Behavioral responses of the diamondback moth, Plutella xylostella, to green leaf volatiles of Brassica oleracea subsp. capitata

Green leaf volatiles (GLVs) from Brassica oleracea subsp. capitata L. have been identified as 1-hexanol, (Z)-3-hexen-1-ol, 1-hexen-3-ol, hexanal, (E)-2-hexenal, hexyl acetate, and (Z)-3-hexenyl acetate, by their mass spectra and retention times in comparison with authentic samples. No isothiocyanates were found in the extract. The activity of these chemicals has been determined on mated and unmated males and females of the diamondback moth (DBM) Plutella xylostella in the laboratory (wind tunnel) and in the field. On unmated males, mixtures of (Z)-3-hexenyl acetate, (E)-2-hexenal, and (Z)-3-hexen-1-ol with the pheromone induced attractant/arresting behavior in 80-100% of the males tested, significantly higher than the effect induced by the pheromone alone. On mated males and unmated females the effect of the GLVs alone or in combination with the pheromone was poor, while on mated females these compounds elicited upwind flight and arresting behavior in 40-60% of the females assayed. There was no synergism when these chemicals were mixed with the pheromone. In the field, (Z)-3-hexenyl acetate, the most active GLV in laboratory tests, when mixed with the pheromone in 1:1 ratio, enhanced 6-7-fold the number of females and 20-30% the number of males caught by traps over those baited with the pheromone alone. Our results indicate that the enhancement of the attraction of both males and females of the DBM to traps baited with pheromone blended with the relatively inexpensive and environmentally safe (Z)-3-hexenyl acetate may be important for future control strategies of the pest.     

Effects of cyclamen mite (Phytonemus pallidus) and leaf beetle (Galerucella tenella) damage on volatile emission from strawberry (Fragaria x ananassa Duch.) plants and orientation of predatory mites (Neoseiulus cucumeris, N. californicus, and Euseius finlandicus)

Volatile emission profile of strawberry (Fragaria x ananassa Duch.) plants (cvs. Polka and Honeoye) damaged by cyclamen mite (Phytonemus pallidus Banks) or leaf beetle Galerucella tenella (L.) (cv. Polka) was analyzed to determine the potential of these strawberry plants to emit herbivore-induced volatiles. The total volatile emissions as well as emissions of many green leaf volatiles (e.g., (Z)-3-hexen-1-ol and (Z)-3-hexenyl acetate) and methyl salicylate were greater from cyclamen mite-damaged strawberry plants than from intact plants. Leaf beetle feeding increased emissions of monoterpenes (Z)-ocimene and (E)-beta-ocimene, sesquiterpenes (E)-beta-caryophyllene, (E,E)-alpha-farnesene, and germacrene-D, and a homoterpene (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) significantly. Nevertheless, the na?ve generalist predatory mites, Neoseiulus cucumeris, Neoseiulus californicus, and Euseius finlandicus did not prefer P. pallidus- or G. tenella-damaged plants over intact plants in a Y-tube olfactometer, suggesting that these predatory mite species are not attracted by the herbivore-induced volatiles being released from young strawberry plants.     

Timing of intensity perception of a polar vs nonpolar aroma compound in the presence of added vegetable fat in milk

Differences in timing of intensity perception of the retronasal aroma of a nonpolar (linalool) vs polar (diacetyl) compound when the matrix (milk) fat content was varied (0%, 1%, 5%, or 10% rapeseed oil) were studied using a time-intensity method. Aromas were also evaluated by orthonasal means and with static headspace gas chromatography (GC). With increasing fat content, linalool was considerably retained in the matrix, while the release of diacetyl was not affected. As little as 1% fat was sufficient to significantly reduce the volatility (GC results) of linalool and orthonasal, but not retronasal, intensity. No effect of fat was found on the rate of linalool release. The linalool perception of the sample containing the greatest amount of fat lasted a shorter time than that of the samples containing less fat; however, the decrease in intensity perception was steeper in lower fat samples. The observed temporal release of linalool partly challenges the often-repeated statement that reduction of fat results in a more rapid and shorter aroma release.     

Sweetener/sweetness-induced changes in flavor perception and flavor release of fruity and green character in beverages

Green leaf volatile (GLV) mixtures, commercial orange flavors, and commercial strawberry flavors were applied to beverage bases in which concentrations of citric acid as well as a sweetener (sucrose or aspartame/acesulfame-K) were varied. Sensory profiling showed that flavor-specific fruity character increased as perceptible sweetness increased, independent of whether the sweetness resulted from sucrose (a change from 9 to 12 Brix) or aspartame/acesulfame-K (a change from 0.2 to 0.4 Brix). Sweetness was affected only by the tastants in the base and not by the flavors, although flavor-specific interactions between sweetener type and sweetener level occurred. Flavor release from the sucrose bases was compared to flavor release from bases containing aspartame/acesulfame-K by static headspace measurements and by MS-Nose measurements using an artificial throat. These measurements showed greater flavor volatility from bases having low Brix (fewer soluble solids). This negative Brix effect was also evident in the sensory data for perception of some GLV green notes. The headspace data could not support a positive Brix effect, the typical salting out, which would correspond to the observed perceptual enhancement of fruity notes.     

Lutein and zeaxanthin in leafy greens and their bioavailability: olive oil influences the absorption of dietary lutein and its accumulation in adult rats

This study determined the lutein level in various green leafy vegetables (GLVs) and the influence of olive and sunflower oils on the postprandial plasma and eye response of dietary lutein in adult rats, previously induced with lutein depletion (LD). Fresh GLVs (n = 35) were assessed for lutein (L) and its isomer zeaxanthin (Z) levels by high-performance liquid chromatography and liquid chromatography-mass spectrometry. Among GLVs analyzed, Commelina benghalensis L. contained a higher level of L + Z (183 mg/100 g dry wt) and was used as a lutein source for feeding studies. Rats with LD were fed a diet containing powdered C. benghalensis (2.69 mg lutein/kg diet) with either olive oil (OO group), sunflower oil (SFO group), or groundnut oil (GNO group) for 16 days. The L + Z levels of the OO group were markedly (p > 0.05) higher than those of SFO and GNO groups, in plasma (37.6 and 40.9%) and eyes (22.7 and 30.8%), respectively. These results suggest that oleic acid or OO can be used as a suitable fat source to modulate the absorption of dietary lutein to manage age-related macular degeneration.     

不同有机肥对肥城桃果实产量及品质的影响

为了探讨不同有机肥（牛粪、鸡粪、羊粪、猪粪、混粪）对肥城桃果实产量和品质的影响,为肥城桃的高产优质提供理论依据,通过连续3年处理,研究不同有机肥对白里肥城桃果实产量及品质的影响。结果表明,施用有机肥后,果实单果重与对照相比差异均不显著,但产量均显著提高。各有机肥处理都不同程度地提高了叶片的叶绿素a、叶绿素b、叶绿素a+b及类胡萝卜素含量。所有处理的叶片净光合速率（Pn）日变化趋势均呈高低高低的双峰曲线,峰值均在11:30和15:30时出现;其中11:30时为大峰,此时混粪处理的峰值最大,为21.5mol/(m2﹒s),15:30时为小峰,其中鸡粪处理的峰值最大,为18.6mol/(m2﹒s),对照的这两个峰值均低于各有机肥处理。鸡粪处理的果实硬度与对照相比显著提高;有机肥处理提高了果实的可溶生固形物（TSS）、固酸比（TSS/TA）和维生素C（Vc）含量;除猪粪处理外,其它处理的TSS含量与对照相比显著提高;羊粪、猪粪和混粪处理的TSS/TA值比对照分别提高了17.40%、7.14%和15.60%,差异显著;施入有机肥不但增加了香气的种类,还提高了香气物质的相对含量;各有机肥处理,C6醛类和醇类等青香型化合物的相对总量都低于对照,而果香型酯类和甜香型内酯类化合物的相对含量都高于对照,推测施入有机肥后,果实香气有由青香型转向果香型和甜香型的趋势。另外发现了肥城桃果实的特征香气成分,如酯类中的乙酸乙酯、乙酸丙酯、甲酸甲酯、乙酸己酯和丙酸甲酯,(E)-2-己烯-1-醇、(Z)-2-己烯-1-醇和(Z)-4-己烯-1-醇等C6醇,醛类中的(E)-2-己烯醛、2,4-己二烯醛等C6醛,还有苯甲醛。综合以上结果,施入各种有机肥均能提高果实的营养和香气品质,因此在生产中非常值得大力推广。     

茶叶挥发物对鞍形花蟹蛛觅食行为的影响

为了探明茶叶挥发物在鞍形花蟹蛛(Xysticus ephippiatus Simon)搜寻猎物——茶尺蠖(Ectropis obliqua Prout)过程中的作用,采用固相微萃取气相色谱质谱联用技术研究了茶尺蠖取食对茶树叶片挥发物释放的影响,并通过蜘蛛行为观测平台研究了蟹蛛在不同味源侧(觅食斑块)的活动行为。结果表明:对照叶片没有释放出挥发物,经茶尺蠖幼虫取食后的叶片能释放31种挥发物,其中有12种绿叶挥发物、9种萜类及其衍生物、4种芳香族挥发物和6种未知化合物。行为观测表明,雌、雄蟹蛛进入处理味源侧(茶尺蠖取食后的茶树叶片)和对照味源侧(未损伤茶树叶片)的初次选择均不存在差别(P>0.05),雌蛛进入处理味源侧和对照味源侧的频次分别为3.37±0.18和3.43±0.15,二者无明显区别(P>0.05);雄蛛进入两侧的频次分别为3.86±0.21和3.66±0.20,也无明显区别(P>0.05);雌蛛在处理味源侧和对照味源侧的停留时间分别为(922.57±19.59)s和(818.89±29.63)s,有极显著差异(P<0.01),雄蛛在两侧的停留时间分别为(937.97±18.05)s和(814.83±18.97)s,也有极显著差异(P<0.01),表明雌蛛、雄蛛在处理侧的停留时间明显延长。这说明,猎物取食诱导改变了茶树叶片挥发物的释放,而鞍形花蟹蛛能感知挥发物的变化并由此调整在不同觅食斑块中的停留时间。另外,本文还讨论了挥发物在蟹蛛搜寻猎物过程中的生态学意义。     

Intensity and persistence profiles of flavor compounds in synthetic solutions. Simple model for explaining the intensity and persistence of their aftersmell

Hydroalcoholic solutions containing a single aroma-active compound were evaluated by a sensory panel to determine the difference between ortho and retronasal odor intensities (DeltaI(ro)), buccal savoring, and aftersmell duration. Eight compounds were used. Buccal perception seems to be just a physiologically restricted form of retronasal perception. DeltaI(ro) values were dependent on the panel, although results from the two panels were significantly correlated. Such differences and the aftersmell persistence were also significantly correlated with different physicochemical parameters related to volatility. A simple model to explain such dependence is proposed. The model considers the mouth-throat system as a perfect mixing tank with a finite amount of odorants being progressively diluted by swallowing and purging (both taken as continuous processes). Retronasal intensity is modeled from the odor properties of the liquid in such a tank calculated from orthonasal odor intensity versus concentration (I/log C) curves. The model explains successfully experimental results and has also been successfully applied to instrumental data from other authors.     

Abscisic acid related compounds and lignans in prunes (Prunus domestica L.) and their oxygen radical absorbance capacity (ORAC)

Four new abscisic acid related compounds (1-4), together with (+)-abscisic acid (5), (+)-beta-D-glucopyranosyl abscisate (6), (6S,9R)-roseoside (7), and two lignan glucosides ((+)-pinoresinol mono-beta-D-glucopyranoside (8) and 3-(beta-D-glucopyranosyloxymethyl)-2- (4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-7-methoxy-(2R,3S)-dihydrobenzofuran (9)) were isolated from the antioxidative ethanol extract of prunes (Prunus domestica L.). The structures of 1-4 were elucidated on the basis of NMR and MS spectrometric data to be rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (1), rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid 3'-O-beta-d-glucopyranoside (2), rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (3), and rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxabicyclo[3,2,1]- oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (4). The antioxidant activities of these isolated compounds were evaluated on the basis of oxygen radical absorbance capacity (ORAC). The ORAC values of abscisic acid related compounds (1-7) were very low. Two lignans (8 and 9) were more effective antioxidants whose ORAC values were 1.09 and 2.33 micromol of Trolox equiv/micromol, respectively.     

Cross-modality of texture and aroma perception is independent of orthonasal or retronasal stimulation

To assess the influence of orthonasal and retronasal stimulation on cross-modal interactions between texture and flavor perception of food, a series of experiments have been conducted. Healthy human subjects were exposed to strawberry aroma pulses delivered by a computer-controlled stimulator based on air dilution olfactometry. Just prior to exposure to the aroma, the human subjects consumed water, custard, or protein gels with different textures without any added aroma. The aroma was delivered as a sequence of aroma pulses, in either an orthonasal or a retronasal fashion. The retronasal presentation of aroma with concomitant presentation of texture is thought to more closely mimick the in vivo flavor release of semisolid food products as compared to orthonasal stimulation. The time between oral consumption of the food, including swallowing, and the exposure to the aroma varied between 0.5 and 6.5 s. The subjects rated the intensity of the strawberry aroma. It was observed that the intensity of aroma decreased with increasing firmness of the food that was consumed. Aroma pulses delivered 6.5 s after swallowing were perceived as being more intense as compared to aroma pulses delivered immediately after swallowing. In conjunction with late delivery, the effect cross-modal interactions apparently decreased. Significantly higher odor intensities were reported for the aroma stimuli supplied orthonasally in comparison to retronasal administration. The observed cross-modal effect of texture on aroma intensity was not significantly altered by the mode of aroma delivery, i.e., orthonasal or retronasal stimulus administration.     

Volatile organic nitrogen-containing constituents in ambrette seed Abelmoschus moschatus Medik (Malvaceae)

A detailed investigation of the basic fraction of a CO2 extract of ambrette seeds (Abelmoschus moschatus) revealed a total of 58 nitrogen-containing compounds. The identification of these compounds was carried out by GC-MS and NMR. All the identified nitrogen-containing compounds are reported here for the first time in ambrette seeds. Among these are 27 pyrazine derivatives and 12 pyridines, including the tentative identification of four new natural compounds, 1-(6-ethyl-3-hydroxypyridin-2-yl)ethanone (1), 1-(3-hydroxy-5,6-dimethylpyridin-2-yl)ethanone (2), 1-(3-hydroxy-6-methylpyridin-2-yl)ethanone (3), and 1-(3-hydroxy-5-methylpyridin-2-yl)ethanone (4). The odor of the basic fraction was assumed to be due to these pyrazines and pyridines and also the presence of seven thiazoles. The odors described suggest that these N-compounds contribute to what is described in perfumery terms as the "natural and rounded" character of the ambrette extract.     

Fresh cucumber flavor in refrigerated pickles: comparison of sensory and instrumental analysis

The ability of nonacidified, refrigerated pickled cucumbers to produce the fresh cucumber flavor impact compounds (E,Z)-2,6-nonadienal and (E)-2-nonenal declined during storage. Production of these compounds decreased as the pH of refrigerated cucumbers was reduced. Despite the fact that the concentrations of (E,Z)-2,6-nonadienal and (E)-2-nonenal generated were over 10(5)-fold greater than the threshold levels, it was possible for a sensory panel to consistently detect differences in the intensity of fresh cucumber flavor, provided the pH difference between samples was 1 unit or greater. The presence of spices did not interfere with the ability of panelists to detect differences in fresh flavor intensity. There was a linear correlation between sensory scores and the amount of (E,Z)-2,6-nonadienal produced by cucumbers equilibrated at different pH levels.     

Reaction of tryptophan with carbohydrates: identification and quantitative determination of novel beta-carboline alkaloids in food

The formation of various carbohydrate-derived beta-carbolines was observed when model reactions of tryptophan with glucose were studied by means of HPLC with diode array detection, as well as by means of HPLC-MS. Isolation of these compounds and subsequent characterization by tandem mass spectrometry and NMR spectroscopy led to the identification of diastereomeric 1-(1,3,4,5-tetrahydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (1a/b), 1-(1,4,5-trihydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (2a/b), and E/Z isomers of 1-(1,5-dihydroxypent-3-en-1-yl)-9H-pyrido[3,4-b]indole (3a/b). HPLC-MS was used to prove the presence of these novel beta-carboline alkaloids in various food samples. In addition, quantitative determination of beta-carbolines 1a, 1b, and 2a/b in numerous products was achieved by means of HPLC with fluorometric detection. Concentrations ranged from 12 to 1922 microg/L for 1a and 1b and from 3 to 644 microg/L for 2a/b. The highest concentrations of all carbohydrate-derived beta-carbolines under study were found in ketchup, soy sauce, and fish sauce.     

Identification of character impact odorants of different soybean lecithins.

The potent odorants of standardized, enzymatically hydrolyzed, and deoiled soybean lecithins were characterized systematically by combined gas chromatography/mass spectrometry and olfactometry. Sixty-one odorants were identified; 53 of these odor-active compounds have not previously been reported as odorants of soybean lecithin flavor. By aroma extract dilution analysis and modified combined hedonic and response measurement the following odorants showed the highest flavor dilution factors and CHARM values: (E,E)-2, 4-decadienal (deep-fried), (E)-beta-damascenone (apple-like), 2, 3-diethyl-5-methylpyrazine (roasty, earthy), (E)-2-nonenal (cardboard-like), trans-4,5-epoxy-(E)-2-decenal (metallic), 1-nonen-3-one (mushroom-like), 2-ethyl-3,5-dimethylpyrazine (roasty, earthy), and 1-octen-3-one (mushroom-like). Enzymatic hydrolysis intensified especially the roasty sensation of 2, 3-diethyl-5-methylpyrazine, whereas deoiling effected a general significant decrease in olfactory perception on the nitrogen-containing compounds. In addition, sensory profiles of nasal and retronasal lecithin odor were performed.     

Effect of fungicide residues on the aromatic composition of white wine inoculated with three Saccharomyces cerevisiae strains

The effects of three fungicide residues (cyprodinil, fludioxonil, and pyrimethanil) on the aromatic composition (acids, alcohols, and esters) of Vitis vinifera white wines (var. Airén) inoculated with three Saccharomyces cerevisiae strains (syn. bayanus, cerevisiae, and syn. uvarum) are studied. The aromatic exponents were extracted and concentrated by adsorption-thermal desorption and were determined by gas chromatography using a mass selective detector. The addition of the three fungicides at different doses (1 and 5 mg/L) produces significant differences in the acidic fraction of the aroma, especially in the assays inoculated with S. cerevisiae, although the final contents do not exceed the perception thresholds. The lower quality wines, according to isomeric alcohol content [(Z)-3-hexen-1-ol and 3-(methylthio)propan-1-ol] are those obtained by inoculation with S. cerevisiae(syn. bayanus) and addition of cyprodinil. The addition of fungicides in the assays inoculated with S. cerevisiae (syn. bayanus) produces an increase in the ethyl acetate and isoamyl acetate contents, which causes a decrease in the sensorial quality of the wine obtained.     

Quantification and sensory studies of character impact odorants of different soybean lecithins.

Fifty-four potent odorants in standardized, hydrolyzed, and deoiled and hydrolyzed soybean lecithins were quantified by high-resolution gas chromatography/mass spectrometry (HRGC/MS). The characterization of their aroma impact was performed by calculation of nasal (n) and retronasal (r) odor activity values (OAVs). For this, the nasal and retronasal recognition thresholds of 18 odor-active compounds were determined in vegetable oil. The following compounds showed the highest nOAVs: 2,3-diethyl-5-methylpyrazine, methylpropanal, acetic acid, pentanoic acid, 2-ethyl-3,5-dimethylpyrazine, pentylpyridine, (Z)-1,5-octadien-3-one, 2-methylbutanal, and beta-damascenone. In addition to the compounds above, 1-octen-3-one, 1-nonen-3-one, and 3-methyl-2,4-nonandione showed potent rOAVs. The results of quantification and OAV calculation were confirmed by a model mixture of 25 impact odorants, which yielded a highly similar sensory profile to that of the original soybean lecithin. The sensory importance of pyrazines and free acids increased through enzymatic hydrolysis and decreased by the process of deoiling. The impact of unsaturated ketones on the lecithin aroma was not changed by either process.     

Identification of the main odor-active compounds in musts from French and Romanian hybrids by three olfactometric methods

Three olfactometric methods (frequency of detection, time--intensity method, and aroma extract dilution analysis) were used to evaluate the main odorants of three musts obtained from French--Romanian hybrids (Valerien, Admira, and Brumariu). The three methods allow detection of the same odor-active compounds. The results obtained from these methods were closely related. Nineteen odor-active compounds were detected, and 13 were identified. The three methods showed the importance of an unidentified compound with a grape and grape juice aroma note in the three musts. Among the other compounds, 3-hexen-1-al, (E,Z)-2,6-nonadien-1-ol, and 1-ccten-3-one seemed to contribute actively to the odor of Valerien must. 3-(Methylthio)propanal and hexanal were contributors to the Admira and Brumariu odor. Phenylacetaldehyde was one of the main odor-active compounds in must from Admira.     

Effects of sonication on the kinetics of orange juice quality parameters

The effects of sonication on pH, degrees Brix, titratable acidity (TA), cloud, browning index, and color parameters ( L*, a*, and b*) of freshly squeezed orange juice samples were studied. Ultrasonic intensity (UI) levels of 8.61, 9.24, 10.16, 17.17, and 22.79 W/cm2 and treatment times of 0 (control), 2, 4, 6, 8, and 10 min were investigated. No significant changes in pH, degrees Brix, and TA ( p < 0.05) were found. Cloud value, browning index, and color parameters were significantly affected by ultrasonic intensity and treatment time. Changes in cloud value followed first-order kinetics, whereas browning index, L*, a*, and b* values followed zero-order kinetics. Reaction rate constants were linearly correlated ( R2 > 0.90) to ultrasonic intensity.     

Quantitative studies and sensory analyses on the influence of cultivar, spatial tissue distribution, and industrial processing on the bitter off-taste of carrots (Daucus carota l.) and carrot products

Although various reports pointed to 6-methoxymellein (1) as a key player imparting the bitter taste in carrots, activity-guided fractionation experiments recently gave evidence that not this isocoumarin but bisacetylenic oxylipins contribute mainly to the off-taste. Among these, (Z)-heptadeca-1,9-dien-4,6-diyn-3-ol (2), (Z)-3-acetoxy-heptadeca-1,9-dien-4,6-diyn-8-ol (3), and (Z)-heptadeca-1,9-dien-4,6-diyn-3,8-diol (falcarindiol, 4) have been successfully identified. In the present study, an analytical procedure was developed enabling an accurate quantitation of 1-4 in carrots and carrot products. To achieve this, (E)-heptadeca-1,9-dien-4,6-diyn-3,8-diol was synthesized as a suitable internal standard for the quantitative analysis of the bisacetylenes. On the basis of taste activity values, calculated as the ratio of the concentration and the human sensory threshold of a compound, a close relationship between the concentration of 4 and the intensity of the bitter off-taste in carrots, carrot puree, and carrot juice was demonstrated, thus showing that compound 4 might offer a new analytical measure for an objective evaluation of the quality of carrot products. Quantitative analysis on the intermediate products in industrial carrot processing revealed that removing the peel as well as green parts successfully decreased the concentrations in the final carrot puree by more than 50%.