Key aroma volatile compounds of gulupa (Passiflora edulis Sims fo edulis) fruit

By application of the aroma extract dilution analysis of gulupa (Passiflora edulis Sims fo edulis), fruit pulp extract obtained by solvent-assisted flavour extraction, and also comparison of chromatographic, spectroscopic (mass spectrum), and odour properties with standards, β-ionone, γ-nonalactone, ethyl butanoate, and ethyl cinnamate were identified as volatiles exhibiting the highest flavour dilution (FD) factor. Among the nineteen odour-active compounds of gulupa, only those showing the highest FD factors were quantified by stable isotope dilution assay. After calculation of odour activity values (OAVs; ratio of concentration to odour threshold in water), ethyl butanoate, ethyl hexanoate, and β-ionone were identified as key aroma compounds in gulupa, responsible for the fruity and floral odour notes.     

Characterisation of the key aroma compounds in a freshly reconstituted orange juice from concentrate

Application of an aroma extract dilution analysis on the entire volatile fraction isolated from an orange juice freshly reconstituted from concentrate revealed 40 odour-active constituents in the flavour dilution (FD) factor range of 4–2,048. Among them, ethyl butanoate and linalool showed the highest FD factor of 2,048, followed by octanal with an FD factor of 512. Thirty-six of the 40 odour-active compounds detected could be identified, all of which have previously been reported as volatile constituents of various orange juices. Quantification of 17 key odorants by stable isotope dilution assays followed by a calculation of odour activity values (OAVs) on the basis of odour thresholds in water or citrate buffer (pH 3.8), respectively, revealed the following most important odorants in the overall aroma of the freshly reconstituted juice: (R/S)-linalool, (R)-limonene and (S)-ethyl 2-methylbutanoate with the highest OAVs (>1,000) followed by octanal, (R)-α-pinene, ethyl butanoate, myrcene, acetaldehyde, decanal and (E)-β-damascenone with OAVs > 100. A model mixture containing all 14 aroma compounds with OAVs > 1 in their actual concentrations in the juice showed a good similarity with the aroma of the original orange juice under investigation, thus corroborating that the key odorants of a freshly reconstituted orange juice were characterised for the first time.     

Odour-active compounds in banana fruit cv. Giant Cavendish

Application of solid-phase microextraction, simultaneous distillation–extraction and liquid–liquid extraction, combined with GC–FID, GC–MS, aroma extract dilution analysis, and odour activity value were used to analyse volatile compounds from banana fruit cv. Giant Cavendish and to estimate the most odour-active compounds. The analyses led to the identification of 146 compounds, 124 of them were positively identified. Thirty-one odourants were considered as odour-active compounds and contribute to the typical banana aroma, eleven of them are reported for the first time as odour-active compounds.     

Important odorants of sweet bell pepper powder (Capsicum annuum cv. annuum): differences between samples of Hungarian and Morrocan origin

 By application of gas chromatography–olfactometry on aroma extracts prepared from Hungarian sweet bell pepper powder (HBP) and Moroccan sweet bell pepper powder (MBP), 35 and 42 odour-active compounds were detected in the HBP and the MBP, respectively. The identification experiments, in combination with the flavour dilution (FD) factors obtained by application of aroma extract dilution analysis, revealed that β-ionone (violet-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol; caramel-like), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon; seasoning-like) and 2- and 3-methylbutanoic acids had the highest odour activities (FD factors of 8192 to 32768) among the 33 odorants that could be identified in the HBP. All odorants identified in the HBP were also characterized as odour-active volatiles in the MBP. The overall different aroma of the Moroccan sample could, however, be attributed to the lower FD factors of the five key odorants mentioned above and, in addition, to the higher FD factors of 10 odorants not present among the aroma compounds of the HBP, e.g. (Z)-1,5-octadien-3-one. In total, 20 odour-active volatiles are reported here for the first time as volatile bell pepper constituents. Received: 30 July 1999 / Revised version: 11 October 1999     

Quantitation of the odour-active compounds in Andes berry (Rubus glaucus Benth) fruit using the molecular sensory approach

The odour-active volatiles of Andes berry fruit (Rubus glacus Benth) were isolated by solvent-assisted flavour evaporation. Subsequent gas chromatography–olfactometry and gas chromatography coupled to mass spectrometry analyses and application of stable isotopic dilution analyses allow identifying 2-heptanol and ethyl butanoate as key aroma compounds in this fruit. Other relevant odorants were 4-hydroxy-2,5-dimethyl-3(2H)-furanone and ethyl benzoate, because of their contribution to the overall Andes berry aroma (high OAVs).     

The impact of maturation on concentrations of key odour active compounds which determine the aroma of tequila

Samples of non‐mature and añejo (matured) tequila of the same brand/provenance were analysed using GC–MS and gas chromatography olfactometry (GC‐O)/aroma extract dilution analysis (AEDA) to provide quantitative data on the most odour active compounds that contribute to the aroma of these spirits. Extracts of non‐mature tequila were characterized by 26 odour‐active regions, which included ethyl hexanoate, ethyl octanoate, 2‐phenylethyl acetate, β‐damascenone, isoamyl alcohol and octanoic acid as the most odour‐active compounds (flavour dilution, FD, factor ≥ 6561). In contrast, extracts of the mature spirit showed 36 odour‐active zones, where the compounds with the highest FD factors (6561) were ethyl hexanoate, ethyl octanoate, 2‐phenylethyl acetate, isoamyl alcohol, phenethyl alcohol, guaiacol, 4‐ethyl guaiacol, vanillin, cis/trans whisky lactones, β‐damascenone and octanoic acid. The aromagram of mature tequila was thus differentiated from that of the non‐mature spirit owing to the presence of cask‐extractive compounds and the increased FD factors of certain terpenes, higher alcohols and acetals. This study provides a comprehensive and quantitative understanding of changes in key odourants of tequila as a result of the maturation process and also reveals a further characterization of the likely impact of each compound on overall spirit flavour, in terms of odour activity values. Copyright © 2016 The Institute of Brewing & Distilling     

Characterisation of odour‐active compounds in papaya (Carica papaya L.) wine

The volatile compounds of papaya wine were isolated by continuous solvent extraction and analysed by gas chromatography‐flame ionization detector and gas chromatography‐mass spectrometry. A total of 118 volatile constituents were detected, and ninety‐seven were positively identified. The composition of papaya wine included fifty‐three esters, twenty‐two alcohols, nine acids, seven phenols and derivatives, seven sulphur compounds, five lactones, five terpenes, three ketones, two aldehydes and five miscellaneous compounds. The aroma‐active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis and by odour activity values. Six odorants were considered as odour‐active volatiles: ethyl octanoate, (E)‐β‐damascenone, 3‐methylbutyl acetate, benzyl isohtiocyanate; ethyl hexanoate and ethyl butanoate.     

Evaluation of the most odour-active compounds in the peel oil of clementines (<Emphasis Type="Italic">citrus reticulata blanco cv. clementine</Emphasis>)

In an extract of the peel from clementines, prepared by solvent extraction, 42 odour-active compounds were detected by application of an aroma extract dilution analysis and subsequently identified by using the respective reference odorants. Among them, by far the highest flavour dilution factors were determined for the flowery smelling linalool, the fatty smelling (E,E)-deca-2,4-dienal and the winelactone eliciting a sweet odour quality. These were followed by !-pinene, myrcene and octanal with pinetree-like, geranium leaf-like and citrus-like aromas. Among the 30 odour-active compounds identified, 11 aroma compounds are reported here for the first time as important contributors to clementine peel aroma, e.g. winelactone, (E,E)-nona-2,4-dienal, carvone, (Z)-hex-3-enal or tr-4,5-epoxy-(E)-dec-2-enal.     

Characterisation of the most odour-active compounds in a peel oil extract from Pontianak oranges (<Emphasis Type="Italic">Citrus nobilis</Emphasis> var. Lour. <Emphasis Type="Italic">microcarpa</Emphasis> Hassk.)

Isolation of the volatile fraction from the peel of Pontianak orange (Citrus nobilis var. Lour. microcarpa Hassk.) by a careful solvent extraction/vacuum distillation process followed by application of an aroma extract dilution analysis (AEDA) revealed 32 odour-active compounds in the flavour dilution (FD)-factor range of 4–2048, 26 of which could be identified. On the basis of high FD-factors, (R)/(S)-linalool, myrcene, (R)-limonene, and 1,8-cineole were characterised as the most potent odorants, followed by octanal, (E,E)-2,4-decadienal, nerol, (E)-2-dodecenal, geraniol, and (E,E)-2,4-nonadienal. In addition, one odorant resembling the characteristic sulphurous, resinous aroma of the Pontianak peel oil was detected with a quite high FD-factor of 128. By mass spectrometry followed by synthesis, 1-phenylethanethiol exhibiting an intense sulphurous, resinous smell at the very low odour threshold of 0.005 ng/L in air, was found to be responsible for the odour impression detected in the extract. 1-Phenylethanethiol occurring as a mixture of the (R)-(76%) and the (S)-enantiomer (24%) has previously not been reported as odorant in foods. Application of static headspace aroma dilution analysis (SHA) on Pontianak peel revealed the green, grassy smelling odour-active compounds hexanal and (Z)-3-hexenal as further important odorants in the headspace above the peels.     

Exposure to hypoxia conditions alters volatile concentrations of apple cultivars

Brief periods of hypoxia at ambient temperatures (20 °C) have potential for disinfestation treatments or as pre‐treatments to maintain fruit quality during extended storage. Nine cultivars of apple (Cox's Orange Pippin, Fuji, Golden Delicious, Granny Smith, Pacific Rose, Red Delicious, Royal Gala, Splendour and Southern Snap) were exposed to hypoxia using an atmosphere of 100% carbon dioxide for 24 h at 20 °C. Quantitative and qualitative analyses of volatile compounds were undertaken after removal of fruits from a high‐carbon‐dioxide atmosphere and during 1 week at 20 °C. Concentrations of acetaldehdye, ethanol, ethyl acetate and ethyl esters were consistently enhanced by hypoxia, while concentrations of acetate esters and aldehydes were depressed. Cultivars varied considerably in response to high carbon dioxide, with Cox's Orange Pippin and Golden Delicious having the least and Fuji and Red Delicious the greatest enhancement in ethyl esters. Fruits exposed to hypoxia had larger odour unit scores than control fruits, suggesting that such changes in volatile concentration may affect aroma and/or flavour. Enhanced ethyl ester concentrations in fruits exposed to hypoxia may be due to increases in ethanol concentration that competitively inhibit formation of non‐ethyl esters. There may also have been a change in ester‐forming enzyme activity and/or substrate specificity of the volatile biosynthetic pathway. This study has shown that short‐term exposure to hypoxia has the potential to change the aroma/flavour of apples. © 2000 Society of Chemical Industry     

Volatile composition and key flavour compounds of spirits from unifloral honeys

The volatile components of industrially produced spirits from three unifloral honeys of campanilla morada (Ipomoea crassicaulis [Benth.] B.L. Robinson), citrus (Citrus spp. L.) and romerillo de costa (Viguiera dentata [Cav.] Spreng.) were studied by combined sensory and instrumental techniques. GC and GC‐MS analyses of the isolated extracts led to the detection of 205 volatile compounds, 150 of them were positively identified. In general, the most abundant classes were saturated alcohols, ethyl esters of saturated fatty acids and terpenes in all samples. Relative aroma intensity of individual volatile components was evaluated by aroma extract dilution analysis of solvent extracts, by gas chromatography‐olfactometry and by odour activity values. Results indicated that 11 compounds: ethanol, ethyl esters of isopentanoic, hexanoic, octanoic and decanoic acids, 2‐phenylethyl acetate, (E)‐β‐damascenone, hotrienol, decanal, methyl anthranilate and ethyl (E)‐cinnamate were the most potent odorants in the honey spirits.     

郫县豆瓣特征香气物质的研究鉴定

以三种一级传统郫县豆瓣为研究对象,通过同时蒸馏萃取法（SDE）提取豆瓣中的挥发性化合物,再通过气质联用技术（GC-MS）对其进行定性定量分析,进一步采用气相色谱-嗅觉测量法（GC-O）及香气活性值法（OAV值）对郫县豆瓣中的特征香气物质进行鉴定。结果发现,在三种郫县豆瓣中共检测出112种挥发性物质,其中糠醛、异戊醛、3-甲硫基丙醛、芳樟醇、苯乙醇、4-乙基-2-甲氧基苯酚、十六酸乙酯对郫县豆瓣的贡献最大（OAV值＞1）,初步确定此七种香气化合物为一级传统郫县豆瓣中的特征香气物质。     

清香型志都五谷酒关键香气成分分析

通过液液萃取和顶空固相微萃取技术,结合气相色谱-质谱-嗅闻联用仪分析一种清香型志都五谷酒香气活性成分。通过香气提取稀释分析法共得到40 种香气物质,且香气稀释（flavor dilution,FD）因子最大的为异丁酸、月桂酸乙酯、愈创木酚和2-苯乙醇（FD＞4 096）,通过质谱、保留指数、香气特征和标准品比对共定性出35 种香气活性化合物,以乙酸肉桂酯、4-辛醇和2-甲基己酸为内标对30 种化合物进行标准曲线法定量,通过计算香气活性值（odor activity value,OAV）,将香气贡献较大（OAV＞1）的17 种化合物进行重组,获得了模拟酒样,与原酒样相比有良好的相似性。结合FD因子与OAV贡献,对清香型志都五谷酒香气有重要贡献的化合物为乙酸异戊酯、3-苯丙酸乙酯、愈创木酚、异丁酸、月桂酸乙酯、3-甲硫基丙醇、乙酸乙酯、2-苯乙醇和3-甲基丁醇。     

High-cell-density fermentation of Saccharomyces cerevisiae for the optimisation of mead production

Mead is a traditional drink that contains 8%–18% (v/v) of ethanol, resulting from the alcoholic fermentation of diluted honey by yeasts. Mead fermentation is a time-consuming process and the quality of the final product is highly variable. Therefore, the present investigation had two main objectives: first, to determine the adequate inoculum size of two commercial wine-making strains of Saccharomyces cerevisiae for the optimisation of mead fermentation; and second, to determine if an increase in yeast pitching rates in batch fermentations altered the resulting aroma profiles. Minor differences were detected in the growth kinetics between the two strains at the lowest pitching rate. With increasing pitching rates net growth of the strain ICV D47 progressively decreased, whereas for the QA23 the increasing inoculum size had no influence on its net growth. The time required to reach the same stage of fermentation ranged from 24 to 96 h depending on the inoculum size. The final aroma composition was dependent on the yeast strain and inoculum size. Fourteen of the twenty-seven volatile compounds quantified could contribute to mead aroma and flavour because their concentrations rose above their respective thresholds. The formation of these compounds was particularly pronounced at low pitching rates, except in mead fermented by strain ICV D47, at 10⁶ CFUs/mL. The esters isoamyl acetate, ethyl octanoate and ethyl hexanoate were the major powerful odourants found in the meads. The results obtained in this study demonstrate that yeast strain and inoculum size can favourably impact mead's flavour and aroma profiles.     

Changes in odour-active compounds of two varieties of Colombian guava (Psidium guajava L.) during ripening

Changes in the concentrations of odour-active compounds in two varieties of Colombian guava (Psidium guajava L.) fruits during ripening were followed by application of stable isotopic dilution analyses (SIDA). The data revealed that, in particular, the concentration of C₆-aldehydes, as well as the amount of the sulphur compounds 3-sulphanylhexyl acetate and 3-sulphanyl-1-hexanol, decreased with ripening, while the concentrations of aliphatic esters and furanones increased during this process. A calculation of odour activity values indicated that although the C₆-aldehydes decreased during ripening, these still made the greatest contribution to the overall aroma at all stages of ripening. Changes in odour-active compounds in white- and pink-fleshed guavas showed the same behaviour.     

Comparison of the key aroma compounds in hand-squeezed and unpasteurised,commercial NFC juices prepared from Brazilian Pera Rio oranges

Application of a comparative aroma extract dilution analysis on a hand-squeezed (juice A) and an industrially squeezed, unpasteurised orange juice (juice B), revealed qualitatively almost the same set of odour-active compounds. However, while in juice A, vanillin, ethyl butanoate, wine lactone, (Z)-3-hexenal, (S)-ethyl 2-methylbutanoate and (S)-linalool were detected with the highest flavour dilution (FD) factors, in juice B prepared by means of an FMC extractor, several compounds, like (R)-limonene, (R)-α-pinene and octanal showed higher FD factors, in addition to ethyl butanoate, wine lactone and (S)-ethyl 2-methylbutanoate. Quantification of seventeen odorants in both juices by means of stable isotope dilution assays followed by a calculation of odour activity values (OAV; ratio of concentration to odour threshold) revealed a clear change in the ranking order: while (S)-ethyl 2-methylbutanoate, (R)-limonene, (Z)-3-hexenal and linalool were first in rank among the odorants of juice A, in juice B, (R)-limonene and (S)-linalool followed by (S)-ethyl 2-methylbutanoate showed the highest OAVs. Sensory experiments revealed that the much higher concentrations of the seven peel oil constituents, and the lack in (Z)-3-hexenal, are the reason for the aroma differences observed for both juices. Further experiments indicated that lowering the pressure during commercial juicing, and also the avoidance of a freezing/thawing process could be helpful in getting closer to the aroma of hand-squeezed orange juice, because peel oil constituents are lowered and, in particular, the latter procedure leads to a complete degradation of (Z)-3-hexenal.     

Effect of fusel oil addition on volatile compounds in papaya wine fermented with Williopsis saturnus var. mrakii NCYC 2251

The impact of fusel oil addition on volatile compounds formation in papaya wine fermented with yeast Williopsis saturnus var. mrakii NCYC2251 was studied with a view to enhancing papaya wine aroma production. Time-course papaya juice fermentations were carried out using W. saturnus var. mrakii NCYC2251 with fusel oil added (0, 0.1 and 0.5% v/v). Fermentation characteristics in terms of yeast growth, Brix and pH changes were similar for all fermentations except for those added with 0.5% (v/v) fusel oil. The addition of 0.5% (v/v) fusel oil inhibited yeast growth. A wide range of volatile compounds were produced during fermentation including acids, alcohols, esters and aldehydes with esters being the most abundant volatile compounds produced. The addition of 0.1% (v/v) fusel oil reduced the production of undesirable volatiles such as ethyl acetate and acetic acid, while increasing the desirable volatiles production such as ethanol and acetate esters. This study suggests that papaya juice fermentation with W. saturnus var mrakii NCYC 2251 together with a low concentration of added fusel oil can be another means of modulating papaya wine aroma compound formation.     

Volatile compounds in uninoculated and inoculated table olives with Lactobacillus plantarum (Olea europaea L., cv. Moresca and Kalamata)

Table olives' flavour plays an important role in consumer's acceptability and it depends on various factors such as varieties, intrinsic characteristics, ripening of fruit and processing technologies. Flavour biogenesis is also influenced by addition in brine medium of lactic acid bacteria as inoculants, which reduce spoilage risks and improve sensory characteristics. In this work, flavour profiles of uninoculated and inoculated table olives with Lactobacillus plantarum (cv. Moresca and Kalamata) have been analytically characterised and compared. Twenty-one volatile compounds comprise alcohols, aldehydes, ketones, esters as well as acids formed during Greek-style olive fermentation (3 months brining after) have been characterised by gas chromatography and GC/mass spectrometry. Very high contents of ethanol and appreciable amounts of ethyl acetate, isobutanol, 2-butanone, 1-propanol and 1-hexanol were revealed in all samples with a significant increase in inoculated samples with respect to uninoculated ones. Also 1-butanol, 3-pentanol, 3-hydroxy-2-butanone, cis-3-hexen-1-ol and 2-butanol which were present in lower amounts, disclosed a meaningful increase in inoculated samples of both varieties, especially in Moresca inoculated sample. Acetic acid, isopentanol, 2-pentanol, propyl acetate, ethyl propanoate and 4-penten-1-ol showed a significant increase in inoculated Kalamata sample. These results showed that inoculation of brine medium with lactic acid bacteria starters significantly influenced aroma profiles of both varieties, in particular an increase in concentration of various flavour compounds has been revealed in inoculated table olives.     

Influence of yeast on the yield of fermentation and volatile profile of ‘Węgierka Zwykła’ plum distillates

The character of plum brandies depends on a unique aroma profile of the plum and the microbiota present on the surface of the fruits, as well as yeast used for fermentation. In this study, an evaluation of the effect of microorganisms applied for the fermentation of W?gierka Zwyk?a var. plum mashes and processing temperature (18 °C, 30 °C) on its efficiency and volatile profile, as well as taste and flavour of distillates obtained was performed. An estimation of the odour activity values (OAVs) of the volatile compounds was also conducted. Regardless of whether the fermentation was carried out using Saccharomyces bayanus wine yeast or by native microflora present on plums as well as raisins, the efficiency of this process was high and ranged between 91.7 and 96.7% of the theoretical efficiency. Especially rich in esters (among others ethyl acetate and isoamyl acetate) was the distillate derived after fermentation with the microflora of plums and raisins, at 18 °C. An evaluation of the individual aromatic effect of chemical compounds present in tested distillates, in terms of their OAVs, revealed that the highest OAVs were reached with isovaleraldehyde. Other compounds that showed aroma values >1 and possibly had an effect on the overall aroma of tested plum distillates were the following: hexanal, benzaldehyde, ethyl acetate, isoamyl acetate, ethyl benzoate, ethyl hexanoate, 1‐propanol, 2‐methyl‐1‐butanol, 3‐methyl‐1‐butanol and 1‐hexanol. The performed sensory ranking showed that the best rated distillate was the one obtained after fermentation with the indigenous microflora of plums and raisins, at 18 °C. Copyright © 2016 The Institute of Brewing & Distilling