Preparation of reminiscent aroma mixture of Japanese soy sauce

To prepare an aroma mixture of Japanese soy sauce by fewest components, the aroma concentrate of good sensory attributes was prepared by polyethylene membrane extraction, which could extract only the volatiles with diethyl ether. GC-MS-Olfactometry was done with the aroma concentrate, and 28 odor-active compounds were detected. Application of aroma extract dilution analysis to the separated fraction revealed high flavor dilution factors with respect to acetic acid, 4-hydroxy-2(or5)-ethyl-5(or2)-methyl-3(2H)-furanone (HEMF), 3-methyl-1-butanol (isoamyl alcohol), and 3-(methylsulfanyl)propanal (methional). A model aroma mixture containing above four odorants showed a good similarity with the aroma of the soy sauce itself. Consequently, the reminiscent aroma mixture of soy sauce was prepared in water. The ratio of acetic acid, HEMF, isoamyl alcohol, and methional was 2500:300:100:1.     

Key compounds contributing to the fruity aroma characterization in Japanese raw soy sauce

In order to clarify the aroma characteristics of raw soy sauce (RS), the application of gas chromatography?olfactometry analysis to the aroma concentrate from a RS revealed 76 aroma peaks, of which 25 peaks showed fruit-like aromas. Furthermore, the head space aromatic compounds of RS were analyzed with 32 peaks detected. Ethyl 2-methylpropanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, and ethyl 4-methylpentanoate were detected with higher flavor dilution factor (FD factor) than other aroma compounds by aroma extract dilution analysis. Quantitative analysis suggested that these compounds were common in all RS samples tested in this study, and were present at higher concentrations than their perception thresholds. The concentrations and the FD factors of these compounds were significantly decreased during the heating of the RS. Fruitiness is one of the key aroma characteristics of RS and the ethyl esters identified in this study are the key components contributing to this distinct aroma.     

Aroma compounds in Japanese sweet rice wine (Mirin) screened by aroma extract dilution analysis (AEDA)

Thirty-nine key aroma compounds were newly identified or tentatively identified in the aroma concentrate of Japanese sweet rice wine (Mirin) by an aroma extract dilution analysis technique based on the 68 detected peaks. Among them, 3-(methylthio)propanal, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, 3-methylbutanoic acid, 2-methylbutanoic acid, and 2-methoxy-4-vinylphenol were detected with the highest FD factors in this study.     

Volatile compounds with characteristic odour in moso‐bamboo stems (Phyllostachys pubescens Mazel ex Houz. De ehaie)

Introduction – Moso‐bamboo (Phyllostachys pubescens) is well known as an edible shoot in Asia, and the stems of moso‐bamboo are used as tableware due to its characteristic odour. Despite the pleasant odour of bamboo stems, no detailed analysis of the volatile compounds has been reported. Objective – To clarify the potent odourants contributing to the characteristic aroma of the bamboo, the aroma extract dilution analysis (AEDA) method was performed through gas chromatography olfactometry (GC‐O) analysis. In addition, relative flavour activity (RFA) was calculated, in which both the flavor dilution (FD) factor and weight percentage of each compound are involved. Results – Eighty‐nine compound in bamboo stems oil were identified by GC and GC‐MS. The main components of the oil were palmitic acid (16.5%), (E)‐nerolidol (10.2%) and indole (8.1%). In sensory analysis, 18 aroma‐active compounds were detected by aroma extract dilution analysis (AEDA). The most intense aroma‐active compounds were eugenol (sweet, clove‐like, green) and (E)‐2‐nonenal (green). Conclusion – The results of the sniffing test, RFA and FD factor indicated that (E)‐2‐nonenal and eugenol were estimated to have a bamboo‐like aroma, and aldehyde compounds, such as a phenylacetaldehyde (floral) and C9–C10 unsaturated aldehydes, make the aroma of bamboo. Copyright © 2010 John Wiley & Sons, Ltd.     

Evaluation of aroma active compounds in <Emphasis Type="Italic">Tuber</Emphasis> fruiting bodies by gas chromatography–olfactometry in combination with aroma reconstitution and omission test

The aroma active compounds of three Tuber fruiting bodies (i.e., Tuber himalayense, Tuber indicum, and Tuber sinense) were firstly systematically evaluated by instrumental gas chromatography–olfactometry combining with quantitative analysis, aroma reconstitution, and omission tests. Twelve aroma active compounds were characterized by aroma extract dilution analysis, and 3-(methylthio) propanal, 3-methylbutanal, and 1-octen-3-ol with the highest flavor dilution (FD) factor (i.e., 1,024–2,048) were suggested as key contributors to the aroma. Odor activity value (OAV) was employed to determine the relative contribution of each compound to the aroma, and the compound with the highest FD factor also had the highest OAV (i.e., 10,234–242,951). Then, the synthetic blends of odorants (aroma reconstitution) were prepared with OAV larger than 15, and their aromas were very similar to the originals. Omission tests were carried out to verify the significance of 3-(methylthio) propanal, 1-octen-3-ol, and 3-methylbutanal as key compounds in the aroma of tested Tuber fruiting bodies.     

葡萄果实香气成分的厌氧萃取研究

采用厌氧液-液萃取对葡萄果实中的香气成分进行了萃取,用气相色谱-质谱联用技术对其进行成分分析,并与葡萄果实常规萃取方法得到的香气成分进行比较。结果显示,采用厌氧萃取方法得到的萃取物含有的香气成分较多,一次性萃取可分析得到39种香气成分,且以内标物2-辛醇表示的香气成分含量明显高于常规萃取方法;香气成分归属的化学类别更多,比分液漏斗萃取方法多出2类香气成分。结果表明,厌氧萃取所得果实香气成分更真实,更典型,为葡萄果实香气成分的分析提供了一种有效的提取方法。     

Identification of the possible new odor-active compounds “12-methyltridecanal and its analogs” responsible for the characteristic aroma of ripe Gouda-type cheese

The aroma concentrates of the three maturation stages of Gouda-type cheeses were prepared by combining the solvent extraction and the solvent assisted flavor evaporation techniques. The aroma extract dilution analysis applied to the volatile fraction revealed 31 odorants that were identified or tentatively identified from the 38 odor-active peaks with FD factors between 4³ and 4⁸. By comparison with the FD factors in the three maturation stages of the cheeses, 16 odorants, including 12-methyltridecanal, which is a newly identified odorant from the cheese, increased with the increasing maturation stage of the cheese. In addition, many iso- and anteiso-methyl-branched long-chain aliphatic aldehydes could be identified as the analogs of 12-methyltridecanal, which have a unique odor note. It may be then expected that these aldehydes were able to influence the flavor of the highly ripened Gouda cheese, since these compounds also increased with the increasing maturation stage.     

Characteristics of aroma-active compounds in the pectin-elicited suspension culture of Zanthoxylum piperitum (prickly ash)

Zanthoxylum piperitum (prickly ash) was grown as a suspension culture in Schenk and Hildebrandt medium supplemented with 50 g sucrose l^–1 and 0.5 mg 2,4-dichlorophenoxyacetic acid l^–1 for 21 days with elicitation by pectin added at day 15. Volatile compounds were extracted from the culture and 3-hydroxy-2-butanone was identified by GC-MS as the most abundant compound, followed by -butyrolactone and 2,3-butanedione. 2,3-Butanedione, ethyl 3-methylbutyrate, and ethyl 2-methylpropanoate were identified as the most intense aroma-active compounds and represented the characteristic aroma of the culture.     

Influence of wine fermentation temperature on the synthesis of yeast-derived volatile aroma compounds

The yeast Saccharomyces cerevisiae synthesises a variety of volatile aroma compounds during wine fermentation. In this study, the influence of fermentation temperature on (1) the production of yeast-derived aroma compounds and (2) the expression of genes involved in aroma compounds’ metabolism (ADH1, PDC1, BAT1, BAT2, LEU2, ILV2, ATF1, ATF2, EHT1 and IAH1) was assessed, during the fermentation of a defined must at 15 and 28°C. Higher concentrations of compounds related to fresh and fruity aromas were found at 15°C, while higher concentrations of flowery related aroma compounds were found at 28°C. The formation rates of volatile aroma compounds varied according to growth stage. In addition, linear correlations between the increases in concentration of higher alcohol and their corresponding acetates were obtained. Genes presented different expression profiles at both temperatures, except ILV2, and those involved in common pathways were co-expressed (ADH1, PDC1 and BAT2; and ATF1, EHT1 and IAH1). These results demonstrate that the fermentation temperature plays an important role in the wine final aroma profile, and is therefore an important control parameter to fine-tune wine quality during winemaking.     

产香酵母Pichia myanmarensis LX15的分离纯化及对精酿啤酒风味物质形成的影响

为了适应精酿啤酒对个性化风味的需求,能产生特定风味化合物的产香酵母成为研究者的研究重点。从精酿啤酒原液中分离到1株产香酵母LX15菌,该菌细胞呈圆形或卵圆形、多极芽殖生长;LX15菌在玉米粉培养基上培养7~10 d不形成假菌丝,在酵母膏蛋白胨培养基上培养3 d能够形成子囊孢子。经生理生化特征和系统发育分析,确认该生香酵母为Pichia myanmarensis菌中的一个菌株,所产主要风味化合物包括乙酸乙酯、乙酸异戊酯、己酸乙酯和辛酸乙酯。当LX15菌与啤酒酵母C1菌共发酵时,能够产生协同效应,提高酯类化合物和高级醇类的含量,并与LX15菌的接种比例正相关,但并不影响啤酒酿造的整体发酵速率和发酵能力。因此,LX15菌是一株适于提高精酿啤酒风味的产香酵母菌。     

Large-Scale Selection and Breeding To Generate Industrial Yeasts with Superior Aroma Production

The concentrations and relative ratios of various aroma compounds produced by fermenting yeast cells are essential for the sensory quality of many fermented foods, including beer, bread, wine, and sake. Since the production of these aroma-active compounds varies highly among different yeast strains, careful selection of variants with optimal aromatic profiles is of crucial importance for a high-quality end product. This study evaluates the production of different aroma-active compounds in 301 different Saccharomyces cerevisiae, Saccharomyces paradoxus, and Saccharomyces pastorianus yeast strains. Our results show that the production of key aroma compounds like isoamyl acetate and ethyl acetate varies by an order of magnitude between natural yeasts, with the concentrations of some compounds showing significant positive correlation, whereas others vary independently. Targeted hybridization of some of the best aroma-producing strains yielded 46 intraspecific hybrids, of which some show a distinct heterosis (hybrid vigor) effect and produce up to 45% more isoamyl acetate than the best parental strains while retaining their overall fermentation performance. Together, our results demonstrate the potential of large-scale outbreeding to obtain superior industrial yeasts that are directly applicable for commercial use.     

GC-MS and GC-olfactometry analysis of aroma compounds extracted from culture fluids of <Emphasis Type="Italic">Antrodia camphorata</Emphasis>

A comprehensive inventory of the organic components and aroma-active compounds produced by Antrodia camphorata during growth in submerged culture has been established by extracting culture fluids using three different organic solvent systems and subjecting the extracts to gas chromatography-mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC-O). Forty-two organic components, of which esters, alcohols, acids and ketones were the most prevalent, were identified in pentane/ether (1/1, v/v) extracts. The most representative of A. camphorata aroma-active compounds were detected in pentane/ether and ether extracts (eleven and nine aroma-active compounds, respectively) by GC-O. Of these, ethyl acetate, γ-undecalactone, linaloöl and 3-hydroxy-2-butanone were assessed to be present at the highest intensity.     

Odor-active constituents in fresh pineapple (Ananas comosus [L.] Merr.) by quantitative and sensory evaluation

By application of aroma extract dilution analysis (AEDA) to an aroma distillate prepared from fresh pineapple using solvent-assisted flavor evaporation (SAFE), 29 odor-active compounds were detected in the flavor dilution (FD) factor range of 2 to 4,096. Quantitative measurements performed by stable isotope dilution assays (SIDA) and a calculation of odor activity values (OAVs) of 12 selected odorants revealed the following compounds as key odorants in fresh pineapple flavor: 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDF; sweet, pineapple-like, caramel-like), ethyl 2-methylpropanoate (fruity), ethyl 2-methylbutanoate (fruity) followed by methyl 2-methylbutanoate (fruity, apple-like) and 1-(E,Z)-3,5-undecatriene (fresh, pineapple-like). A mixture of these 12 odorants in concentrations equal to those in the fresh pineapple resulted in an odor profile similar to that of the fresh juice. Furthermore, the results of omission tests using the model mixture showed that HDF and ethyl 2-methylbutanoate are character impact odorants in fresh pineapple.     

New xanthine oxidase inhibitors from the fruiting bodies of Tyromyces fissilis

Excessive uric acid production, which causes gout and hyperuricemia, can be blocked by inhibiting xanthine oxidase (XO). However, some agents to block on XO often cause side effects, thereby necessitating the identification of new inhibitors. During the screening of XO inhibitors from various mushroom extracts, we found that a methanolic extract of the fruiting bodies of Tyromyces fissilis, an inedible and non-toxic fungus, showed inhibitory activity. Both n-hexane and ethyl acetate layers, obtained by partitioning this extract exhibited XO inhibitory activity. Subsequently, using an activity-guided separation method, eight active compounds (1–8) were isolated. The structures of five of the new compounds, 2–4, 6, and 7, were elucidated by spectral analysis and chemical derivatization. All compounds had a salicylic acid moiety with an aliphatic group at the C-6 position. Notably, 2-hydroxy-6-pentadecylbenzoic acid (1) showed the highest level of XO noncompetitive inhibition (58.9 ± 2.2% at 25 µM).     

Chemical Composition and Aroma Evaluation of Essential Oils from Evolvulus alsinoides L.

The aim of this study was to investigate the chemical composition and the odor‐active compounds of the essential oils from Evolvulus alsinoides, which is a well‐known edible and medicinal plant. The volatile compounds in the oils were identified by hydrodistillation (HD) and solvent‐assisted flavor evaporation (SAFE) in combination with GC, GC/MS, GC/O (=olfactometry), aroma extract dilution analysis (AEDA), and relative flavor activities (RFA values). The most abundant compound in the HD oil was cis‐α‐necrodol (12.62%), an irregular monoterpene with a cyclopentane skeleton, which is very unusual in the plant kingdom. In the SAFE oil, the main components included 2‐butoxyethanol (9.01%), benzyl alcohol (8.01%), and γ‐butyrolactone (7.37%). Through sensory analysis, 21 aroma‐active compounds were identified by GC/O. The most intense aroma‐active compounds in the HD oil were hexan‐1‐ol and γ‐nonalactone, both of which showed high RFA values. α‐Methyl‐γ‐butyrolactone and dimethyl sulfone contributed more strongly to the aroma of the SAFE oil. These results imply that the essential oils of E. alsinoides deserve further investigation in the food industry.     

不同地域黄枝香乌龙茶的香气化学组成

用气相色谱／质谱联用法分析了高香型乌龙茶凤凰单枞—黄枝香在不同地域的香气化学组成．结果表明,不同地域样品香气化合物在检测的种数上差异不大,但类别及含量则有明显差异．黄枝香从山地引种于平地种植后,在其香气化合物中未能检测到乌龙茶的主要赋香成分——吲哚和茉莉酮,此外,橙花叔醇亦只有痕量检出,初步认为凤凰名枞—黄枝香存在着明显的地域香．     

Volatile constituents of glutathione--ribose model system and its antioxidant activity

Summary.  Reaction between glutathione and ribose was carried out to study the volatiles formed via Maillard reaction and their antioxidant activity as well as their role in inhibition of LDL oxidation. The simultaneous distillation – extraction technique was used for trapping the volatile components followed by GC – MS analysis. Thirty six compounds were identified with the predominance of carbonyls and sulfur – containing compounds in the volatiles of this model system. Sensory evaluation was performed for the model system product according to the International Standard Methods (ISO). The results showed a high decrease in roasted and burnt attributes and remarkable increase in the like – boiled and roasted meat attributes. The sensory results of the model system product were confirmed by the presence of high concentrations of some volatile compounds having meat – like aroma such as 2-methyl-3-furanthiol and 2-furylmethanethiol. The radical scavenging activity of glutathione – ribose model system was quantified spectrophotometrically, using DPPH radical. The activity of the model system product was found to be slightly lower than that of gallic acid and BHA, but it was much higher than that of cinnamic acid (200 ppm. for each). A highly antioxidative activity was recorded by the model system product during the inhibition of LDL – oxidation in comparison with L-ascorbic acid as well as reduced glutathione (as a concentration of 0.5 μmol/L, for each) which may be due to the presence of some compounds such as 2-furylmethanethiol, 2-acetyl thiazole, 4-hydroxy-5-methyl-3(2H)-furanone. Received October 15, 2001 Accepted April 3, 2002 Published online September 4, 2002 Authors' address:  Khaled Farouk El-massry, Flavour and Aromatic Chemistry Department, National Research Center, Tahrir st., Dokki, Cairo, Egypt, Fax: 002 02 337 0 931, E-mail: kfarouk@yahoo.com     

Evaluation of Characteristic Aroma Compounds of Citrus natsudaidai Hayata (Natsudaidai) Cold-Pressed Peel Oil

The characteristic aroma compounds of Citrus natsudaidai Hayata essential oil were evaluated by a combination of instrumental and sensory methods. Sixty compounds were identified and quantified, accounting for 94.08% of the total peel oil constituents. Limonene was the most abundant compound (80.68%), followed by γ-terpinene (5.30%), myrcene (2.25%) and α-pinene (1.30%). Nineteen compounds which could not be identified in the original oil were identified in the oxygenated fraction. Myrcene, linalool, α-pinene, β-pinene, limonene, nonanal, γ-terpinene, germacrene D, and perillyl alcohol were the active aroma components (FD-factor > 3⁶), whereas β-copaene, cis-sabinene hydrate and 1-octanol were suggested as characteristic aroma compounds, having a Natsudaidai-like aroma in the GC effluent. Three other compounds, heptyl acetate, (E)-limonene oxide and 2,3-butanediol, which each showed a high RFA value (>35) were considered to be important in the reconstruction of the original Natsudaidai oil from pure odor chemicals. The results indicate that 1-octanol was the aroma impact compound of C. natsudaidai Hayata peel oil.     

Volatile aroma constituents of Sri Lankan ginger

Two types of Sri Lankan ginger were examined (Sidda and Chinese varieties) and essential oils of both fresh and dried samples were prepared by standard procedures. Both varieties yielded relatively high percentages of oil (between 1.8 and 4.3%) and total aroma volatiles (ca 5 mg/g for dried samples). Analysis by GC and GC/MS showed terpenes to be the main aroma components (ca 99% for all samples). A number of the identified compounds have not previously been reported as ginger volatiles, including trans-β-ocimene, thujyl alcohol, terpinen-4-ol, myrtenal, guaiene, α-cubebene, δ-cadinene and farnesol. On drying, both varieties of Sri Lankan ginger showed considerable decrease in monoterpene content and very high increase in sesquiterpene concentration. Comparing the aroma volatiles of Sri Lankan dried ginger with those previously reported for dried ginger from some other countries, it was concluded that Sri Lankan ginger was as good as, if not superior to, other types. In particular, SriLankan dried ginger showed high levels of ar-curcumene together with reasonable levels of citral isomers and all other constituents previously claimed to be important to ginger aroma. Sri Lankan ginger would appear to be unusual in containing very low amounts of zingiberene but very high amounts of β-bisabolene.