Characterization of volatiles in strawberry guava (Psidium cattleianum Sabine) fruit.

Volatile compounds were isolated from strawberry guava fruit by simultaneous steam distillation-solvent extraction according to Likens-Nickerson. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing GC. Two hundred and four compounds were identified in the aroma concentrate, of which ethanol, alpha-pinene, (Z)-3-hexenol, (E)-beta-caryophyllene, and hexadecanoic acid were found to be the major constituents. The presence of many aliphatic esters and terpenic compounds is thought to contribute to the unique flavor of the strawberry guava fruit.     

Sulfur volatiles in guava (Psidium guajava L.) leaves: possible defense mechanism

Volatiles from crushed and intact guava leaves (Psidium guajava L.) were collected using static headspace SPME and determined using GC-PFPD, pulsed flame photometric detection, and GC-MS. Leaf volatiles from four common citrus culitvars were examined similarly to determine the potential component(s) responsible for guava's protective effect against the Asian citrus psyllid (Diaphorina citri Kuwayama), which is the insect vector of Huanglongbing (HLB) or citrus greening disease. Seven sulfur volatiles were detected: hydrogen sulfide, sulfur dioxide, methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), methional, and dimethyl trisulfide (DMTS). Identifications were based on matching linear retention index values on ZB-5, DB-Wax, and PLOT columns and MS spectra in the case of DMDS and DMS. DMDS is an insect toxic, defensive volatile produced only by wounded guava but not citrus leaves and, thus, may be the component responsible for the protective effect of guava against the HLB vector. DMDS is formed immediately after crushing, becoming the major headspace volatile within 10 min. Forty-seven additional leaf volatiles were identified from LRI and MS data in the crushed guava leaf headspace.     

Volatile compounds of Psidium salutare (H.B.K.) Berg. fruit

Volatile compounds were isolated from Psidium salutare fruits by simultaneous steam distillation-solvent extraction according to the Likens-Nickerson procedure. Compounds were identified by capillary GC and GC-MS. One hundred and fifty compounds were identified in the aroma concentrate, from which limonene, myrcene, and alpha-pinene were found to be the major constituents in the fruit.     

Characterization of the aroma-active compounds in pink guava (Psidium guajava, L.) by application of the aroma extract dilution analysis

The volatiles present in fresh, pink-fleshed Colombian guavas ( Psidium guajava, L.), variety regional rojo, were carefully isolated by solvent extraction followed by solvent-assisted flavor evaporation, and the aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis. The results of the identification experiments in combination with the FD factors revealed 4-methoxy-2,5-dimethyl-3(2 H)-furanone, 4-hydroxy-2,5-dimethyl-3(2 H)-furanone, 3-sulfanylhexyl acetate, and 3-sulfanyl-1-hexanol followed by 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, ( Z)-3-hexenal, trans-4,5-epoxy-( E)-2-decenal, cinnamyl alcohol, ethyl butanoate, hexanal, methional, and cinnamyl acetate as important aroma contributors. Enantioselective gas chromatography revealed an enantiomeric distribution close to the racemate in 3-sulfanylhexyl acetate as well as in 3-sulfanyl-1-hexanol. In addition, two fruity smelling diastereomeric methyl 2-hydroxy-3-methylpentanoates were identified as the ( R,S)- and the ( S,S)-isomers, whereas the ( S,R)- and ( R,R)-isomers were absent. Seven odorants were identified for the first time in guavas, among them 3-sulfanylhexyl acetate, 3-sulfanyl-1-hexanol, 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, trans-4,5-epoxy-( E)-2-decenal, and methional were the most odor-active.     

Genetic characterization of guava (Psidium guajava L.) germplasm in the United States using microsatellite markers

Genetic diversity of 35 Psidium guajava L. accessions and three related species (P. guineense Sw., P. sartorianum (O. Berg) Nied. and P. friedrichsthalianum (O. Berg) Nied.) maintained at the U.S. Department of Agriculture (USDA), National Plants Germplasm System, Hilo, HI, was characterized using 20 simple sequence repeat (SSR) markers. Diversity analysis detected a total of 178 alleles ranging from 4 to 16 alleles per locus. The observed mean heterozygosity (0.2) and inbreeding coefficient (0.8) indicated a high level of inbreeding among the accessions tested. Multi-locus DNA fingerprints based on the 20 SSR loci unambiguously differentiated all accessions and revealed the absence of duplicated samples. Ordination and cluster analyses suggested that the genetic relationships between majorities of the accessions could be explained by geographic origin, mainly including tropical America, Southeast Asia and Hawaii. A Bayesian cluster analysis partitioned the accessions into two groups and the partition was largely compatible with the result of ordination analyses. Distance-based cluster analyses further indicated that accessions from same geographical region or breeding programs grouped together in spite of the inter-regional exchange of germplasm. Accessions from Southeast Asia were dominantly white fleshed, whereas accessions from tropical America and Hawaii exhibited diverse flesh colors. The results also indicated that accessions from the same region were likely derived from a small number of common ancestors or progenitors. All 20 SSRs were transferable to P. guineense, P. sartorianum and P. friedrichsthalianum, indicating a close relationship between the cultigens and wild relatives. Application of SSR markers in the USDA/Agricultural Research Service germplasm collection provides new insight into the diversity of the guava germplasm, which will be valuable in future breeding endeavors and the conservation of guava genetic resources.     

Volatile components and aroma active compounds in aqueous essence and fresh pink guava fruit puree (Psidium guajava L.) by GC-MS and multidimensional GC/GC-O

Characterization of the aromatic profile in commercial guava essence and fresh fruit puree by GC-MS yielded a total of 51 components quantified. Commercial essence was characterized to present a volatile profile rich in components with low molecular weight, especially alcohols, esters, and aldehydes, whereas in the fresh fruit puree terpenic hydrocarbons and 3-hydroxy-2-butanone were the most abundant components. In the olfactometric analyses totals of 43 and 48 aroma active components were detected by the panelists in commercial essence and fruit puree, respectively. New components were described for the first time as active aromatic constituents in pink guava fruit (3-penten-2-ol and 2-butenyl acetate). Principal differences between the aroma of the commercial guava essence and the fresh fruit puree could be related to acetic acid, 3-hydroxy-2-butanone, 3-methyl-1-butanol, 2,3-butanediol, 3-methylbutanoic acid, (Z)-3-hexen-1-ol, 6-methyl-5-hepten-2-one, limonene, octanol, ethyl octanoate, 3-phenylpropanol, cinnamyl alcohol, alpha-copaene, and an unknown component. (E)-2-Hexenal seems to be more significant to the aroma of the commercial essence than of the fresh fruit puree.     

Characterization of odor-active compounds in guava wine

The volatile compounds of guava wine were isolated by continuous solvent extraction and analyzed by GC-FID and GC-MS. A total of 124 volatile constituents were detected, and 102 of them were positively identified. The composition of guava wine included 52 esters, 24 alcohols, 11 ketones, 7 acids, 6 aldehydes, 6 terpenes, 4 phenols and derivatives, 4 lactones, 4 sulfur-compounds, and 5 miscellaneous compounds. The aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis and by odor activity values. Twelve odorants were considered as odor-active volatiles: (E)-β-damascenone, ethyl octanoate, ethyl 3-phenylpropanoate, ethyl hexanoate, 3-methylbutyl acetate, 2-methyltetrahydrothiophen-3-one, 2,5-dimethyl-4-methoxy-3(2H)-furanone, ethyl (E)-cinnamate, ethyl butanoate, (E)-cinnamyl acetate, 3-phenylpropyl acetate, and ethyl 2-methylpropanoate.     

Characterization of terpenoid volatiles from cultivars of eastern hemlock (Tsuga canadensis)

The volatile terpenoid fraction from needles in 13 cultivars of Tsuga canadensis L. (Carriere) was analyzed by gas chromatography with mass spectrometry (GC-MS). The results of this study are considered along with previously reported results for foliar terpenoid levels of the Asian (T. sieboldii, T. chinensis, T. diversifolia), western North American (T. mertensiana, T. heterophylla), and eastern North American species (T. canadensis, T. caroliniana) of hemlock to draw conclusions about the potential of cultivar host resistance to the hemlock woolly adelgid (Adelges tsugae Annand). It is suggested that hemlocks in eastern North America have adapted their terpenoid chemistry for protection against endemic defoliators and that this has made them vulnerable to non-native, sucking pests such as adelgids and scales. Some cultivars of T. canadensis have a terpenoid profile that resembles that of the resistant noneastern North American species and are candidates for biological screening for resistance. Among the cultivars, the variation in terpenoid chemistry did not absolutely correspond with the considerable differences in morphological characters observed, indicating that the terpenoid chemistry is not definitively coupled with hemlock morphology.     

Characterization of volatiles in unhopped wort

The volatile fraction of wort components was studied during boiling. Not less than 118 volatile compounds were identified when unhopped pilsner wort was boiled and samples of wort and condensed vapors were analyzed with headspace SPME-GC/MS, of which 54 were confirmed with reference compounds. The wort samples contained 61 identifiable compounds, while the vapor condensate yielded 108 different compounds. Almost 30 known compounds were found that have not been described before in unhopped pilsner wort. One previously unknown aldol reaction product was tentatively identified as 2-phenyl-2-octenal. The detection of branched 2-alkenals underlines the importance of the aldol condensation in Maillard-type reactions, while the tentative identification of alkyloxazoles and alkylthiazoles could once more accentuate the central role of alpha-dicarbonyl compounds, aldehydes, and amino acids in flavor generation. The condensation of wort vapors joined with the SPME-GC/MS technique has proven to be a useful tool in volatile analysis.     

Characterization of volatiles in different dry gins

A HS-SPME method coupled to GC-MS was developed and applied for the qualitative and semiquantitative characterization of distilled gin volatile fraction. Sampling, chromatographic conditions, and method performances were evaluated, and the developed method was applied as a comparative study of some of the most popular commercial London Dry Gins and other gins with geographic denominations. During this study, 70 components of the gins' volatile fraction were isolated, tentatively identified or identified by reference compounds. They were mainly represented by mono- and sesquiterpenic compounds, which were quantitatively determined. The comparative study of London Dry Gins and gins with geographical indication permitted clear differentiation between the gins with geographical indication and one of the London Dry Gins tested.     

Characterization of the odor-active volatiles in citrus Hyuganatsu (Citrus tamurana Hort. ex Tanaka)

The volatile components of Hyuganatsu (Citrus tamurana Hort. ex Tanaka) peel oil, isolated by cold-pressing, were investigated by chemical and sensory analyses. According to chemical analysis by GC and GC-MS, limonene (84.0%) was the most abundant compound, followed by gamma-terpinene (6.9%), myrcene (2.2%), alpha-pinene (1.2%), and linalool (1.0%). Monoterpene hydrocarbons were predominant in Hyuganatsu peel oil. The odor-active volatiles in Hyuganatsu flavor were studied by GC-olfactometry and omission tests. The characteristic flavor was present in the oxygenated fraction. Flavor dilution (FD) factors of the volatile flavor components of the Hyuganatsu cold-pressed oil were determined by aroma extraction dilution analysis (AEDA). Furthermore, relative flavor activity was investigated by means of FD factor and weight percent. Ten kinds of odor compounds having Hyuganatsu-like aroma were detected by AEDA: limonene, linalool, octanol, neral, neryl acetate, tridecanal, trans-carveol, cis-nerolidol, trans,trans-farnesyl acetate, and trans,trans-farnesol. Linalool and octanol were regarded as the most odor-active or key compounds of Hyuganatsu aroma. Diluted solutions of linalool and octanol of approximately 2 ppm gave a fresh and fruity aroma note similar to Hyuganatsu flavor.     

Characterization of volatiles in extracts from oak chips obtained by accelerated solvent extraction (ASE)

Sixteen commercially available oak chips, differing in origin (French or American) and toasting level, were extracted by an accelerated solvent extraction method and characterized by their volatile composition. About 80 compounds were identified and quantified, a great part of them from the thermodegradation of lignin and cellulose. One furanone (solerone) and two C-13 norisoprenoids (3-oxo-alpha-ionol and a 3-oxoretro-alpha-ionol isomer) were also tentatively identified and reported for the first time in toasted wood. Quantitative data demonstrated the oak chips to be not so different from the composition of light- or medium-toasted wood barrels, which was reported by other authors. The same data suggest that toasting level had the strongest influence on the volatile composition of chip samples. Phenyl ketones, volatile phenols, and some furanic compounds were the most influenced. On the other hand, the influence of wood origin was found to be weaker.     

Guava fruit (Psidium guajava L.) as a new source of antioxidant dietary fiber.

Guava (Psidium guajava L.) is a tropical fruit, widely consumed fresh and also processed (beverages, syrup, ice cream, and jams). Pulp and peel fractions were tested, and both showed high content of dietary fiber (48.55-49.42%) and extractable polyphenols (2.62-7.79%). The antioxidant activity of polyphenol compounds was studied, using three complementary methods: (i) free radical DPPH* scavenging, (ii) ferric reducing antioxidant power assay (FRAP), and (iii) inhibition of copper-catalyzed in vitro human low-density lipoprotein (LDL) oxidation. All fractions tested showed a remarkable antioxidant capacity, and this activity was correlated with the corresponding total phenolic content. A 1-g (dry matter) portion of peel contained DPPH* activity, FRAP activity, and inhibition of copper-induced in vitro LDL oxidation, equivalent to 43 mg, 116 mg, and 176 mg of Trolox, respectively. These results indicate that guava could be a suitable source of natural antioxidants. Peel and pulp could also be used to obtain antioxidant dietary fiber (AODF), a new item which combines in a single natural product the properties of dietary fiber and antioxidant compounds.     

Depth distribution of aluminum and heavy metals in soils of Costa Rican coffee cultivation areas

Depth distributions of metals in soil profiles are indicative of weathering and soil genesis and anthropogenic pollution. We studied the depth distribution of total Al, Cd, Cu, Fe, Mn, Pb, and Zn concentrations in 8 Oxisols, 5 Andisols, 2 Mollisols, and 2 Alfisols of coffee plantation areas in Costa Rica. The concentrations of the mainly geo‐/pedogenic Al (means of 76 g kg^—1 in the A horizons and of 106 g kg^—1 in the lowermost sampled B horizons) and Fe (A: 56 g kg^—1, B: 66 g kg^—1) generally increased with profile depth. In spite of the regular application of Cu‐containing fungicides, Cu (A: 135 mg kg^—1, B: 158 mg kg^—1) showed accumulations in the A horizons of only three profiles. Higher Cd (A: 0.14 mg kg^—1, B: 0.09 mg kg^—1) and Pb concentrations (A: 7.3 mg kg^—1, B: 5.5 mg kg^—1) in most topsoils compared to the subsoils indicated anthropogenic inputs. The mean Mn (A: 1190 mg kg^—1, B: 1150 mg kg^—1) and Zn (A: 59 mg kg^—1, B: 66 mg kg^—1) concentrations varied little with depth. In general, the metal depth distribution in the studied tropical soils was similar to that of temperate soils although the weathering regime is quite different.     

Characterization of the most odor-active volatiles in fresh, hand-squeezed juice of grapefruit (Citrus paradisi Macfayden)

By application of the aroma extract dilution analysis on an extract prepared from fresh grapefruit juice, 37 odor-active compounds were detected in the flavor dilution (FD) factor range of 4-256 and subsequently identified. Among them the highest odor activities (FD factors) were determined for ethyl butanoate, p-1-menthene-8-thiol, (Z)-3-hexenal, 4,5-epoxy-(E)-2-decenal, 4-mercapto-4-methylpentane-2-one, 1-heptene-3-one, and wine lactone. Besides the 5 last mentioned compounds, a total of 13 further odorants were identified for the first time as flavor constituents of grapefruit. The data confirmed results of the literature on the significant contribution of 1-p-menthene-8-thiol in grapefruit aroma but clearly showed that a certain number of further odorants are necessary to elicit the typical grapefruit flavor.     

Changes in sugars,acids, and volatiles during ripening of koubo [Cereus peruvianus (L.) Miller] fruits

The columnar cactus Cereus peruvianus (L.) Miller, Cactaceae (koubo), is grown commercially in Israel. The unripe fruits are green, and the color changes to violet and then to red when the fruit is fully ripe. The content of soluble sugars was found to increase 5-fold during ripening. Glucose and fructose were the main sugars accumulated in the fruit pulp, and each increased from 0.5 to 5.5 g/100 g fresh weight during ripening. The polysaccharides content decreased during ripening from 1.4 to 0.4 g/100 g fresh weight. The titratable acidity decreased and the pH increased during ripening. The major organic acid found in the fruit was malic acid, which decreased from 0.75 g/100 g fresh weight at the mature green stage to 0.355 g/100 g fresh weight in ripe fruits. Citric, succinic, and oxalic acids were found in concentrations lower than 0.07 g/100 g fresh weight. Prominent accumulation of aroma volatiles occurred toward the end of the ripening process. The main volatile found in the ripe fruit was linalool, reaching concentrations of 1.5-3.5 microg/g fresh weight.     

Molecular Characterization of Local Spanish Peach [Prunus persica (L.) Batsch] Germplasm

A collection of 85 local Spanish peach cultivars has been studied with SSR markers. To carry out this work 42 SSRs previously developed in peach were screened to select the microsatellite loci that presented high polymorphism and that were easier to score in high resolution agarose gels. Ten SSRs were selected to identify the peach cultivars and to estimate the genetic similarity among them. The selected microsatellites resulted in the amplification of 35 fragments in the 85 genotypes studied, differentiating 46 genotypic profiles, from which 31 correspond to unique cultivars. The rest of the profiles correspond to groups of two to five cultivars and one group of 17 undistinguishable cultivars. The genetic similarity estimated from the molecular data clearly separated the flat and most of the white-fleshed peaches from the rest of genotypes that are mostly yellow non-melting local peaches. The results obtained in this work will help to improve the conservation and management of local Spanish peach germplasm allowing the establishment of core collections that represent most of the diversity conserved.     

Identification of potent odorants in different cultivars of snake fruit [Salacca zalacca (Gaert.) Voss] using gas chromatography-olfactometry

Three cultivars of snake fruits, Pondoh Hitam, Pondoh Super, and Gading, were freshly extracted using liquid-liquid extraction. The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using the nasal impact frequency (NIF) method. A total of 24 odor-active compounds were associated with the aroma of snake fruit. Methyl 3-methylpentanoate was regarded as the character impact odorant of typical snake fruit aroma. 2-Methylbutanoic acid, 3-methylpentanoic acid, and an unknown odorant with very high intensity were found to be responsible for the snake fruit's sweaty odor. Other odorants including methyl 3-methyl-2-butenoate (overripe fruity, ethereal), methyl 3-methyl-2-pentenoate (ethereal, strong green, woody), and 2,5-dimethyl-4-hydroxy-3[2]-furanone (caramel, sweet, cotton candy-like) contribute to the overall aroma of snake fruit. Methyl dihydrojasmonate and isoeugenol, which also have odor impact, were identified for the first time as snake fruit volatiles. The main differences between the aroma of Pondoh and Gading cultivars could be attributed to the olfactory attributes (metallic, chemical, rubbery, strong green, and woody), which were perceived by most of the panelists in the Pondoh samples but were not detected in the Gading samples. This work is a prerequisite for effective selection of salak genotypes with optimal aroma profiles for high consumer acceptance.