

采用顶空固相微萃取（HS-SPME）结合气相色谱-质谱（GC-MS）联用技术,对泸州老窖浓香型白酒（泸型酒）酿造过程中上、中、下层酒醅的主要挥发性风味物质的变化规律进行分析,并基于酯类物质进行主成分分析（PCA）。结果表明,三层酒醅的主要挥发性风味物质为醇类、酸类和酯类,其在不同层酒醅发酵过程中的变化趋势相似,醇类物质相对含量变化不明显;发酵前期（0～15 d）,酯类物质相对含量上升,酸类物质相对含量下降,发酵后期（18～39 d）这两种物质变化趋于平稳。发酵结束时,上层酒醅主要挥发性风味物质含量最高,下层酒醅次之,中层酒醅最低。PCA结果表明,泸型酒发酵过程分两个阶段,发酵前期特征酯类物质为乙酸乙酯和丁酸乙酯等,发酵后期特征酯类物质为己酸乙酯、乳酸乙酯等。     

SPME-GC-MS联用检测东坡肘子中挥发性风味成分

采用固相微萃取-气质联用（SPME-GC-MS）的方法,对王家渡、惠通、蜀州、梅林及楼外楼5种东坡肘子中的挥发性风味成分进行分离鉴定。共鉴定出118种挥发性风味化合物,其中烃类41种,醛类16种,酮类9种,醚类2种,醇类18种,酯类4种,酸类2种,酚类7种,呋喃及含N、S类19种。其中烃类、醛类、醇类和呋喃及含N、S类物质对东坡肘子的风味可能有着较为显著的影响。      

Dehydration kinetics of red pepper (Capsicum annuum L var Jaranda)

Shredded and whole red pepper samples were dehydrated in a laboratory drier with a through‐flow air velocity of 0.5 m s^?1 at 50, 55, 60 and 70 °C. Shredded peppers dried faster than whole peppers. The drying behaviour of whole samples was characterised by a constant‐ and a falling‐rate drying period, whilst that of shredded samples was characterised by a falling‐rate drying period only. The mass transfer coefficient for whole samples during the constant‐rate period was computed experimentally. The effect of temperature on the mass transfer coefficient was described by the Arrhenius model. The activation energy was 58 kJ mol^?1. In the falling‐rate period the mass transfer was described by a diffusional model, and the effective diffusion coefficient at each temperature was determined. Diffusion coefficients were estimated to lie between 4.38 × 10^?11 and 10.99 × 10^?11 m² s^?1 for whole peppers and between 37.23 × 10^?11 and 99.61 × 10^?11 m² s^?1 for shredded peppers. The effect of temperature on the effective diffusion coefficient was described by the Arrhenius equation, with an activation energy of 44 kJ mol^?1 for whole peppers and 56 kJ mol^?1 for shredded peppers. © 2003 Society of Chemical Industry     

Study of volatile compounds of defective virgin olive oils and sensory evaluation: a chemometric approach

It is well known that olive oils are the only foods whose legal control must also involve sensory evaluation, and that a harmonised protocol is used for this purpose: EEC regulation 2568/91 and an IOOC trade norm of the 1990s introduced a standard method among those used to assess the quality of virgin oils, after which a modified method known as the ‘panel test’ was developed and adopted, firstly by the IOOC and later by the EEC. One problem in applying the panel method often depends on the lack of reference standards for training judges, in addition to, in some cases, a lack of exact knowledge of the origin of some defects; for these reasons, several judges have suggested the unification of some defects, even when these originate from different kinds of problems. In this paper we have applied headspace analyses to a number of samples of oils that were also characterised by a panel. Besides the samples, standard defective oils obtained by the IOOC and used for training sensory judges were also analysed, with the aim of obtaining a model for use in method validation. Seventy‐six peaks were detected and most of them identified by gas chromatography/mass spectrometry; their distribution was different in the samples characterised by different defects as assessed by the panel test. The well‐known compounds of virgin olive oils were detected, including the series of C₆ compounds, whose importance in defining positive (‘green’ flavour) and negative (rancid) characteristics of olive oils is well known. No samples classified as extra virgin ever present peaks with magnitudes as great as those found in defective oils. Chemometric data evaluation was carried out and samples were clustered on the basis of the headspace composition; the results were found to agree with those of the panel test, so a number of compounds were related to the presence of particular defects. Copyright © 2005 Society of Chemical Industry     

柑橘花不同部位香气成分的测定及主成分分析

应用顶空—固相微萃取—气相色谱—质谱联用法(headspace solid-phase microextraction-gas chromatographymass spectrometry,HS-SPME-GC-MS)分离鉴定柑橘花4个部位(花瓣、花托、雌蕊、雄蕊)的香气成分,运用主成分分析法(PCA)评价柑橘花的主要香气成分及各部位香气成分差异程度。结果表明,烃类和醇类是柑橘花的主要香气类物质;花瓣、花托、雌蕊挥发性香气成分以芳樟醇、桧烯、柠檬烯、β-月桂烯、α-罗勒烯为主,而雄蕊以芳樟醇、桧烯、橙花叔醇、β-月桂烯为主;主成分分析表明,柑橘花4个部位香气成分差异程度较大,桧烯、柠檬烯、α-侧柏烯、β-月桂烯、顺-β-金合欢烯为主的烯烃类是导致花托与雄蕊香气成分差异较大的物质,香茅醛、反式-柠檬醛、4-萜烯醇、α-松油醇为主的醛醇类是导致花瓣与雌蕊香气成分差异较大的物质。     

Optimization of equilibrium headspace analysis of volatile flavor compounds of malaysian soursop (Annona muricata): Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS)

Headspace solid-phase microextraction (HS-SPME) coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOFMS) was applied for equilibrium headspace analysis of Malaysian soursop (Annona muricata) volatile flavor compounds. A two-level fractional factorial design (2^5-1) was used to determine the effect of SPME variables, namely, SPME fibers, adsorption temperature, extraction time, amount of salt, sample amount and sample concentration on the extraction efficiency of volatile flavor compounds. A total of 37 volatile compounds were identified, comprising 21 esters, 6 alcohols, 3 terpenes, 2 acids, 2 ketones, 2 aldehydes and an aromatic with different hydrophobicities (log P) ranging between −0.14 and 4.83. Extraction using 10 g of diluted (5% w/w) blended soursop pulp with CAR/PDMS fiber at 25 °C for 30 min and 30% (w/w) of NaCl under stirring mode resulted in the highest extraction efficiency of volatile flavor compounds. The principal component analysis score discriminated the influence of SPME variables on the equilibrium headspace concentration of target volatile compounds.     

Characterization of the Lipid Fraction of Wild Sea Urchin from the Sardinian Sea (Western Mediterranean)

The fatty acid (FA) composition of Spatangus purpureus, Echinus melo, Sphaerechinus granularis, and Paracentrotus lividus, sea urchins, has been studied. Sea urchins were collected at different depth along Sardinia coast in the Mediterranean sea, and their gonad was measured, separated, and analyzed for FA composition by gas chromatography‐mass spectrometry. A total of 53 FAs were detected, 16 saturated (SFA), 10 monounsaturated (MUFA), 9 polyunsaturated (PUFA), and 13 highly unsaturated (HUFA). Moreover, 5 furan FAs (FFAs) were revealed for the first time in sea urchin. The HUFA and PUFA classes were the most represented accounting for almost 80% of total FAs. Among these compounds, C20:4 n6 (19.64, 20.52, 23.37, and 8.48 mg/g, respectively) and C22:6 n3 (19.68, 20.05, 3.83, and 1.78 mg/g, respectively) were the most abundant. The results of principal component analysis indicated that the sea urchin samples could be clearly discriminated with respect to their FAs composition.     

柠檬果肉真空冻结过程中挥发性风味成分变化

目的：探索柠檬果肉真空冻结过程中挥发性风味成分的变化规律。方法：利用电子鼻（E-nose）和气质联用（GC-MS）技术分别对新鲜、真空冻结10,20,30 min的柠檬果肉样品的挥发性风味物质进行分析。结果：E-nose可从整体上分析柠檬果肉中不同类别的挥发性风味成分,主成分分析和线性判别分析可区分新鲜和不同冻结时间的样品;GC-MS分析发现真空冻结过程中柠檬果肉挥发性风味物质的种类和含量均显著下降（P<0.05）;柠檬果肉中的主要挥发性风味物质主要是烯烃类、醇类、醛类化合物,其在真空冻结过程中的损失均呈先快后慢的趋势,通过热图和聚类分析可将真空冻结过程中所出现的挥发性风味成分划分为四大类;真空冻结10 min后,D-柠檬烯损失率最高;真空冻结20 min后,烯烃类、醇类和醛类化合物含量下降较为显著,酮类化合物含量变化不明显;真空冻结30 min后,出现了2,4-二甲基苯甲醛和2,4-二叔丁基苯酚新生挥发性风味成分。结论：柠檬果肉中绝大多数挥发性风味成分在真空冻结过程中呈明显下降趋势,并有部分新物质生成。     

固相微萃取在食品挥发性组分测定方面研究进展

固相微萃取是一种新颖的样品前处理与富集技术,其克服传统预处理方法几乎所有缺点,可与多种色谱技术联用;对食品风味组分检测大多采用固相微萃取与GC、GC–MS等技术联用,而新涂层开发、与其它分析方法联用是固相微萃取测定挥发性组分研究方面重要方向。     

基于气质联用法的两种香型白酒挥发性成分差异分析

采用气质谱联用（GC-MS）法对酱香型和浓香型白酒的挥发性物质进行了分析,并采用主成分分析（PCA）法研究不同香型白酒挥发性物质差异。结果表明,酱、浓香型酒样挥发性成分分别共检测出62种（定性60种）和36种（定性35种）,前者酯类、酸类、吡嗪类等化合物的种类多于后者。酱、浓香型酒样在39种挥发性物质含量上有显著差异（P＜0.05）,其中酱香型酒样中呋喃类及吡嗪类化合物含量分别是浓香型酒样的7.54倍和46.95倍,且醇类物质含量高于浓香型白酒;而浓香型酒样中4-甲基苯酚、己酸及其酯类物质含量分别是酱香型酒样的16.67倍、16.67倍和2.63倍,己酸异戊酯、己酸己酯、己酸乙酯等酯类含量显著高于酱香型酒样（P＜0.05）。酒体挥发性物质的构成差异是白酒香型及风格差异的实质。