Chemical and sensory properties of liquid beet sugar.

Sensory analysis and headspace gas chromatography-flame ionization detection (GC-FID) analysis of liquid sugars (sucrose) designated for food-industrial use were performed in order to elucidate which compounds are responsible for perceived off-odors and off-flavors in liquid sugar. The liquid sugar samples investigated had various kinds of off-odors and off-flavors that might influence the quality of any food product in which they might be used, such as a jam or a soft drink. The sensory scores for the different attributes and the levels of different volatile compounds as measured by GC were analyzed for correlation using partial least-squares (PLS) analysis. A link between sensory analysis and GC analysis was thereby established, and compounds critical for the odor and flavor were identified using MS (mass spectrometry). Approximately 10 compounds were found to be correlated with the defined sensory attributes. Among these compounds associated with the sensory attributes were dimethyl disulfide, 2,6-dimethylpyrazine, 4-methoxyphenol, and 2, 5-dimethylfuran.     

Identification of major volatile odor compounds in frankfurters

More than 100 volatile compounds have been identified in the headspace of frankfurter sausages. Most abundant were the terpene hydrocarbons, monoterpene alcohols, phenyl propanoids, and phenols. Separate analyses of solutions of spices and smoke demonstrated that most of the terpenes were derived from the spices, whereas the phenols originated mostly from the smoke ingredients. Many of the compounds contributing to the overall odor of the frankfurters have been identified. Some odors, characteristic of the smokiness and spiciness of frankfurters, were caused by phenols and terpenes, whereas others were due to compounds derived from the meat fraction; these compounds included aldehydes, ketones, furanthiols, and alicyclic sulfur compounds.     

Extractable components of the aerial parts of Salvia lavandulifolia and composition of the liquid smoke flavoring obtained from them.

The fraction extractable with dichloromethane of the aerial parts of sage (Salvia lavandulifolia) and the liquid smoke obtained from this plant are studied by means of gas chromatography/mass spectrometry and gas chromatography. The extract of the aerial parts of the sage plant contains not only terpene, sesquiterpene hydrocarbons, and their oxygenated derivatives, which are interesting compounds both for their organoleptic properties and for their antioxidant activity, but also a large group of phenolic compounds with abietatriene or related structure, the mass spectra of which are given, many of them having antioxidant, antiviral, and antibacterial properties. The liquid sage smoke obtained is slightly acidic and contains common smoke components in specific proportions, and a large group of aromatic nitrogenated derivatives such as pyrazine and pyridine derivatives in small proportions, together with the main oxygenated terpene derivatives present in the plant; some of the compounds detected in this liquid smoke have not been described as smoke components before.     

Olfactometric determination of the most potent odor-active compounds in salmon muscle (Salmo salar) smoked by using four smoke generation techniques

The volatile compounds of salmon fillets smoked according to four smoked generation techniques (smoldering, thermostated plates, friction, and liquid smoke) were investigated. The main odor-active compounds were identified by gas chromatography coupled with olfactometry and mass spectrometry. Only the odorant volatile compounds detected by at least six judges (out of eight) were identified as potent odorants. Phenolic compounds and guaiacol derivatives were the most detected compounds in the olfactometric profile whatever the smoking process and could constitute the smoky odorant skeleton of these products. They were recovered in the aromatic extracts of salmon smoked by smoldering and by friction, which were characterized by 18 and 25 odor-active compounds, respectively. Furannic compounds were more detected in products smoked with thermostated plates characterized by 26 odorants compounds. Finally, the 27 odorants of products treated with liquid smoke were significantly different from the three others techniques applying wood pyrolysis because pyridine derivatives and lipid oxidation products were perceived in the aroma profile.     

Characterization of pyrazines in some Chinese liquors and their approximate concentrations

Pyrazines are very important impact aroma compounds in Chinese liquors. The identification of pyrazine derivatives was carried out by liquid-liquid extraction (LLE). The liquor sample was adjusted to the H(+) concentration of 1 N with 12 N HCl and then concentrated by rotatory evaporator under vacuum condition. The concentrated liquor was extracted by diethyl ether, and the residual aqueous phase was adjusted to pH 10. The basic compounds were detected and identified by gas chromatography (GC)-mass spectrometry (MS). A total of 27 pyrazines were identified in Chinese liquors, mainly alkyl- and acetylpyrazines. A method for determining pyrazines in Chinese liquors was developed. It involves extraction by headspace (HS) solid phase microextraction (SPME) and determination using GC-flame thermionic detector (FTD). The optimum method was that the sample alcohol concentration was diluted to 12% vol by freshly redistilled-deionized water, and the diluted samples were saturated with NaCl and equilibrated at 50 degrees C for 15 min and extracted for 30 min at the same temperature. The developed method enabled detection limits of <200 ng/L. Linearity (R(2) > 0.99) and recovery rate were satisfied in all cases. Pyrazines of 12 commercial typical Chinese liquors were quantified by HS-SPME followed by GC-FTD and had a wide range of concentration.     

Amelioration of odorous components in spent mushroom compost

Volatile sulfur compounds, as well as other volatiles found in the headspace above spent mushroom compost (SMC), were analyzed by gas chromatography and mass spectrometry. Data from these techniques as well as organoleptic evaluation of both the SMC and the chromatographic eluant indicated that the volatile sulfur compounds and cresol were important odorous components in SMC; cresol was reported as a musty, cattle-feces aroma. Samples consisted of headspaces from untreated SMC as well as SMC stirred with 1% (by weight) powered activated carbon (PAC). SMC stirred with and without PAC reduced headspace volatile concentrations, but the stirred with added PAC further decreased concentrations of important malodorants such as volatile sulfur compounds and cresol.     

Volatile flavor components of rice cakes.

Volatiles were obtained from commercially prepared and laboratory-prepared rice cakes using high-flow dynamic headspace isolation with Tenax trapping. Analysis was carried out by capillary GC/MS. More than 60 compounds were identified. Major volatiles included 1-hydroxy-2-propanone, furfuryl alcohol, 2, 5-dimethylpyrazine, 2-methylpyrazine, pyrazine, hexanal, furfural, pentanol, 3-hydroxy-2-butanone (acetoin), and ethyl-3, 6-dimethylpyrazine. Although not ideally applicable to a dry product, concentration/threshold ratios indicated that the compounds with a high probability of contributing to the aroma and flavor included 3-methylbutanal, dimethyl trisulfide, 2-ethyl-3,5-dimethylpyrazine, 4-vinylguaiacol, hexanal, (E,E)-2,4-decadienal, 2-methylbutanal, 2-acetyl-1-pyrroline, 1-octen-3-ol, and 1-octen-3-one.     

Volatile compounds produced from monosodium glutamate in common food cooking

A mixture of soybean oil and/or water, sugar and/or monosodium glutamate (MSG) was water-boiled or oil-heated at 100, 120, 140, 160, or 170 degrees C, respectively, and volatile compounds produced were isolated by solid-phase microextraction and then identified by GC and GC/MS. Oxidative thermal degradation products of fatty acids (OTDPFA) were the major volatile compounds detected for all water-boiled samples. When MSG and sugar were heated together, 2, 5-dimethyl pyrazine and methyl pyrazine were also detected at or after 160 min heating. Water added in soybean oil increased OTDPFA production. In oil-heated samples of soybean oil alone, soybean oil with MSG, and soybean oil with sugar, OTDPFA were also the major compounds found. The samples containing MSG also produced 2-pyrrolidone, and the samples containing sugar also produced furfural and 5-hydroxy methyl furfural. The samples containing soybean oil, sugar, and MSG produced 23 pyrazines, OTDPFA, and gamma-butyrolactone as the major volatile compounds. The contents of OTDPFA were lower in MSG plus sugar and MSG-added samples, and it is postulated that antioxidant activities were produced in cooking.     

Effect of pH and temperature on the formation of volatile compounds in cysteine/reducing sugar/starch mixtures during extrusion cooking

Mixtures of cysteine, reducing sugar (xylose or glucose), and starch were extrusion cooked using feed pH values of 5.5, 6.5, and 7.5 and target die temperatures of 120, 150, and 180 degrees C. Volatile compounds were isolated by headspace trapping onto Tenax and analyzed by gas chromatography--mass spectrometry. Eighty and 38 compounds, respectively, were identified from extrudates prepared using glucose and xylose. Amounts of most compounds increased with temperature and pH. Aliphatic sulfur compounds, thiophenes, pyrazines, and thiazoles were the most abundant chemical classes for the glucose samples, whereas for xylose extrudates highest levels were obtained for non-sulfur-containing furans, thiophenes, sulfur-containing furans, and pyrazines. 2-Furanmethanethiol and 2-methyl-3-furanthiol were present in extrudates prepared using both sugars, but levels were higher in xylose samples. The profiles of reaction products were different from those obtained from aqueous or reduced-moisture systems based on cysteine and either glucose or ribose.     

Volatile constituents of fermented sugar baits and their attraction to lepidopteran species

The volatile compounds emanating from four fermented sugar baits, palm sugar, golden cane syrup, port wine, and molasses, were isolated by headspace sampling and analyzed by gas chromatography-mass spectrometry. Three classes of compounds including esters, alcohols, and aromatic compounds were identified in the headspace of the four fermented sugar baits. There was a high degree of qualitative similarity between the headspace contents of the four fermented sugar baits, although quantitatively they varied considerably. Ethyl acetate, 3-methylbutanol, ethyl hexanoate, 2-phenylethanol, ethyl octanoate, ethyl (E)-4-decenoate, ethyl decanoate, and ethyl dodecanoate were the major compounds identified in the headspace of the four fermented sugar baits. The efficacy of the four fermented sugar baits was investigated in field trapping experiments. Fermented palm sugar and golden cane syrup were superior in attracting significant numbers of moths as compared to port wine and molasses. Fermented molasses was the least attractive among the four baits. Over 90% of the insects caught were noctuids with Graphania mutans and Tmetolophota spp. being the main noctuids captured (over 55%) in the four fermented sugar baits. Male and female G. mutans were equally attracted to the four sugar baits. A number of tortricid species were also trapped.     

Carbohydrate and nitrogenated compounds in liquid smoke flavorings

Commercial smoke flavorings were extracted with dichloromethane and the remaining aqueous phase was evaporated at room temperature; the residues obtained were dissolved in methanol and studied by gas chromatography/mass spectrometry. The composition of these residues was totally different from that of the dichloromethane extracts, constituting a small number of compounds that were also detected in the dichloromethane extract, as well as a large number of compounds not described before as components of either smoke for food smoking or smoke flavorings. Among those compounds not previously described there are some furan, pyran, and phenolic derivatives, as well as some pyridine and carbohydrate derivatives. The main component of these fractions is 1,6-anhydro-beta-D-glucopyranose, or levoglucosan. Likewise, aqueous residues of liquid smoke flavorings, prepared at a laboratory scale from beech, vine shoots, thyme, and sage, were studied in the same way. These contained compounds of the same groups cited above, but showed clear differences. The aqueous residue of beech smoke flavoring was the most similar to that of the commercial smoke flavorings. The aqueous residues of vine shoots, thyme, and sage smoke flavorings contained a lower number of furan, pyran, and carbohydrate derivatives and a higher number of nitrogenated derivatives. Instead of levoglucosan, the main component was an unidentified compound, present in all samples, included in the carbohydrate derivatives group. In the samples studied, the influence of the vegetal source on the composition of the aqueous fraction has been shown. In the future, attention must be paid to the functionality of these smoke components.     

Characterization of aroma compounds in apple cider using solvent-assisted flavor evaporation and headspace solid-phase microextraction

The aroma-active compounds in two apple ciders were identified using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (MS) techniques. The volatile compounds were extracted using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). On the basis of odor intensity, the most important aroma compounds in the two apple cider samples were 2-phenylethanol, butanoic acid, octanoic acid, 2-methylbutanoic acid, 2-phenylethyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, 4-ethylguaiacol, eugenol, and 4-vinylphenol. Sulfur-containing compounds, terpene derivatives, and lactones were also detected in ciders. Although most of the aroma compounds were common in both ciders, the aroma intensities were different. Comparison of extraction techniques showed that the SAFE technique had a higher recovery for acids and hydroxy-containing compounds, whereas the HS-SPME technique had a higher recovery for esters and highly volatile compounds.     

Aroma-active components in fermented bamboo shoots.

Bamboo shoots (Phyllostachys pubescens) were fermented and prepared in a traditional Taiwanese manner. Static and dynamic headspace extractions of volatile compounds were conducted by solid phase microextraction (SPME) and by cryogenic focusing purge and trap, respectively. Volatile analysis was conducted with gas chromatography and mass spectrometry. Gas chromatography-olfactometry (GCO) was conducted utilizing the Osme time-intensity method. Of 70 volatile compounds detected, 29 possessed aroma activity, and the most odor active included p-cresol (barn-like), 2-heptanol (mushroom), acetic acid (vinegar), and 1-octen-3-ol (mushroom). SPME extracted 66 compounds, purge and trap extracted 14 compounds, and 12 compounds were common to both methods. The Osme GCO technique coupled with SPME is an effective tool for the extraction and evaluation of aroma-active headspace volatiles.     

Comparison of different methods: static and dynamic headspace and solid-phase microextraction for the measurement of interactions between milk proteins and flavor compounds with an application to emulsions

Interactions between 10 aroma compounds from different chemical classes and 5 mixtures of milk proteins have been studied using static or dynamic headspace gas chromatography and solid-phase microextraction (SPME). Static headspace analysis allows the quantification of the release of only the most abundant compounds. Dynamic headspace analysis does not allow the discrimination of flavor release from the different protein mixtures, probably due to a displacement of headspace equilibrium. By SPME analysis and quantification by GC-MS (SIM mode) all of the volatiles were quantified. This method was optimized to better discriminate aroma release from the different milk protein mixtures and then from oil/water emulsions made with these proteins. The highest difference between the release in different proteins was observed for ethyl hexanoate, which has a great affinity for beta-lactoglobulin. Ethyl hexanoate is thus less released from models and emulsions containing this protein.     

Model studies on the release of aroma compounds from structured and nonstructured oil systems using proton-transfer reaction mass spectrometry

Relative retention, volatility, and temporal release of volatile compounds taken from aldehyde, ester, and alcohol chemical classes were studied at 70 degrees C in model systems using equilibrium static headspace analysis and real time dynamic headspace analysis. These systems were medium-chain triglycerides (MCT), sunflower oil, and two structured systems, i.e., water-in-oil emulsion and L2 phase (water-in-oil microemulsion). Hydrophilic domains of the emulsion type media retained specifically the hydrophilic compounds and alcohols. Four kinetic parameters characterizing the concentration- and time-dependent releases were extracted from the aroma release curves. Most of the kinetic parameter values were higher in structured systems than in oils particularly when using MCT. The oil nature was found to better control the dynamic release profiles than the system structures. The release parameters were well-related (i) to the volatile hydrophobicity as a function of the oil used and (ii) to the retention data in the specific case of the L2 phase due to a specific release behavior of alcohols.     

Volatile composition of some Brazilian fruits: umbu-caja (Spondias citherea), camu-camu (Myrciaria dubia), Araça-boi (Eugenia stipitata), and Cupuaçu (Theobroma grandiflorum)

Twenty-one volatile compounds were identified for the first time by GC-MS in umbu-caja and in camu-camu, plus 30 volatile compounds were identified in ara?a-boi samples. Terpenic compounds predominated among the volatile compounds in these fruit samples, with the major compounds being identified as cis-beta-ocimene and caryophyllene in the northeastern fruit; alpha-pinene and d-limonene were the most abundant volatile compounds in the headspace of the Amazonian fruit camu-camu. Sesquiterpenes were the most abundant compounds in the ara?a-boi sample, with germacrene D presenting a higher relative percentage. The chemical class of esters predominated in the cupua?u sample. Ethyl butyrate and hexanoate were the major compounds in the headspace of this Amazonian 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.     

不同品种鲜食糯玉米清汁与籽粒中挥发性成分比较

为研究不同品种鲜食糯玉米香气成分之间的差异,本研究对6个品种糯玉米进行了清汁制作和煮制两种熟化生香处理,并采用顶空固相微萃取法结合气相色谱-质谱联用技术(HS-SPME-GC-MS)对其挥发性成分进行测定。结果表明,清汁中检出的挥发性成分数量和总量均高于籽粒:清汁中检出38种挥发性成分,熟粒中检出24种,其中仅在清汁中检出的成分中有7种为吡嗪类化合物;而各品种糯玉米清汁中检测到的挥发性成分总量是籽粒的3.98~10.92倍。主成分分析(PCA)结果显示,前两个主成分可解释清汁样品总方差的72.6%,高于煮制籽粒(60.9%),但两种PCA结果均显示JDN-517、SYN-602与SYN-11的特色值得关注,并与吡嗪以及醛醇类成分含量差异有关。本研究结果为不同品种鲜食糯玉米风味品质评价中的样品处理以及数据分析提供了一定的参考。     

Characterization of the most odor-active volatiles of orange wine made from a Turkish cv. Kozan (Citrus sinensis L. Osbeck)

The aroma-active compounds of cv. Turkish Kozan orange wine were analyzed by sensory and instrumental analyses. Liquid-liquid extraction with dichloromethane was used for extraction of volatile components. According to sensory analysis, the aromatic extract obtained by liquid-liquid extraction was representative of orange wine odor. A total of 63 compounds were identified and quantified in orange wine. The results of the gas chromatography-olfactometry analysis showed that 35 odorous compounds were detected by the panelists. Of these, 28 aroma-active compounds were identified. Alcohols followed by terpenes and esters were the most abundant aroma-active compounds of the orange wine. Among these compounds, ethyl butanoate (fruity sweet), 3-methyl-1-pentanol (roasty), linalool (floral citrusy), gamma-butyrolactone (cheesy burnt sugar), 3-(methylthio)-propanol (boiled potato, rubber), geraniol (floral citrusy), and 2-phenylethanol (floral rose) were the most important contributors to the aroma of the orange wine because they were perceived by all eight panelists.