Aroma Changes in Fresh Bell Peppers (Capsicum annuum) after Hot-air Drying

The aroma of fresh and hot-air dried bell peppers (Capsicum annuum) was evaluated by sensory and instrumental methods. Hot-air drying decreased levels of the odor compounds (Z)-3-hexenal, 2-heptanone, (Z)-2-hexenal, (E)-2-hexenal, hexanol, (Z)-3-hexanol, (E)-2-hexenol, and linalool, which have green, vegetable-like, fruity, and floral notes, while intensity scores of corresponding sensory aroma attributes also decreased. The aroma of rehydrated dried samples was mainly characterized as savory, rancid/sweaty, sweet/sickly, hay-like, cacao, caramel, and nutty. Drying increased the levels of 2-methylpropanal, 2-and 3-methylbutanal, which have cacao, spicy, and rancid/sweaty odor notes; these volatiles may be correlated with the corresponding aroma attributes in the dried fruits. Principal component analysis demonstrated relationships between instrumental and sensory data for fresh samples, whereas they were more complex for dried fruits.     

Changes in volatile compounds of Habanero chile pepper (Capsicum chinense Jack. cv. Habanero) at two ripening stages

The steam volatile components of Yucatan Habanero chile pepper (Capsicum chinense Jack. cv. Habanero) at two ripening stages (green and orange) were analyzed using GC and GC/MS. Both samples had several compounds in common. One hundred and two compounds were identified, from which (E)-2-hexenal, hexyl 3-methylbutanoate, (Z)-3-hexenyl 3-methylbutanoate, hexyl pentanoate, 3,3-dimethylcyclohexanol, and hexadecanoic acid were found to be the major constituents. During Habanero chile pepper maturation, the majority of volatile compounds decreased or even disappeared, some of them with green odour notes while esters, which have fruity odour notes, increased at the same time.     

Olfactory and quantitative analysis of volatiles in elderberry (Sambucus nigra L) juice processed from seven cultivars

Aroma compounds emitted from elderberry juices processed from seven cultivars were collected by the dynamic headspace technique and analysed by GC–FID and GC–MS. Forty aroma compounds were identified and quantified, including nine compounds which had not previously been detected in elderberry juice. Significant differences were found among cultivars in the concentration levels of 30 compounds. The sensory characteristics of the individual aroma compounds in elderberry juice were determined by a GC‐sniffing technique, and the compounds were grouped according to their odour. The characteristic elderberry odour is due to dihydroedulan and β‐damascenone, of which the former occurs in relatively high concentrations in the headspace of elderberry juice. The fruity group consisted of aliphatic alcohols and aldehydes and aromatic esters, of which 1‐pentanal, 2‐methyl‐1‐propanol, 2‐ and 3‐methyl‐1‐butanol, 1‐octanal, 1‐octanol and methyl and ethyl benzoate contributed with fruity notes. In the flowery group, 1‐nonanal, nerol oxide and (Z)‐ and (E)‐rose oxide contributed with characteristic elder flower odour, whereas other flowery notes were associated with hotrienol, linalool and α‐terpineol. Fresh and grassy odours were correlated with 1‐hexanal, (E)‐2‐hexen‐1‐al, (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol and (E)‐2‐octen‐1‐al of the grassy group, whereas 1‐octen‐3‐ol and 1‐octen‐3‐one of the agrestic group contributed significantly with the characteristic aroma of mushrooms. © 2000 Society of Chemical Industry     

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-active compounds of butter: a review

This review article shows that more than 230 volatile compounds have been identified in butter, however, only a small number of them can be considered as key odorants of butter aroma. Gas chromatography olfactometry was used to determine the character impact odorants of different kinds of butter. Sweet cream butter is characterised by lactones with fruity and creamy notes and by sulphur compounds, having corn-like and garlic odours. The key odour compounds of sour cream butter are diacetyl (buttery-like), butanoic acid (cheesy) and δ-decalactone (peach), mainly due to lactic acid bacteria fermentation. The aroma of butter oil is characterised by aldehydes, such as (E)- and (Z)-2-nonenal and (E,E)-2,4-decadienal, conferring green and oily notes. Olfactometric studies of heated butter showed the formation of new aroma compounds during heating, such as 3-methylbutanoic acid (cheesy), methional (potato-like) and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (caramel-like). High temperature treatment of butter can also induce off-flavour development. Off-odours in butter originate from autooxidative and as well as from lipolytic reactions, microbial contamination and animal feeding. The views expressed in this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use, which might be made of the information contained herein.     

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     

Comparison of Volatile Release in Tomatillo and Different Varieties of Tomato during Chewing

ABSTRACT: The release of volatiles from tomatillos (Physalis ixocarpa Brot.) and tomatoes in the mouthspace and nosespace was measured in real-time using selected ion flow tube mass spectrometry (SIFT-MS). (Z)-3-Hexenal, (E)-2-hexenal, hexanal, and 1-penten-3-one increased, while isobutyl alcohol, nonanal, and methylbutanal showed no significant change in the first 30 s of chewing. Cherry tomato released more (E)-2-hexenal, (Z)-3-hexenal, and 1-penten-3-one than tomatillo, Roma tomato, and vine-ripened tomato during chewing. The proportion of the average concentration of volatiles in the mouthspace after swallowing to before swallowing (MSas/MSbs) varied from 2.8% to 73.9% between different volatiles and varieties. Methylbutanal, hexanal, and nonanal were retained at a higher percentage in the mouth after swallowing than (Z)-3-hexenal, (E)-2-hexenal, 1-penten-3-one, and isobutyl alcohol. The proportion of the average volatile concentration in the mouthspace, to the headspace in a glass container (MS/HS) of 1-penten-3-one, hexanal, methylbutanal, and nonanal, and the proportion of nosespace to headspace (NS/HS) for 1-penten-3-one, hexanal, (Z)-3-hexenal, and nonanal was significantly higher in tomatillo than in tomatoes. There was no difference between tomatoes of different varieties in NS/HS ratio. Practical Application: The real-time volatile release from tomatillos and tomatoes was measured and compared. The information obtained on the dynamic generation of volatile compounds provides a better understanding of volatile release in the headspace of tomatillo and tomatoes. The compounds and their volatile release patterns were similar for the tomatillo and tomatoes. The green aldehydes released during chewing were not significantly higher than most tomato varieties, except for Roma tomatoes. Cherry tomato released relatively more volatiles during chewing, whereas Roma tomatoes were generally poor in mouthspace volatiles. The lingering of volatiles in the mouth after swallowing was different for different volatiles and varieties, which may appear as a sensory difference detected by consumers.     

Character impact odorants of boiled chicken: changes during refrigerated storage and reheating

 The most potent odorants of freshly boiled chicken and boiled, refrigerated and reheated chicken showing warmed-over flavour (WOF) were screened by dilution experiments. In total, 20 odorants were selected for quantification by stable isotope dilution assays. Calculation of odour activity values (ratio of concentration to odour threshold) indicated methanethiol, (E,E)- and (E,Z)-2,4-decadienal, (E,E)-2,4-nondienal, 2-furfurylthiol, hexanal, octanal and acetaldehyde as the character impact odorants of freshly boiled chicken. Refrigerated storage and reheating of boiled chicken led to a loss of meaty, chicken-like and sweet odour notes and to the formation of green, cardboard-like, metallic off-odours. These changes were mainly caused by a sevenfold increase of hexanal and a sixfold decrease of both (E,E)-2,4-decadienal and 2-furfurylthiol. Sensory experiments confirmed this conclusion. Received: 11 February 1997     

Character impact odorants of boiled chicken: changes during refrigerated storage and reheating

 The most potent odorants of freshly boiled chicken and boiled, refrigerated and reheated chicken showing warmed-over flavour (WOF) were screened by dilution experiments. In total, 20 odorants were selected for quantification by stable isotope dilution assays. Calculation of odour activity values (ratio of concentration to odour threshold) indicated methanethiol, (E,E)- and (E,Z)-2,4-decadienal, (E,E)-2,4-nondienal, 2-furfurylthiol, hexanal, octanal and acetaldehyde as the character impact odorants of freshly boiled chicken. Refrigerated storage and reheating of boiled chicken led to a loss of meaty, chicken-like and sweet odour notes and to the formation of green, cardboard-like, metallic off-odours. These changes were mainly caused by a sevenfold increase of hexanal and a sixfold decrease of both (E,E)-2,4-decadienal and 2-furfurylthiol. Sensory experiments confirmed this conclusion. Received: 11 February 1997     

Odour‐active compounds in pineapple (Ananas comosus [L.] Merril cv. Red Spanish)

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 was used to analyse volatile compounds from pineapple (Ananas comosus [L.] Merril cv. Red Spanish) and to estimate the most odour‐active compounds. The analyses led to the identification of ninety‐four compounds, seventy‐two of them were positively identified. Twenty odorants were considered as odour‐active compounds, from which ethyl 2‐methylbutanoate, 2,5‐dimethyl‐4‐hydroxy‐3(2H)‐furanone, 1‐(E,Z,Z)‐3,5,8‐undecatetraene, ethyl 3‐(methylthio)propanoate, 1‐(E,Z)‐3,5‐undecatriene, ethyl hexanoate and methyl hexanoate were the most odour contributors and contribute to the typical pineapple aroma, while the others are responsible for fruity and sweet odour notes.     

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.     

Changes in flavour compound profiles of precooked pork after reheating (warmed-over flavour) using gas chromatography–olfactometry–mass spectrometry with chromatographic feature extraction

The unclear components and complex evaluation indicators affect the effectiveness of inhibition methods for warmed-over flavour (WOF). To evaluate the main components of WOF, the changes in flavour compound profiles of precooked pork after reheating were investigated quantitatively by using gas chromatography–olfactometry–mass spectrometry with chromatographic feature extraction. A total of 49 volatile compounds were identified, including 22 aroma-active compounds that were primarily derived from lipid oxidation. Fifteen key volatile compounds were obtained that represented principal components of the changes in flavour compound profiles, of which 1-octen-3-ol, (Z)-2-octenal and (E,E)-2,4-decadienal made the greatest contribution to the principal components and achieved odour activity value (OAVs) >1.0 after reheating. The results showed that the three compounds are the dominant volatile compounds and potential evaluation indicators of WOF. This study provides a further understanding of the components of WOF in precooked pork and an effective analysis method of gas chromatography.     

Identification and olfactometry of French fries flavour extracted at mouth conditions

The aim of this study was to isolate and identify odour active compounds from French fries at mouth conditions. Volatile compounds were released from French fries by purge-and-trap, trapped on Tenax TA, and identified with GC–MS. GC–olfactometry was used to determine odour active compounds with a trained panel using the detection frequency method. A total of 122 compounds were identified of which 85% originated from either sugar degradation and/or Maillard reaction and 15% from lipid degradation, based on relative areas. About 50 odour active compounds were, due to coelution, responsible for 41 odours perceived by the panel. 3-Methylbutanal and 2-methylbutanal, hexanal, 2,3-dimethylpyrazine, 2-methylpropanal, 2,3-butanedione, pyridine, heptanal, 2,5-dimethylpyrazine and/or 2,6-diemethylpyrazine and/or ethylpyrazine, dimethyl trisulfide, octanal, phenylacetaldehyde, 2,5-diethylpyrazine, (E)-2-nonenal, 3-methylbutanoic acid and/or 2-methylbutanoic acid, (E,Z)-2,4-heptadienal, (E)-2-octenal, 5-ethyl-2,3-dimethylpyrazine and/or 2-ethyl- 3,5-dimethylpyrazine, nonanal, and tentatively 2-methylpyrrole had the highest detection frequencies. This resulted in a strong malty and fried potato note, combined with caramel/buttery, green, spicy, and deep-fried notes. Also chemical and sweaty odours were observed.     

Identification of aroma‐active compounds in fresh and stored ‘Mor’ mandarins

In this study, gas chromatography–olfactometry (GC‐O) (sniffing) combined with gas chromatography–mass spectrometry (GC‐MS) analysis was applied to identify volatile aroma‐active compounds in homogenised segments of fresh and stored ‘Mor’ mandarins. The GC‐O nasal impact frequency method was used to identify Twenty‐three aroma‐active compounds, of which seventeen odorants were identified by GC‐MS. The aroma of fresh ‘Mor’ mandarins derived from a mixture of eleven odorants that contribute ‘green’ [(E)‐3‐hexenol and hexanal], ‘fresh’ [(E)‐carveol], ‘fruity’ (ethyl 2‐methylbutanoate), ‘citrus’ (limonene), ‘floral’ (linalool), ‘musty’ (β‐myrecene and γ‐terpinene), ‘potato’ (α‐terpinene), ‘mushroom’ (unknown 2) and ‘cabbage’ (α‐cubebene) odours. During postharvest, storage losses were observed in ‘green’ [(E)‐3‐hexenol] and ‘fresh’ [(E)‐carveol] odours, accompanied by increases in ‘fruity’ (ethyl propanoate) and several unpleasant aromas, such as ‘alcohol’ (ethanol), ‘musty’ [α‐pinene, (E)‐2‐nonenal and 1‐terpinen‐4‐ol] and ‘fatty’ (octyl acetate and δ‐cadinene) odours, all of which possibly account for the observed decrease in sensory acceptability after harvest.     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

Fishy and hay-like off-flavours of dry spinach

 Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw spinach: methylpropanal, 2- and 3-methylbutanal and propanal were identified as the odorants with higher odour activity values. It was also found that (Z)-1,5-octadien-3-one and methional, in a concentration ratio of about 1 : 100, are responsible for the fishy off-flavour as dry spinach stored at lower temperatures under nitrogen. The hay-like flavour was caused by oxidative degradation of furan fatty acids, yielding 3-methyl-2,4-nonanedione. Received: 24 July 1997     

Fishy and hay-like off-flavours of dry spinach

 Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw spinach: methylpropanal, 2- and 3-methylbutanal and propanal were identified as the odorants with higher odour activity values. It was also found that (Z)-1,5-octadien-3-one and methional, in a concentration ratio of about 1 : 100, are responsible for the fishy off-flavour as dry spinach stored at lower temperatures under nitrogen. The hay-like flavour was caused by oxidative degradation of furan fatty acids, yielding 3-methyl-2,4-nonanedione. Received: 24 July 1997     

Effect of dietary lipid sources on odour‐active compounds in muscle of turbot (Psetta maxima)

Odour‐active compounds in muscle of turbot (Psetta maxima) fed experimental diets containing fish oil (FO), soybean oil (SO) or linseed oil (LO) were investigated by a gas chromatography/olfactometry technique. Thirty‐one areas associated with odours were detected in muscle extracts. Among the compounds responsible for these odours, 23 were formed by oxidation of unsaturated fatty acids. Independently of diet, (E)‐2‐penten‐1‐ol and (E)‐3‐hexen‐1‐ol contribute strongly to the odour of turbot. (E,Z)‐2,6‐Nonadienal, (E)‐2‐pentenal and (E,E)‐1,3‐(Z)‐5‐octatriene seem to contribute strongly to the odour of turbot fed diets containing high levels of n‐3 PUFA (FO and LO groups). Hexanal and decanal show a high detection frequency in turbot fed diets containing vegetable oils. Odorous compounds which are not formed by lipid oxidation (methional, 1‐acetyl pyrazine, 4‐ethyl benzaldehyde and 2‐acetyl‐2‐thiazoline) were not affected by dietary lipid sources. © 2001 Society of Chemical Industry     

Evaluation of volatile flavour compounds from cashew apple (Anacardium occidentale L) juice by the Osme gas chromatography/olfactometry technique

The headspace volatile components of the juice of cashew apples from a commercial Brazilian dwarf genotype were separated by high‐resolution gas chromatography and identified by GC/MS. Five judges evaluated the GC effluents using the Osme technique in order to determine the importance of each compound to the characteristic cashew aroma. Esters methyl 3‐methyl butanoate, ethyl 3‐methyl butanoate, methyl butanoate, ethyl butanoate, ethyl trans‐2‐butenoate and methyl 3‐methyl pentanoate were important to the sweet, fruity and cashew‐like aroma. Cis‐3‐hexenol, hexanal and 2‐methyl‐2‐pentenal presented different green notes. In spite of the flame ionisation detector being unable to detect sulphur compounds, the olfactometric analysis revealed chromatographic regions where sulphur‐like odours were perceived by the Osme sensory panel. The most intense unpleasant odour was due to 2‐methyl butanoic acid, which was described as very stinky. The sensory panel showed good olfactory sensitivity and reproducibility. Sensory and instrumental data correlation allowed a greater understanding of the role of several volatile compounds in the sensory quality of the juice. Copyright © 2003 Society of Chemical Industry     

Determination of microwave drying and rehydration kinetics of green peppers with the bioactive and textural properties

The aim of this study was to determine the effect of microwaves on drying and rehydration kinetics of green pepper varieties (sweet, green, and bell) and the bioactive and textural properties of dried and rehydrated peppers. Drying was performed at 90, 180, and 90 + 180 W and dried peppers were rehydrated at 25, 50, and 70°C. The best drying fits were obtained using the equations of both Sigmoid and Hii et al. for drying, and two term exponential decay was the most appropriate model for rehydration. The lowest and highest final rehydration ratio values were obtained for the peppers dried at 180 and 90 W, respectively at each temperature and pepper variety. Among peppers, bell pepper showed the lowest color change (ΔE) and it was the most potent to recover initial color in rehydration. Peppers had softer texture in both drying and rehydration treatment. Total phenolic content of peppers was reduced around 56–65% compared to the fresh pepper by drying and this decrement was reached up to 87% in rehydrated peppers. Results showed that drying at 180 W and rehydration at 70°C provided faster drying and rehydration as well maintained the quality characteristics of green peppers.