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1.
Apple (Malus x domestica Borkh., cv. Gala) fruit treated with 0.5 microL x L(-1) 1-methylcyclopropene (MCP) or air (non-MCP) for 12 h at 20 degrees C were exposed to gamma radiation at doses of 0, 0.44, 0.88, or 1.32 kGy at 23 degrees C and then stored at 20 degrees C. Production of volatile compounds was measured on the day of irradiation and 1, 3, 7, 14, and 21 days after irradiation. Both MCP treatment and irradiation inhibited ethylene production. MCP treatment reduced production of all volatile esters and alcohols detected, whereas irradiation inhibited production of most, but not all, esters and some alcohols by non-MCP-treated fruit. The inhibition of volatile production following irradiation increased with dose. Production of methyl and propyl esters was inhibited more than that of other esters following irradiation or MCP treatment. The impact of irradiation on production of esters and alcohols by MCP-treated fruit was minimal. Non-MCP-treated fruit irradiated at 0.44 kGy produced the most esters during the 21-day period at 20 degrees C following irradiation, and the ester production rate in these fruit was comparable to that of the nonirradiated fruit 21 days after irradiation. Fruit treated with doses higher than 0.44 kGy did not recover their ability to produce volatile compounds. These results indicate both MCP and ionizing radiation inhibit production of many aroma compounds produced by ripening apple fruit.  相似文献   

2.
Consumption of salsas and dishes containing cilantro has been linked to several recent outbreaks of food-borne illness due to contamination with human pathogens. Ionizing irradiation can effectively eliminate food-borne pathogens from various vegetables including cilantro. However, the effect of irradiation on aroma of fresh cilantro is unknown. This study was conducted to investigate the effect of irradiation on volatile compounds of fresh cilantro leaves. Fresh cilantro leaves (Coriandrum sativum L) were irradiated with 0, 1, 2, or 3 kGy gamma radiation and then stored at 3 degrees C up to 14 days. Volatile compounds were extracted using solid-phase microextraction (SPME), followed by gas chromatographic separation and mass spectra detection at 0, 3, 7, and 14 days after irradiation. Most of the volatile compounds identified were aldehydes. Decanal and (E)-2-decenal were the most abundant compounds, accounting for more than 80% of the total amount of identified compounds. The amounts of linalool, dodecanal, and (E)-2-dodecenal in irradiated samples were significantly lower than those in nonirradiated samples at day 14. However, the most abundant compounds [decanal and (E)-2-decenal] were not consistently affected by irradiation. During storage at 3 degrees C, the amount of most aldehydes peaked at 3 days and then decreased afterward. Our results suggest irradiation of fresh cilantro for safety enhancement at doses up to 3 kGy had minimal effect on volatile compounds compared with the losses that occurred during storage.  相似文献   

3.
The aim of this work was to assess whether extra time spent under AIR conditions after storage in an ultra low oxygen (ULO) atmosphere could allow the regeneration of volatile compound emission without negatively affecting quality parameters and the consumer acceptability of Fuji apples. Fruits were stored for 19 and 30 weeks at 1 degrees C and 92% RH under ULO atmosphere conditions (1 kPa O 2:1 kPa CO 2) or under ULO conditions followed by different periods (2 and 4 weeks) in cold AIR atmosphere (ULO + 2w or ULO + 4w, respectively). Standard quality and emission of volatile compounds were analyzed after storage plus 1 and 7 days at 20 degrees C. Sensory attributes and acceptability were also determined after 7 days at 20 degrees C. The extra period of 30 weeks in an AIR atmosphere after ULO storage resulted in an increase in the concentration of the compounds that most contribute to the flavor of Fuji apples. These fruits were relatively well accepted by consumers despite a slight decline in firmness and acidity.  相似文献   

4.
Ionizing radiation is an effective processing technology for pathogen inactivation on various foods. However, the generation of off-odor is a concern for some irradiated meats. This study was conducted to investigate volatile sulfur compounds of precooked ready-to-eat turkey breast as functions of radiation dose and subsequent storage. Precooked turkey breast was exposed to 0, 1, 2, 3, 4, and 5 kGy of gamma radiation and stored for 14 days at 5 degrees C. Volatile sulfur compounds were extracted using solid phase microextraction (SPME), followed by gas chromatographic separation and pulsed flame photometric detection. Irradiation dramatically increased concentrations of hydrogen sulfide, sulfur dioxide, methanethiol, and dimethyl disulfide. The rate of increase was higher at low doses (0-2 kGy) than at higher doses of 3-5 kGy. Carbon disulfide was the only volatile sulfur compound that was reduced by irradiation. Concentrations of all volatile sulfur compounds decreased in both irradiated and nonirradiated samples stored at 5 degrees C.  相似文献   

5.
The essential oil of leaves and peel from the Cretan variety Zambetakis (Citrus limon) was obtained by steam distillation with a Clevenger apparatus. The essential oil was subjected to GC-MS analysis, and 35 substances were identified. The main component in both essential oils was limonene. beta-Pinene, myrcene, neral, geranial, neryl acetate, geranyl acetate, and beta-caryophyllene have been identified in the leaf oil. The peel oil contained gamma-terpinene, beta-pinene, myrcene, neral, and geranial. The quantification of volatile substances was based on the internal standard method, using octyl acetate as internal standard, and expressed in milligrams per kilogram of the essential oil. The high contents of neral and geranial were indicative of the high quality of both essential oils. The aroma profile and quantitative variations among the essential oil components were measured at six different time intervals over a period of greater than one year. Differences between the components of lemon leaves and peel were observed.  相似文献   

6.
Experiments of accelerated oxidation of "fino" sherry wines have been conducted at 25 degrees C and under the influence of UV-visible radiation (a xenon lamp of 1500 W). With the aim of determining the contribution of UV-vis radiation to the browning phenomenon, two types of glass bottles were employed: topaz bottles (with low values of transmittance in the UV-visible range) and transparent bottles. To identify significant differences between the wine before and after being subjected to the influence of the UV-vis radiation, the values of absorbance at 420 nm and the concentrations of various polyphenolic and volatile compounds were submitted to a multivariate variance analysis. Both factors considered (time and type of bottle) had a statistically significant effect on the values of absorbance at 420 nm and on the concentration of most of the polyphenolic compounds, whereas only the "time" factor was significant for volatile compounds. All wines showed losses in several polyphenolic compounds, which were more severe for the wines bottled in transparent glasses. However, these wines exhibited a lower degree of visual browning (abs 420 nm). In the case of volatile compounds, most of these presented increases during storage exposed to the influence of the UV-vis radiation.  相似文献   

7.
Tomato near-isogenic lines differing in fruit carotenogenesis genes accumulated different aroma volatiles, in a strikingly similar fashion as compared to watermelon cultivars differing in fruit color. The major volatile norisoprenoids present in lycopene-containing tomatoes and watermelons were noncyclic, such as geranial, neral, 6-methyl-5-hepten-2-one, 2,6-dimethylhept-5-1-al, 2,3-epoxygeranial, (E,E)-pseudoionone, geranyl acetone, and farnesyl acetone, seemingly derived from lycopene and other noncyclic tetraterpenoids. Beta-ionone, dihydroactinodiolide, and beta-cyclocitral were prominent in both tomato and watermelon fruits containing beta-carotene. Alpha-ionone was detected only in an orange-fleshed tomato mutant that accumulates delta-carotene. A yellow flesh (r) mutant tomato bearing a nonfunctional psy1 gene and the yellow-fleshed watermelon Early Moonbeam, almost devoid of carotenoid fruit pigments, also lacked norisoprenoid derivatives and geranial. This study provides evidence, based on comparative genetics, that carotenoid pigmentation patterns have profound effects on the norisoprene and monoterpene aroma volatile compositions of tomato and watermelon and that in these fruits geranial (trans-citral) is apparently derived from lycopene in vivo.  相似文献   

8.
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   

9.
The vapors of citral, its isomers geranial and neral, and its related compounds were examined for their effect on Penicillium digitatum, Penicillium italicum, and Geotrichum candidum, the major fungi responsible for postharvest spoilage of citrus. Vapor of citral and its two isomers generated from 15 microL L(-1) aqueous solutions in Petri dishes inhibited development of the three pathogens, with concentrations of 2-6 microL L(-1) also being effective against P. italicum. Vapors of citral and geranial from 15 microL L(-1) solutions were fungicidal to P. digitatum and G. candidum, while neral was fungicidal to G. candidum. Citral-related compounds were much less effective, with effectiveness decreasing from citronellal to citronellol and citronellic acid. R and S isomers of these three citral-related compounds generally had similar effects on the fungi tested.  相似文献   

10.
Climacteric Fuji apples were treated with 10 microL x L(-1) MCP (1-methylcyclopropene), 2 mmol x L(-1) MJ (methyl jasmonate), or a combination of 10 microL x L(-1) MCP and 2 mmol x L(-1) MJ. Fruit were kept at 20 degrees C for 15 days after treatment. Production of ethylene and other volatile compounds was measured prior to and 3, 7, 11, and 15 days after treatment. Ethylene production decreased 3 days following MJ treatment and then increased. MCP treatment alone or in combination with MJ inhibited ethylene production. MJ and MCP inhibited production of many volatile alcohols and esters. The production of individual alcohols and esters appears to be differentially inhibited by MJ or MCP. MJ and MCP inhibited not only production of alcohols but also formation of esters from alcohols.  相似文献   

11.
Bologna was processed from ground turkey breast meats containing one of four antioxidant treatments (none, rosemary extract, sodium erythorbate, and sodium nitrite). After it was cooked, the bologna was sliced, sealed in gas impermeable bags, exposed to 0, 1.5, and 3.0 kGy gamma-radiation, and then stored at 5 degrees C for up to 8 weeks. Thiobarbuturic acid reactive substances (TBARS), color, and volatile sulfur compounds were measured every 2 weeks during storage. Irradiation had no consistent effect on TBARS values. The rosemary extract and sodium nitrite inhibited, while erythorbate increased, TBARS values, independent of radiation dose or storage time. Irradiation promoted redness and reduced yellowness of the control (no antioxidant) bologna at weeks 0 and 2. The use of nitrite and rosemary extract inhibited the changes in color due to irradiation. Several volatile sulfur compounds (hydrogen sulfide, methanethiol, methyl sulfide, and dimethyl disulfide), measured using a pulsed flame photometric detector, increased with radiation dose. However, none of the antioxidants had any substantial effect on volatile sulfur compounds induced by irradiation. Our results suggest that antioxidants did not consistently affect irradiation-induced volatile sulfur compounds of turkey bologna although they did significantly impact color and lipid oxidation.  相似文献   

12.
The aim of this study was to examine the occurrence and concentrations of volatile organic compounds (VOCs), in particular, volatile monoterpenes, in soil atmosphere under silver birch (Betula pendula L.) and two conifers, Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.), and to determine the effects of the most relevant monoterpenes on transformations of soil N. The study site was a 70-year-old tree species experiment in Kivalo, northern Finland. VOCs were collected using two methods, passive air samplers and a chamber method. In soil atmosphere under spruce and especially under pine, the concentrations of monoterpenes were high, α- and β-pinene, Δ-3-carene and myrcene being the most abundant compounds, whereas concentrations of monoterpenes in soil atmosphere under birch were negligible. Samples of humus layer from the birch stand incubated in vitro and exposed to vapors from monoterpenes typical of coniferous forest soil showed decreased rates of net N mineralization but simultaneously increased rates of C mineralization. The response of soil microbial biomass C and N to different monoterpenes varied, but some monoterpenes considerably decreased soil microbial biomass. Altogether these results suggest that these compounds have negative effects on soil N transformations, but may serve as carbon and energy source for part of soil microbes.  相似文献   

13.
The chemical composition of several commercial Italian Limoncellos, lemon-peel-based alcoholic beverages, was studied by chromatographic techniques. These methods allowed a rapid monitoring of Limoncello, giving information on quality markers and possible adulteration of the product. Quantitative data for more than 60 compounds are reported. Limoncellos were characterized by the presence of selected volatile (terpenes, aldehydes, alcohols) and nonvolatile compounds (psoralens, coumarins, phenolics, carbohydrates and acids). On the basis of their composition, the samples were grouped by PCA analysis in two sets; the first group showed a composition similar to lemon essential oils, with a high content of b-pinene, myrcene, trans-a-bergamottene, and b-bisabolene, and a low content in neral and geranial. The composition of the second group suggested the occurrence of oxidative phenomena and/or the addition of flavors. The presence of ethyl acetate, acetaldehyde, 2-methyl-1-propanol and glycerol showed that a fermentation probably occurred in the sugar syrup used to dilute the Limoncello after the extraction process.  相似文献   

14.
A gas chromatography flame ionization detection method for the quantification of bioactive marker compounds (neral, geranial, geraniol, limonene, citronellal, and beta-myrcene) in the essential oil of Cymbopogon citratus (lemon grass) was developed. Four procedures for the extraction of essential oils from C. citratus were compared including solvent extraction, steam distillation extraction, accelerated solvent extraction, and supercritical fluid extraction. Solvent extraction by sonication with nonpolar solvents showed comparable results to the steam distillation method. Several commercial products prepared from C. citratus and Cymbopogon flexuosus were analyzed and compared.  相似文献   

15.
Freshly squeezed orange juice aroma is due to a complex mixture of volatile compounds as it lacks a specific character impact compound. Fresh hand-extracted juice is unstable, and thermal processing is required to reduce enzyme and microbial activity. Heating protocols range from the lightly heated not from concentrate, NFC, to the twice heated, reconstituted from concentrate, RFC, juices. Thermal processing profoundly effects aroma composition. Aroma volatiles are further altered by subsequent time-temperature storage conditions. Heating reduces levels of reactive aroma impact compounds such as neral and geranial, and creates off-flavors or their precursors from Maillard, Strecker, and acid catalyzed hydration reactions. Off-flavors such as 4-vinylguaiacol, p-cymene, and carvone are the products of chemical reactions. Other off-flavors such as butane-2,3-dione, guaiacol, and 2,6-dichlorophenol are indicators of microbial contaminations. Since most orange juice consumed worldwide is processed, the goal of this review is to summarize the widely scattered reports on orange juice aroma differences in the three major juice products and subsequent aroma changes due to packaging, storage, and microbial contamination with special emphasis on results from GC-O studies.  相似文献   

16.
Cantaloupe cultivar variability from various U.S. regions and growing seasons within a given year was evaluated. As expected, there was often considerable quality and volatile variation among cultivars. Eight of 11 cultivars met the standard U.S. No. 1 requirement for degrees Brix (> or =9), and in most cultivars, degrees Brix declined during fresh-cut storage at 4 degrees C. Hunter L (loss of lightness color value) and a (decline of typical orange hue) colors also generally declined during storage in most cultivars. Volatile ester compounds generally decreased during fresh-cut storage or exhibited a transient increase before declining after 5-7 days of storage. The relative percentage of acetate esters declined during storage in all cultivars, and declines were accompanied by simultaneous non-acetate ester increases. Slight imbalances in compound concentrations may alter the overall perception of desirable, typical "cantaloupe" aroma/flavor during fresh-cut storage. Upsetting the unique aroma balance through storage may negatively affect flavor and the consumer's perception of desirable attributes, even though total volatile levels might not decrease substantially until after 5-7 days in storage. Subtle volatile and quality decreases are likely to be exacerbated with immature-harvested cantaloupe and are likely in out-of-season exports that have likewise been harvested at less mature stages. Altogether, this study indicates the difficulty in procuring cantaloupes of consistent quality from local producers, in a given year, for domestically grown fruit.  相似文献   

17.
The aroma compounds in broccoli stored in different modified atmospheres were studied. The packaging materials used were oriented polypropylene (OPP), poly(vinyl chloride) (PVC), and low-density polyethylene (LDPE) containing an ethylene-absorbing sachet. All samples were stored for either 1 week at a constant temperature of 10 degrees C or for 3 days at 4 degrees C, followed by 4 days at 10 degrees C. The atmospheres that developed inside the packaging materials differed significantly. The broccoli samples were analyzed raw and after cooking, with regard to volatile compounds, using gas-phase (headspace) extraction followed by gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), hexanal, 3-cis-hexen-1-ol, nonanal, ethanol, and a group of thiocyanates were selected for a detailed study because these compounds cause off-odor and can be used as indicators of stress. Significant differences were found in the aroma profiles of the broccoli samples relative to the packaging materials used for storage. Storage in OPP (14% O(2), 10.5% CO(2)) resulted in most of the off-odors, while storage in LDPE (6% O(2), 7% CO(2)) and PVC (17.9% O(2), 4% CO(2)) was found to maintain the concentration of DMS, DMDS, and DMTS during storage. Heat treatment of the broccoli increased the content of aroma compounds as well as the number of compounds containing sulfur.  相似文献   

18.
Volatile emissions of navel orange (Citrus sinensis L. Osbeck cv. Washington) fruit were evaluated as a means for predicting and gauging freeze damage. The fruits were subjected to -5 or -7 degrees C treatments in a laboratory freezer for various time periods of 2-9.5 h and stored at 23 degrees C for 1, 2, or 7 days, after which time the emission of volatiles from the fruit was measured. Following the final day of volatile measurements the fruits were stored at 5 degrees C for an additional 2-3 weeks and then evaluated for fruit quality characteristics. Peel injury in the form of brown lesions, drying of the juice vesicles, a decline in acidity, and a loss of flavor were observed to occur as a result of freezing. Corresponding to the loss in fruit quality were large increases in the emissions of ethanol, ethyl butanoate, methyl hexanoate, and ethyl octanoate. With the exception of methyl hexanoate, for which volatile emissions decreased during storage for 7 days at 23 degrees C, all of the other volatiles were relatively unchanged in amount by storage. Treatment at -7 degrees C caused greater injury, quality loss, and more volatile emanation than did freezing at -5 degrees C. The measurement of volatile emissions appears to be a useful approach to identify freeze-damaged navel oranges.  相似文献   

19.
Dynamic headspace sampling was used to collect aroma compounds from raw samples of four carrot (Daucus carota L.) cultivars (Brasilia, Duke, Fancy, and Cortez). The collected volatiles were analyzed by capillary GC-FID and GC-MS using large-volume cool on-column injection (LVI-COC). Of the 36 compounds identified, 6 had not been previously detected in carrots. Significant differences between the carrot cultivars were found for 31 of the identified volatiles as well as for total monoterpenes, sesquiterpenes, and total volatile content. Mono- and sesquiterpenes accounted for about 98% of the total volatile mass in all cultivars. LVI-COC injection was used to determine the loss of carrot volatiles during concentration of headspace samples under a stream of nitrogen. The loss among major monoterpenes in the concentrated samples varied from 16% for p-cymene to >40% for alpha-pinene as compared to nonconcentrated samples. The loss among high-boiling sesquiterpenes varied from not detectable (beta-caryophyllene, alpha-humulene, and caryophyllene oxide) to approximately 7% for (E)- and (Z)-gamma-bisabolene.  相似文献   

20.
Camellia oil is widely used in some parts of the world partly because of its high oxidative stability. The effect of heating a refined camellia oil for 1 h at 120 degrees C or 2 h at 170 degrees C with exogenous antioxidant, namely, caffeic acid and tyrosol, was studied. Parameters used to assess the effect of heating were peroxide and K values, volatile formation, and fatty acid profile. Of these, volatile formation was the most sensitive index of change as seen in the number of volatiles and the total area count of volatiles in gas chromatograms. Hexanal was generally the dominant volatile in treated and untreated samples with a concentration of 2.13 and 5.34 mg kg(-1) in untreated oils heated at 120 and 170 degrees C, respectively. The hexanal content was significantly reduced in heated oils to which tyrosol and/or caffeic acid had been added. Using volatile formation as an index of oxidation, tyrosol was the more effective antioxidant of these compounds. This is contradictory to generally accepted antioxidant structure-activity relationships. Changes in fatty acid profiles after heating for up to 24 h at 180 degrees C were not significant.  相似文献   

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