Bioautography and chemical characterization of antimicrobial compound(s) in commercial water-soluble annatto extracts

Annatto preparations based on extracts of the seed of tropical bush Bixa orellana L consist of carotenoid-type pigments. Previous reports indicate that commercial annatto extracts have biological activities against microorganisms of significance to food fermentation, preservation, and safety. The objective of this study was to separate and identify the compound(s) responsible for the antimicrobial activity of annatto preparations. Commercial water-soluble annatto extracts were screened by thin-layer chromatography and bioautography followed by liquid chromatography/photodiode array/mass spectrometry (LC/PDA/MS) analysis of active fractions. Bioautography revealed two fractions with antimicrobial activity against Staphylococcus aureus. LC/PDA/MS analysis of both fractions revealed 9'-cis-norbixin (UV(max) 460 and 489 nm) and all-trans-norbixin (UV(max) 287, 470, and 494 nm) as the major components. Structure confirmation was achieved by (1)H NMR spectroscopy. Results indicate that 9'-cis-norbixin and all-trans-norbixin are responsible for the antimicrobial properties of annatto.     

Aroma compounds of fresh milk from New Zealand cows fed different diets

Volatile compounds were extracted from fresh milk produced by New Zealand cows using the newly developed solvent-assisted flavor evaporation (SAFE) technique. The two samples that were used came from cows that had been fed on different diets and represented the considerably different flavors of Northern hemisphere and New Zealand milk. Using gas chromatography-olfactometry (GC-O), 71 aroma compounds were found from the milk extracts, 66 of which were identified. Nearly all of the aroma compounds were common to both extracts, despite the two milk samples having quite different flavors. Only one compound, gamma-12:2 lactone, was significantly odor-active for the extract of milk from cows fed a supplement diet, but was not found for the extract of milk from cows fed a pasture diet. Thus, differences in milk flavor are primarily caused by concentration differences of a common set of flavor compounds, rather than by the occurrence of compounds uniquely associated with a particular feed.     

Aroma content of fresh basil (Ocimum basilicum L.) leaves is affected by light reflected from colored mulches

Sweet basil (Ocimum basilicum L.) is an herb that is used to add a distinct aroma and flavor to food. Volatile compounds emitted from fully expanded fresh leaves grown in drip-irrigated plots that were covered with six colors of mulch were compared. The colors reflected a range of photosynthetic photon flux, far-red, red, and blue light from the soil surface to developing leaves. Our objective was to determine whether reflection from the different colors could influence concentrations of volatile compounds emitted from the fresh leaves. Volatile compounds were isolated by headspace sampling and quantified by gas chromatography. Twenty-six compounds were identified, of which the terpenoids linalool and 1,8-cineole comprised more than 50% of the total yield. Concentrations of volatile compounds from leaves that developed over green, blue, yellow, white, and red mulches followed the same patterns as they did for air-dried leaves of the same cultivar. However, the concentration of volatile compounds from fresh leaves was about 50-fold higher than those found in the previous study of air-dried leaves.     

Volatile components of the cyanobacterium Oscillatoria perornata (Skuja).

Volatile compounds were identified from unialgal continuous cultures of the cyanobacterium Oscillatoria perornata. Steam distillates of the unialgal cultures were continuously extracted with pentane, and the pentane extracts were analyzed by GC-MS. Retention indices and mass spectral data were used to identify 15 components. Relative amounts of individual components were expressed as percent peak area relative to total peak area. The main volatile components were heptadecane (57.0%), 2-methylisoborneol (29.4%), and benzaldehyde (1.2%). Together with the previously known 2-methylisoborneol, which is the major cause of the musty off-flavor problem in catfish farming operations in Mississippi, other components identified were dimethyl disulfide (1.0%), dimethyl trisulfide (0.5%), and benzothiazole (0.6%). These compounds and their organoleptic characteristics are discussed in relation to their possible contributions to cultured catfish off-flavor problems.     

Characterization of volatiles in bullock's heart (Annona reticulata L.) fruit cultivars from Cuba

Volatile compounds were isolated from four cultivars of bullock's heart fruit (Cenizo, Rojo, Verde, and De Ojo) by simultaneous steam distillation-solvent extraction. Compounds were identified by HRGC and capillary GC-MS. One hundred and eighty compounds were identified in the aroma extracts, of which alpha-pinene, beta-pinene, myrcene, limonene, terpinen-4-ol, and germacrene D were found to be the major constituents. Fruit from cv. De Ojo containing the highest concentration of total volatile and the highest major terpenoid content had the highest custard-like and overall fruity aroma intensity. The presence of many terpenic compounds is thought to contribute to the unique flavor of the bullock's heart fruit.     

Influence of rearing conditions on the volatile compounds of cooked fillets of Silurus glanis (European catfish)

Volatile compounds of cooked fillets of Silurus glanis reared under two conditions occurring in France were studied. They were extracted by dynamic headspace, identified by gas chromatography/mass spectrometry, and quantified by gas chromatography-flame ionization detection. Odor active volatile compounds were characterized by gas chromatography-olfactometry. Sixty volatile compounds were detected in dynamic headspace extracts, among which 33 were odor active. Rearing conditions affected their estimated concentrations and their odor intensities, but very few qualitative differences were exhibited (only seven volatile compounds were concerned). A good correlation between quantitative and olfactometric results is shown. 2-Methylisoborneol and (E)-2-hexenal were less represented in OUTDOOR extracts, while 2-butanone was less represented in INDOOR extracts. In addition, olfactometric results can be closely related to those previously obtained by sensory analysis. Boiled potato sensory odor of the silurus cooked fillets can be related to (Z)-4-heptenal and methional, and buttery odor can be related to 2,3-butanedione, an unknown compound (RI = 1010), and 2,3-pentadione.     

Volatile components and key odorants of fennel (Foeniculum vulgare Mill.) and thyme (Thymus vulgaris L.) oil extracts obtained by simultaneous distillation-extraction and supercritical fluid extraction

Volatile oil extracts of fennel seeds (Foeniculum vulgare Mill.) and thyme leaves (Thymus vulgaris L.) were obtained by simultaneous distillation-extraction (SDE) and supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). In general, fennel oil extracted by SDE and SFE showed similar compositions, with trans-anethole, estragole, and fenchone as the main components. In contrast, thymol and p-cymene, the most abundant compounds in thyme leaves, showed big differences, with generally higher amounts of monoterpenes obtained by SDE. However, in this case, the differences between the extracts were higher. Key odorants of fennel seeds determined by gas chromatography-olfactometry (GC-O) showed similar patterns when applying SDE and SFE. trans-Anethole (anise, licorice), estragole (anise, licorice, sweet), fenchone (mint, camphor, warm), and 1-octen-3-ol (mushroom) were the most intense odor compounds detected in fennel extracts. Thymol and carvacrol, with oregano, thyme, and spicy notes, were identified as key compounds contributing to the aroma of thyme leaves.     

Ambient ionization-accurate mass spectrometry (AMI-AMS) for the identification of nonvisible set-off in food-contact materials

Set-off is the unintentional transfer of substances used in printing from the external printed surface of food packaging to the inner, food-contact surface. Ambient ionization-accurate mass spectrometry (AMI-AMS) detected and identified compounds from print set-off not visible to the human eye. AMI mass spectra from inner and outer surfaces of printed and nonprinted food packaging were compared to detect and identify nonvisible set-off components. A protocol to identify unknowns was developed using a custom open-source database of printing inks and food-packaging compounds. The protocol matched print-related food-contact surface ions with the molecular formulas of common ions, isotopes, and fragments of compounds from the database. AMI-AMS was able to detect print set-off and identify seven different compounds. Set-off on the packaging samples was confirmed using gas chromatographic-mass spectrometric (GC-MS) analysis of single-sided solvent extracts. N-Ethyl-2(and 4)-methylbenzenesulfonamide, 2,4-diphenyl-4-methyl-1(and 2)-pentene, and 2,4,7,9-tetramethyl-5-decyne-4,7-diol were present on the food-contact layer at concentrations from 0.21 to 2.7 ± 1.6 μg dm?2, corresponding to nearly milligram per kilogram concentrations in the packaged food. Other minor set-off compounds were detected only by AMI-AMS, a fast, simple, and thorough technique to detect and identify set-off in food packaging.     

Odor-active compounds in cooked rice cultivars from Camargue (France) analyzed by GC-O and GC-MS

Volatile compounds of cooked rice from scented (Aychade, Fidji) and nonscented (Ruille) cultivars grown in the Camargue area in France were compared to that of a marketed Asian scented one (Thai) by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). GC-O analyses of the organic extracts resulted in the perception of 40 odorous compounds. Only two compounds, oct-1-en-3-one and 2-acetyl-1-pyrroline, were almost always perceived. Hierarchical cluster analysis showed that most of the difference between rice odors was linked to quantitative differences with only 11 compounds being specific to some of the rice. Sixty compounds were identified and quantified by GC-MS, including a few new odor-active components. Principal component analysis enabled us to differentiate scented cultivars from a nonscented one, and scented rice cultivars from Camargue from a Thai sample. Calculated odor-active values evidenced that the Thai sample odor differed from that of scented Camargue cultivars because of the degradation of lipids and of cinnamic acid compounds.     

Formation of volatile organic products in soils under anaerobiosis—II: Metabolism of amino acids

Volatile organic compounds generated microbiologically under anaerobic conditions from various soils amended with glucose and amino acids were identified by combined gas chromatographymass spectrometry. Volatile compounds were usually found up to 4 weeks and sometimes longer. Acetaldehyde, acetone, methyl ethyl ketone, methyl propyl ketone, diacetyl, ethanol, n- and iso-propanol, n-, 2- and iso-butanol, acetic acid, butyric acid, ethyl acetate, ethyl butyrate, butyl acetate, butyl butyrate, methane thiol, dimethysulfide, dimethyldisulfide and methyl thioacetate were detected at various time intervals. Volatile organic sulfur compounds were evolved from soils amended with glucose and methionine but not with glucose and cysteine. Volatile nitrogen containing organic compounds were not detected with any of the amended soils.     

Partial identification of antifungal compounds from Punica granatum peel extracts

Aqueous extracts of pomegranate peels were assayed in vitro for their antifungal activity against six rot fungi that cause fruit and vegetable decay during storage. The growth rates of Alternaria alternata , Stemphylium botryosum , and Fusarium spp. were significantly inhibited by the extracts. The growth rates were negatively correlated with the levels of total polyphenolic compounds in the extract and particularly with punicalagins, the major ellagitannins in pomegranate peels. Ellagitannins were also found to be the main compounds in the bioactive fractions using bioautograms, and punicalagins were identified as the main bioactive compounds using chromatographic separation. These results suggest that ellagitannins, and more specifically punicalagins, which are the dominant compounds in pomegranate peels, may be used as a control agent of storage diseases and to reduce the use of synthetic fungicides.     

Induction of enzyme activity in cell culture: a rapid screen for detection of planar polychlorinated organic compounds.

Induction of aryl hydrocarbon hydroxylase (AHH) activity in rat hepatoma cell line serves as a simple and rapid method to detect minute (pg) amounts of certain classes of compounds, e.g., dibenzo-p-dioxins, dibenzofurans, and biphenyls. This method may provide a quick screen for such substances in extracts from foods prior to chemical identification. AHH activity is measured by conversion of benzo[a]pyrene (BP) to 3-hydroxy BP in homogenized cell extracts from control and treated cultures and is reported as pmol product formed/mg protein/min. Substances screened by this method include polyhalogenated analogs of dibenzo-p-dioxin (24 compounds), dibenzofuran (11 compounds), biphenyl (7 compounds), and extracts from several food sources. Response of the most reactive compound, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was used to prepare a standard curve, and the AHH activity induced by mole doses of test substance is reported as an ED50 response (the estimated dose needed to produce 50% maximum enzyme induction). The AHH activity induced by food extracts is equated to the standard curve and reported as TCDD equivalents. A potent ED50 response in cell culture appears to correlate well with known toxic responses in other mammalian and avian systems for certain test substances. This correlation suggests that the cell culture enzyme induction method is a useful model for screening food extracts that are suspected to be contaminated with polychlorinated planar substances. A collaborative study would demonstrate the reproducibility of the method.     

Volatile constituents of Chinese chive (Allium tuberosum Rottl. ex Sprengel) and rakkyo (Allium chinense G. Don)

Volatile components were isolated from Chinese chive and rakkyo by simultaneous steam distillation-solvent extraction and analyzed by GC and GC-MS. Sulfur compounds account for 88 and 94% of the total volatiles in the isolated extract of Chinese chive and rakkyo, respectively. In addition to the sulfur compounds commonly reported in the genus Allium, 27 novel volatile sulfur-containing components were found in the isolated extracts of both species. Among them were a sulfide, disulfides, trisulfides, and tetrasulfides with ethyl, butyl, and pentyl groups.     

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.     

Development of a biocatalytic process for the production of c6-aldehydes from vegetable oils by soybean lipoxygenase and recombinant hydroperoxide lyase

Volatile C6- and C9-aldehydes and alcohols are widely used as food flavors to reconstitute the "fresh green" odor of fruits and vegetables lost during processing. To meet the high demand for natural flavors, an efficient, cheap, and versatile biocatalytic process was developed to produce C6-aldehydes on a large scale. Vegetable oils were converted by soybean lipoxygenase and recombinant hydroperoxide lyase into hexanal and (2E)- or (3Z)-hexenal. In contrast to plant extracts, generally used as enzyme sources, high molar conversions were obtained with recombinant hydroperoxide lyase (50% for hexanal and 26% for hexenal formation), and no side products were formed. Furthermore, recombinant hydroperoxide lyase lacks isomerase activity, allowing production of (3Z)-hexenal, which could not be obtained in previously described processes. Recombinant hydroperoxide lyase is stable and can be stored at 4 degrees C for 1 month without significant loss of activity.     

Effects of water content on volatile generation and peptide degradation in the maillard reaction of glycine, diglycine, and triglycine

Peptides abundant in food and protein hydrolysates are known to be important to process flavors. The present study reports the volatile profile of the Maillard reactions of glycine, diglycine, and triglycine. The reaction with glucose was conducted at 0-100% water content in glycerol medium at 160 degrees C for 1 h. Volatile compounds were quantified by stir bar sorptive extraction-gas chromatography-mass spectrometry, and nonvolatile compounds were quantified by high-performance liquid chromatography-tandem mass spectrometry. The major volatiles produced from each of the reaction systems were trimethylpyrazine and 2,5-dimethylpyrazine. Volatile generation increased as water decreased, and the overall reactivity of the glycine and glycine peptides in volatile formation was glycine approximately triglycine > diglycine. Triglycine was very unstable and mainly degraded into cyclic Gly-Gly and glycine, whereas diglycine had a higher stability than triglycine toward hydrolytic cleavage of the peptide bond. The amounts of glycine, diglycine, cyclic (Gly-Gly), and triglycine in the peptide-glucose reaction mixtures at different water content were reported.     

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.     

Phenolic compound profiles and antioxidant capacity of Persea americana Mill. peels and seeds of two varieties

Avocado processing by the food and cosmetic industries yields a considerable amount of phenolic-rich byproduct such as peels and seeds. Utilization of these byproducts would be favorable from an economic point of view. Methanolic (80%) extracts obtained from lyophilized ground peels and seeds of avocado (Persea americana Mill.) of the Hass and Shepard varieties were characterized for their phenolic compound profiles using the HPLC-PAD technique. The structures of the identified compounds were subsequently unambiguously confirmed by ESI-MS. Compositional analysis revealed that the extracts contained four polyphenolic classes: flavanol monomers, proanthocyanidins, hydroxycinnamic acids, and flavonol glycosides. The presence of 3-O-caffeoylquinic acid, 3-O-p-coumaroylquinic acid, and procyanidin A trimers was identified in seeds of both varieties. Intervarietal differences were apparent in the phenolic compound profiles of peels. Peels of the Shepard variety were devoid of (+)-catechin and procyanidin dimers, which were present in the peels of the Hass variety. Peels of both varieties contained 5-O-caffeoylquinic acid and quercetin derivatives. The differences in the phenolic profiles between varietals were also apparent in the different antioxidant activity of the extracts. The peel extracts had a higher total phenolic compound content and antioxidant activity when compared to the seed extracts. The highest TEAC and ORAC values were apparent in peels of the Haas variety in which they amounted to 0.16 and 0.47 mmol Trolox/g DW, respectively. No significant (p > 0.05) differences were apparent between the TEAC values of seeds of the two varieties but the ORAC values differed significantly (p < 0.05). Overall these findings indicate that both the seeds and peel of avocado can be utilized as a functional food ingredient or as an antioxidant additive.     

Variation of chemical composition of the lipophilic extracts from yellow birch (Betula alleghaniensis) foliage

The occurrence of biologically active compounds identified for the first time in the lipophilic extracts of yellow birch (Betula alleghaniensis Britt.) foliage led to the quantification of the seasonal variation of their concentrations. Yellow birch foliage was collected from late June until late September 2003 in two different regions of Quebec. The extraction yields using hexane as a solvent were determined, and the extracts were analyzed by GC-MS to identify their molecular composition. In terms of both extraction yields and the concentration of the targeted molecules present in the extracts, mid-September has been determined as the best time to collect foliage samples. A total of 14 constituents were identified in these extracts. This is the first report of the presence of all of these constituents in yellow birch foliage and of some of them in the genus Betula. The most important compounds identified in yellow birch foliage extracts are triterpene squalene and aliphatic hydrocarbon tetracosan, aliphatic alcohol phytol, fatty acids hexadecanoic and octadecanoic, pentacyclic triterpenes alpha- and beta-amyrin, and phytosterol stigmast-5-en-3-ol.