IDENTIFICATION OF VOLATILE COMPOUNDS FROM RIPE MAYHAW FRUIT (CRATAEGUS OPACA,C. AESTIVALIS,AND C. RUFULA)1

Steam volatile fractions obtained from three commercial mayhaw cultivars and two native selections were analyzed by GC and GC/MS. Twenty-four compounds were identified. The nine major components, which comprised 70–80% of the volatile fraction, were hexanal, butyl acetate, (E)-2-hexenal, butyl butyrate, linalool, butyl hexanoate, methyl octanoate, pentyl hexanoate, and hexyl hexanoate. Minor constituents included eight esters, four terpenes, two benzenoid compounds and (E)-2-hexenol.     

Quantitative Analyses of Major Carotenoid Fatty Acid Esters in Fruits by Liquid Chromatography: Persimmon and Papaya

A procedure for the quantitative analyses of major carotenoids and carotenoid esters in persimmons and papayas using column and liquid chromatography is described. The carotenoids and carotenoid esters were first separated by column chromatography on alumina into three fractions by elution with petroleum ether-benzene (80:20), benzene and methanol. The column fractions were further separated by reversed phase liquid chromatography and characterized. The total carotenoid contents in persimmon and papaya calculated as beta-carotene equivalents were 43 and 25 μg/g, respectively. The major carotenoids in persimmon were beta-cryptoxanthin, zeaxanthin, beta-carotene, lycopene and antheraxanthin and the major carotenoids in papaya were beta-cryptoxanthin, cryptoxanthin 5,6-epoxidc, beta-carotene and antherxanthin. The xanthophylls were acylated with C₈ to C₁₆ saturated fatty acids.     

Comparison of Tomatillo and Tomato Volatile Compounds in the Headspace by Selected Ion Flow Tube Mass Spectrometry (SIFT-MS)

ABSTRACT: The concentration of 31 volatiles were measured in the headspace of tomatillos using selected ion flow tube-mass spectrometry (SIFT-MS), and were compared with those in vine-ripened tomato, roma tomato, cherry tomato, and grape tomato. None of the volatiles were higher in the headspace of tomatillos than of tomatoes. Compounds (E)-2-octenal, (E)-2-pentenal, 2-isobutylthiazole, 6-methyl-5-hepten-2-one, and phenylacetaldehyde were significantly lower in tomatillo than in the tomato varieties in the headspace. After blending, volatiles in the headspace increased, and then decreased after reaching a maximum concentration, due to further degradation or depletion. Compounds (E)-2-pentenal and 1-penten-3-one reached a maximum concentration later than (E)-2-hexenal, (Z)-3-hexenal, and hexanal for tomatillo and tomatoes. The slope of the ratio of (E)-2-hexenal and (Z)-3-hexenal was not significantly different for any of the samples, implying that the activity of cis/trans isomerase was not different between tomatillos and tomatoes.     

Oregano: chemical analysis and evaluation of its antimalarial, antioxidant, and cytotoxic activities

Abstract: GC‐FID and GC‐MS analysis of essential oil from oregano leaves (Origanum compactum) resulted in the identification of 46 compounds, representing more than 98% of the total composition. Carvacrol was the predominant compound (36.46%), followed by thymol (29.74%) and p‐cymene (24.31%). Serial extractions with petroleum ether, ethyl acetate, ethanol, and water were performed on aerials parts of Origanum compactum. In these extracts, different chemical families were characterized: polyphenols (gallic acid equivalent 21.2 to 858.3 g/kg), tannins (catechin equivalent 12.4 to 510.3 g/kg), anthocyanins (cyanidin equivalent 0.38 to 5.63 mg/kg), and flavonoids (quercetin equivalent 14.5 to 54.7 g/kg). The samples (essential oil and extracts) were subjected to a screening for antioxidant (DPPH and ABTS assays) and antimalarial activities and against human breast cancer cells. The essential oil showed a higher antioxidant activity with an IC₅₀= 2 ± 0.1 mg/L. Among the extracts, the aqueous extract had the highest antioxidant activity with an IC₅₀= 4.8 ± 0.2 mg/L (DPPH assay). Concerning antimalarial activity, Origanum compactum essential oil and ethyl acetate extract showed the best results with an IC₅₀ of 34 and 33 mg/mL, respectively. In addition, ethyl acetate extract (30 mg/L) and ethanol extract (56 mg/L) showed activity against human breast cancer cells (MCF7). The oregano essential oil was considered to be nontoxic.     

Characterization of odor-active compounds in three varieties of ciruela (Spondias purpurea L.) fruit

The aroma-active compounds present in tree ripened fruits of ciruela (Spondias purpurea L.) cultivars Chi abal, Campech abal, and Ek abal were isolated by means of simultaneous distillation solvent extraction and solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Application of odor activity values (OAV) afforded 22 compounds in higher amounts than their threshold concentrations (OAVs >1). Results of the identification experiments in combination with the OAVs suggested that methyl 3-methylbutanoate, ethyl butanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, hexyl acetate, with fruity odor notes; (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 1-hexanol, and (Z)-3-hexenyl acetate, with grassy odor notes, and limonene (citrus-like) were the potentially important common odorants in all ciruela cultivars. Clear differences in the OAVs of some odorants between each of the cultivars suggested that they contributed to the unique sensory profiles of the individual cultivars.     

Evaluation of Methods for Detecting the Production of H2S, Volatile Sulfides, and Greening by Lactobacilli

The ability to produce volatile sulfides by 41 lactobacilli was not associated with species but depended on the composition of the media and the sensitivity of the indicator. Only a restricted number of L. plantarum strains and seven isolates were H₂S-positive on peptone iron, TSI and SIM agars. Lead acetate agar detected a greater number of H₂S-positive lactobacilli but the lead acetate (or DTNB) paper method was superior in a modified motility sulfide broth. Cured meat agar detected the production of greening by H₂CO₂-producing lactobacilli (L. fructovorans, L. jensenii, L. lactis, L. viridescens, F-74, F-99). Such tests, however, were not applicable to detect lactobacilli producing green sulfmyoglobin.     

Changes in the odours of apple juice during enzymatic browning

Changes in the odours of apple juice during enzymatic browning after squeeze at different time points (0–6 h) were investigated by sensory evaluation and gas chromatography (GC). Trained panelists assessed a decrease in green odour with an increase in sweet odour during the browning. Fresh, fruity and apple-like odours temporarily increased in the first 2 h of browning, and gradually decreased thereafter. In the GC determination, butyl-, pentyl- and hexyl acetate as well as trans-2-hexenal were used as the volatile representatives because of their highest aroma values. Volatile release which was estimated from the proportion of volatile concentration in the vapour phase to that in the juice phase was used to elucidate the changes in odours of apple juice. The decrease in volatile release of trans-2-hexenal and the increases in those of all acetate esters during the browning corresponded well with the low intensity of green odour and the high intensity of sweet odour, respectively.     

Extending shelf-life of persimmon (<Emphasis Type="Italic">Diospyros kaki</Emphasis> L.) fruit by hot air treatment

‘Qiandaowuhe’ persimmon fruits (Diospyros kaki L.) were stored at 20 °C after exposed to 20 °C (control), 44 °C (T ₄₄), 48 °C (T ₄₈) or 52 °C (T ₅₂) hot air for 3 h, respectively. Firmness, weight loss, peel color, total carotenoids content, soluble solids content (SSC), titratable acidity (TA), respiration, and ethylene production and cell wall hydrolysis enzymes activities were monitored to determine the efficacy of hot air treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak of CO₂ and ethylene production was observed after 4 days. Fruit softening was accompanied by a progressive increase in weight loss, total carotenoids content and decrease in h°. The activities of pectinmethylesterase (PME) and polygalacturonase (PG) sharply increased and reached maximal values after 4 and 6 days, respectively. Hot air treatment significantly delayed the onset of climacteric ethylene production, respiration, PME and PG activities in persimmon fruit. Moreover, it also significantly retarded the increase in carotenoids content and SSC, while decreased the firmness, h°, and TA. The hot air treatment promoted fruit weight loss. The shelf-life of persimmon ripening increased 4 days by T ₄₄, and 6 days by T ₄₈ or T ₅₂. Results suggest that hot air treatments can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.     

Headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC–MS) determination of volatile compounds in roasted plantains (French sombre and Dwarf Kalapua)

Volatile compounds from roasted plantains (French sombre, AAB) and (Dwarf Kalapua, ABB) at different stages of ripening were evaluated by a gas chromatography–mass spectrometry (GC–MS) with headspace solid-phase microextraction (HS-SPME). A total of 42 volatile compounds were identified in the roasted plantain cultivars. Some of the volatile compounds with high concentration were 2,3-dimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, (E)-2-hexenal, 2,5-dimethylpyrazine and 2,3-dihydro-5-hydroxyl-6-methyl-(4H)-pyran-4-on respectively. Principal component analysis (PCA) based on the relationships between ripening/quality of volatiles showed that 2-methyl propanol, furfural, 2,5-dimethyl pyrazine, 2,3-butanedione, guaiacol, 2-ethyl-3-methyl pyrazine, 5-, ethyl acetate, 2-pentanol, 3-isobutyl-2-methoxy pyrazine and 7,8-dihydro-β-ionol were considered to contribute significantly to the overall aroma quality of fairly riped (stages 4 & 5) and roasted plantains.     

“玉金香”甜瓜常温贮藏期间香气构成变化分析

采用顶空固相微萃取-气相色谱-质谱联用技术,分析“玉金香”甜瓜常温贮藏过程中香气构成的变化。结果表明：贮藏过程中,样品中共检出香气成分71 种,其中酯类最多29 种,其次为醛酮类15 种,醇类12 种。醇醛类化合物是贮藏前期的主体香气成分,相对含量41.9%,清香感突出;以清香感为主的正己醛、顺-3-己烯醇、2-己烯醛、（E,Z）-2,6-壬二烯醛、（E,Z）-3,6-壬二烯-1-醇、（Z）-6-壬烯醛相对含量较高。随贮藏时间的延长,酯类化合物相对含量增加,成为主体香气成分,其中果香感突出的乙酸乙酯和乙酸苯甲酯释放量显著增加。贮藏第10天酯类化合物相对含量增加至91.57%,成为主体香气成分,此时果香突出。“玉金香”甜瓜常温贮藏不同时期,香气构成差异显著。     

Influence of technological processing on apple aroma analysed by high resolution gas chromatography–mass spectrometry and on-line gas chromatography-combustion/pyrolysis-isotope ratio mass spectrometry

Extracts obtained by simultaneous distillation extraction (SDE) from industrial raw materials, namely single strength apple juices, and concentrates and aromas made thereof (each n = 31, from one production line; origin Poland, Germany, Turkey, Romania and China), as well as commercially available juices (n = 27), were analysed by standard controlled capillary gas chromatography–mass spectrometry (HRGC–MS). During the technological processing from juice to the aroma, no qualitative changes in the apple aroma profile were observed. Major constituents of the juices and aromas under study were found to be 1-hexanol (juice, 0.06–5.9 mg/l; aroma, 47–685 mg/l), 1-butanol (juice, 0.1–4.7 mg/l; aroma, 17–370 mg/l); E-2-hexenol (juice, 0.01–3.4 mg/l; aroma, 12–300 mg/l); E-2-hexenal (juice, 0–3.0 mg/l; aroma 0–470 mg/l), and butyl acetate (juice, 0–1.7 mg/l; aroma, 0–165 mg/l). By far the major component of the apple juice concentrates under study was furfural (2.4–56 mg/kg). The observed occurrence of 3-methyl-1-butanol (juice, 0.01–2.1 mg/l; aroma, 1.5–134 mg/l) and, in part, its acetate (juice, 0–0.3 mg/l; aroma, 0–3.3 mg/l), both known not to be genuine apple constituents, was obviously caused by fermentative effects in the course of industrial juice production. In addition, on-line capillary gas chromatography–isotope ratio mass spectrometry was used in the combustion (C) and the pyrolysis (P) modes (HRGC–C/P–IRMS) for the determination of δ¹³C_V-PDB and δ²H_V-SMOW values of selected apple flavour constituents to check potential isotope discrimination during distillative aroma production. As shown by means of the representative examples of E-2-hexenal, 1-hexanol and E-2-hexenol, their δ²H_V-SMOW values were slightly depleted. However, authenticity assessment by stable IRMS will not be influenced by this effect.     

Comparison of Volatile Release in Tomatillo and Different Varieties of Tomato during Chewing

ABSTRACT: The release of volatiles from tomatillos (Physalis ixocarpa Brot.) and tomatoes in the mouthspace and nosespace was measured in real-time using selected ion flow tube mass spectrometry (SIFT-MS). (Z)-3-Hexenal, (E)-2-hexenal, hexanal, and 1-penten-3-one increased, while isobutyl alcohol, nonanal, and methylbutanal showed no significant change in the first 30 s of chewing. Cherry tomato released more (E)-2-hexenal, (Z)-3-hexenal, and 1-penten-3-one than tomatillo, Roma tomato, and vine-ripened tomato during chewing. The proportion of the average concentration of volatiles in the mouthspace after swallowing to before swallowing (MSas/MSbs) varied from 2.8% to 73.9% between different volatiles and varieties. Methylbutanal, hexanal, and nonanal were retained at a higher percentage in the mouth after swallowing than (Z)-3-hexenal, (E)-2-hexenal, 1-penten-3-one, and isobutyl alcohol. The proportion of the average volatile concentration in the mouthspace, to the headspace in a glass container (MS/HS) of 1-penten-3-one, hexanal, methylbutanal, and nonanal, and the proportion of nosespace to headspace (NS/HS) for 1-penten-3-one, hexanal, (Z)-3-hexenal, and nonanal was significantly higher in tomatillo than in tomatoes. There was no difference between tomatoes of different varieties in NS/HS ratio. Practical Application: The real-time volatile release from tomatillos and tomatoes was measured and compared. The information obtained on the dynamic generation of volatile compounds provides a better understanding of volatile release in the headspace of tomatillo and tomatoes. The compounds and their volatile release patterns were similar for the tomatillo and tomatoes. The green aldehydes released during chewing were not significantly higher than most tomato varieties, except for Roma tomatoes. Cherry tomato released relatively more volatiles during chewing, whereas Roma tomatoes were generally poor in mouthspace volatiles. The lingering of volatiles in the mouth after swallowing was different for different volatiles and varieties, which may appear as a sensory difference detected by consumers.     

Virgin olive oil aroma: Characterization of some Tunisian cultivars

Fruits from four Tunisian cultivars of Olea europaea L. grown in the North of Tunisia were handpicked at the same ripening degree and processed with a laboratory mill. The oils were submitted to dynamic headspace and their volatile composition was determined.The results showed that the most important contributors to olive oil aroma are C₆ aldehydes, alcohols, and esters. These compounds are biogenerated from polyunsaturated fatty acids through the lipoxygenase (LOX) pathway. Furthermore, they pointed out the predominance of the oxidation of linolenic (LnA) acid over linoleic (LA) acid one.In this predominant part of LOX, the branch A giving rise to trans-2-hexenal, trans-2-hexenol was more important than the branch B giving rise to cis-3-hexenol and cis-3-hexenyl acetate. This pointed out that the isomerization of cis-3-enals forms to trans-2-enal ones is the dominant process of the branch B.The accumulation of the different metabolites in the oils varied according to cultivar indicating a close dependence on the enzymatic store which is genetically determined.     

Volatile Compounds from Raspberry and Strawberry Fruit Inhibit Postharvest Decay Fungi

Fifteen volatiles released by red raspberries and strawberries during ripening were analyzed for the inhibition of postharvest decay fungi. Five compounds completely inhibited all fungi directly on fruit at 0.4 μL/mL., Of these, benzaldehyde at 0.04 μL/mL completely inhibited isolated cultures of Alternaria altemata, Botrytis cinerea, and Col-Ietotrichum gloeosporioides, while 1-hexanol, E-2-hexenal and 2-non-anone inhibited all three fungal species at 0.1 μL/mL. When added directly to media, 0.1% (v/v) benzaldehyde or E-2-hexenal inhibited all three species. Starch encapsulated 2-nonanone reduced fungal decay of raspberries and strawberries in enclosed containers after 7 days at 10°C.     

Identification of Lepidium meyenii (Walp.) based on spectra and chromatographic characteristics of its principal functional ingredients

Lepidium meyenii Walp. (maca), a perennial herbaceous plant with narrow distribution in the Andean region, was cultivated by local residents as early as 1600 BC . It has high nutritional value and multiple medicinal effects. The plant source of maca is now scarce because maca products are becoming increasingly popular in the world as dietary supplements. This means that studies on the identification of maca materials are now urgent. In present work, natural plants with similar appearance or medicinal effects, including maca, radish (Raphanus sativus L.), oriental ginseng (Panax ginseng C. A. Mey.), American ginseng (Panax quinquefolium L.) were investigated. Their alkaloid extracts of the hypogeal parts were analysed by FTIR and TLC. The essential oils (steam distillates) were analysed by GC/MS. Through comparison of the characteristics of their spectra and chromatograms, it was found that the functional ingredient extracts of maca have unique FTIR, TLC and GC/MS behaviours. The secondary amide group (? CH₂? NH? CO? CH₂? ) and the phenyl structure in FTIR, the multiple spots at different R_F values colourised by modified Dragendorff's reagent, and the characteristic peaks produced by the major essential oil components (e.g. phenylacetonitrile, benzaldehyde, 3‐methoxyphenylacetonitrile) in GC/MS are distinct. These behaviours can be applied to the identification of maca or maca products in the market. Copyright © 2007 Society of Chemical Industry     

Production of (2E)-hexenal by a hydroperoxide lyase from Amaranthus tricolor and salt-adding steam distillation for the separation

(2E)-Hexenal is widely used in flavors and perfumes; however, it is mainly derived from chemical synthesis. In this study, hydroperoxide lyase (HPL) naturally originated from Amaranthus tricolor was used to catalyze the reaction to generate (2E)-hexenal from 13-hydroperoxy-9Z, 11E, 15 Z-octadecatrienoic acid (13-HPOT), and salt-adding steam distillation was used for the separation of (2E)-hexenal. A maximum yield of (2E)-hexenal that reached 1,156.4?mg?L^?1 was obtained with a high substrate concentration (40?mM 13-HPOT) under the following conditions: 10?min, pH 7.5, 20?°C, HPL 16 U?mL^?1, butylated hydroxytoluene (BHT) 1?mM, and dithiothreitol (DTT) 15?mM. Then the separation of (2E)-hexenal was conducted by salt-adding steam distillation. It was found that AlCl₃ had the greatest effect on the separation of (2E)-hexenal, followed by CaCl₂ and NaCl. The distillate yield with the addition of AlCl₃ was 93.2?%, while the distillate yield without the addition of salt was 81.2?%. The distillate concentration with AlCl₃ was 6,464.2?mg?L^?1, while the distillate concentration without the addition of salt was 4,490.3?mg?L^?1. The addition of salt improved the efficiency of the steam distillation. This study was greatly meaningful for providing a green method to the large-scale production of (2E)-hexenal.     

Volatile and non-volatile chemical composition of the white guava fruit (Psidium guajava) at different stages of maturity

The effect of the maturation stages on the chemical composition and volatile compounds of the white Guava (Psidium guajava) Cv. Cortibel was investigated during three different stages. The stages were characterized by evolution of color, pH, titratable acidity, sugars, soluble solids, vitamin C and volatile components. The fruits were stored at 24 °C and air humidity of 74% for 13 days. The volatile extracts were obtained using headspace technique and analyzed using gas chromatograph/mass spectrometry (GC/MS) system. The titratable acidity and sugars decreased. The pH level and amount of vitamin C increased throughout progress of maturation. The behavior of volatile compounds of fruits in the three stages of maturation was: in immature fruits and those in their intermediate stage of maturation, were predominantly the aldehydes such as (E)-2-hexenal and (Z)-3-hexenal. In mature fruits, esters like Z-3-hexenyl acetate and E-3-hexenyl acetate and sesquiterpenes caryophyllene, α-humulene and β-bisabollene are present.     

Characterization of aroma-impact compounds in dry jujubes (Ziziphus jujube Mill.) by aroma extract dilution analysis (AEDA) and gas chromatography-mass spectrometer (GC-MS)

Aroma-impact compounds of dry jujubes obtained from Z. jujuba Mill. cv. “tangzao” (Y1), Z. jujuba Mill. cv. “muzao” (Y2), Z. jujuba Mill. cv. “lizao” (Y3), and Z. jujuba Mill. cv. “qingrunhongzao” (Y4) were analyzed by gas chromatography-olfactometry (GC-O). The result revealed 35, 29, 34, and 33 aroma-impact volatiles in the Y1, Y2, Y3, and Y4 samples, respectively. The compounds bearing the highest FD factor in each sample were (E)-2-hexenal, (E)-2-heptenal (FD = 256) for Y1, 2,3-butanedione, (E)-2-hexenal, 2,5-dimethylpyrazine, (E)-2-heptenal and β-damascenone (FD = 64) for Y2, 2,3-butanedione and β-damascenone (FD = 256) for Y3, and 2,5-dimethylpyrazine (FD = 256) for Y4.     

Characterisation of the most odour-active compounds in a peel oil extract from Pontianak oranges (<Emphasis Type="Italic">Citrus nobilis</Emphasis> var. Lour. <Emphasis Type="Italic">microcarpa</Emphasis> Hassk.)

Isolation of the volatile fraction from the peel of Pontianak orange (Citrus nobilis var. Lour. microcarpa Hassk.) by a careful solvent extraction/vacuum distillation process followed by application of an aroma extract dilution analysis (AEDA) revealed 32 odour-active compounds in the flavour dilution (FD)-factor range of 4–2048, 26 of which could be identified. On the basis of high FD-factors, (R)/(S)-linalool, myrcene, (R)-limonene, and 1,8-cineole were characterised as the most potent odorants, followed by octanal, (E,E)-2,4-decadienal, nerol, (E)-2-dodecenal, geraniol, and (E,E)-2,4-nonadienal. In addition, one odorant resembling the characteristic sulphurous, resinous aroma of the Pontianak peel oil was detected with a quite high FD-factor of 128. By mass spectrometry followed by synthesis, 1-phenylethanethiol exhibiting an intense sulphurous, resinous smell at the very low odour threshold of 0.005 ng/L in air, was found to be responsible for the odour impression detected in the extract. 1-Phenylethanethiol occurring as a mixture of the (R)-(76%) and the (S)-enantiomer (24%) has previously not been reported as odorant in foods. Application of static headspace aroma dilution analysis (SHA) on Pontianak peel revealed the green, grassy smelling odour-active compounds hexanal and (Z)-3-hexenal as further important odorants in the headspace above the peels.