Gary Takeoka - Academia.edu (original) (raw)

Papers by Gary Takeoka

Flavour and Fragrance Journal, May 26, 2004

The volatile constituents of taheebo (the dried inner bark of Tabebuia impetiginosa Martius ex DC... more The volatile constituents of taheebo (the dried inner bark of Tabebuia impetiginosa Martius ex DC) were isolated by three methods: solvent-assisted flavour evaporation (SAFE); steam distillation under reduced pressure, followed by continuous liquid-liquid extraction (DRP-LLE); and high-flow dynamic headspace sampling (including closed-loop stripping) (DHS). The extracts were analysed qualitatively and quantitatively by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The masses of total volatile components recovered from 50 g taheebo by SAFE, DRP-LLE and DHS were 26.3 ± ± ± ± ± 2.0, 19.4 ± ± ± ± ± 1.0 and 1.2 ± ± ± ± ± 0.2 mg, respectively. The major constituents isolated with the SAFE method were 4-methoxyphenol (121.65 µ µ µ µ µg/g), 4-methoxybenzyl alcohol (96.49 µ µ µ µ µg/g), 1,2propanediol (92.95 µ µ µ µ µg/g) and 4-methoxybenzaldehyde (31.33 µ µ µ µ µg/g). The DRP-LLC method yielded 4-methoxybenzaldehyde (64.54 µ µ µ µ µg/g), 4-methoxyphenol (42.30 µ µ µ µ µg/g), 5-(2-propenyl)-1,2,3-trimethoxybenzene (elemicin; 41.22 µ µ µ µ µg/g), and 1-methoxy-4-(1E)-1-propenylbenzene (trans-anethole; 39.16 µ µ µ µ µg/g) as major volatiles, while the main compounds recovered with the DHS method were 4-methoxybenzaldehyde (2.61 µ µ µ µ µg/g), 4-methoxyphenol (2.10 µ µ µ µ µg/g), 2-methyl-5-(1-methylethenyl)-2cyclohexen-1-one (carvone; 1.71 µ µ µ µ µg/g) and 3,7-dimethyl-1,6-octadien-3-ol (linalool; 1.64 µ µ µ µ µg/g).

Journal of Food Biochemistry, Apr 1, 1992

This book is the sixth in a recent series of symposia on food flavor. It follows such books as me... more This book is the sixth in a recent series of symposia on food flavor. It follows such books as me Maillard Reaction in Foods and Nutrition (1983), Biogeneration of Aromas (1986), Biojhvour '87 (1987), lltermal Generation of Aromas (1989) and Flavor Chemistry Trends and Developments (1989). The symposia covered by this book addressed two major areas of current flavor research, viz.,

Journal of Food Processing and Preservation, Jul 12, 2017

Lipid oxidation is a very complex and important event causing quality loss of foods, especially t... more Lipid oxidation is a very complex and important event causing quality loss of foods, especially those containing highly unsaturated fats. There is growing interest in replacing synthetic antioxidants in food by natural counterparts. Olive leaf is an abundant by-product of the olive oil industry. The aim of this study was to investigate the antioxidant capacity of olive leaf powder (OLP) in minced Atlantic horse mackerel stored at 4 8C over 3 days. OLP was introduced in the minced at concentrations of 0 (control), 1.5, 3.5, and 4.5%. OLP characterization showed high antioxidant capacity and fiber content. The addition of OLP significantly prevented and delayed minced fish oxidation over storage. The antioxidant effectiveness of OLP was concentrationdependent, as observed in all the parameters analyzed. The results showed OLP as a potential natural antioxidant for fish products. Practical applications Olive leaves are an important agrifood by-product produced worldwide. This by-product is valorized for the first time, as far as the authors are aware, as natural antioxidant in fish. Olive leaves are rich in polyphenols (principally oleuropein) and a-tocopherol. Consumers may benefit from this research as there is an increasing demand for natural ingredients, along with concern about the environmental effects of food production. The results of the present study suggest that olive leaf powder can be successfully employed as natural ingredient to prevent oxidation in chilled horse mackerel mince. This allows transforming this by-product stream into a commercially valuable antioxidant.

Phytotherapy Research, Aug 11, 2008

Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibito... more Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibitory effect on washed rabbit platelet aggregation induced by collagen, arachidonic acid (AA) and platelet activating factor (PAF), without any inhibitory effect on that induced by thrombin. Piperlongumine was used as a lead compound for the synthesis of new antiplatelet agents. Seven synthetic compounds were newly synthesized from 3,4,5-trimethoxycinnamic acid (TMCA). They were 1-piperidin-1-yl-3-(3,4,5-trimethoxy-phenyl)prop-2-en-1-one (1'), 1-morpholin-4-yl-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (2'), 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3'), 1-(2-methylpiperidin-1-yl)-3-(3,4,5-tri-methoxyphenyl)prop-2-en-1-one (4'), 1-(3-hydroxypiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)- prop-2-en-1-one (5'), 1-[3-(3,4,5-tri-methoxyphenyl) acryloyl]-piperidin-2-one (6') and ethyl 1-[3-(3,4,5-trimethoxyphenyl)-acryloyl]piperidine-4-carboxylate (7'). Among those seven synthetic derivatives, 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3') had the most inhibitory effect on platelet aggregation induced by collagen, AA and PAF.

Journal of Agricultural and Food Chemistry, Jun 9, 2001

Commercial grapefruit seed extracts (GSE) were extracted with chloroform. The solvent was evapora... more Commercial grapefruit seed extracts (GSE) were extracted with chloroform. The solvent was evaporated, and the resulting solid was subsequently analyzed by high-performance liquid chromatography, electrospray ionization mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis (by proton-induced X-ray emission [PIXE] analysis). The main constituent was identified as benzethonium chloride, a synthetic antimicrobial agent commonly used in cosmetics and other topical applications. This compound comprised 8.03% (n) 2) of the liquid GSE sample. Higher amounts of benzethonium chloride were found in powder GSE samples.

Journal of Agricultural and Food Chemistry, Jul 8, 2000

Acs Symposium Series, Aug 13, 1996

Springer eBooks, 1999

Vegetables are edible plant products which can be modified stems, roots, leaves, flowers, or even... more Vegetables are edible plant products which can be modified stems, roots, leaves, flowers, or even fruits. They are usually classified on the basis of the part of the plant that is used for food. Stem vegetables include asparagus and kohlrabi while beets, carrots, radishes and turnips are root vegetables. Among the leaf and leafstalk vegetables are brussel sprouts, cabbage, celery, endive, kale, lettuce, rhubarb and spinach. The head or flower vegetables include artichokes, broccoli, and cauliflower. Garlic, leeks, and onions are classified as bulb vegetables. Botanically, the term “fruit” applies to the structure, usually containing seeds, which develops from the flower ovary after pollination and fertilization (Vaughan and Geissler, 1997). Therefore, beans, cucumbers, eggplant, okra, peppers, squash, sweet corn and tomatoes would be classified as fruits according to this definition. However, the important distinction between fruits and vegetables has come to be made on a usage basis; those plant products that are usually consumed with the main course of a meal are considered to be vegetables while those used mainly as desserts are considered fruits.

American Chemical Society eBooks, Nov 8, 1985

Phytochemistry, Sep 1, 2010

Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition... more Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition to the known acyclic sesquilavandulol and a sesquilavandulyl aldehyde, two thapsanes, one epithapsane, and 14 sesquiterpenoids representing eight hitherto unknown carbon skeletons were found.

Acs Symposium Series, May 13, 1992

Journal of Agricultural and Food Chemistry, Aug 1, 1994

Journal of Agricultural and Food Chemistry, Oct 1, 1991

The volatiles of pineapple essence were isolated by liquid-liquid extraction, fractionated on neu... more The volatiles of pineapple essence were isolated by liquid-liquid extraction, fractionated on neutral alumina, and analyzed by high-resolution gas chromatography and coupled gas chromatography/mass spectrometry (GC/MS). Twenty-six constituents (1 tentative) were identified for the first time in pineapple including the following sulfur compounds: methyl 3-(methylthio)-(E)-2-propenoate, methyl 3-(methylthio)-(Z)-2-propenoate, ethyl 3-(methylthio)-(E)-2-propenoate, ethyl 3-(methylthio)-(Z)-2propenoate, methyl 4-(methylthio)butanoate, ethyl 44methylthio) butanoate (tentative), and dimethyl trisulfide. Their odor contribution t o pineapple aroma is assessed.

Journal of Agricultural and Food Chemistry, Aug 1, 1997

Acs Symposium Series, Sep 30, 2008

Functional foods & nutraceuticals series, Apr 16, 2002

Phytomedicine, Jun 1, 2008

Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodi... more Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodium falciparum was tested using a [ 3 H]-hypoxanthine and 48 h culture assay in vitro. Anthotechol showed potent antimalarial activity against malaria parasites with IC 50 values of 1.4 and 0.17 mM using two different assays. Also, gedunin had antimalarial activity with IC 50 values of 3.1 and 0.14 mM. However, the citrus limonoids, limonin and obacunone did not show any antimalarial activity. The antimalarial activities were compared with the three currently used antimalarial medicines quinine, chloroquinine and artemisinin.

Journal of Agricultural and Food Chemistry, Jan 29, 2005

The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the ... more The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the inner bark of taheebo, Tabebuia impetiginosa, toward 10 human intestinal bacteria was evaluated by using a paper disk diffusion bioassay and compared to those of seven lapachol congeners (1,4-naphthoquinone, naphthazarin, menadione, lawsone, plumbagin, juglone, and dichlone) as well as two commercially available antibiotics, chloramphenicol and tetracycline. Anthraquinone-2-carboxylic acid exhibited very strong growth inhibition of Clostridium paraputrificum at 1 microg/disk while 100 microg/disk of lapachol was needed for moderate growth inhibition of the same organism. These two isolates exhibited weak inhibition of Clostridium perfringens and Escherichia coli at 100 microg/disk while no adverse effects were observed on the growth of Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium infantis, Lactobacillus acidophilus, and Lactobacillus casei at 1000 microg/disk. Structure-activity relationships indicate that a methyl group in the C-2 position of 1,4-naphthoquinone derivatives might play an important role in antibacterial activity.

Journal of Agricultural and Food Chemistry, Oct 1, 1992

The volatiles of Asian pear (Seuri cultivar) were studied by high-resolution gas chromatography a... more The volatiles of Asian pear (Seuri cultivar) were studied by high-resolution gas chromatography and combined gas chromatography/mass spectrometry (G U M S) using vacuum simultaneous distillationextraction of blended fruit and dynamic headspace sampling of intact and enzymatically inhibited blended fruit. Esters were the dominant constituents in all of the samples. A total of 72 components were identified in the headspace of intact fruit, including 39 constituents reported for the first time in pear. Odor unit values calculated from concentration and odor threshold data indicate that the following compounds are important contributors to pear aroma: ethyl 2-methylbutanoate, ethyl hexanoate, ethyl butanoate, ethyl 2-methylpropanoate, hexyl acetate, ethyl heptanoate, hexanal, ethyl pentanoate, and ethyl propanoate. Asian pears (Pyrus serotina) are a completely distinct species from the more common European-type pears (Pyrus communis L.) such as Bartlett and La France and are not a cross between apples and pears. Though the volatile constituents of Bartlett pears have been extensively investigated (Maarse and Visscher, 1984), there has been, to our knowledge, only one publication on the flavor compounds of Asian pears (Shiota et al., 1981). These researchers studied four Asian pear cultivars [Nijisseiki (20th Century), Kosui, Hosui, and Kikusuil and found distinct compositional differences between the peel and pulp. The peel contained major amounts of nonanal, cy-farnesene, phenylacetaldehyde, and straight-chain hydrocarbons with 19-23 carbon atoms, while the pulp had ethyl butanoate, hexanol, hexyl acetate, butylbenzene, and phenylacetaldehyde as major constituents. The flavor of pears was recently reviewed by Paillard (1990). EXPERIMENTAL PROCEDURES Materials. Sample Preparation. 1. Vacuum Simultaneow Distillation-Eltraction (Vacuum SDE). Theskinand pulp (1.0 kg, core and seeds were excluded) were blended with 600 mL of water in a Waring blender for 20 s. Three batches were prepared using a total of 3.0 kg of fruit pulp and skin. The slurry was added to a 12 L round-bottomed flask. An additional 1.5 L of water and 60 mL of antifoam solution were added to the flask.

Flavour and Fragrance Journal, May 26, 2004

The volatile constituents of taheebo (the dried inner bark of Tabebuia impetiginosa Martius ex DC... more The volatile constituents of taheebo (the dried inner bark of Tabebuia impetiginosa Martius ex DC) were isolated by three methods: solvent-assisted flavour evaporation (SAFE); steam distillation under reduced pressure, followed by continuous liquid-liquid extraction (DRP-LLE); and high-flow dynamic headspace sampling (including closed-loop stripping) (DHS). The extracts were analysed qualitatively and quantitatively by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The masses of total volatile components recovered from 50 g taheebo by SAFE, DRP-LLE and DHS were 26.3 ± ± ± ± ± 2.0, 19.4 ± ± ± ± ± 1.0 and 1.2 ± ± ± ± ± 0.2 mg, respectively. The major constituents isolated with the SAFE method were 4-methoxyphenol (121.65 µ µ µ µ µg/g), 4-methoxybenzyl alcohol (96.49 µ µ µ µ µg/g), 1,2propanediol (92.95 µ µ µ µ µg/g) and 4-methoxybenzaldehyde (31.33 µ µ µ µ µg/g). The DRP-LLC method yielded 4-methoxybenzaldehyde (64.54 µ µ µ µ µg/g), 4-methoxyphenol (42.30 µ µ µ µ µg/g), 5-(2-propenyl)-1,2,3-trimethoxybenzene (elemicin; 41.22 µ µ µ µ µg/g), and 1-methoxy-4-(1E)-1-propenylbenzene (trans-anethole; 39.16 µ µ µ µ µg/g) as major volatiles, while the main compounds recovered with the DHS method were 4-methoxybenzaldehyde (2.61 µ µ µ µ µg/g), 4-methoxyphenol (2.10 µ µ µ µ µg/g), 2-methyl-5-(1-methylethenyl)-2cyclohexen-1-one (carvone; 1.71 µ µ µ µ µg/g) and 3,7-dimethyl-1,6-octadien-3-ol (linalool; 1.64 µ µ µ µ µg/g).

Journal of Food Biochemistry, Apr 1, 1992

This book is the sixth in a recent series of symposia on food flavor. It follows such books as me... more This book is the sixth in a recent series of symposia on food flavor. It follows such books as me Maillard Reaction in Foods and Nutrition (1983), Biogeneration of Aromas (1986), Biojhvour '87 (1987), lltermal Generation of Aromas (1989) and Flavor Chemistry Trends and Developments (1989). The symposia covered by this book addressed two major areas of current flavor research, viz.,

Journal of Food Processing and Preservation, Jul 12, 2017

Lipid oxidation is a very complex and important event causing quality loss of foods, especially t... more Lipid oxidation is a very complex and important event causing quality loss of foods, especially those containing highly unsaturated fats. There is growing interest in replacing synthetic antioxidants in food by natural counterparts. Olive leaf is an abundant by-product of the olive oil industry. The aim of this study was to investigate the antioxidant capacity of olive leaf powder (OLP) in minced Atlantic horse mackerel stored at 4 8C over 3 days. OLP was introduced in the minced at concentrations of 0 (control), 1.5, 3.5, and 4.5%. OLP characterization showed high antioxidant capacity and fiber content. The addition of OLP significantly prevented and delayed minced fish oxidation over storage. The antioxidant effectiveness of OLP was concentrationdependent, as observed in all the parameters analyzed. The results showed OLP as a potential natural antioxidant for fish products. Practical applications Olive leaves are an important agrifood by-product produced worldwide. This by-product is valorized for the first time, as far as the authors are aware, as natural antioxidant in fish. Olive leaves are rich in polyphenols (principally oleuropein) and a-tocopherol. Consumers may benefit from this research as there is an increasing demand for natural ingredients, along with concern about the environmental effects of food production. The results of the present study suggest that olive leaf powder can be successfully employed as natural ingredient to prevent oxidation in chilled horse mackerel mince. This allows transforming this by-product stream into a commercially valuable antioxidant.

Phytotherapy Research, Aug 11, 2008

Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibito... more Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibitory effect on washed rabbit platelet aggregation induced by collagen, arachidonic acid (AA) and platelet activating factor (PAF), without any inhibitory effect on that induced by thrombin. Piperlongumine was used as a lead compound for the synthesis of new antiplatelet agents. Seven synthetic compounds were newly synthesized from 3,4,5-trimethoxycinnamic acid (TMCA). They were 1-piperidin-1-yl-3-(3,4,5-trimethoxy-phenyl)prop-2-en-1-one (1'), 1-morpholin-4-yl-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (2'), 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3'), 1-(2-methylpiperidin-1-yl)-3-(3,4,5-tri-methoxyphenyl)prop-2-en-1-one (4'), 1-(3-hydroxypiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)- prop-2-en-1-one (5'), 1-[3-(3,4,5-tri-methoxyphenyl) acryloyl]-piperidin-2-one (6') and ethyl 1-[3-(3,4,5-trimethoxyphenyl)-acryloyl]piperidine-4-carboxylate (7'). Among those seven synthetic derivatives, 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3') had the most inhibitory effect on platelet aggregation induced by collagen, AA and PAF.

Journal of Agricultural and Food Chemistry, Jun 9, 2001

Commercial grapefruit seed extracts (GSE) were extracted with chloroform. The solvent was evapora... more Commercial grapefruit seed extracts (GSE) were extracted with chloroform. The solvent was evaporated, and the resulting solid was subsequently analyzed by high-performance liquid chromatography, electrospray ionization mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis (by proton-induced X-ray emission [PIXE] analysis). The main constituent was identified as benzethonium chloride, a synthetic antimicrobial agent commonly used in cosmetics and other topical applications. This compound comprised 8.03% (n) 2) of the liquid GSE sample. Higher amounts of benzethonium chloride were found in powder GSE samples.

Journal of Agricultural and Food Chemistry, Jul 8, 2000

Acs Symposium Series, Aug 13, 1996

Springer eBooks, 1999

Vegetables are edible plant products which can be modified stems, roots, leaves, flowers, or even... more Vegetables are edible plant products which can be modified stems, roots, leaves, flowers, or even fruits. They are usually classified on the basis of the part of the plant that is used for food. Stem vegetables include asparagus and kohlrabi while beets, carrots, radishes and turnips are root vegetables. Among the leaf and leafstalk vegetables are brussel sprouts, cabbage, celery, endive, kale, lettuce, rhubarb and spinach. The head or flower vegetables include artichokes, broccoli, and cauliflower. Garlic, leeks, and onions are classified as bulb vegetables. Botanically, the term “fruit” applies to the structure, usually containing seeds, which develops from the flower ovary after pollination and fertilization (Vaughan and Geissler, 1997). Therefore, beans, cucumbers, eggplant, okra, peppers, squash, sweet corn and tomatoes would be classified as fruits according to this definition. However, the important distinction between fruits and vegetables has come to be made on a usage basis; those plant products that are usually consumed with the main course of a meal are considered to be vegetables while those used mainly as desserts are considered fruits.

American Chemical Society eBooks, Nov 8, 1985

Phytochemistry, Sep 1, 2010

Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition... more Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition to the known acyclic sesquilavandulol and a sesquilavandulyl aldehyde, two thapsanes, one epithapsane, and 14 sesquiterpenoids representing eight hitherto unknown carbon skeletons were found.

Acs Symposium Series, May 13, 1992

Journal of Agricultural and Food Chemistry, Aug 1, 1994

Journal of Agricultural and Food Chemistry, Oct 1, 1991

The volatiles of pineapple essence were isolated by liquid-liquid extraction, fractionated on neu... more The volatiles of pineapple essence were isolated by liquid-liquid extraction, fractionated on neutral alumina, and analyzed by high-resolution gas chromatography and coupled gas chromatography/mass spectrometry (GC/MS). Twenty-six constituents (1 tentative) were identified for the first time in pineapple including the following sulfur compounds: methyl 3-(methylthio)-(E)-2-propenoate, methyl 3-(methylthio)-(Z)-2-propenoate, ethyl 3-(methylthio)-(E)-2-propenoate, ethyl 3-(methylthio)-(Z)-2propenoate, methyl 4-(methylthio)butanoate, ethyl 44methylthio) butanoate (tentative), and dimethyl trisulfide. Their odor contribution t o pineapple aroma is assessed.

Journal of Agricultural and Food Chemistry, Aug 1, 1997

Acs Symposium Series, Sep 30, 2008

Functional foods & nutraceuticals series, Apr 16, 2002

Phytomedicine, Jun 1, 2008

Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodi... more Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodium falciparum was tested using a [ 3 H]-hypoxanthine and 48 h culture assay in vitro. Anthotechol showed potent antimalarial activity against malaria parasites with IC 50 values of 1.4 and 0.17 mM using two different assays. Also, gedunin had antimalarial activity with IC 50 values of 3.1 and 0.14 mM. However, the citrus limonoids, limonin and obacunone did not show any antimalarial activity. The antimalarial activities were compared with the three currently used antimalarial medicines quinine, chloroquinine and artemisinin.

Journal of Agricultural and Food Chemistry, Jan 29, 2005

The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the ... more The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the inner bark of taheebo, Tabebuia impetiginosa, toward 10 human intestinal bacteria was evaluated by using a paper disk diffusion bioassay and compared to those of seven lapachol congeners (1,4-naphthoquinone, naphthazarin, menadione, lawsone, plumbagin, juglone, and dichlone) as well as two commercially available antibiotics, chloramphenicol and tetracycline. Anthraquinone-2-carboxylic acid exhibited very strong growth inhibition of Clostridium paraputrificum at 1 microg/disk while 100 microg/disk of lapachol was needed for moderate growth inhibition of the same organism. These two isolates exhibited weak inhibition of Clostridium perfringens and Escherichia coli at 100 microg/disk while no adverse effects were observed on the growth of Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium infantis, Lactobacillus acidophilus, and Lactobacillus casei at 1000 microg/disk. Structure-activity relationships indicate that a methyl group in the C-2 position of 1,4-naphthoquinone derivatives might play an important role in antibacterial activity.

Journal of Agricultural and Food Chemistry, Oct 1, 1992

The volatiles of Asian pear (Seuri cultivar) were studied by high-resolution gas chromatography a... more The volatiles of Asian pear (Seuri cultivar) were studied by high-resolution gas chromatography and combined gas chromatography/mass spectrometry (G U M S) using vacuum simultaneous distillationextraction of blended fruit and dynamic headspace sampling of intact and enzymatically inhibited blended fruit. Esters were the dominant constituents in all of the samples. A total of 72 components were identified in the headspace of intact fruit, including 39 constituents reported for the first time in pear. Odor unit values calculated from concentration and odor threshold data indicate that the following compounds are important contributors to pear aroma: ethyl 2-methylbutanoate, ethyl hexanoate, ethyl butanoate, ethyl 2-methylpropanoate, hexyl acetate, ethyl heptanoate, hexanal, ethyl pentanoate, and ethyl propanoate. Asian pears (Pyrus serotina) are a completely distinct species from the more common European-type pears (Pyrus communis L.) such as Bartlett and La France and are not a cross between apples and pears. Though the volatile constituents of Bartlett pears have been extensively investigated (Maarse and Visscher, 1984), there has been, to our knowledge, only one publication on the flavor compounds of Asian pears (Shiota et al., 1981). These researchers studied four Asian pear cultivars [Nijisseiki (20th Century), Kosui, Hosui, and Kikusuil and found distinct compositional differences between the peel and pulp. The peel contained major amounts of nonanal, cy-farnesene, phenylacetaldehyde, and straight-chain hydrocarbons with 19-23 carbon atoms, while the pulp had ethyl butanoate, hexanol, hexyl acetate, butylbenzene, and phenylacetaldehyde as major constituents. The flavor of pears was recently reviewed by Paillard (1990). EXPERIMENTAL PROCEDURES Materials. Sample Preparation. 1. Vacuum Simultaneow Distillation-Eltraction (Vacuum SDE). Theskinand pulp (1.0 kg, core and seeds were excluded) were blended with 600 mL of water in a Waring blender for 20 s. Three batches were prepared using a total of 3.0 kg of fruit pulp and skin. The slurry was added to a 12 L round-bottomed flask. An additional 1.5 L of water and 60 mL of antifoam solution were added to the flask.