Pigments in the fruit of red-fleshed kiwifruit (Actinidia chinensis and Actinidia deliciosa)

Kiwifruit cultivars (Actinidia chinensis and A. deliciosa) generally have fruit with yellow or green flesh when ripe. A small number of genotypes also have red pigments, usually restricted to the inner pericarp but varying in intensity and in distribution within the fruit. Carotenoids, chorophylls, and anthocyanins were extracted from the fruit pericarp of such red-fleshed kiwifruit selections. Pigments were analyzed by HPLC and identified by comparison with authentic standards and by liquid chromatography-mass spectroscopy to obtain a tentative identification of the major anthocyanins in red-fleshed kiwifruit. The yellow and green colors of the outer fruit pericarp are due to different concentrations and proportions of carotenoids and chlorophylls. The red color found mainly in the inner pericarp is due to anthocyanins. In the A. chinensis genotypes tested the major anthocyanin was cyanidin 3-O-xylo(1-2)-galactoside, with smaller amounts of cyanidin 3-O-galactoside. In the A. deliciosa genotypes analyzed, cyanidin 3-O-xylo(1-2)-galactoside was not detected; instead, the major anthocyanins identified were cyanidin 3-O-galactoside and cyanidin 3-O-glucoside. However, the two species did not differ consistently in anthocyanin composition.     

Survey of baby bottle rubber nipples for volatile N-nitrosamines

A local market survey of 27 baby bottle rubber nipples for volatile N-nitrosamines was conducted. N-Nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine, and N-nitrosopiperidine were found at levels up to 387 ppb. All 4 nitrosamines migrated from the rubber nipples into water, milk, and infant formula when sterilized together in a manner typical of that used in the home. The source of the nitrosamines is the chemical accelerators and stabilizers added to raw rubber during the vulcanization process.     

New volatile sulfur-containing constituents in a simultaneous distillation-extraction extract of red bell peppers (Capsicum annuum)

An extract of red bell peppers ( Capsicum annuum) was prepared by simultaneous distillation-extraction (SDE, Likens-Nickerson). In addition to the already known (3 E)-3-hepten-2-one ( 1), the unsaturated C9-ketones 1-nonen-4-one ( 2), (2 E)-2-nonen-4-one ( 3), and (2 E,5 E)-2,5-nonadien-4-one ( 4), 2-methoxy-3-isobutylpyrazine ( 5), and heptane-2-thiol ( 6), we identified 19 new thiols (the aliphatic saturated and unsaturated thiols 14- 16, and 22- 27, the mercapto-ketones 12 and 13, the mercapto-alcohols 17, 18, and 30, the dithiols 19 and 28, the methylthio-thiols 20 and 21, and the thiophene-thiol 31) and the two new dithiolanes 10 and 29. All of them are structurally related to the unsaturated C7- and C9-ketones 1- 4. The free thiols were enriched using Affi-Gel 501 ( p-aminophenyl-mercuric acetate grafted on an agarose gel). The new compounds were confirmed by syntheses and were organoleptically evaluated.     

Chemical composition of the volatile extract and antioxidant activities of the volatile and nonvolatile extracts of Egyptian corn silk (Zea mays L.)

A total of 36 compounds, which comprised 99.4% of the extract, were identified by gas chromatography and mass spectrometry (GC-MS) in the volatile dichloromethane extract obtained from Egyptian corn silk. The main constituents of the volatile extract were cis-alpha-terpineol (24.22%), 6,11-oxidoacor-4-ene (18.06%), citronellol (16.18%), trans-pinocamphone (5.86%), eugenol (4.37%), neo-iso-3-thujanol (2.59%), and cis-sabinene hydrate (2.28%). Dried Egyptian corn silk was also directly extracted with petroleum ether, ethanol, and water. All extracts from solvent extraction and the volatile extract described above exhibited clear antioxidant activities at levels of 50-400 microg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH)/linoleic acid assay. The ethanol extract inhibited DPPH activity by 84% at a level of 400 microg/mL. All samples tested via the beta-carotene bleaching assay also exhibited satisfactory antioxidant activity with clear dose responses. This study indicates that corn silk could be used to produce novel natural antioxidants as well as a flavoring agent in various food products.     

Chemical composition of volatile extract and biological activities of volatile and less-volatile extracts of juniper berry (Juniperus drupacea L.) fruit

Volatile chemicals in a dichloromethane extract from a steam distillate of juniper berry fruit (Juniperus drupacea L.) and its two column chromatographic fractions (eluted with hexane and ethyl ether) were analyzed by gas chromatography/mass spectrometry. The major compounds in the dichloromethane extract were alpha-pinene (23.73%), thymol methyl ether (17.32%), and camphor (10.12%). A fraction eluted with hexane contained alpha-pinene (44.24%) as the major constituent. A fraction eluted with ethyl ether had thymol methyl ether (22.27%) and camphor (19.65%) as the main components. Three samples prepared from the distillate and two additional samples prepared by petroleum ether and ethanol extraction directly from juniper berry fruits exhibited clear antioxidant activities with dose response in both 1,2-diphenyl picrylhydrazyl and beta-carotene assays. All samples except the hexane fraction showed comparable activities to that of the synthetic antioxidant t-butyl hydroquinone at a level of 200 microg/mL in the two testing systems. The extracts of dichloromethane, petroleum ether, and ethanol exhibited appreciable antimicrobial activities against six microorganisms with minimum inhibitory concentrations ranging from 0.5 mg/mL (volatile extract against Candida albicans ) to 1.2 mg/mL (ethanol extract against Aspergillus niger ). The results of the present study suggest that this fruit could be a natural antioxidant supplement for foods and beverages.     

Improved method for determination of volatile nitrosamines in baby bottle rubber nipples and pacifiers

A method is described for determining volatile nitrosamines in baby bottle rubber nipples and pacifiers. The method consists of overnight soaking of the sample with dichloromethane in the presence of propyl gallate, an inhibitor for artifactual formation of nitrosamines; extraction with dichloromethane using an ambient temperature column procedure; distillation from aqueous alkali; extraction of the aqueous distillate with dichloromethane and concentration of the extract using a Kuderna-Danish concentrator; and final analysis by gas chromatography with detection by thermal energy analyzer. Major improvements over other published methods include a simpler extraction, a more efficient distillation and concentration to minimize losses, and incorporation of propyl gallate inhibitor as well as of a test to detect unsuitable dichloromethane solvent that otherwise might lead to artifactual formation. The method is highly accurate (approximately 90% recovery) and precise (av. CV = 4.7% at greater than 9 ppb levels) and is applicable to determination of nitrosamines in both rubber- and plastic-based products.     

Characterization of phenolic compounds from lingonberry (Vaccinium vitis-idaea)

Phenolic compounds from the lingonberry (Vaccinium vitis-idaea) were identified using LC-TOFMS, LC-MS/MS, and NMR experiments. The compounds were extracted from the plant material using methanol in an ultrasonicator and further isolated and purified using solid-phase extraction and preparative liquid chromatographic techniques. A total of 28 phenolic compounds were at least tentatively identified, including flavonols, anthocyanidins, catechins and their glycosides, and different caffeoyl and ferulic acid conjugates. This is apparently the first report of coumaroyl-hexose-hydroxyphenol, caffeoyl-hexose-hydroxyphenol, coumaroyl-hexose-hydroxyphenol, quercetin-3-O-alpha-arabinofuranoside, kaempferol-pentoside, and kaempferol-deoxyhexoside in the plant, and the flavonol acylglycosides quercetin-3-O-[4' '-(3-hydroxy-3-methylglutaroyl)]-alpha-rhamnose and kaempferol-3-O-[4' '-(3-hydroxy-3-methylglutaroyl)]-alpha-rhamnose are presented here for the first time ever. In addition, more detailed structure in comparison to earlier reports is described for some compounds previously known to exist in lingonberry.     

Characterization of paprika (Capsicum annuum) extract in orange juices by liquid chromatography of carotenoid profiles.

The carotenoid pigment profiles of authentic pure orange juices from Spain and Florida and an industrial paprika (Capsicum annuum) extract used for food coloring were obtained using reversed-phase liquid chromatography with a C18 packed column and an acetone/methanol/water eluent system. The procedure involving the carotenoid extraction is described. Both retention times and spectral properties using photodiode array detection for characterization of the major carotenoids at 430 and 519 nm are given. The influence of external addition of tangerine juice and/or paprika extract on orange juice color is described using the U.S. Department of Agriculture scale and adulterated orange juice. The procedure for quantitation of externally added paprika extract to orange juice is investigated, and the limit of quantitation, coefficient of variation, and recoveries are determined.     

Characterization of the volatile pattern and antioxidant capacity of essential oils from different species of the genus Ocimum

The antioxidant capacity of essential oils obtained by steam hydrodistillation from five species of the genus Ocimum, namely Ocimum basilicum var. purpurascens, Ocimum basilicum, Ocimum gratissimum, Ocimum micranthum, and Ocimum tenuiflorum (syn. O. sanctum), were evaluated using a high-performance liquid chromatography-based hypoxanthine/xanthine oxidase and the DPPH assays. The yield of oils from the leaves of the five species was variable with the greater amount obtained from Ocimum gratissimum (3.5%) and the least from Ocimum basilicum var. purpurascens (0.5%). In the hypoxanthine/xanthine oxidase assay, strong antioxidant capacity was evident in all the oils but the greater was shown by that obtained from Ocimum tenuiflorum (syn. O. sanctum) (IC50 = 0.46 microL/mL) compared to Ocimum basilicum var. purpurascens (IC50 = 1.84 microL/mL). Antioxidant capacity was positively correlated (r = 0.92, p < 0.05) with a high proportion of compounds possessing a phenolic ring such as eugenol, while a strong negative correlation (r = -0.77, p > 0.1) with other major volatiles was observed. These correlations were confirmed to a large extent in the DPPH assay. The results of a 24 h experiment with Ocimum tenuiflorum (syn. O. sanctum) shows that the antioxidant capacity factor (amount of essential oil obtained x free radical scavenging capacity; mg x %/100) reaches a threshold between 10 and 12.00 h, corresponding to maximum sunlight intensity in Brasil and furthermore exhibits a clear diurnal variation. The data generated with Ocimum species indicates that essential oils obtained from various herbs and spices may have an important role to play in cancer chemoprevention, functional foods, and in the preservation of pharmacologic products.     

Characterization of the key aroma compounds in cooked grey mullet (Mugil cephalus) by application of aroma extract dilution analysis

Aroma and aroma-active compounds of wild grey mullet ( Mugil cephalus ) were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). According to sensory analysis, the aromatic extract obtained by simultaneous distillation and extraction (SDE) was representative of grey mullet odor. A total of 50 aroma compounds were identified and quantified in grey mullet. Aldehydes were qualitatively and quantitatively the most dominant volatiles in grey mullet. Aroma extract dilution analysis (AEDA) was used for the determination of aroma-active compounds of fish sample. A total of 29 aroma-active compounds were detected in aromatic extract of grey mullet, of which 24 were identified. On the basis of the flavor dilution (FD) factor, the most powerful aroma active compounds identified in the extract were (Z)-4-heptenal and nonanal, which were described as the strong cooked fish and green-fruity odor, respectively.     

Characterization of volatile compounds from the reaction of 3-hydroxy-2-butanone and ammonium sulfide model system

The reactions between 3-hydroxy-2-butanone and ammoniun sulfide at 25, 50, 75, 100, 125, and 150 degrees C were studied. Four well-known flavor compounds, 2,4,5-trimethyloxazole, 2,4, 5-trimethyl-3-oxazoline, 2,4,5-trimethylthiazole, and 2,4, 5-trimethyl-3-thiazoline, were identified. Another four interesting intermediate compounds, 2-(1-hydroxyethyl)-2,4, 5-trimethyl-3-oxazoline, 2-(1-mercaptoethyl)-2,4, 5-trimethyl-3-oxazoline, 2-(1-hydroxyethyl)-2,4, 5-trimethyl-3-thiazoline, and 2-(1-mercaptoethyl)-2,4, 5-trimethyl-3-thiazoline, were also identified by GC-EIMS and GC-CIMS. All these intermediate compounds were formed at 25 degrees C. On the other hand, tetramethylpyrazine was the major product with a reaction temperature higher than 100 degrees C.     

Characterization of volatile compounds of Mezcal, an ethnic alcoholic beverage obtained from Agave salmiana

Commercial mezcals (white, white with worm, rested, rested with worm, and aged) produced from Agave salmiana were analyzed by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). Thirty-seven compounds were identified, and nine of them were classified as major compounds of mezcal (MCM). Saturated alcohols, ethyl acetate, ethyl 2-hydroxypropanoate, and acetic acid form the MCM group. Minor compounds of mezcal group include other alcohols, aldehydes, ketones, large chain ethyl esters, organic acids, furans, terpenes, alkenes, and alkynes. Most of the compounds found in mezcals in this study are similar to those present in tequilas and other alcoholic beverages. However, mezcals contain unique compounds such as limonene and pentyl butanoate, which can be used as markers for the authenticity of mezcal produced from A. salmiana.     

Characterization and extract ability of immobilized 15N from the soil microbial biomass

The microbial biomass of a typical Illinois Mollisol (Flanagan silt loam) was labeled with ¹⁵N, and several extradants were tested to determine their effectiveness in separating the immobilized ¹⁵N from the native soil N. From 3 to 5% of the total N and from 7 to 11% of the tracer N were removed by the milder extradants (i.e. hot water, hot 10mM CaCl₂, hot 5mm NaHCO₃, and cold 10mm NaHCO₃). Acidified permanganate (0.1 m KMnO₄ in 2 m H₂SO₄) and anhydrous formic acid were the most intensive extradants tested; they removed from 10 to 13% of the total N and about 14% of the immobilized ¹⁵N. An inverse relationship was observed between the amount of N extracted and selectivity of the extradants for removing the microbial ¹⁵N, indicating that the milder procedures were more selective in extracting the immobilized ¹⁵N.Distinct differences in the chemical distribution of organic N were observed for the immobilized ¹⁵N and native soil N. Lower proportions of the immobilized ¹⁵N were accounted for as acid-insoluble N and ammonia N (NH₃-N); while higher proportions were found in the amino acid and hydrolyzable unknown (HUN) N fractions.     

Characterization of the p-coumaric acid decarboxylase from Lactobacillus plantarum CECT 748(T)

It was previously reported that cell cultures from Lactobacillus plantarum CECT 748 (T) were able to decarboxylate phenolic acids, such as p-coumaric, m-coumaric, caffeic, ferulic, gallic, and protocatechuic acid. The p-coumaric acid decarboxylase (PDC) from this strain has been overexpressed and purified. This PDC differs at its C-terminal end when compared to the previously reported PDC from L. plantarum LPCHL2. Because the C-terminal region of PDC is involved in enzymatic activity, especially in substrate activity, it was decided to biochemically characterize the PDC from L. plantarum CECT 748 (T). Contrarily to L. plantarum LPCHL2 PDC, the recombinant PDC from L. plantarum CECT 748 (T) is a heat-labile enzyme, showing optimal activity at 22 degrees C. This PDC is able to decarboxylate exclusively the hydroxycinnamic acids p-coumaric, caffeic, and ferulic acids. Kinetic analysis showed that the enzyme has a 14-fold higher K(M) value for p-coumaric and caffeic acids than for ferulic acid. PDC catalyzes the formation of the corresponding 4-vinyl derivatives (vinylphenol and vinylguaiacol) from p-coumaric and ferulic acids, respectively, which are valuable food additives that have been approved as flavoring agents. The biochemical characteristics showed by L. plantarum PDC should be taken into account for its potential use in the food-processing industry.     

Characterization of volatile aroma compounds in cooked black rice

Black rice ( Oryza sativa L.), an aromatic specialty rice popular in Asia, has a unique flavor, the volatile chemistry of which has not been reported. The objectives of this research were to study volatile profiles of cooked black rice and to characterize the odor-active compounds. Thirty-five volatile compounds were identified by gas chromatography-mass spectrometry using a dynamic headspace system with Tenax trapping. Aldehydes and aromatics were quantitatively in the greatest abundance, accounting for 80.1% of total relative concentration of volatiles. The concentration of 2-acetyl-1-pyrroline (2-AP) was high, exceeded only by hexanal, nonanal, and 2-pentylfuran. A total of 25 odor-active compounds, determined by gas chromatography-olfactometry, were applied to principal component analysis, demonstrating significant differences between a black and a traditional white rice cultivar in terms of aroma and explaining 93.0% of the total variation. 2-AP, guaiacol, indole, and p-xylene largely influenced the difference between the aroma in cooked black and white rice. 2-AP and guaiacol were major contributors to the unique character of black rice based on odor thresholds, relative concentrations, and olfactometry.     

Pectin methylesterase from kiwi and kaki fruits: purification, characterization, and role of pH in the enzyme regulation and interaction with the kiwi proteinaceous inhibitor

Pectin methylesterase was purified from kiwi (Actinidia chinensis) and kaki fruit (Diospyros kaki). The pH values of the fruit homogenates were 3.5 and 6.2, respectively. The kiwi enzyme is localized in the cell wall and has a neutral-alkaline pI, whereas the kaki enzyme is localized in the soluble fraction and has a neutral-acidic pI. The molecular weights of the kiwi and kaki enzymes were 50 and 37 kDa, respectively. The two enzymes showed a similar salt and pH dependence of activity, and a different pH dependence of the inhibition by the kiwi proteinaceous inhibitor.     

Immunostimulating activity of a crude polysaccharide derived from green tea (Camellia sinensis) extract

Green tea extract is well-known to reduce the risk of a variety of diseases. Here, we investigated the immunostimulating activity of tea polysaccharide (TPS), one of the main components in green tea extract. The water extracts from mature or immature tea leaves were precipitated by using ethanol at room temperature. The sediment was washed with ethanol and acetone alternately and then dried. We used the phagocytic activity of macrophage-like cells as an indicator of immune function activation. Chemical components were analyzed by HPLC. The immunostimulating activity of TPS from immature leaves extract was higher than that of TPS from mature leaves, and its activities were dependent on the content of strictinin in the leaf extract. Futhermore, a mixture of catechin and TPS that removed polyphenols did not increase the immunostimulating activity. These results suggest that the catechin-polysaccharide complex is a very important molecule in the immunomodulating activity of tea extracts.     

Characterization of the key aroma compounds in dried fruits of the West African peppertree Xylopia aethiopica (Dunal) A. Rich (Annonaceae) using aroma extract dilution analysis.

Application of aroma extract dilution analysis on an extract of the dried fruits of the West African peppertree Xylopia aethiopica obtained by extraction with diethyl ether followed by sublimation in vacuo revealed 28 odor-active compounds in the flavor dilution (FD) factor range of 4-8192, all of which could be identified. The highest FD factor was found for linalol (floral), followed by (E)-beta-ocimene (flowery), alpha-farnesene (sweet, flowery), beta-pinene (terpeny), alpha-pinene (pine needle-like), myrtenol (flowery), and beta-phellandrene (terpeny). Vanillin (vanilla-like) and 3-ethylphenol (smoky, phenolic) showing somewhat lower FD factors (FD = 128) were detected for the first time as constituents of the dried fruit.