Changes in the volatile compounds and chemical and physical properties of Kuerle fragrant pear (Pyrus serotina Reld) during storage

Volatiles from stored Kuerle fragrant pears (Pyrus serotina Reld) were studied using high-resolution gas chromatography and the solid-phase microextraction (SPME) method of gas chromatography/mass spectrometry (GC/MS). The dominant components were hexanal, ethyl hexanoate, ethyl butanoate, ethyl acetate, hexyl acetate, ethanol, alpha-farnesene, butyl acetate, and ethyl (E,Z)-2,4-decadienoate. By using GC-olfactometry, it demonstrated that the volatile compounds from SPME were responsible for the aroma of the Kuerle fragrant pear. The levels of sugars, organic acids, and phenolic acids in Kuerle fragrant pears were investigated using high-performance liquid chromatography (HPLC). Fructose was the dominant sugar, followed by glucose and sucrose. With increasing storage time, sucrose levels decreased; however, changes in fructose and glucose levels were not remarkable. There was a slight decrease in flesh firmness during storage. The general soluble solids concentration (SSC) declined slightly after 5 months storage. Some aroma-related volatile components increased during storage, while others decreased, especially the esters. The organic acids and phenolic acids also changed. The flavor of the Kuerle fragrant pears was affected by the change of volatile compounds and changes in chemical and physical properties.     

“风味2号”甜瓜果实成熟过程中的品质变化

以60Coγ射线育出甜瓜新品种"风味2号"为材料,研究其果实发育和品质形成的动态变化。结果表明,从授粉后第5天开始果实快速膨大,第30天时鲜重达最大。从授粉后第29天开始,果肉可溶性糖含量迅速增加,其后保持稳定,至第34天显著降低。可滴定酸含量随果实的发育逐渐增加,糖酸比的高峰出现在授粉后第30-34天。气相色谱表明,"风味2号"果实中主要可溶性糖为果糖、葡萄糖和蔗糖,有机酸为苹果酸和柠檬酸,其中柠檬酸是主要有机酸。气相色谱-质谱联用分析显示:果实有35种挥发性物质,其中酯类占35.24%,酸类占19.21%,醇类为14.28%,醛类为11.71%。     

Changes in physicochemical characteristics and volatile constituents of strawberry (Cv. Cigaline) during maturation

Changes in the volatile composition of strawberries (cv. Cigaline) at six stages of maturity, from 28 to 44 days after anthesis, were investigated over two harvesting seasons. Volatiles were isolated by direct solvent extraction and analyzed by means of GC-FID and GC-MS, with special attention to the quantification of furanones. Firmness, skin color, soluble solids (SS), titratable acidity (TA), SS/TA ratio, organic acids, and sugars were also determined. With increasing maturity, soluble solids, SS/TA ratio, Minolta a value, and levels of sucrose, glucose, fructose, and malic acid increased, whereas Minolta L value, hue angle (), titratable acidity, and levels of citric acid decreased. Furanones and esters were generally not detected before half-red fruits, whereas C(6) compounds were the main compounds in immature fruits. During maturation, levels of these so-called green components decreased drastically, whereas levels of key flavor compounds increased significantly and were closely correlated with skin color development. Maximum volatile production was observed in fully red fruits.     

Characterization of aroma compounds in apple cider using solvent-assisted flavor evaporation and headspace solid-phase microextraction

The aroma-active compounds in two apple ciders were identified using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (MS) techniques. The volatile compounds were extracted using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). On the basis of odor intensity, the most important aroma compounds in the two apple cider samples were 2-phenylethanol, butanoic acid, octanoic acid, 2-methylbutanoic acid, 2-phenylethyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, 4-ethylguaiacol, eugenol, and 4-vinylphenol. Sulfur-containing compounds, terpene derivatives, and lactones were also detected in ciders. Although most of the aroma compounds were common in both ciders, the aroma intensities were different. Comparison of extraction techniques showed that the SAFE technique had a higher recovery for acids and hydroxy-containing compounds, whereas the HS-SPME technique had a higher recovery for esters and highly volatile compounds.     

Postharvest changes in physicochemical properties and volatile constituents of apricot (Prunus armeniaca L.). Characterization of 28 Cultivars

To investigate the changes in physicochemical properties and volatile constituents in apricot during postharvest ripening, the volatile compounds of 28 apricot cultivars were investigated by means of liquid-liquid microextraction (LLME), GC-FID, and GC-MS. Fruits picked at their optimal harvestable stage of maturity were analyzed at harvest and after ripening at 20 degrees C under controlled conditions. Soluble solids (SS), titratable acidity (TA), levels of sugars (saccharose, fructose, and glucose), and organic acids (citric and malic acids) were also determined. Thirty-three volatile compounds, including 6 esters, 5 C6 compounds, 4 alcohols, 3 carbonyl compounds, 6 terpenic compounds, and 9 lactones, were identified. Changes in the levels of volatiles have been found to increase greatly during post-harvest ripening in comparison to the modifications observed for the other physicochemical characteristics. The discrimination of the 28 apricot cultivars into four distinguishable aroma groups was achieved by statistical treatment of the data including ANOVA, principal component, and cluster analyses.     

Physicochemical characterization of a new pineapple hybrid (FLHORAN41 Cv.)

The physicochemical characteristics (pH, total and soluble solids, and titratable acidity), sugars, organic acids, carotenoids, anthocyanins, volatile compounds, and cell wall polysaccharides of a new pineapple hybrid (FLHORAN41 cultivar) were measured throughout maturation and compared with the Smooth Cayenne cv. At full maturity, the FLHORAN41 cv. has a higher titratable acidity and soluble solids content than the Smooth Cayenne cv. The golden yellow flesh and red-orange to scarlet shell of ripe FLHORAN41 cv. fruits are due to carotenoid and anthocyanin levels that are, respectively, 2.5 and 1.5 times higher than those of the flesh and shell of the ripe Smooth Cayenne cv., respectively. During maturation of the FLHORAN41 cv., there was an increase in all classes of aroma compounds (mainly terpene hydrocarbons and esters), although their relative proportions were similar in both cultivars at full maturity. Cell wall polysaccharides undergo little change during maturation.     

五九香梨贮藏期间挥发性化合物和理化性状的变化(英)

利用高效液相色谱法测定贮藏期间五九香梨的糖和有机酸的组成及变化,采用固相微萃取方式（SPME）进行萃取,并结合气相色谱和质谱（GC/MS）分析检测梨果实中的挥发性香气成分。得出以下主要结论：果糖是五九香梨的主要糖类,其次是葡萄糖和蔗糖。随着贮藏期的延长,果糖先有增加的趋势,在贮藏的第三个月内,果糖含量处于最高,而蔗糖和葡萄糖减少趋势不明显。五九香梨果实中的主要有机酸是苹果酸和柠檬酸,整个贮藏期间,柠檬酸和酒石酸含量处于上升趋势,苹果酸和奎宁酸含量在第一、二月贮藏期间增加,而后开始下降;莽草酸含量在贮藏期第一到第三阶段上升,而后略下降;琥珀酸含量在第一到第二阶段变化不明显,接着有上升的趋势,在第三阶段含量达到最高,第四和第五阶段略低于第三阶段;乙酸含量变化不明显。梨果实的硬度略有下降,贮藏的前3个月,可溶性固形物含量有上升的趋势,随后开始缓慢下降。五九香梨的主要香气成分化合物有乙酸己酯 (49.35%),乙酸丁酯 (19.56%),己酸乙酯 (5.16%),丁酸乙酯 (4.92%),乙酸乙酯 (1.08%),(E,Z)-2,4-癸二烯酸乙酯 (0.84%)等。在整个贮藏期间,部分香气成分随着贮藏期的延长而略有增加,尤其是酯类化合物。结果显示：果实硬度、可溶性固形物、糖、有机酸和香气的组成与变化对五九香梨果实的品质都有一定的影响。     

Relationship of ethylene biosynthesis to volatile production, related enzymes, and precursor availability in apple peel and flesh tissues

Regulation of ethylene biosynthesis or action has a major effect on volatiles production in apples. To understand the biochemical processes involved, we used Greensleeves apples from a transgenic line with a high suppression of ethylene biosynthesis. The study was focused at the level of the aroma volatile-related enzymes, including alcohol acyltransferase (AAT), alcohol dehydrogenase (ADH), and lipoxygenase (LOX) and at the level of amino acids and fatty acids as aroma volatile precursors in peel and flesh tissues. In general, volatile production, enzyme activity levels, and precursor availability were higher in the peel than the flesh and were differentially affected by ethylene regulation. AAT enzyme activity showed a clear pattern concomitant with ethylene regulation. Contrarily, ADH and LOX seem to be independent of ethylene modulation. Isoleucine, an important precursor of aroma compounds including 2-methylbutanoate esters, showed a major increase in the peel during ripening and responded significantly to ethylene regulation. Other important aroma volatiles precursors, like linoleic and linolenic acid, showed an accumulation during ripening associated with increases in aldehydes. The significance of these changes in relation to aroma volatile production is discussed.     

Evaluation of genotype and environment effects on taste and aroma flavor components of Spanish fresh tomato varieties

Taste and aroma related compounds have been analyzed in a collection of four traditional varieties and two tomato hybrids, representing a wide variability in fruit shape and color, grown in different environments: screenhouse and open field. Protected cultivation tended to show lower sugar concentration (fructose and glucose) but similar acid contents (citric, malic, and glutamic acids). The decreased levels of sucrose equivalents and the similar ratios of sucrose equivalents to citric or glutamic acid contents indicated that protected cultivation, despite being useful to reduce the incidence of pests and viral diseases, reduces the organoleptic quality. Additionally, it doubles the interaccession variability and increased the level of intra-accession variability. In the case of aroma, the genotypic effect was considerably higher than the environmental component on the 12 main volatiles analyzed. Only hexanal and methyl salicylate were significantly affected by environment, while 10 out of 12 volatiles were affected by the genotype. Biplot analysis showed that, even in considerably different environments, it is possible to identify genotype-dependent main aroma profiles. In the case of 13 background volatiles, the environment showed no significant effects and the genotypic effect was lower, though it is possible to identify genotypic trends in background notes.     

Preharvest calcium sprays improve volatile emission at commercial harvest of 'Fuji Kiku-8' apples

Apple (Malus × domestica Borkh.) fruit intended for long-term storage are frequently harvested commercially before becoming fully ripe, often resulting in poor aroma development. Since postharvest calcium dips have proved effective for the enhancement of flavor-related volatile esters after cold storage of apples, this study was undertaken in order to assess whether preharvest calcium sprays (7 weekly applications at 1.6%, w/v, 81-123 days after full bloom) could also aid in improving this important attribute at harvest. This procedure significantly increased calcium content in treated fruit. The emission of aroma-related volatile esters by untreated and calcium-treated 'Fuji' apples was then monitored during maturation and ripening over two months prior to commercial harvest. Results indicate that most of the compounds contributing to overall flavor in ripe fruit were enhanced in response to preharvest calcium applications, suggesting that this procedure may be suitable for the improvement of fruit aroma at harvest. The emission of acetate esters was particularly favored, consistent with higher acetaldehyde contents in treated fruit. These effects arose apparently from increased pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities, possibly leading to a better supply of alcohols and acyl CoAs for ester biosynthesis.     

加热处理对蜂蜜酒香气物质的影响

为研究适合蜂蜜酒发酵的优良工艺条件,以2批荆条蜜(白色和浅琥珀色)为原料,在酒精发酵前对发酵醪液进行加热处理,以不加热处理的样品为对照,采用酿酒酵母FX10进行发酵,发酵结束后测定蜂蜜酒的各项理化指标及挥发性化合物的含量。结果表明,供试酒样中共检测出77种挥发性物质,其中酯类39种、醇类20种、酸类8种、萜烯类4种、羰基化合物6种。加热处理可以显著增加蜂蜜酒中香气物质的种类和含量,含量较高的香气物质有乙酸乙酯、乙酸苯乙酯、乙酸异戊酯、己酸乙酯、辛酸乙酯、癸酸乙酯、月桂酸乙酯、9-十六碳烯酸乙酯、异戊醇、β-苯乙醇、辛酸和癸酸。对蜂蜜酒中香气物质进行主成分分析,发现加热处理的酒样中酯类物质对酒香贡献较大;对照酒样中酯类物质对酒香贡献较小,而醇类物质是其主要挥发性成分。本研究结果为蜂蜜酒的生产提供了一定的理论依据。     

Influence of eggs on the aroma composition of a sponge cake and on the aroma release in model studies on flavored sponge cakes

The use of solvent-assisted flavor evaporation extraction (SAFE) and purge and trap in Tenax allowed the identification of more than 100 volatile compounds in a sponge cake (SC-e). Gas chromatography-olfactometry (GC-O) of the SAFE extracts of crumb and crust were achieved in order to determine the most potent odorants of SC-e. The change in the traditional dough formulation of SC-e in which eggs were substituted by baking powder (SC-b) as the leavening agent produced important changes in some key aroma compounds. The release curves of some aroma compounds-some of them generated during baking and others added in the dough-were followed by cumulative headspace analysis. In the flavored SC-b, the aroma release curves showed a plateau after 15 min of purge, while the release increased proportionally with the purge time in the flavored SC-e. In general, except for some of the aroma compounds with the highest log P values, the rate of release of most of the added and generated aroma compounds was significantly influenced by the changes in the cake formulation. The higher rates of release found for the aroma compounds in SC-b could contribute to explain its rapid exhaustion of aroma compounds in the purge and trap experiments and might lead to poorer sensorial characteristics of this cake during storage.     

施有机肥及套袋对鸭梨果实风味品质的影响

为探讨施有机肥和套袋对鸭梨果实风味品质的影响,采用气相色谱-质谱联用技术（GC-MS）及高效液相色谱技术（HPLC）,研究了生长期施有机肥和套袋对鸭梨果实挥发性成分、 糖类和有机酸组分等风味物质的组成和含量的影响。结果表明, 供试鸭梨共检测到挥发性物质3类30种,其中酯类26种、 烯类3种、 醇类1种。施有机肥和套袋改变了鸭梨果实的特征香气成分的种类和含量。施用有机肥使套袋和不套袋鸭梨香气物质种类分别增加8种和6种,香气物质总量分别增加182.89%和127.16%。套袋使施有机肥和复合肥鸭梨的香气物质种类分别减少了8种和10种,香气物质总量分别减少66.32%和72.98%。不同处理鸭梨共检测到4种糖、 7种有机酸组分,其中糖组分主要为果糖,其次为蔗糖、 山梨醇、 葡萄糖; 有机酸组分主要为苹果酸,其次为乙酸、 柠檬酸、 莽草酸、 奎宁酸、 酒石酸、 琥珀酸。施用有机肥使鸭梨糖总量和酸总量升高,套袋使鸭梨糖总量和有机酸总量降低。施有机肥使鸭梨果实香气物质种类和含量增加,糖类和有机酸含量升高,而套袋使鸭梨果实香气物质种类和含量减少,糖类和有机酸含量降低。     

Influence of packaging on the aroma stability of strawberry syrup during shelf life

Different types of packaging (glass bottle, PVC, and PET) were compared for the preservation of aroma quality of a strawberry syrup during shelf life. Esters, alcohols, and aldehydes were analyzed by solid-phase micro-extraction (SPME) and solvent extraction. During storage, hydrolysis of esters in acids and alcohols led to a modification of the aroma profile which can be explained by the replacement of "fruity" and "fresh" notes by "dairy note" in the syrup. Aroma compounds that are responsible for fruity notes, such as methyl cinnamate, methyl anthranilate, and methyl dihydrojasmonate, were strongly reduced after 90 days. This could be explained by a selective interaction of these compounds with the polymer matrix (PET or PVC). After 330 days, a later and important decrease of the "fruity notes" occurred in both PETs; so PVC2 and the glass bottle were found to be able to maintain a balanced aroma for long-term storage.     

Characterization of volatile compounds contributing to naturally occurring fruity fermented flavor in peanuts

Published research has indicated that ethyl 2-methylpropanoate, ethyl 2-methybutanaote, ethyl 3-methylbutanoate, hexanoic acid, butanoic acid, and 3-methylbutanoic acid are responsible for fruity fermented (FF) off-flavor; however, these compounds were identified in samples that were artificially created by curing immature peanuts at a constant high temperature. The objective of this study was to characterize the volatile compounds contributing to naturally occurring FF off-flavor. Volatile compounds of naturally occurring FF and no-FF samples were characterized using solvent-assisted flavor evaporation (SAFE), solid phase microextraction (SPME), gas chromatography-olfactometry (GC-O), and gas chromatography-mass spectrometry (GC-MS). Aroma extract dilution analysis (AEDA) identified 12 potent aroma active compounds, none of which were the previously identified esters, with no consistent differences among the aroma active compounds in no-FF and FF samples. Hexanoic acid alone was identified in the naturally occurring FF sample using the SAFE GC-MS methodology, whereas two of the three previously identified esters were identified in natural and artificially created samples. The same two esters were confirmed by SPME GC-MS in natural and artificially created samples. This study demonstrated the need for caution in the direct application of data from artificially created samples until those compounds are verified in natural samples. However, these results suggest that a laboratory method using SPME-GC techniques could be developed and correlated on an ester concentration versus FF intensity basis to provide an alternative to sensory analysis for detection of FF off-flavor in peanut lots.     

Effect of carbohydrate substrate on fermentation by kefir yeast supported on delignified cellulosic materials

The suitability of delignified cellulosic (DC) material supported kefir yeast to ferment raw materials that contain various single carbohydrates, for the production of potable alcohol and alcoholic drinks, is examined in this investigation. Results are reported of fermentations carried out with sucrose, fructose, and glucose in synthetic media. Repeated batch fermentations at various initial sugar concentrations of sucrose, fructose, and glucose were performed at 30 degrees C in the presence of the aforementioned biocatalyst. The results clearly show feasible yields in the range of 0.38-0.41 g/g, alcohol concentrations of 7.6-8.2% v/v, fermentation time of 90-115 h, and conversion of 92-96%. DC material supported kefir fermented 11-fold more rapidly than free cells and 9-fold more rapidly in comparison to kissiris supported kefir. The main volatile byproducts such as amyl alcohols (mixture of 2-methyl-1-butanol and 3-methyl-1-butanol), ethanal, and ethyl acetate were formed in all sugar fermentation products. The formation of 65-110 ppm of ethyl acetate is as high and even higher than that obtained with traditional wine yeasts. The increase of the initial concentration of sugar in the fermentation media resulted in an increase in contents of volatiles. The fine aroma that was obtained in the product of fructose could be attributed to the high percentage of ethyl acetate on total volatiles. The efficiency of DC material supported kefir was the same for the fermentations of individual sugars or a mixture of fructose, sucrose, and glucose. When whey with raisin extracts was fermented, lower yields were obtained but the aroma of the product was even better.     

Effect of oak extract application to Verdejo grapevines on grape and wine aroma

Volatile compounds from a commercial aqueous oak extract application to white Verdejo grapevines at veraison have been studied. Treated grapes under two types of formulation (25% and 100%) have been analyzed at the optimum maturation time, and winemaking was then subsequently carried out. The volatile compounds were analyzed by stir bar sorptive extraction-gas chromatography-mass spectrometry. The results suggest that after the grapevine treatments, grapes store the volatiles in the form of nonvolatile precursors, and some of the volatiles are released during the winemaking process, especially six months after the alcoholic fermentation. The sensory analysis shows that wines maintain the typical aroma properties of Verdejo wines at the end of fermentation; but after six months, the wine color is greener and more astringent, and, in terms of aroma, it has wooden notes as if the wine has been aged in oak barrels.     

Evolution of the aroma profile of sherry wine vinegars during an experimental aging in wood

Changes in the aroma profile of five Sherry wine vinegars submitted to an experimental static aging in wood were followed along 24 months. Eighteen volatile compounds were determined by GC-FID. The results were subjected to multivariate analyses: principal component analysis and linear discriminant analysis. The aroma profile of vinegar can be useful to discriminate vinegars produced from different substrates or with different aging times. During the experimental aging, volatile compounds such as methyl acetate, methanol, diacetyl, and gamma-butyrolactone underwent significant concentration increases. Moreover, the initial ethanol content of vinegars is a factor in the final aromatic richness. The formation of ethyl acetate stood out in samples with an initial ethanol content of approximately 2 alcoholic degrees.     

Impacts of ionizing radiation on volatile production by ripening gala apple fruit

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.     

Changes in the concentration of yeast-derived volatile compounds of red wine during malolactic fermentation with four commercial starter cultures of Oenococcus oeni

The effects of malolactic fermentation (MLF) on the concentration of volatile compounds released by yeasts during the production of red wine were investigated by inoculation with four commercial starters of Oenococcus oeni. Volatile compounds in wine at the end of MLF were extracted, analyzed by GC-MS and GC, and compared with those extracted form a noninoculated reference sample. Several esters known to play a role in the aroma profile of red wine, such as C4-C8 ethyl fatty acid esters and 3-methylbutyl acetate, were found to increase with MLF, and their final concentration was dependent on the bacterial starter employed for the induction of MLF. The overall increase of ethyl fatty acid esters was generally larger than the one observed for acetate esters. Ethyl lactate, 3-hydroxybutanoate, 2-phenylethanol, methionol, and gamma-butyrolactone were also increased by bacterial metabolism. The impact of MLF on other volatiles or red wine, including several higher alcohols, fatty acids, and nitrogen compounds, was generally negligible.