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1.
The volatile components from intact tea shoots (ITS), obtained by air entrainment, were identified by their mass spectra and retention times and confirmed by comparison with standard samples. They are E-2-hexenal, ocimene, Z-3-hexenyl acetate, Z-3-hexen-1-ol, butanoic acid-3-hexenyl ester, linalool, 1-octanol, geraniol, and indole. Volatiles from mechanically pierced tea shoots (MPTS) were identified as E-2-hexenal, ocimene, Z-3-hexen-1-ol, butanoic acid-3-hexenyl ester, linalool, geraniol, indole, E-2-hexenoic acid, Z-3-hexenyl formate, methyl salicylate, and benzyl alcohol, and volatiles from tea aphid-tea shoot complexes (TATSC) were identified as E-2-hexenal, ocimene, Z-3-hexenyl acetate, Z-3-hexen-1-ol, linalool, geraniol, indole, benzaldehyde, and E-2-hexenoic acid. Z-3-Hexen-1-ol is the main component in the three different types of volatiles, and the amount of benzaldehyde in TATSC volatiles is very ample. The attraction of the volatiles from ITS, MPTS, and TATSC, and the nine components of TATSC volatiles to the natural enemies, the coccinellid, Coccinella septempunctata, the parasite, Aphidius sp., and the lacewing, Chrysopa sinica, were determined by electroantennogram (EAG) and the wind tunnel bioassay. TATSC volatiles and benzaldehyde elicited much larger EAG responses and stronger upwind flight and arresting behavior from each natural enemy in the wind tunnel than other infochemicals.  相似文献   

2.
Changes were studied in the concentration of 38 volatile compounds during chilled storage at 5 degrees C of six lots of commercially produced vacuum-packed cold-smoked salmon and sterile cold-smoked salmon. The majority of volatile compounds produced during spoilage of cold-smoked salmon were alcohols, which were produced by microbial activity. Partial least-squares regression of volatile compounds and sensory results allowed for a multiple compound quality index to be developed. This index was based on volatile bacterial metabolites, 1-propanol and 2-butanone, and 2-furancarboxaldehyde produced by autolytic activity. Only a few of the volatile compounds produced during spoilage of cold-smoked salmon had an aroma value high enough to indicate contribution to the spoilage off-flavor of cold-smoked salmon. These were trimethylamine, 3-methylbutanal, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-penten-3-ol, and 1-propanol. The potency and importance of these compounds was confirmed by gas chromatography-olfactometry. The present study provides valuable information on the bacterial reactions responsible for spoilage off-flavors of cold-smoked salmon, which can be used to develop biosensors for on-pack shelf-life determinations.  相似文献   

3.
A total of 33 virgin olive oil samples of the two main Tunisian cultivars, Chemlali and Chétoui, were characterized by their volatile compounds. The olive oil samples were obtained from olives harvested at four stages of ripeness in costal and inland farms of different geographical places. Major volatiles, mostly C6 and C5 compounds produced from linolenic and linoleic acids through the lipoxygenase cascade, were quantified by solid-phase microextraction-gas chromatography. Mathematical procedures allowed for the determination of the volatiles that not only are able to discriminate the olive oils by their olive cultivar (hexanal, E-2-hexenal, and total ketones) and ripeness (pentanal and 1-penten-3-one) but also contribute to their distinctive aroma. Finally, an electronic nose based on metal oxide sensors was checked for a rapid and at-line implementation of Tunisian olive oil varietal traceability. The classification of the samples by the sensors was explained by their sensitivity to volatiles E-2-hexanal, hexanal, 1-penten-3-one, ethanol, and Z-3-hexenol. Multivariate procedures of discriminant analysis and principal component analysis were used in the study.  相似文献   

4.
Olive oil and fruit samples from six cultivars sampled at four different maturity stages were discriminated into cultivars and maturity stages. The variables-volatile and phenolic compounds-that significantly (p < 0.01) discriminated cultivars and maturity stage groups were identified. Separation by stepwise linear discriminant analysis revealed that Manzanilla olive cultivar was separated from cultivars Leccino, Barnea, Mission, Corregiola, and Paragon, whereas cultivars Corregiola and Paragon formed a cluster. The volatile compounds hexanol, hexanal, and 1-penten-3-ol were responsible for the discrimination of cultivars. All maturity stages were discriminated, with the separation of early stages attributed to oil phenolic compounds, tyrosol and oleuropein derivatives, whereas the volatile compounds (E)-2-hexenal, hexanol, 1-penten-3-ol, and (Z)-2-penten-3-ol characterized the separation of all maturity stages and in particular the late stages. Hexanol and 1-penten-3-ol characterized the separation of both cultivars and maturity stages.  相似文献   

5.
Cloudy apple juice has been found to develop off-flavors during storage in daylight. The development of off-flavors and volatile compounds was monitored in reconstituted juice prepared from 'Golden Delicious' and 'Fuji' apple concentrates stored in glass bottles under fluorescent light (3000 lx, 8 degrees C). A strong metallic off-flavor was formed by photooxidation. A major contributor to the off-flavor was identified as 1-octen-3-one by gas chromatography-olfactometry. In addition, six volatile compounds, pentanal, 2-methyl-1-penten-3-one, hexanal, (E)-2-heptenal, 6-methyl-5-hepten-2-one, and (E)-2-octenal, increased significantly after light exposure and could contribute to the off-flavor. Except for pentanal and hexanal, these volatiles were found only after light exposure. Higher levels of volatiles were observed in juice from 'Golden Delicious' apples than in juice from 'Fuji' apples, and this difference was consistent with higher levels of suspended solids. When the suspended solids were removed by centrifugation, the development of volatiles on exposure to light was reduced significantly.  相似文献   

6.
Protection against lipid oxidation and formation of unpleasant fishy and rancid off-flavors in oil-in-water food emulsions, such as fish oil enriched mayonnaise, is difficult to achieve. Volatile profiles from stored mayonnaises with different oil phase compositions were collected using a developed dynamic headspace sampling technique, in which interfering acetic acid was removed in situ with potassium hydroxide, and subsequently 148 volatiles were characterized and monitored by gas chromatography/mass spectrometry. Multivariate statistics showed correlation between the concentration of 62 volatiles and the fish oil and storage parameters, indicating the formation of lipid oxidation products, which impose fishy off-flavors. Further verification was obtained by gas chromatography/olfactometry, by which, among 78 odors, cis-4-heptenal and trans,cis-2,4-heptadienal were detected as distinct fishy notes. In total, 27 volatiles, including 1-penten-3-one, cis-2-penten-1-ol, cis-3-hexenal, cis-4-heptenal, 1-octen-3-one, 1,cis-5-octadien-3-one, 1-octen-3-ol, trans,cis-2, 4-heptadienal, and trans,cis-2,6-nonadienal, were suggested to contribute to the developed unpleasant fishy and rancid off-flavors.  相似文献   

7.
Cultured and wild sea bream were compared for differences in their volatile components over a 23 day storage period in ice. A total of 60 compounds in cultured and 78 compounds in wild sea bream were tentatively identified (in addition to this, there were 23 unknowns in cultured and 29 unknowns in wild sea bream volatiles). These included aldehydes, ketones, alcohols, aromatics, terpenes, furans, sulfur-containing compounds, an acid, and miscellaneous compounds. Although selection of best fish is a subjective matter, more aldehydes, ketones, aromatics, and terpenes were found in wild sea bream as compared to that of its cultured counterpart. Both sea bream samples exhibited complex volatile profiles over the entire storage period. The combination of several classes of volatile compounds, dependent upon their concentrations and odor thresholds, is responsible for the distinctive and unique flavor of fresh cultured and wild sea bream. Relative concentrations of several compounds (trimethylamine, piperidine, methanethiol, dimethyl disulfide, dimethyl trisulfide, 1-penten-3-ol, 3-methyl-1-butanol, and acetic acid) increased continually throughout the storage period, and these may have the potential to be used as indicators of sea bream quality.  相似文献   

8.
Volatile and nonvolatile compounds, which could contribute to flavor, were analyzed in salmon. One hundred twenty-three volatile compounds were identified in the headspace of two different samples of cooked salmon, including lipid-derived volatiles, Maillard-derived volatiles, sulfur volatiles, Strecker aldehydes, nitrogen heterocyclic compounds, terpenes, and trimethylamine. Significant differences between samples were found for 104 of the volatiles. Although the levels of free cysteine and methionine were low in the salmon, sulfur volatiles were formed in the cooked fish, demonstrating that there were sufficient sulfur amino acids present for their formation. Notable differences in sulfur compounds between the samples suggested that small changes in sulfur amino acids could be responsible. When this hypothesis was tested, salmon heated with cysteine had increased levels of many thiophenes, thiazoles, alicyclic sulfides, and nitrogen heterocycles. With the addition of methionine, levels of dimethyl sulfides, two alicyclic sulfides, pyrazines, some unsaturated aldehydes, and alcohols and 2-furanmethanethiol increased. The largest difference found among the nonvolatile (low molecular weight water-soluble) compounds was in inosine monophosphate.  相似文献   

9.
李大婧  卓成龙  江宁  刘春泉 《核农学报》2010,24(6):1219-1225
使用固相微萃取(HS/SPME)-气质联用(GC/MS)技术对苏99-8毛豆仁鲜样和热风干燥毛豆仁挥发性成分进行分析,同时对2种干燥产品的感官品质、营养成分含量和质构特性进行比较。结果表明,在毛豆仁鲜样、热风干燥和热风联合压差膨化干燥制备的毛豆仁产品中分别检测出32、31、35种风味成分。鲜样中(Z)-3-己烯醇、正己醛、(E)-2-己烯醛、1-辛烯-3酮和1-戊烯-3酮对其风味相对贡献较大。热风联合压差膨化干燥后毛豆仁醛类化合物明显增多,出现了杂环类、酯类、酸类及含硫化合物,2-庚烯醛、正己醛、正戊醛、1-辛烯-3-醇、2-辛烯醇、1-辛烯-3酮、乙酸异丙烯酯、2,3,5-三甲基吡嗪和2,6-二甲基吡嗪、二甲基亚砜对热风联合压差膨化干燥后毛豆仁风味贡献较大,使毛豆具有较浓的豆类清香味和浓厚的焙烤香气,造就了热风联合压差膨化干燥毛豆仁脆粒的独特风味。热风联合压差膨化干燥毛豆仁的感官品质和质构特性明显优于热风干燥毛豆仁。  相似文献   

10.
Aroma of fresh oysters Crassostrea gigas: composition and aroma notes   总被引：3，自引：0，他引：3  
In contrast to many foods, very little is known about the aroma of fresh oysters. This study deals with the relationship between extracted volatiles of oysters and their olfactory properties. Nearly 50 volatiles were identified: most of them were principally related to fatty acid oxidation (86%) and particularly to n-3 polyunstaturated fatty acid oxidation (66%). Only one volatile arose from amino acid degradation. Panelists detected 42 odors by sniffing. Among them, only 12 odors were definitely attributed to identified volatile. These odors were green/sulfur/crustacean, mushroom/citrus, and marine/cucumber notes and were attributed to dimethyl sulfide, 1-penten-3-one, hexanal, (2,4)-E,E-heptadienal, 1-octen-3-one, 1-octen-3-ol, 6-methyl-5-hepten-3-one, octanal, (E,Z)-2,6-nonadienal, (E)-2-octenal, and decanal, respectively.  相似文献   

11.
The effect of milk protein concentrate (MPC) at 0, 2, 4, and 6% on lipid oxidation and volatile formation in frozen stored herring mince (-18 degrees C) was evaluated by analyzing samples at 0, 2, and 4 months for fatty acid composition, volatiles, and thiobarbituric acid reactive substances (TBARS). Sensory evaluation was also conducted to assess the intensity of fishy odor, and the volatiles were analyzed using static headspace gas chromatography-mass spectrometry (SHGC-MS). The addition of 4 and 6% MPC to herring mince resulted in a 33% and 50% reduction of TBARS, respectively, at month 4 and lessened the intensity of fishy odor throughout storage. However, MPC did not protect fatty acids from enzymatic degradation unless it was added immediately after mincing. Volatile analysis using SHGC-MS showed that 4% MPC was able to reduce headspace volatiles associated with fishy odor. MPC is most effective for reducing 4-heptenal, 3-methyl-1-butanol, 2-hexenal, and 1-penten-3-ol, which are known to be potent odorants associated with lipid oxidation.  相似文献   

12.
Virgin olive oils produced at wide ranges of malaxation temperatures (15, 30, 45, and 60 degrees C) and times (30, 60, 90, and 120 min) in a complete factorial experimental design were discriminated with stepwise linear discriminant analysis (SLDA) revealing differences with processing conditions. Virgin olive oils produced at 15 and 60 degrees C for 30 min showed the most significant (p < 0.01) differences. Discrimination was based upon volatile and phenolic compounds detected in olive oils, peroxide value (PV), free fatty acids (FFA), ultraviolet (UV) absorbances, and oil yield. There were different discriminating variables for processing conditions illustrating the dependence of virgin olive oil quality on malaxation time and temperature. Volatile compounds were the dominant discriminating variables. Common oxidation indicators of olive oil (PV, K232, and K270) were not among the variables that significantly (p < 0.01) changed with malaxation time and temperature. Variables that discriminated both malaxation time and temperature were hexanal, 3,4-dihydroxyphenyl ethyl alcohol-decarboxymethyl elenolic acid dialdehyde (3,4-DHPEA-DEDA) and FFA, whereas 1-penten-3-ol, E-2-hexenal, octane, tyrosol, and vanillic acid significantly (p < 0.01) changed with temperature only and Z-2-penten-1-ol, (+)-acetoxypinoresinol, and oil yield changed with time only. Virgin olive oil quality was significantly influenced by malaxation temperature, whereas oil yield discriminated malaxation time. This study demonstrates the two modes of hexanal formation: enzymatic and nonenzymatic during virgin olive oil extraction.  相似文献   

13.
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14.
A total of 15 green tea samples were prepared from fresh tea leaves obtained from three different countries: two from Laos, seven from Myanmar, and six from Vietnam. The volatile aroma constituents of the 15 samples were analyzed by gas chromatography/mass spectroscopy. Eleven aroma constituents were chosen from over 100 chemicals found in the samples to compare differences among various teas. They were hexanal, 1-penten-3-ol, heptanal, 1-pentenal, (Z)-2-penten-1-ol, (Z)-3-penten-1-ol, linalool oxide (trans-furanoid), linalool oxide (cis-furanoid), linalool, linalyl propanoate, and geraniol. Generally, concentrations of linalool and hexanal seem to play an important role in the quality of green teas. Green teas from Laos and Myanmar contained heterocyclic compounds, such as pyridines and pyrazines, formed by high-temperature processing. The presence of these heterocyclic compounds suggested that the temperature used for tea processing plays an important role in the formation of aroma chemicals in green teas.  相似文献   

15.
Fresh elder flowers (Sambucus nigra L.) were extracted with an aqueous solution containing sucrose, peeled lemon slices, tartaric acid, and sodium benzoate to make elder flower syrup. Aroma compounds emitted from the elder flower syrup were collected by the dynamic headspace technique and analyzed by GC-FID and GC-MS. A total of 59 compounds were identified, 18 of which have not previously been detected in elder flower products. The concentrations of the identified volatiles were measured in five elder cultivars, Allesoe, Donau, Sambu, Sampo, and Samyl, and significant differences were detected among cultivars in the concentration levels of 48 compounds. The odor of the volatiles was evaluated by the GC-sniffing technique. cis-Rose oxide, nerol oxide, hotrienol, and nonanal contributed to the characteristic elder flower odor, whereas linalool, alpha-terpineol, 4-methyl-3-penten-2-one, and (Z)-beta-ocimene contributed with floral notes. Fruity odors were associated with pentanal, heptanal, and beta-damascenone. Fresh and grassy odors were primarily correlated with hexanal, hexanol, and (Z)-3-hexenol.  相似文献   

16.
Gala apples exposed to the ethylene action inhibitor 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C in air or a controlled atmosphere (CA) maintained at 1 kPa O2 and 2 kPa CO2. Volatile compounds were measured after 4, 12, 20, and 28 weeks plus 1 or 7 days at 20 degrees C. Treatment with 1-MCP and then storage in air or CA or storage in CA without 1-MCP treatment reduced volatile production as compared to apples not treated with 1-MCP stored in air. The reduced production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene was observed. Ester production by fruit stored in CA decreased throughout the storage period regardless of previous 1-MCP treatment. The production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene by 1-MCP-treated fruit stored in air plus 7 days at 20 degrees C increased after 20 or 28 weeks of storage. Continuous exposure to 417 micromol m(-3) ethylene for 7 days at 20 degrees C after 12 or 28 weeks of storage stimulated production of many volatile compounds, primarily esters and alcohols, by fruit stored in CA or 1-MCP-treated apples stored in air. However, exposure to ethylene had no effect on the production of aldehydes or acetic acid.  相似文献   

17.
Antioxidative compounds were isolated from the methanol extract of fresh rhizome of smaller galanga (Alpinia officinarum Hance). Seven phenylpropanoids (1-7) were finally obtained by reversed-phase HPLC, and their structures were elucidated by MS and NMR analyses. They comprised the two known compounds, (E)-p-coumaryl alcohol gamma-O-methyl ether (1) and (E)-p-coumaryl alcohol (6), and the five novel compounds, stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-methoxy-2-(methoxymethyl)-4-pentene (2a and 2b), stereoisomers of (4E)-1,5-bis(4-hydroxyphenyl)-1-ethoxy-2-(methoxymethyl)-4-pentene (3a and 3b), (4E)-1,5-bis(4-hydroxyphenyl)-1-[(2E)-3-(4-acetoxyphenyl)-2-propenoxy]-2-(methoxymethyl)-4-pentene (4), (4E)-1,5-bis(4-hydroxyphenyl)-2-(methoxymethyl)-4-penten-1-ol (5), and (4E)-1,5-bis(4-hydroxyphenyl)-2-(hydroxymethyl)-4-penten-1-ol (7). Compounds 1-7 were detected for the first time as constituents of galanga rhizomes and exhibited antioxidative activities against the autoxidation of methyl linoleate in bulk phase.  相似文献   

18.
To identify aromatic compounds in Jiashi melon juice, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) analysis was used. Odor activity values (OAVs) were also calculated on the basis of the qualitative and quantitative analysis of volatile compounds. Results showed that 42 volatiles were identified, among which 4 compounds, namely, diethyl carbonate, isophorone, 2-butoxyethyl acetate, and menthol, were identified or tentatively identified for the first time as volatiles in melon fruit. Twelve compounds, namely, (2E,6Z)-nona-2,6-dienal, (3Z,6Z)-nona-3,6-dien-1-ol, ethyl butanoate, ethyl 2-methylbutyrate, ethyl 2-methylpropanoate, (Z)-non-6-enal, (E)-2-nonenal, heptanal, methyl 2-methylbutyrate, nonanal, hexanal, and 2-methylpropyl acetate, were identified as the potent odorants of Jiashi melon juice by both OAV and detection frequency analysis (DFA). In addition, seven odorants were detected by all of the panelists and showed higher OAVs, indicating that DFA and OAV resulted in relatively similar "Jiashi" melon aroma patterns.  相似文献   

19.
Three olfactometric methods (olfactometry global analysis, OSME, and AEDA) were compared to evaluate the main impact odorants of cooked mussels. The results obtained from these methods were very similar and well correlated. On the basis of the three techniques, 42 odor-active compounds were detected and 28 were identified. Among these compounds, 6 odorants seem to contribute actively to the aroma of mussels: 2,3-butanedione (4) (buttery, caramel-like odor), (Z)-4-heptenal (14) (boiled potato-like odor), (E)-2-penten-1-ol (17) (mushroom-like odor), 2-ethylpyrazine (19) (nutty odor), methional (25) (boiled potato-like odor), and (E,E)-2,4-octadienal (32) (cucumber-like odor).  相似文献   

20.
Development of objectionable fishy off-flavors is an obstacle in the development of fish oil enriched foods. Only little is known about the sensory impact of specific volatile fish oil oxidation products in food emulsions. This study examined the volatiles profiles of fish oil enriched milk during cold storage (2 degrees C) for 14 days by dynamic headspace sampling followed by gas chromatography-mass spectrometry analyses. Different volatiles (n = 60) comprising alkenals, alkadienals, alkatrienals, and vinyl ketones were identified in the fish oil enriched milk. The potent odorants identified by gas chromatography-olfactometry were 1-penten-3-one, (Z)-4-heptenal, 1-octen-3-one, (Z)-1,5-octadien-3-one, (E,E)-2,4-heptadienal, and (E,Z)-2,6-nonadienal, but despite their potency, none of the separated volatiles imparted a fishy or metallic odor. Two isomers, (E,Z,Z) and (E,E,Z) of 2,4,7-decatrienal were identified in fish oil enriched milk emulsions with peroxide values 0.8 and 3.4 meq/kg, respectively. To our knowledge, this is the first report on appearance of these decatrienals in food emulsions having a relatively low peroxide value.  相似文献   

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