RESUMO
In northern Mexico, the distilled spirit sotol with a denomination of origin is made from species of Dasylirion. The configuration of the volatile metabolites produced during the spontaneous fermentation of Dasylirion sp. must is insufficiently understood. In this study, the aim was to investigate the composition of the microbial consortia, describe the variation of volatile metabolites, and relate such profiles with their particular flavor attributes during the fermentation of sotol (Dasylirion sp.) must. Ascomycota was the phylum of most strains identified with 75% of total abundance. The genus of fermenting yeasts constituted of 101 Pichia strains and 13 Saccharomyces strains. A total of 57 volatile metabolites were identified and grouped into ten classes. The first stage of fermentation was composed of diesel, green, fruity, and cheesy attributes due to butyl 2-methylpropanoate, octan-1-ol, ethyl octanoate, and butanal, respectively, followed by a variation to pungent and sweet descriptors due to 3-methylbutan-1-ol and butyl 2-methylpropanoate. The final stage was described by floral, ethereal-winey, and vinegar attributes related to ethyl ethanimidate, 2-methylpropan-1-ol, and 2-hydroxyacetic acid. Our results improve the knowledge of the variations of volatile metabolites during the fermentation of sotol must and their contribution to its distinctive flavor.
Assuntos
Bebidas Alcoólicas , Asparagaceae/metabolismo , Fermentação , Aromatizantes/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Bebidas Alcoólicas/análise , Asparagaceae/química , Aromatizantes/análise , México , Pichia/metabolismo , Saccharomyces cerevisiae/metabolismo , Paladar , Compostos Orgânicos Voláteis/análiseRESUMO
Mezcal, a traditional beverage that originated in Mexico, is produced from species of the Agavaceae family. The esters associated with the yeasts utilized during fermentation are important for improving the organoleptic properties of the beverage. We improved the ester contents in a mezcal beverage by using the yeast Kluyveromyces marxianus, which was engineered with the ATF1 gene. ATF1 expression in the recombinant yeast significantly increased compared with that in the parental yeast, but its fermentative parameters were unchanged. Volatile-organic-compound-content analysis showed that esters had significantly increased in the mezcal produced with the engineered yeast. In a sensory-panel test, 48% of the panelists preferred the mezcal produced from the engineered yeast, 30% preferred the mezcal produced from the wild type, and 15 and 7% preferred the two mezcal types produced following the routine procedure. Correlation analysis showed that the fruitiness/sweetness description of the mezcal produced using the ATF1-engineered K. marxianus yeast correlated with the content of the esters, whose presence improved the organoleptic properties of the craft mezcal beverage.
Assuntos
Bebidas Alcoólicas/análise , Asparagaceae/química , Ácidos Graxos/análise , Kluyveromyces/genética , Proteínas/genética , Sensação , Comportamento do Consumidor , Ésteres/análise , Fermentação , Expressão Gênica , Humanos , Kluyveromyces/metabolismo , México , Microrganismos Geneticamente Modificados/genética , Proteínas/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismoRESUMO
Crassulacean acid metabolism plants have some morphological features, such as succulent and reduced leaves, thick cuticles, and sunken stomata that help them prevent excessive water loss and irradiation. As molecular constituents of these morphological adaptations to xeric environments, succulent plants produce a set of specific compounds such as complex polysaccharides, pigments, waxes, and terpenoids, to name a few, in addition to uncharacterized proteases. Since all these compounds interfere with the analysis of proteins by electrophoretic techniques, preparation of high quality samples from these sources represents a real challenge. The absence of adequate protocols for protein extraction has restrained the study of this class of plants at the molecular level. Here, we present a rapid and reliable protocol that could be accomplished in 1 h and applied to a broad range of plants with reproducible results. We were able to obtain well-resolved SDS/PAGE protein patterns in extracts from different members of the subfamilies Agavoideae (Agave, Yucca, Manfreda, and Furcraea), Nolinoideae (Dasylirion and Beucarnea), and the Cactaceae family. This method is based on the differential solubility of contaminants and proteins in the presence of acetone and pH-altered solutions. We speculate about the role of saponins and high molecular weight carbohydrates to produce electrophoretic-compatible samples. A modification of the basic protocol allowed the analysis of samples by bidimensional electrophoresis (2DE) for proteomic analysis. Furostanol glycoside 26-O-ß-glucosidase (an enzyme involved in steroid saponin synthesis) was successfully identified by mass spectrometry analysis and de novo sequencing of a 2DE spot from an Agave attenuata sample.
Assuntos
Extração Líquido-Líquido/métodos , Folhas de Planta/química , Proteínas de Plantas/isolamento & purificação , Proteômica/métodos , beta-Glucosidase/isolamento & purificação , Acetona/química , Agave/química , Asparagaceae/química , Cactaceae/química , Eletroforese em Gel Bidimensional , Espectrometria de Massas , Solventes/química , Yucca/químicaRESUMO
Four new steroidal saponins (1-4) along with 13 known saponins were isolated from the leaves of Furcraea hexapetala. The new compounds were identified as (20R,22R,25R)-3ß-hydroxy-5α-spirostan-12-one 3-O-{α-l-rhamnopyranosyl-(1â4)-O-ß-d-glucopyranosyl-(1â3)-O-[ß-d-glucopyranosyl-(1â3)-O-ß-d-glucopyranosyl-(1â2)]-O-ß-d-glucopyranosyl-(1â4)-O-ß-d-galactopyranoside} (1), (25R)-3ß-hydroxy-5α-spirost-20(21)-en-12-one 3-O-{α-l-rhamnopyranosyl-(1â4)-O-ß-d-glucopyranosyl-(1â3)-O-[ß-d-glucopyranosyl-(1â3)-O-ß-d-glucopyranosyl-(1â2)]-O-ß-d-glucopyranosyl-(1â4)-O-ß-d-galactopyranoside} (2), (25R)-5α-spirostan-3ß-ol 3-O-{ß-d-glucopyranosyl-(1â2)-O-ß-d-glucopyranosyl-(1â2)-O-ß-d-glucopyranosyl-(1â4)-O-ß-d-galactopyranoside} (3), and (25R)-5ß-spirostan-3ß-ol 3-O-{ß-d-glucopyranosyl-(1â6)-O-ß-d-galactopyranoside} (4) by spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry, and chemical methods. The phytotoxicity of the isolated compounds against the standard target species Lactuca sativa was evaluated. Structure-activity relationships for these compounds with respect to phytotoxic effects are discussed.
Assuntos
Alcaloides/isolamento & purificação , Alcaloides/farmacologia , Asparagaceae/química , Fitosteróis/isolamento & purificação , Fitosteróis/farmacologia , Folhas de Planta/química , Saponinas/isolamento & purificação , Saponinas/farmacologia , Alcaloides/química , Cuba , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Fitosteróis/química , Saponinas/química , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The roots of the South American vine Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae) are used in traditional medicine by several Amerindian groups of the Paraguayan Chaco. Little is known on the chemistry of the plant, despite its widespread use across the South American Chaco. From the ethyl acetate/methanol 1:1 extract of the roots, four new and one known homoisoflavanoid, two flavan derivatives, a stilbene, a new alkaloid, and three new and four known spirostane steroids were isolated. The corresponding structures were elucidated by spectroscopic and spectrometric means. The homoisoflavonoids of the plant are related to compounds isolated from the Dracaenaceae (formerly Agavaceae) sources of the Chinese crude drug Dragon's Blood. The new alkaloid is a novel skeleton that can be used as a chemical marker of Herreria. The spirostane steroids suggest chemotaxonomic relations with the Liliales. This is the first comprehensive report on the chemistry of a South American Herreria species.
Assuntos
Alcaloides/química , Asparagaceae/química , Raízes de Plantas/química , Esteroides/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Extratos Vegetais/químicaRESUMO
The water-accumulating leaves of crassulacean acid metabolism plants belonging to five different families were investigated for the presence of biominerals by infrared spectroscopic and microscopic analyses. Spectroscopic results revealed that the mineral present in succulent species of Agavaceae, Aizoaceae, and Asphodelaceae was calcium oxalate monohydrate (whewellite, CaC2O4 x H2O). Crystals were predominantly found as raphides or solitary crystals of various morphologies. However, representative Crassulaceae members and a succulent species of Asteraceae did not show the presence of biominerals. Overall, these results suggest no correlation between calcium oxalate generation and crassulacean acid metabolism in succulent plants.