RESUMO
The aim of this study was to evaluate the biosynthesis of flavor compounds from rice bran by fermentation facilitated by Kluyveromyces marxianus and Debaryomyces hansenii. The growth of both yeasts was assessed by specific growth rates and doubling time. The biosynthesis of flavor compounds was evaluated by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and Spectrum™ sensory analysis. The specific growth rate (µ) and doubling time (td) of K. marxianus was calculated as 0.16/h and 4.21h, respectively, whereas that of D. hansenii was determined as 0.13/h and 5.33h, respectively. K. marxianus and D. hansenii produced significant levels of higher alcohols and acetate esters from rice bran. Results showed that K. marxianus can produce 827.27 µg/kg of isoamyl alcohol, 169.77 µg/kg of phenyl ethyl alcohol, and 216.08 µg/kg of phenyl ethyl acetate after 24-h batch fermentation. A significant amount of isovaleric acid was also synthesized by K. marxianus (4013 µg/kg) after the batch fermentation of 96 h. 415.64 µg/kg of isoamyl alcohol and 135.77 µg/kg of phenyl ethyl acetate was determined in rice bran fermented by D. hansenii after 24-h fermentation. Fermented cereals and rose were the characteristic flavor descriptors of the fermented rice bran samples. Rose flavor in fermented rice bran samples was found to be associated with phenyl ethyl alcohol, phenyl ethyl acetate, isoamyl acetate, and guaiacol. Thus, the findings of this study demonstrate that the valorization of rice bran can be achieved with the production of natural flavor compounds by yeast metabolism.
Assuntos
Debaryomyces , Kluyveromyces , Oryza , Etanol/metabolismo , Fermentação , Cromatografia Gasosa-Espectrometria de Massas , Kluyveromyces/metabolismo , Oryza/metabolismo , Leveduras/metabolismoRESUMO
The human nose has been used as a detector in gas chromatography analysis to evaluate odoriferous compounds related to aroma and quality of wine. Several olfactometric techniques are available to access the description, intensity, and/or duration of the odor of each compound. Olfactometry can be associated with one-dimensional gas chromatography or multidimensional gas chromatography, including heart-cut gas chromatography and comprehensive two-dimensional gas chromatography. Multidimensional gas chromatography may help to resolve coeluted compounds and detect important trace components for the aroma. The identification of odor-active compounds may help to differentiate wines according to terroir, grapes cultivars used in winemaking or types of aging, understand the role of fungal infection of grapes for wine quality, find the best management practices in vineyard and vinification to obtain the greatest quality. In addition, when the instrumental techniques are combined with sensory analysis, even more accurate information may be obtained regarding the overall wine aroma. This review discloses the state of the art of olfactometric methods and the analytical techniques used to investigate odor-active compounds such as one-dimensional gas chromatography, multidimensional gas chromatography, and comprehensive two-dimensional gas chromatography. The advances in knowledge of wine aroma achieved with the use of these techniques in the target and profiling approaches were also discussed.
Assuntos
Odorantes/análise , Olfatometria , Vinho/análise , Cromatografia Gasosa , HumanosRESUMO
This study describes the GC-FID, GC/MS, GC-O, and enantioselective GC analysis of the essential oil hydrodistilled from leaves of Lepechinica mutica (Lamiaceae), collected in Ecuador. GC-FID and GC/MS analyses allowed the characterization and quantification of 79 components, representing 97.3% of the total sample. Sesquiterpene hydrocarbons (38.50%) and monoterpene hydrocarbons (30.59%) were found to be the most abundant volatiles, while oxygenated sesquiterpenes (16.20%) and oxygenated monoterpenes (2.10%) were the minor components. In order to better characterize the oil aroma, the most important odorants, from the sensorial point of view, were identified by Aroma Extract Dilution Analysis (AEDA) GC-O. They were α-Pinene, ß-Phellandrene, and Dauca-5,8-diene, exhibiting the characteristic woody, herbaceus, and earthy odors, respectively. Enantioselective GC analysis of L. mutica essential oil revealed the presence of twelve couples and two enantiomerically pure chiral monoterpenoids. Their enantiomeric excesses were from a few percent units to 100%. Moreover, the essential oil exhibited moderate in vitro activity against five fungal strains, being especially effective against M. canis, which is a severe zoophilic dermatophyte causal agent of pet and human infections.
Assuntos
Antifúngicos/química , Lamiaceae/química , Antifúngicos/análise , Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Cromatografia Gasosa , Equador , Cromatografia Gasosa-Espectrometria de Massas , Lamiaceae/metabolismo , Microsporum/efeitos dos fármacos , Óleos Voláteis/análise , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Estações do Ano , Estereoisomerismo , Trichophyton/efeitos dos fármacosRESUMO
The aroma of strawberry and lemon guava fruits (Psidium cattleianum Sabine) was studied by sensory analysis, gas chromatography-olfactometry (GC-O) and quantitative analysis. Volatiles released from the pulps were collected in a trapping system consisting of LiChrolut EN resins and eluted with dichloromethane/methanol. In total, 23 odour zones were detected by GC-O, of which 16 were found in the extract from the strawberry guava pulp and 17 in the extract from the lemon guava pulp. Among the compounds identified, only 10 were common to both strawberry and lemon guavas. The descriptive sensorial analysis differentiated between the aroma profiles of the strawberry guava pulp with the descriptor "tomato" and the lemon guava pulp with the descriptor "tropical fruit". The typical aroma of the guava fruits was dominated by the presence of numerous aldehydes and ketones among which (Z)-3-hexenal was the most intense odorant, while 1,8-cineole and linalool were also revealed as important aroma constituents.
Assuntos
Aromatizantes/química , Fragaria/química , Odorantes/análise , Psidium/química , Adulto , Feminino , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Masculino , Olfato , Adulto JovemRESUMO
BACKGROUND: Fragaria chiloensis (L.) Mill spp. chiloensis form chiloensis, is a strawberry that produces white fruits with unique aromas. This species, endemic to Chile, is one of the progenitors of Fragaria x ananassa Duch. In order to identify the volatile compounds that might be responsible for aroma, these were extracted, and analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O) and compared with sensory analyses. RESULTS: Three methods of extraction were used: solvent-assisted evaporation (SAFE), headspace solid phase micro-extraction (HS-SPME) and liquid-liquid extraction (LLE). Ninety-nine volatile compounds were identified by GC-MS, of which 75 showed odor activity using GC-O. Based on the highest dilution factor (FD = 1000) and GC-O intensity ≥2, we determined 20 major compounds in white strawberry fruit that contribute to its aroma. We chose 51 compounds to be tested against their commercial standards. The identities were confirmed by comparison of their linear retention indices against the commercial standards. The aroma of white strawberry fruits was reconstituted with a synthetic mixture of most of these compounds. CONCLUSION: The volatile profile of white strawberry fruit described as fruity, green-fresh, floral, caramel, sweet, nutty and woody will be a useful reference for future strawberry breeding programs.
Assuntos
Produtos Agrícolas/química , Fragaria/química , Frutas/química , Modelos Biológicos , Odorantes , Percepção Olfatória , Compostos Orgânicos Voláteis/metabolismo , Encéfalo/metabolismo , Chile , Produtos Agrícolas/metabolismo , Feminino , Fragaria/metabolismo , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Extração Líquido-Líquido , Mucosa Nasal/inervação , Mucosa Nasal/metabolismo , Concentração Osmolar , Pigmentos Biológicos/biossíntese , Sensação , Células Receptoras Sensoriais/metabolismo , Olfato , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/análiseRESUMO
BACKGROUND: Solid phase microextraction and simultaneous distillation-extraction combined with GC-FID, GC/MS, aroma extract dilution analysis and odour activity values were used to analyse volatile compounds from guava (Psidium guajava L. cv. Red Suprema) and to estimate the most odour-active compounds. RESULTS: The analysis led to the detection of 141 compounds, 121 of which were positively identified. The composition of guava fruit volatiles included 43 esters, 37 terpenes, 18 aldehydes, 16 alcohols, ten acids, six ketones, four furans and seven miscellaneous compounds. CONCLUSION: Seventeen odorants were considered as odour-active compounds, with (E)-ß-ionone, ethyl hexanoate, ethyl butanoate, hexanal, (Z)-3-hexenal, hexyl acetate, (E)-2-hexenal and limonene contributing most to the typical guava aroma of this cultivar.