Effects of ethanol,tannin and fructose on the headspace concentration and potential sensory significance of odorants in a model wine

The effects of ethanol (8, 10, 12, 14, and 16% v/v), tannin (500, 1000, and 1500 mg/L) and fructose (200 and 2000 mg/L) concentrations on the headspace of eight selected odorants were investigated using headspace solid phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC–MS). Analysis of variance results (ANOVA) showed significant interaction effects for the majority of odorants (P < 0.05). In general, higher tannin concentration enhanced the release of odorants while fructose induced a retention effect, both of which were largely dependent upon ethanol concentration. The net magnitude effect was a substantial reduction in the headspace concentration of odorants with the dominant contribution from ethanol concentration. The percent reduction in extracted odorant was more pronounced on larger molecular weight compounds. Further multivariate analysis discriminated model wines with different ethanol concentrations and, to a lesser extent, separated model wines with different fructose and tannin concentrations. Subsequent gas chromatography–olfactometry (GC–O) analysis revealed differences in the estimated odor thresholds of odorants in the model wines. Threshold values increased between 2 and 10,000-fold for 2-methoxyphenol and eugenol, respectively, at higher ethanol, tannin and fructose concentrations. Consequently, odor unit values (OUV) of odorants decreased indicating a reduction in the potential contribution of the odorants to the aroma of model wine. These results highlighted the significant impact that wine matrix interactions can have on wine aroma quality.     

Characterization of odor-active compounds in three varieties of ciruela (Spondias purpurea L.) fruit

The aroma-active compounds present in tree ripened fruits of ciruela (Spondias purpurea L.) cultivars Chi abal, Campech abal, and Ek abal were isolated by means of simultaneous distillation solvent extraction and solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Application of odor activity values (OAV) afforded 22 compounds in higher amounts than their threshold concentrations (OAVs >1). Results of the identification experiments in combination with the OAVs suggested that methyl 3-methylbutanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, hexyl acetate, with fruity odor notes; (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 1-hexanol, and (Z)-3-hexenyl acetate, with grassy odor notes, and limonene (citrus-like) were the potentially important common odorants in all ciruela cultivars. Clear differences in the OAVs of some odorants between each of the cultivars suggested that they contributed to the unique sensory profiles of the individual cultivars.     

Aroma components of American country ham

ABSTRACT:  The aroma-active compounds of American country ham were investigated by using direct solvent extraction-solvent assisted flavor evaporation (DSE-SAFE), dynamic headspace dilution analysis (DHDA), gas chromatography-olfactometry (GCO), aroma extract dilution analysis (AEDA), and gas chromatography-mass spectrometry (GC-MS). The results indicated the involvement of numerous volatile constituents in the aroma of country ham. For DHDA, 38 compounds were identified as major odorants, among them, 1-octen-3-one, 2-acetyl-1-pyrroline, 1-nonen-3-one, decanal, and (E)-2-nonenal were the most predominant, having FD-factors ≥ 125 in all 3 hams examined, followed by 3-methylbutanal, 1-hexen-3-one, octanal, acetic acid, phenylacetaldehyde, and Furaneol™. For the DSE-SAFE method, the neutral/basic fraction was dominated by 1-octen-3-one, methional, guaiacol, (E)-4,5-epoxy-(E)-decenal, p-cresol as well as 3-methylbutanal, hexanal, 2-acetyl-1-pyrroline, phenylacetaldehyde, and γ-nonalactone. The acidic fraction contained mainly short-chain volatile acids (3-methylbutanoic acid, butanoic acid, hexanoic acid, and acetic acid) and Maillard reaction products (for example, 4-hydroxy-2,5-dimethyl-3(2H)-furanone). The above compounds identified were derived from lipid oxidation, amino acid degradation, and Maillard/Strecker and associated reactions. Both methods revealed the same nature of the aroma components of American country ham.     

Potent aroma-active compounds of cooked Korean non-aromatic rice

To characterize the aroma of cooked Korean non-aromatic rice, volatiles were extracted by simultaneous steam distillation and solvent extraction (SDE) and dynamic headspace sampling (DHS). The potent aroma-active compounds were then evaluated using gas chromatography-olfactometry. A total of 16 aroma-active compounds with log3 flavor dilution >1 were detected by SDE. On the other hand, 10 aroma-active compounds were detected by DHS. 2-Methyl-3-furanthiol (2-MF) and 2-acetyl-1-pyrroline were considered the most potent aroma-active compounds in cooked Korean non-aromatic rice. Especially, 2-MF was identified for the first time as a potential aroma-active compound of cooked Korean non-aromatic rice.     

Characterization of aroma-active volatiles in three Chinese bayberry (Myrica rubra) cultivars using GC–MS–olfactometry and an electronic nose combined with principal component analysis

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is one of the most popular and valuable fruits in China because of its unique and exquisite flavor. In this study, headspace solid-phase micro-extraction (HS-SPME) coupled with gas chromatography–mass spectrometry and olfactometry (GC–MS–O) analyses were used to characterize the aroma-active profiles of the fruits from three different bayberry cultivars. The aim was to differentiate the bayberry cultivars by their aroma. Fifty-five volatile components, composed of aldehydes (10), alcohols (9), esters (8), terpenes (17), and others (11), were identified by optimized HS-SPME/GC–MS. Meanwhile, 36 aroma-active compounds were detected by olfactometry using detection frequency analysis (DFA). Hexanal (grass-like), (E)-2-hexenal (green), nonanal (fruit, flower), 1-hexanol (flower), and isocaryophillene (wood) were identified in all three cultivars. Further principal component analysis (PCA) of the active aromas revealed their contributions to the odor differences among the bayberry cultivar groups. The BQ bayberry was characterized by having a stronger “herb” odor, which is mainly caused by benzoic acid and methyl ester. DK bayberry had a stronger “grass” odor, which is mainly caused by 2,6-dimethyl-2,4,6-octatriene, while FHZ bayberry had a stronger “pine” odor, which is caused mainly by α-pinene. The GC–MS–O and electronic nose techniques, when combined with PCA, could be used to successfully distinguish between different bayberry cultivars.     

Investigation of important odorants of palm wine (Elaeis guineensis)

Palm wine (Elaeis guineensis) was sensorially evaluated and the key odorants were investigated by means of high resolution gas chromatography–olfactometry and mass spectrometry of solvent extracts as well as headspace samples. A total of 41 compounds were identified, 32 of them previously unknown in palm wine. From these, a total of 13 compounds were quantified by means of stable isotope dilution assays. Quantitation and calculation of the odour-activity values (OAVs) of the 13 key odorants revealed that the earthy-smelling 3-isobutyl-2-methoxypyrazine, the buttery-smelling acetoin, the fruity compounds ethyl hexanoate, 3-methylbutyl acetate and the popcorn-like-smelling 2-acetyl-1-pyrroline are likely to be important odorants of palm wine, with 3-isobutyl-2-methoxypyrazine, acetoin, and 2-acetyl-1-pyrroline being reported here for the first time as aroma constituents of palm wine.     

Chemistry of bread aroma: A review

The roles of ingredient formulation, dough fermentation, and baking conditions on bread aroma are reviewed. More than 540 volatile compounds have been reported in bread. However, only a relative small portion of the volatile compounds in bread contribute to the desirable aroma properties. The primary odorants reported to contribute to the flavor of wheat bread crust were 2-acetyl-1-pyrroline, (E)-2-nonenal, 3-methylbutanal, 2,3-butanedione, methional, and (Z)-2-nonenal, whereas for bread crumb, (E)-2-nonenal, (E,Z)-2,6-nonadienal, (E,E)-2,4-decadienal, 2,3-butanedione, methional, 1-octen-3-ol, and (E,E)-2,4-nonadienal were identified. One compound, in particular, 2-acetyl-1-pyrroline has been suggested to be the key odorants of the crust and is considered to be responsible for the cracker-like odor properties. These compounds are primarily generated during thermal processing but also influence by ingredient composition and fermentation conditions.     

Potent odorants of boiled potatoes

The potent odorants of boiled potatoes were screened by aroma extract dilution analysis, aroma extract concentration analysis, and gas chromatography-olfactometry of static headspace samples. Altogether 45 odorants were found of which 42 were identified. trans-4,5-Epoxy-(E)-2-decenal, methional, 2-acetyl-1-pyrroline, dimethyltrisulfide, 2,3-diethyl-5-methylpyrazine, vanillin, sotolon, decanal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, (E)-β-damascenone, furaneol, methanethiol, 3-isopropyl-2-methoxypyrazine, dimethylsulfide appeared in at least one of the three screening experiments with a higher flavour dilution factor.     

Volatile compounds of modified atmosphere packaged cut iceberg lettuce: Effect of extremely low O2, season,cultivar and storage time

This study investigates the changes in volatile compounds in minimally processed iceberg lettuce as a function of season, cultivar, packaging and time. In order to achieve this, iceberg lettuce cultivars Platinas, Diamantinas and Morinas were harvested from June to September 2009. Lettuces were minimally processed and stored under three different treatments: two passive modified atmosphere packagings using films of different permeabilities, F1 (OPALEN 65 AF) and F2 (OPP/PE-L 2040 AF), and storage in air. All packages were stored at 5 °C. Gas composition and volatile compounds were assessed at 1, 5, 8 and 11 days of storage in packaged lettuce, whereas in air stored samples volatiles were analyzed only at 1 and 5 days of storage. Twenty one potent odorants were identified by GC–O. Among the months, August presented a notary increase of elemene, β-selinene and 2,3-butanedione, which likely contribute to off-odor of packaged cut lettuce. The content of O₂ and CO₂ was demonstrated to influence the formation of odorants as storage time increased. Higher amount of cis-3-hexenol was related to aerobic conditions found in the modified atmosphere packages and air stored samples after 1 day of storage, whereas levels of odorants such as 2,3-butanedione, elemene and β-selinene were significantly enhanced under anaerobic conditions after 11 days of storage. Film F2 seems to be the most promising because it kept the concentration of elemene and β-selinene lower than film F1. No clear differences were seen between the cultivars Morinas, Diamantinas and Platinas with regard to production of objectionable odorants under anaerobic conditions.     

Evaluation of Potent Odorants in Dill Seed and Dill Herb (Anethum graveolens L.) by Aroma Extract Dilution Analysis

The volatile components of dill seed and herb were analyzed by gas chromatography-olfactometry which revealed the odorants having highest odor-activity value (ratio of concentration to odor threshold). (+)-(4S)-Carvone was the predominent odorant of dill seed. (+)-(3R,4S,8S)-3,9-Epoxy-1-p-menthene, methyl 2-methylbutanoate, (+)-(4S)-α-phellandrene and myristicin were the most important odorants of dill herb. Calculation of odor-activity values on the basis of quantitative and odor threshold data confirmed results of the aroma extract dilution analysis.     

Characterization of the key aroma compounds in roasted duck liver by means of aroma extract dilution analysis: comparison with beef and pork livers

By application of the aroma extract dilution analysis (AEDA) on the volatile fraction isolated by solvent extraction and solvent-assisted flavour evaporation from roasted duck liver, thirty odour-active areas could be detected in the flavour dilution factor (FD) range of 16–2,048. The highest FD factors were found for 2-acetyl-1-pyrroline (roasty, popcorn-like), 2-acetyltetrahydropyridine (roasty), and 2-acetyl-2-thiazoline (roasty), followed by 2-furfurylthiol (roasty, coffee-like) and 3-methylthio(propanal) (cooked potato) with slightly lower FD factors of 1,024. Application of the AEDA on the volatiles isolated from roasted pork and beef livers revealed basically the same set of odorants in about the same range of FD factors in both livers. A main difference, however, was the comparatively low FD factor of 2-acetyltetrahydropyridine in beef and pork livers indicating that this roasty smelling odorant might be responsible for the difference detectable in the overall aroma of duck liver. In total, 15 odorants were identified for the first time in liver.     

Characterization of the differences in the aroma of cherry wines from different price segments using gas chromatography–mass spectrometry,odor activity values,sensory analysis,and aroma reconstitution

The aroma composition, aroma-active compounds, and sensory attributions of cherry wines from three different price segments were investigated. A total of 48 aroma compounds were identified and quantified using headspace solid-phase microextraction (HS-SPME)/gas chromatography–mass spectrometry (GC–MS), among which 23 aroma compounds were further screened out as important odorants based on their odor activity values (OAVs); then, the previously mentioned 23 volatiles were correlated to sensory attributes using partial least-squares regression (PLSR). The result indicates that the differently priced wines were associated with different compounds and aroma attributions. Finally, aroma reconstitution was performed by mixing odor-active aroma compounds (OAVs>1) on the basis of their measured concentrations in the original sample. The result indicated that the aroma profile of the reconstituted sample was similar to that of the original sample.     

The role of congruency in taste–odor interactions

The present study investigated the role that congruency between tastes and odors plays in two types of taste–odor interactions: retronasal odor enhancement by taste and retronasal odor referral to the mouth. In the first experiment, subjects rated (1) the intensities of sweetness, sourness, bitterness, and specific odor of aqueous samples of 3 tastants (sucrose, citric acid, caffeine) and 2 odorants (citral, coffee odor), both alone and in taste–odor mixtures, and (2) the degree of congruency of all possible taste–odor pairs. The results showed that only sucrose significantly enhanced the perceived intensities of citrus and coffee odors (Tukey’s test, p < 0.05), while citric acid and caffeine failed to enhance or even suppressed the odors. In the second experiment, the returning subjects were asked (1) to report the perceived locations of the odors after inhaling 3 odorants (citral, “sweet” and “bitter” coffee odors) through the mouth alone or in the presence of either water or various tastes in the mouth, and (2) to rate the degree of congruency between tastes and odors. The data showed that a highly congruent taste or taste mixture significantly increased localization of odors to the mouth (χ², p < 0.05). These findings suggest that taste–odor congruency is a necessary but not sufficient condition for retronasal odor enhancement. In contrast, taste–odor congruency is a critical component for retronasal odor referral, and the degree of congruency modulates the degree of odor referral to the mouth. The results and implications of the study findings are discussed in terms of cognitive and perceptual factors of flavor perception.     

Evaluation of potent odorants in heated egg yolk by aroma extract dilution analysis

Egg yolk was extracted using the method of Likens-Nickerson (simultaneous distillation/extraction). The resulting aroma extract, which smelled characteristic of heated egg yolk was analysed by aroma extract dilution analysis and gas chromatography–mass spectrometry. Of 41 odorants that were detected, 19 could be identified. Compounds with high flavour dilution factors were methional, phenyl acetaldehyde, 2-acetyl-1-pyrroline, heptanal, 1-octen-3-one and (E,E)-2,4-decadienal. Strecker degradation of methionine, phenylalanine and proline, as well as autoxidation of phospholipid-bound linoleic and arachidonic acids are proposed as the major factors for egg yolk flavour formation.     

Identification of aroma-active compounds in ‘wonderful’ pomegranate fruit using solvent-assisted flavour evaporation and headspace solid-phase micro-extraction methods

During the last few years, there has been a tremendous increase in consumption of pomegranate fruit and juice. Nevertheless, very little is yet known regarding the volatile constituents that determine the unique aroma of pomegranate fruit. We extracted aroma volatiles from fresh ‘Wonderful’ pomegranate juice using solvent-assisted flavour evaporation (SAFE) and headspace solid-phase micro-extraction (HS-SPME) methods, and applied gas chromatography–olfactometry (GC–O) (‘sniffing’) combined with gas chromatography–mass spectrometry (GC–MS) analysis, in order to identify volatile aroma-active compounds. In addition, we performed stir bar sorptive extraction (SBSE) of pomegranate aroma volatiles, coupled with GC–MS analysis, in order to assist in identifying aroma-active compounds. Overall, we tentatively identified 23 volatiles in the SAFE and HS-SPME extracts; they belonged to various chemical classes, including aldehydes, terpenes, alcohols, esters, furans and acids. Using the GC–O nasal impact frequency method, we tentatively detected 12 aroma-active peaks and identified the corresponding odourants by GC–MS. The aroma-active compounds of ‘Wonderful’ pomegranates were ethyl-2-methylbutanoate (fruity, apple), hexanal (green), β-pinene (pine, herbal), β-myrecene (woody, musty), cis-3-hexenal (green), limonene (fruity, musty), cis-2-heptenal (soapy, mushroom), cis-3-hexenol (earthy, grassy), 2-ethylhexanol (floral), β-caryophyllene (fruity, musty), 2(5H)-furanone (sweet, fruity) and β-sesquiphellandrene (terpene, almond). Overall, the flavour of ‘Wonderful’ pomegranate fruit derives from a mixture of various ‘green’, ‘woody’, ‘earthy’, ‘fruity’, ‘floral’, ‘sweet’ and ‘musty’ notes.     

Phenolic and aroma compositions of pitomba fruit (Talisia esculenta Radlk.) assessed by LC–MS/MS and HS-SPME/GC–MS

Pitomba (Talisia esculenta Radlk.) is a Brazilian exotic fruit consumed specially in the Amazonian region. Because of its large consumption and also due to the lack of knowledge regarding its chemical composition, pitomba fruit was studied in relation to its phenolic and aroma constitution. Using liquid chromatography tandem mass spectrometry (LC–MS/MS), 13 phenolic compounds (catechins, flavonoids and organic acids) were tentatively identified by comparison with standards and by fragmentation patterns. A validated method was applied to quantify common phenolic compounds of the pitomba pulp, for which quinic acid was the main compound (507.8 ± 7.4 μg g^− 1 DWP). Gas chromatography mass spectrometry (GC–MS) was employed along with headspace solid-phase microextraction (HS-SPME) to assess the aroma composition of pitomba fruit. A total of 27 volatile organic compounds (VOCs) were tentatively identified for pitomba fruit, for which 2-phenethyl acetate (17.89%) and isopentyl acetate (13.43%) esters were the main VOCs, contributing to the characteristic aroma of pitomba. The antioxidant capacity of the extract of pitomba fruit was evaluated by ABTS, DPPH and ORAC assays. We observed that pitomba has a moderate antioxidant activity.     

Volatile profiles of aromatic and non-aromatic rice cultivars using SPME/GC–MS

Rice (Oryza sativa L.) is enjoyed by many people as a staple food because of its flavour and texture. Some cultivars, like scented rice, are preferred over others due to their distinctive aroma and flavour. The volatile profile of rice has been explored by other investigators, some of whom have also determined a corresponding aroma using GC/olfactometry. However, little research has been done to determine if different aromatic rice cultivars produce different flavour volatiles that would make them more desirable than others when cooked. In this study, seven aromatic and two non-aromatic cultivars were examined for their volatile profiles both before and after storage using solid phase microextraction (SPME) fibres in conjunction with gas chromatography/mass spectrometer (GC–MS). Ninety-three volatile compounds were identified, 64 of which had not been previously reported in rice. Differences were found in the volatile compounds of aromatic and non-aromatic rice besides 2-acetyl-1-pyrroline (2-AP). Most of the volatile compounds were present in freshly harvested rice and rice following storage, with very few new compounds being identified only after storage. Dellrose, an aromatic cultivar, and Cocodrie, a non-aromatic cultivar, had the most complex volatile profiles (over 64 volatiles). Sixteen compounds were found only in the aromatic cultivars, and some volatiles were found to be unique to specific aromatic cultivars. However, no distinctive pattern was observed that would identify a cultivar as being derived from Basmati, Khao Dawk Mali 105 (i.e. jasmine), or other sources of aroma. This study showed that there is a great diversity of volatiles in both aromatic and non-aromatic rice cultivars and, with further research, this may lead to a better understanding of the combination of compounds that gives a cultivar a unique flavour.     

GC-O-MS法鉴定黑巧克力中关键香气物质

采用同时蒸馏萃取法(SDE)和吹扫捕集法(P&T)对醇浓黑巧克力中挥发性物质进行提取。利用气相色谱-嗅闻-质谱联用的方法对其中的挥发性性物质定性分析,共鉴定出52种物质,包括醛类、烯醛类、吡嗪类、醇类、酯类、酮类、呋喃类、酸类等物质,其中吡嗪类物质的种类最多,其次为醛类物质。通过香气提取物稀释分析(AEDA)和动态顶空稀释分析(DHDA),确定关键的香气物质(log3FD≥4/FD值≥125)共有10种,分别为醛4种(2-甲基丙醛、3-甲基丁醛、2-甲基丁醛、苯乙醛),吡嗪4种(乙基吡嗪、2,3-二甲基吡嗪、三甲基吡嗪、四甲基吡嗪),酯1种(苯甲酸异戊酯),吡咯1种(2-乙酰基-1-吡咯啉)。其中巧克力香气特征主要表现为黑巧克力香、爆米花味、烤香、水果香、咖啡香、坚果香等。     

Sensory and flavor profiles as a means of assessing freshness of hake (Merluccius merluccius) during ice storage

Freshness of hake stored in ice was evaluated by sensory and instrumental means. The European Union scheme and the quality index method (QIM) were used to sensorially index freshness. Aroma extract dilution analysis (AEDA) and SPME-headspace determinations were applied to monitor important odorants of hake at different freshness stages. Based on AEDA, potent odorants of hake in the very fresh state were (Z)-1,5-octadien-3-one and 3 unknown volatiles. Attempts were made to relate overall odor changes to individual volatiles: after 2 days storage, the higher FD-factors found for trans-4,5-epoxy-(E)-2-decenal, (Z)-4-heptenal, methional, and 2-acetyl-1-pyrroline were associated with the “masking” of the seaweed character, whereas the higher concentrations of (Z)-1,5-octadien-3-one and (Z)-4-heptenal in hake that reached the B grade were likely responsible for the pungent odor. No highly volatile odorants were detected in hake using SPME-headspace analysis, but in contrast to AEDA, the odor intensity of some volatiles, e.g., (E,Z)-2,6-nonadienal and 3-methylnonane-2,4-dione indicated a higher contribution. The detection of two low boiling odorants associated with fresh fish flavor is reported for the first time.